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GM862-PCS Hardware User Guide

1. GND ___ GND NOISE FILTERING 50804 0 a LGY6502 0600 1 L806 SINGLE ENDED ge H LQG18HN39NJOO EXTERNAL EAR 39nH S N LQG18 LGY650X 812 814 39pF inF a m 0603 0603 _ GND G L INTERNAL EAR AMPLIFIER 6dB o 5 La e t 5 95459 E a N 004 3D 006 10E gt 52 en oF its DER m SEITE 2 EAR MT 004 3D 006 10D MUTE PL803 005 5B 008 10D 009 11C 1215061 03F 7 F 771 MUTE CONTROLLED l ND 3 _1 ALWAYS ON POWER CONTROL c cu e iae ex ieu eee LOW VOLTAGE EXTERNAL EAR AMPLIFIER 12dB Y5V ev 0603 C827 100nF EAR 004 3D 009 11B 811 R804 C828 100nF ev 0603 ie 004 3D 009 11C MUTE PL804 005 5B 008 10B 009 11C 1215061 03F 2 77 MUTE CONTROLLED 3 711 ALWAYS DATE 2214 RUE DESCRIPTION PATH home users area Mobile Terminals S p A E PROJECT Deperini F EL INTERNAL EAR HANDSET EXTERNAL EAR SHEETN OFSHEETS DRAWING CODE Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 55 of 63 TORINESE
2. E a Ecce rcu Ecce EE poe m CY Le Q i END O 1 Lo c W 200 9 O 1 S y ed 5 5 5 55 LE 5 as gt 8 E Lok xm y PES I 1 l1 5 wi 212000000000 poesi e L L O 6 E ac duce 5 3 Ee dO N ea d 1 Se 21k O Lo NE Bs E 2 2 lt T d P m 8 d I s tai seno x L 4 9 E Am nad S elal ol O 4 4 E MEME d I 3 E 1 2 3 a gt 1 5 5 DX e A L L quU 81 OO IA AS Elz 1 1 090 J 510 oc eL N T s 6 LU T i lt 15 01 i v06H 5 Iz RE 2 c 52 qo spp L lt PHPT CPP E gt lt Grm D 5
3. HEYNE DN OFF B BLK B DAT 9 1 m eu m MUT m 0406 CO ET ur P a i 1 pee T 2403 j Ri05r fa ati 5 awe pe 3 0 m 5 VOZ M TM CAM CAM wt s a Riig EET nana nana pe NM 2 58 Sa DR cue EE oc 28 C104 nnMnunt YES LE pk 1 205 vanP nuMgunt TESB 1 1 1 LF39B89IBP 2 E BAT Cio5 C101 c c C102 SAL 04m onge Pia oma a m 04D an POW 1 um VUZ MAIM CAM H Philips 74L VC1G08GW fu EU m g 1 noMaunt ES d u1903 Philips 74LVC4G08 BW a LODK EX Cig inr m WCDEZIBTEAH OTi DT3 oT OT 4 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved 82 2 ay MT Zn 1 n 1 n aKnvABEO 0 ON OFF t 1 E L Y MB7B H DL 101 R114 5 S YAEL Pola m jm m m Tn mmm l l l 1 HIC HIC HIC page 60
4. o m Q 2 x Temperature sensor VT 0502 1215461 Che Ar 25 0102 4 ua NtCenabed C S NOW ee OR JUR ot wr 1 1 NTC disabled 3 Pu WARNING gul m dis R111 ER For a proper battery temperature 2 sensing the Termistor should be 5 FO placed on the battery pack m gt Fa ee c P WARNING When the temperature sensing is disabled the charger must be powered ONLY if the battery temperature is within the charging OT101 range 0 50 C Otherwise the battery may explode R108 il 0 1 5 LR32 OT102 R109 10K 5 0603 C102 47nF X7R 50V 0603 C103 220pF X7R 50V 0603 2503875 25 102 H101 i 10K 596 0603 C105 1uF 35V CONT A OT103 SMB U34 STPS340U D107 Li lon battery charger max current 1A PATH home users area FILE NAME cs944b cir Mod 067 0 03 01 PROJECT Deperini VERIFIED Locatelli M OT104 WARNING Max current limit must be properly set for the size of battery in use Keep max current around 1 2 of battery pack capacity Current Limiting Circuit current limit 500 mA D106 STPS140Z 00123 GN GND ANNOTATION C gt
5. MN I 1 E E a ELS gt 19 Bi uuo NW 0 5 2 2 m P 2 5 T co 1 BE NaaadiguoJ3 BE AYNSOTOSIG ANY NOILOndoudau ANOIZVDINAIC 3 BE qdAuasau SIHOlH TIY LLVAH3SIB LLLIBIQ A QP page 56 of 63 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved 0T102 6994 4B LC 01504 PL5 03 Lo L3 R504 0504 1 8509 18507 PL5 1 01505 PL502 C3 R505 9507 6506 8508 PL901 e 0 69127 oH ego 0 gt 190 gt C910 ipi E R903 C R804 U202 01502 8502 9502 508 a 01501 LC R501 9501 01503 226501 C 28503 9503 RELO PL5Q6 PL804 8780 0 LS C8 7L 5813 0824 50803 C7 C815 1804 cain R204 PL507 PL504 50202 C216 C823 50804 D2202 59502 50501 2814 06812 9516 PL201 Q
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7. i 5 IK R113 GPIOT 1 NOTE To correctly drive a buzzer a driver must be provided characteristics depend on the Buzzer and for them refer to your buzzer vendor Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 42 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 8 Camera This section applies only to Telit GM862 PCS module 8 1 Camera characteristics The GM862 PCS provides a direct support for digital cameras with the following characteristics AGILENT ADCM2650 or compatibles Technology CMOS COLOR camera JPEG 2 Camera interface connectors The interface connection between GM862 PCS and camera is provided by the 50 pins Molex connector of the module and a 18 pins ZIF connector vertical type for the CMOS camera Molex 52991 0508 male ZIF 21181 0 Pin Signal uo 21 SYNC I End of frame 1s an output for the 16 EOF camera and an input for the GM862 PCS 25 MONI The module clock 1 provided by the 17 MCLK MONI CAM output of the GM862 PCS IICSCL CAM IlCbus serial clock 5 DATA 0 sppe popom fo 40 PD 3 I O Parallel Data 3 12 DATA3 o paras 10 sme fo forbidden without DAI Telecom written
8. dept pte pier oie e eee opem 1 z L Ion battery charger 114 8142 LIIS mE a EDI A mn S lix E Box Rias Ring EDEN t 1 1 osos E 0503 joo amp 0603 Ser 13 x sx 35v IL R32 CONI 47nF GNU XTR gt e 0503 50101 FOMMOEO2 BATTERY LI ION 1 o 2 3 7V La Ian Nominal D406 ri a 5 51407 77 max voltage 4 2V Li Ion suggested capacity 1000mAn 1 i 0 i 5x 2603 GND 1 nF 1 10k NTC lo 0603 Temperature sensor 1 FFT PL cin i 124 0102 4 i 1 1 1 1 NOTE In this particular application the battery charger input current must be limited to less than 1 J This can be done by using a current limited wall adapter as the power source For your convenience in the EVK there s also a current unlimited input where the input source is not limited in current and the drawn current is limited to about 0 5A by a MOSFET in the EVK 3 2 2Thermal Design Guidelines The thermal design for the power supply heat sink should be done with the following specifications e Average current consumption during transmission PWR level max rms 350 e Average current consumption during transmission PWR level min rms 100 Average current during Power S
9. 3 nc 060 0603 0603 0603 0603 50704 sali Ox GND GND GND GND GND 22 gt 5 5 EXT MIC caus OS 5 DEAD SINGLE ENDED MICROPHONE POLARIZATION DESETA 1 1615061 08F 3 EXT SINGLE 1 BADANGED R704 ik SINGLE ENDED MICROPHONE BUFFER 10 dB 771 BALANCED qo d 21 15 43V EXT MIC SINGLE Quei xe 3 5 3V_ 3 NC SINGLE ENDED 59701 P E C Ce47BW 2S SOT 323 A m C701 1 SINGLE ENDED 1 E av 02 CONT R EXT SELECTION R701 NOISE FILTERING DECOUPLING CAPACITORS E S22 SELECTIO 7 E 4 L LOGI NONIO Sz S 0702 _ LGK2009 0201 C704 C706 2 gt 00430 39pF c SINGLE ENDED 7 oG EXTERNAL 50v 50v SINGLE EZ 0603 0603 0701 LGK2009 02 TS3V912ID E o gt 43V EXTLMIC SINGLE Ms LLI GND GND 2 O N ae a IRE ER _ m lt N 5 5 tc Sa SO703 TE pou 101001 1944 A w e JIE O N PAL EXT_MIC 5 ci
10. SJE d 0603 GND T o 3 Sr be R602 9 gs L z 0601 de L602 55 LGK2009 0201 eee LOG18HN39NJOO gt 5 C627 R615 p 2 PL603 BALANCED ER 603 m INTERNAL MIC 5528 SINGLE ENDED LGK2009 02 SINGLE 0603 0603 3 INT MIC lo gt ra 100nF C603 L601 LQG18HN39NJ00 0603 16V GND GND C OQ 02 3V912ID 9 39nH 5 cs C614 615 R603 1K d 5 060 C612 613 39pF 39pF 1nF 1nF COG X7R X7R R607 10K 5 0603 INT MIC POWER SELECTION 50V 50V 50V 50V 0603 0603 0603 0603 SO605 J01001A1944 1 INT MIC 004 4D 2 r PL602 43V INTAMIC SINGLE 1615061 08F 609 i HE BALANCED SINGLE ENDED MICROPHONE BUFFER 24 dB Q602 BALANCED c E m o c m m p E es a es E pot er 1Fs C610 43V INT SINGLE Y5V ij 1 1 SINGLE ENDED 1 47uF 3V_INT_MIC_SINGLE 4V SINGLE ENDED CONT R R608 i SIGNAL FILTERING DECOUPLING CAPACITORS pe
11. T T T 9 uw ga 2 8 m tU oc 5 m adm E m a m amp 4 B m E E x 2 z mme u Ogg u Ogg e e s S o REGULATOR GP10 3 1 9 09 09 0 EXT MIC SEL EXT MIC EXT MIC BALANCED BATTERY IN 3 8 4 2V con LL 3 9V EXT MIC 5 E EXT MIC ul 5 gt lt CURR LIMITED NTC 10K NTC CHARGER IN EN 013 mre nee CHARGE CONTROL EB CHARGE i BB FAULT m m g g EB CHARGER IN BATTERY REGULATOR BATT SEL R5232 PWR r1 EN em i INT MIC Telit GM862 S1 EVK v1 2 INT GAL AMP BAL INT MIC BALANCED Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 58 of 63 are EOG INT MIC PWR CURR UNLIMITED CHARGER IN HANDSET AMP EST 8 E HH INT MIC S E INT MIC INT MIC S E Telit GM862 GPRS Hardware User guide 1vv0300613 SR1 02 009 Rev ISSUE 3 10 02 04 Telit 11 Annex B Camera EVB schematics Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 59 of 63 MODULE
12. R605 00008807 ee 08811 Hoo En en to tb oc c amp 30 US EOS SENS ae ee es oo coco 1 724 Cocks 1 7068 s L amp 01 L3 C618 040 RE 3 rum R608 Gens 018101 REN CIR608 cms mew Lj 826607 01104 50702 0601 50602 page 57 of 63 8 18V IN b C5944B LC 12 SWITCHING REGULATOR 041201 SIM CARD HOUSING 412V LL 45V 412V 5V REGULATOR SEL GME62 31 AUX PINS STATE LEDS AND BUTTONS EXT ACC om SENSE IN e EXT PWR ON QUT STEREO MUTE EXT ACC TE CAR STEREO MUTE e MUTE ON CAR STEREO CONTROL STAT LED MUTE CONTROL SELECT INT MUTE ON EXT EAR AMP WUTE ON 4 0V IN b MIC POL REG EXT MIC BAL AMP BAL S E rar rr Hoo PWR CONTROL PWR CONTROL BHO OO EXT MIC PWR PWR CONTROL ER mm mm HE CU EH EHE mm m Eg mm m m E EE EEEE EH HE HH H E S EXT EAR EXT INT EAR INT EAR EXT M1C 0 o o o o e E e e e e e e E 9 o o o o lt EN
13. The commercial values of 15kO amp 5 6kO are then chosen Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 32 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit As a consequence the values of the capacitors C726 and C727 shall be 726 1 2 8000 8719 3 5 10 F C727 1 2p 8000 R711 2 1 2 10 F The commercial values of 3 3nF and InF are then chosen Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 33 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 6 Speaker 6 1 Speaker lines characteristics and requirements The Telit GM862 GPRS provides two audio paths for both the microphone and the earpiece the internal and the external audio paths Only one of the two paths can be active at a time and it 1 selectable by hardware line AXE or by AT command The audio characteristics of the two paths are slightly different and this should be kept in mind when designing your application The internal audio path should be used for handset function while the external audio path 15 suited for hands free function car kit Both speaker outputs from the Telit GM862 GPRS bridged type and the OEM circuitry shall be designed bridged to reduce the common mode noise ty
14. on the microphone membrane At that acoustic pressure the voltage output from the microphone is Voltage Output dB 45 4 7 49 7 dByrms corresponding to Voltage Output 107 20 3 3 103 by having the microphone gain set to 24 dB corresponding to 15 8 times the signal in the nominal conditions on the input mic pins of the GM862 GPRS will be Voltage 9 GM862 GPRS mic 3 3 10 15 82 51 During the spoken conditions the signal varies according to the volume of the voice of the talker usually a rough thumb rule for the dynamic range may be considered 20dB 10 times at maximum voice level talker screaming 50 dB 1 300 times at minimum voice level talker whispering For the handsfree car kit microphone the voice attenuation due to the distance between the microphone and the talker must be taken into account when designing the microphone amplifier For a car cabin usually the distance between the talker and the mic is about 50cm in these conditions the attenuation can be considered as a thumb rule around 20dB Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 24 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit Another thing to consider especially for cabin car use 1s the fact that the external mic will pick up also ambient noise to overcome this pr
15. The buffer gain is given by the formula 604 _ R606 R605 R607 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 29 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit The C636 and C637 capacitors are placed in order to cut off the gain at higher frequencies than the transmitted GSM band the cutoff frequency 3dB should be 8 kHz in order to have 1dB at 4Khz The cutoff frequency 15 given by the formula TE 2 604 C637 2 R606 C636 Hz For example Let s assume you have a microphone with these characteristics sensitivity 45 dByrms pa and you want to use it in the internal mic audio path With the mic having nominal sensitivity 45 at the normal spoken conditions 4 7dB at 7 cm from the mouth of the talker At that acoustic pressure the voltage output from the microphone is Mic Voltage Output dB 45 4 7 49 7 dByrms corresponding to Mic Voltage Output 10 49 7720 3 3 103 Yos in order to have a signal of 50 mV 4 on the GM662 GPRS internal mic inputs then the buffer must have a gain of Voltage 9 GM862 GPRS_intmic Mic Voltage Output 50 10 3 3 10 12 Hence in these conditions the signal level on the input pins of the internal mic of the GM862 GPRS is 24 dB 15 times higher than the microphone
16. MEME 801500 FEET MMC MM CM MEM E C 5 8 Lidi dili 71 L ca LG E EE I A ME MM LEM CO EE em 5314252 Phy yp tt dd oi Ll eap poppe b sos MEME lt 55 gt 8 e eo LE 801500 E Gyon IS AEE Aaa sie a an i EET Si EN ME ease eee EN ili SERE me ee a ee 001 00 g E 32 900 Bu LE EH DEM E E EE E nnn NE 0 ee 58 NN MEN EN MD MM UE 1 MENO UN EE 91 200 E _ 4 pons orado 1 qd T3 T WE EXER pd 5 PES ETSI EPIS lO E Lg G
17. a PIENE L306 C a L308 sonl BENED E 39nH 10018 C330 C331 C332 1 333 C334 1 335 C336 337 C306 C307 C308 C309 C310 C311 C312 1 313 GND 39pF 39pF 39pF 39pF 39pF 39pF 39pF 39pF 1nF 1nF 1nF inF 1nF 1nF 1nF 1nF COG COG COG COG COG COG COG COG X7R X7R X7R X7R X7R X7R X7R X7R 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND PATH home users area FILE NAME cs944b cir Mod 067 0 03 01 EVK for GM862 S1 Mobile Terminals S p A E ANNOTATION RS232 LEVEL TRANSLATOR AND UART INPUT OUTPUT PROJECT Deperini F 301101 PROJECT SHEET N OFSHEETS DRAWING CODE 30208SE10944b DRAWN Serdi M 041201 Quas 0208 31 0 VERIFIED Locatelli M Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 50 of 63 lt en O Q LLI fe Bk or tae oe EAR Ek u rg L US XUL WT or a E FOE L eS EL ee oe Ng sep 5252 72 dp UE eT EIU ee 3542 aser ER 7 WE NE BEIM Du prs ng loma X uj E A re 1151 8 WE d QW I
18. e Qualification and trickle charging e Fast charge 1 constant current e Final charge constant voltage or pulsed charging e Maintenance charge The qualification process consists in a battery voltage measure indicating roughly its charge status If the battery 1s deeply discharged that means its voltage 15 lower than the trickle charging threshold then the charge must start slowly possibly with a current limited pre charging process where the current 15 kept very low with respect to the fast charge value the trickle charging During the trickle charging the voltage across the battery terminals rises when it reaches the fast charge threshold level the charging process goes into fast charge phase During the fast charge phase the process proceeds with a current limited charging this current limit depends on the required time for the complete charge and from the battery pack capacity During this phase the voltage across the battery terminals still raises but at a lower rate Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 12 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit Once the battery voltage reaches its maximum voltage then the process goes into its state Final charging The voltage measure to change the process status into final charge is very important It must be ensured that the
19. GSM Te IC Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 5 4 Microphone buffering As seen previously a microphone shall be connected to the input pins of the GM862 GPRS through a buffer amplifier that boosts the signal level to the required value Again the buffered microphone circuitry can be balanced or unbalanced Where possible it is always preferable a balanced mic solution The buffering circuit shall be placed close to the microphone or close to the microphone wire connector 5 4 1 Buffered Balanced Mic A sample circuit can be BALANCED MICROPHONE 24 dB gt DECOUPLING CAPACITORS H iby 4 x 5 5 i C627 R615 1 GND 2 100nF 47K T 16 in n FROM oS 3M862 MIC m i 13V I 5 D Bj GND GND a LIBO2 e ES i 5 T53v9121ID ou 1 I r i O x 7 4 IP e e GND Te ms This circuit has a gain of 15 times 24 dB and is therefore suited for the internal mic input having a microphone with a sensitivity close to the suggested one 45 dByrmypa if the used microphone has a different sensitivity or if the buffer is connected to the external mic input then a gain adjustment shall be done by changing resistors R604 R605 and R606 R607 and as a consequence the capacitors C636 and C637 to maintain the bandwidth 150 8000 3dB
20. Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 6 2 1 Noise Filtering The I O of the PCB should have a noise filter close to the connector to filter the high frequency GSM noise The filter can be a of 2 capacitor and a inductance with the one capacitor of 39pF 0603 case and the other capacitor of InF 0603 the inductance shall have a value of 39uH 6 3 Handset earphone design As seen previously a 160 speaker be directly connected to the output pins EAR and EAR MT of the GM862 GPRS This solution 15 often the more cost effective reducing the components count to a minimum There are several limitations to the use of this solution speaker direct connect imposes the speaker characteristics to be almost exactly the suggested ones otherwise the power output may be reduced if speaker impedance is bigger than 160 or GM862 GPRS ear port may be damaged if speaker impedance 1 less than 150 The other limitation of the speaker direct connection is the power output capability of the GM862 GPRS which 1s limited and for some particular applications may not be enough For these reasons when the power output of the GM862 GPRS is not enough or if the speaker characteristics are different from the suggested then it is preferable to use an amplifier to increase the power and current output capabilities Again the output from the GM862 GPRS is bridged and both
21. handset external microphone path e line coupling AC 100nF cond e line type balanced e differential input resistance 25kO e line nominal sensitivity mVims Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 23 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit e max input voltage 22 MV rms e microphone nominal sensitivity analog gain suggested 45 dB yop 10 e echo canceller type car kit hands free TIP Due to the difference in the echo canceller type the internal audio path is suited for handset applications while the external audio path is suited for car kit hands free The headset applications should be made by using the external audio path but DISABLING the echo canceller by software AT command If the echo canceller is left active with the headset then some echo might be introduced by the echo cancel algorithm The nominal sensitivity of the line indicates the voltage level on GM862 GPRS pins that should be present during normal spoken conditions for a handset a voice signal coming from the mouth of the talker at 7 cm of distance from the microphone producing an acoustic pressure of 4 7 kHz on the microphone membrane For example With the internal mic having the suggested nominal sensitivity 45 at the normal spoken conditions 4 7dB
22. GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 6 SPEAKER 34 6 1 Speaker lines characteristics and requirements 34 6 2 General Design rules 36 6 2 1 Noise Filtering 27 6 3 Handset earphone design 37 6 4 Hands Free earphone low power design 39 6 5 Car Kit speakerphone design 39 7 GENERAL PURPOSE I O 41 7 1 Using a GPIO pin as INPUT 41 7 23 Using a GPIO pin as OUTPUT 41 7 3 Using the Alarm Output GPIO6 42 7 4 Using the Buzzer Output GPIO7 42 8 CAMERA 43 8 1 Camera characteristics 43 8 2 Camera interface connectors 43 8 3 EVB for camera support 45 9 DOCUMENT CHANGE LOG 46 10 ANNEX A EVK SCHEMATICS 47 11 ANNEX B EVB SCHEMATICS 59 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 3 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 1 Overview The aim of this document 1 the description of some hardware solutions useful for developing a product with the Telit GM862 PCS GPRS GSM modules In this document all the basic functions of a mobile phone will be taken into account for each one of them a proper hardware solution will be suggested and eventually the wrong solutions and common errors to be avoided will be evidenced Obviously this document can not embrace the whole hardware solutions and products that may be designed The wrong solutions to be avoid
23. THD N internal external ear bridged e line coupling e line type e speaker impedance operating conditions e minimum load impedance e signal bandwidth e maximum output e maximum power output THD N DC bridged 16 15 1kHz 150 150 8000 Hz 3 dB 425 mVims 2 5 mW 7 5 mW 2 dB 10 single ended referred to GND 80 80 150 8000 Hz 3 dB 800 mMVims 80 mW 480 1 S0mW DC bridged not referred to GND 80 80 150 8000 Hz 3 dB 1 6 Vims 320 mW 80 1 330mW Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 35 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit high power external ear e line coupling DC e line type bridged not referred to GND e speaker impedance operating conditions 4 e minimum load impedance 40 e signal bandwidth 150 8000 Hz 3 dB e maximum power output 6 W e THD N 10 6W 6 2 General Design rules There are several configurations for the audio output path but the various design requirements can be grouped into three different categories e handset earphone low power typically a handset e hands free earphone low power typically a headset e car kit speakerphone high power typically a speaker The three groups have different power requirements usually the first two applic
24. V 50201 W201 02201 6201 6202 Us R20 4 8201 C3 6203 L3 GM862 51 oes C403 C2 C402 C405 210404 U601 Es 803 102 os EE C2 fL eel ere a ema que Ox 008 8 16403 co oO Ed 2218807 e onm N coc o 5 61085 026707 can 05806 C813 805 msn 27080 Dum o p el 00801 1803 S zT R703 Cuz G gtis Df 0802 cana 9 708 5 e Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved V V V PL101 V V 50101 50102 D Jarn 50103 50104 07103 Es 0101 C381 R112 C104 28116 E ES L3R114 08107 108 0 5 DLID3 5 25 106 6112 8 mo 28113 C105 Rigg 09102 wi PL202 L316 c322 eso PL1001 6374 1 lt 318 50201 ii cines clone 51018 cT 0825 110017 02111007 L313 C1008C3 0261018 gg 3250 10 cima e zz 0063260 eso Rono 5 E sl d 01012 c3 eed 1005 0201004 L302 SED ges PO Mess 0322 301 SED Dess 5100 Desss 6313 00337 1504 cs Co 6827 1405 65200 21 50803 1506 6823 cA 00 onm PLEN PL603 ERE 716 C618 617 Qo 1 0725 caos 0 ces A C606 OOO 119 Reo 000 Je 618 g 222 06726 663002 6836 Un 223 6631 gt 22 118 R615 R619 gt 2
25. Y5V E u gt 25 O EG QR T pM xc 2 Fo tc PATH home users area DESCRIPTION el PROJECT Deperini F EXTERNAL MICROPHONE SECTION PROJECT SHEETN DRAWING CODE 0208 71 0 30208SE10944b Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 54 of 63 FORBIDDEN ALL RIGHTS RESERVED REPRODUCTION AND DISCLOSURE RIPRODUZIONE E DIVULGAZIONE VIETATE TUTTI I DIRITTI RISERVATI B 240211521 2 22 5 521 11 _ NOISE FILTERING SO801 i aie BRIDGED 3 INTERNAL EAR Laie 1 LGY650X G L801 LQG18HN39NJOO LOGIS 0806 C804 805 C806 807 J01001A1944 39pF 39pF inF inF 1 COG COG X7R X7R INT EAR 0 m pr 50V 50V 50V 50V EG ey 0603 0603 0603 0603 o N O G __ __ ________ ___ ___ SO802 LGY6502 0600 L803 SINGLE ENDED ax 2 LQG18HNSONJO0 INTERNAL EAR zo 39nH o 10018 LGY650X S 5 C808 C809 39pF inF zi 0603 0603 INT EAR GND GND GND ETE CNN NOISE FILTERING 0803 ELI M MG d UE LGY6502 0600 L805 BRIDGED LOG18HN39NJOO EXTERNAL EAR Tu LGY650X GND L804 LQG18HN39NJOO C81 813 15 39pF 39pF inF inF 8 COG X7R X7R J01001A1944 50V 50V 50V 50V EXT EAR 0603 0603 0603 0603 s z N
26. authorization All Right res reserved 1 Right of modification reserved page c 43 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 49 PD 7 Parallel Data 7 9 IICSDA o lICbusserialdata serial data 8 DATA o 48 CAM_DRDY Data in an output for the camera and an input for the GM862 PCs CAM PWR ON mum 2 8V power supply enable for the VCC_MAIN E camera Horizontal sync n e Horizontal syne nc n c 6 HSYNC E command for switching power a OFF ON or OFF 2 4 GND Ground 1 GND 6 18 Materi Body PPS With 40 GF UL 94 0 Color Nature Sider PPS With 40 GF UL 84V D Color Brown Conlact Phosphor Bronze With ploted Fixed tab Bross With Tin ploted Ordering Code rel 0000000 Series No No of Circuits code 1 2 051201 Min Tin over 0 76um 30u Nickel Contoct style V Verlical Type Scolo O Nature Packing Type R Tape amp Reel Tube Packing 015mm mm 157 Circuit Cavity of Cir ults i i sadi Other options M I Without Pick and Place Pad Stondard a su P With Pick and Place 10 ajn 0 50 x of Spaces 05 _ 6 4 051005 1 020 002 0 00 03 2 0905 Available
27. m iFa ove 1 lig Power ON OFF inpulse GND 2 Let s assume you need to drive the ON pin directly with an ON OFF button GND Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 6 of 63 J wa Telit GM862 PCS GPRS GSM Te It Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 2 2 Turning OFF the GM 62 GPRS The turning off of the device can be done in three ways e by software command see GM862 GPRS Software User Guide e by hardware shutdown e by hardware unconditional shutdown When the device is shut down by software command or by hardware shutdown it issues to the network a detach request that informs the network that the device will not be reachable any more The hardware unconditional shutdown does not issue this request and shuts down immediately the device The hardware unconditional shutdown must not be used during normal operation of the device since it does not detach the device from the network It shall be kept as an emergency exit procedure to be done the rare case that the device gets stucked waiting for some network or SIM responses If device does not respond to a command in the timeout window retry issuing the command and if still no response 15 received a hardware unconditional shutdown shall be issued and then a restart 2 2 1 1 Hardware shutdown To turn OFF the GM862 GPRS the pin ON mu
28. of 63 EAH HF MIL HF MIC MTt MIC HFt MIC MT ON AXE SIMIU STAAT CAM SYNC RESET SIMAST TEST 32KHz MUN1 CAM CELK GPI92 TICSCL_CAN CTS RING Polo DSA Poli TX THACE TA PHOG 2 STAT LEL 3 HX THALE 4 Pois ATS gPIO3 PD B BGPIO4 IICSDA GPIOS CAM_DADY 7 0 1815081 12F a w __ 1 cute EN rg LT1528LH EN io C201 di atur MEE NIE NI E a ax 5 TO A5232 ann HL 201 1E15hDE1 71DF Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved 1203 LCPESGSRAIMGK 3 0 MAXSP STAT Pii TAIN LEVEL TRANSLATOR 6209 iuf B Uns T B E al B B E cs E page 61 of 63 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 62 of 63 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 63 of 63
29. og 15 859 815 TERDAN IO delet ley Leos Fons a T esp eme eee mm d aaga 1 1 EIU ae ee 4 Pt Aha al 2252 Exe _ lol I 4 p E e e 1 Ii i amp xISIgIzIiIu 1 Papa Ho aed qe d Itlulzi i9ISIEILI mM qp seed apse IOC tTE TE 1Ol tia E EI uj i IIi jl prime J peg SEIN LEE NE EN EBENEN NEN RETE pes 2 AFEFE TERETERE T pol L dil ATA r E ug edn ede op eee Me Males T LLL op gy lb eye poet 4p sss E HEB TET E TY HH 9 E TDI D OFF 8 GNE IM IP E M Wd EI EDDIE Dun MEME p NO 26 900 DART idc EL LL 1 1 521055 S8lesel pp ro lesa XB 221
30. 002 11D SO101 0502 BATTERY LI ION O 212 3 7V Li lon Nominal max voltage 4 2V Li lon suggested capacity 1000mAh Vv WARNING When using battery care must be taken to ensure that the right polarity is respected DESCRIPTION EVK for GM862 S1 Mobile Terminals S p A BATTERY CHARGE CONTROL PROJECT SHEET N OF SHEETS DRAWING CODE Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 48 of 63 20221215 14 5 input linear regulator ose P 5012 2 ne 2 777 Ge ewe ee 777777777777 cr D 22 WO Daz Li zz LU or SO201 U201 FCMM0502 17152800 SSS SS 1 Orr 950 Aapo Tapn co E DZ201 D205 C203 m ST 2 Tov R202 do 4 497 STPS140Z e l 1 Ae SS 1 lt r 7 um Lari Nb 6 24 SOD123 noMount YES ae p E L Be Tet c 77 GND G 7 EE 77 V WARNING iren Care must be taken to ensure that the right polarity in the power input is respected 7 ix os Battery R
31. 0208 10 302085 109440 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 49 of 63 ALL RIGHTS RESERVED REPRODUCTION AND DISCLOSURE FORBIDDEN VIETATE TUTTI I DIRITTI RISERVATI RIPRODUZIONE E DIVULGAZIONE 22242122 22 22 PL302 1215061 02F 1 2 RS232 LEVEL TRANSLATOR POWER SELECTION U301 28 ICL3207CA SSOP 24 gt 9 NO ust c e C VM TO RS232 S0301 o sH 787200 1 L316 8HN39NJOO L315 2 pm 24 5 1214 Se ae QGL 2 CCTSENSONUOS T2 OUT m CTX PROG QG18 L312 24 00460 M 2 pr 20 75 a 39nH 8 39 00 1310 Lo QG18 A 16 39nH 8 LQG18 1058 004 5D 5 004 5D RING 004 5D 5 RTS 004 6D _ RX_PROG 004 5D DTR 004 6D cv J Pj Ll Ll fre i DESCRIPTION GND C321 C322 C320 C323 19 C324 C318 C325 C317 C326 316 39pF 1nF 39pF 1nF 39pF 1nF 39pF 1nF 39pF 1nF 39pF X7R COG X7R COG X7R COG X7R COG X7R COG 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 GND GND GND GND GND GND GND GND GND GND GND 3 7V UART PL301 1615061 10F L301 LQG18HN39NJ00 1302 Q OMINSIJINJUU Q Q
32. 2 level while the receiver is the translator from RS232 level to 0 3 V In order to translate the whole set of control lines of the UART you will need 5 driver 3 receiver NOTE The digital input lines working at 2 8VCMOS have an absolute maximum input voltage of 3 75V therefore the level translator IC shall not be powered by the 3 8V supply of the module Instead it shall be powered from a 2 8V 3 0 dedicated power supply This is because in this way the level translator IC outputs on the module side i e GM862 GPRS inputs will work at 3 8V interface levels stressing the module inputs at its maximum input voltage This can be acceptable for evaluation purposes but not on production devices Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 19 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit An example of level translation circuitry of this kind 15 U 1 13v ICL3207CA SSOP 24 m oa gt OG T mo gt LL eu ce oy gt lt u eO p lt c mm L QJ naars O ce Cu 2 lt wea Oa u GND Bcd uart gt DCD RS232 tx uart IX H5232 Bsr uart gt DSR R5232 cts uart gt CTS RS232 ri _uart gt gt 5232 rx uart lt lt I BX RH5232 rts_uart lt lt RT
33. ATOR Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 53 of 63 E p 22 2 1 414 BALANCED MICROPHONE POLARIZATION DESDE QC DKL LEM GR 1 43V EXT MIC BAL R705 10K 5 3 0603 NS DECOUPLING CAPACITORS SOT 323 BALANCED MICROPHONE BUFFER 10 dB 55 702 1 ESI 1 4 7uF 43V EXT MIC BAL 4v 7 uN CONT R TOOR T044 Sz in R713 43V EXLMIC BAL gt o EXT SLE We 5 158 1 E xd EUCH CES 43V EXT BAL 3 9702 gt R702 TS3V912ID Rus cu 1 70 cr 1 IIS 5 NOISE FILTERING tm 2 T 2 0603 TE DOR Eus aA 216 62 B B BALANCED a SO701 1703 2 Sx 773 SINGLE ENDED LGK2009 0201 LQG18HN39NJOO C718 R712 ES 3 EL e BALANCED 7 E pes OE m n Y5V Or EXTERNAL Lis 58525 wiz XEM cs EXT MIC POWER SELECTION Can LGK2009 02 L702 E gt LOG18HN39NJO0 l 23180 49V EXT BAL Ic M O59 Ladi s U702 oc R703 C703 C705 C707 C708 5 TS3V912ID v Cee a 1 39pF 39pF 1nF 1nF 5 5 23 P COG X7R X7R SE 5 50V 50V 50V 50V
34. M e 1 0 901 4DOnr MUTE 48v 35v PL 801 1 4 END 910 GND GND 1Dur 400nF 2 MUTE CONTRDLLED 1 i 35v 48v 3 atwavs on CUNT E DEDI GNO AMPLI POWER CONTROL gt 41 5 5 5 5 21 131 3 113 3 1191534 22 521 1 2 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 40 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 7 General Purpose I O The general purpose I O pins can be configured to act in three different ways input output alternate function internally controlled Input pins can only be read and report the digital value high or low present on the pin at the read time output pins can only be written or queried and the value of the pin output an alternate function pin is internally controlled by the GM862 GPRS firmware and acts depending on the function implemented Not all GPIO pins support all these three modes GPIOI is an INPUT ONLY GPIO2 is an OUTPUT ONLY open collector GPIO3 GPIO4 and GPIO
35. R503 a R510 5 _ o S PLOC2 1 5 ON A YELLOW C GPIO2 004 4D 2 gt GREEN GPIO2 LED GPIO2 OUTPUT 004 5D LY T670HK DL503 ON BUTTON GND 3 7V SW502 506 BCR148W SOT 323 WEs U501 TC7S08FU TC7S08FU i CHA af us01 2 2 R505 560 GND 5 0603 2 SW501 MUTE CONTROL SELECT YELLO 4 SKHHAL 2 NN GREEN STEREO MUTE LED zt LY T670HK 008 10B 008 10D 009 11C DL505 GND PL504 1215061 02F om Ro im OA noMount YES 2 1215061 02F PL507 MUTE CONTROL EXTERNAL ACCESSORIES Q508 BCR148W 2 CAR STEREO MUTE OUTPUT 512 aes Uo PL505 1215061 02F S9nH 604905 L502 LQG18 LQG18HN39NJ00 GP104 39nH L504 LQG18 LQG18HN39NJ00 GP105 39nH 604 10D L503 LQG18 LQG18HN39NJOO 5 6 39n L501 10618 LQG18HN39NJOO H C510 Laate C511 504 C505 C506 C507 C502 C503 C508 C509 39pF 1nF 39pF 1nF 39pF 1nF 39pF 1nF 39pF 1nF GPIO1 INPUT GND 004 10E GPIO7 004 10E E obse Ole 43 7V COG X7R COG X7R COG X7R COG X7R COG X7R 5061 0 50V 50V 50V 50V 50V 50V 50V 50V 50V 50V 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 EXTERNAL ACCESSORIES 504 i GND G G G GN GN GN G G G G POWER ON OUTPUT 5 060 PLCC2 YELLOW GREEN AXE LED V LY T670HK DL504 worry l Ll L 504 aw PATH hom
36. S RS232 Btr uart lt DTR RS232 GND the 5232 serial port lines are usually connected to a DB9 connector with the following layout _ 5232 gt DSR RS232 gt TX RS232 gt HIS HSEJe RX RS238 2715 55838 gt DTR RSe32 RI_RS232L GND Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 20 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 4 2 5V UART level translation If the OEM application uses a microcontroller with a serial port UART that works at a voltage different from 2 8 3V then a circuitry has to be provided to adapt the different levels of the two set of signals As for the RS232 translation there are a multitude of single chip translators but since the translation requires very few components then also a discrete design can be suited For example a possible inexpensive translator circuit for a 5V driver can be TO Toia lt FROM OEM GM862 HARDWARE lt TxXD 3v and for receiver C4103 TxD SN lt _ PWRCTL 41 WPS SOT 3B4 TS C403 THOS By Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 21 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit NOTE The UART input l
37. S support both input or output mode but not Alternate function GPIO6 supports all three modes and can be input output alarm output Alternate function GPIO7 supports all three modes and can be input output buzzer output Alternate function GPIO pins except from GPIO1 and GPIO2 that are buffered with a transistor are 2 8 CMOS signals and their interface levels are the same specified the paragraph 4 Serial Port 7 1 Using a GPIO pin as INPUT The GPIO pins when used as inputs can be connected to a digital output of another device and report its status provided this device has interface levels compatible with the 2 8 CMOS levels of the GPIO If the digital output of the device to be connected with the GPIO input pin has interface levels different from the 2 8V CMOS then it can be connected to GPIOI or can be buffered with an open collector transistor provided a 47KO pull up resistor is connected as seen in the paragraph 4 2 5V UART level translation 7 2 Using a GPIO pin as OUTPUT The GPIO pins when used as outputs can drive 2 8V CMOS digital devices or compatible hardware When set as outputs the pins except from GPIO2 which is Open Collector have a push pull output and therefore the pull up resistor may be omitted The 2 pin since it 1 an Open Collector output needs an external pull up resistor Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of mo
38. Telit GM862 PCS GPRS GSM Hardware User guide Rev ISSUE 4 10 02 04 Telit Telit GM862 PCS GM862 GPRS GM862 GSM Hardware User Guide DAI Telecom S r l 2003 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit Contents 1 OVERVIEW 4 2 HARDWARE COMMANDS 5 2 1 Turning ON the GM 62 GPRS 5 2 2 Turning OFF the GM862 GPRS 7 2 2 1 1 Hardware shutdown 7 2 2 1 2 Hardware Unconditional shutdown 7 3 POWER SUPPLY 9 3 1 Power Supply Requirements 9 252 General Design Rules 9 9d Electrical design Guidelines 10 3 2 1 1 5V input Source Power Supply Design Guidelines 10 3 2 1 2 12 input Source Power Supply Design Guidelines 11 3 2 1 3 Battery Source Power Supply Design Guidelines 12 3 2 1 4 Battery Charge control Circuitry Design Guidelines 12 302 2 Thermal Design Guidelines 14 3 2 3 Power Supply layout Guidelines 15 4 SERIAL PORT 17 4 1 RS232 level translation 19 42 level translation 21 5 MICROPHONE 23 5 1 Microphone line Characteristic and requirements 23 5 2 General Design Rules 26 5 3 Microphone Biasing 26 289 Balanced Microphone biasing 27 5 3 2 Unbalanced Microphone biasing 28 5 4 Microphone buffering 29 5 4 1 Buffered Balanced Mic 29 5 4 2 Buffered Unbalanced Single Ended Mic 31 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 2 of 63 Telit GM862 PCS
39. ally around 150mA For these reasons the thermal design is rarely a concern and the simple ground plane where the power supply chip is placed can be enough to ensure a good thermal condition and avoid overheating 3 2 3 Power Supply PCB layout Guidelines As seen on the electrical design guidelines the power supply shall have a low ESR capacitor on the output to cut the current peaks and a protection diode on the input to protect the supply from spikes and polarity inversion The placement of these components is crucial for the correct working of the circuitry misplaced component can be useless or can even decrease the power supply performances e The Bypass low ESR capacitor must be placed close to the Telit GM862 GPRS power input pins or in the case the power supply is a switching type it can be placed close to the inductor to cut the ripple provided the PCB trace from the capacitor to the GM862 GPRS is wide enough to ensure a dropless connection even during the 2A current peaks e The protection diode must be placed close to the input connector where the power source is drained e PCB traces from the input connector to the power regulator IC must be wide enough to ensure no voltage drops occur when the 2A current peaks are absorbed Note that this 1s not made in order to save power loss but especially to avoid the voltage drops on the power line at the current peaks frequency of 216 Hz that will reflect on all the components connect
40. ardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 3 2 1 3 Battery Source Power Supply Design Guidelines e The desired nominal output for the power supply is 3 8V and the maximum voltage allowed is 4 2V hence a single 3 7V La Ion cell battery type 1s suited for supplying the power to the Telit GM862 GPRS module The three cells Ni Cd or Ni MH 3 6 V Nom battery types or 4 PB types MUST NOT BE USED since their maximum voltage can rise over the absolute maximum voltage for the GM862 GPRS and damage it NOTE DON T USE any Ni Cd Ni MH and Pb battery types Their use can lead to overvoltage on the 8 GM862 GPRS and damage it USE ONLY Li lon battery types A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption peaks a 100uF tantalum capacitor is usually suited e Make sure the low ESR capacitor usually a tantalum one is rated at least 10V e A protection diode should be inserted close to the power input in order to save the GM8062 GPRS from power polarity inversion Otherwise the battery connector should be done in a way to avoid polarity inversions when connecting the battery e The battery capacity must be at least 500mAh in order to withstand the current peaks of 2A the suggested capacity 1s from 500mAh to 1000mAh 3 2 1 4 Battery Charge control Circuitry Design Guidelines The charging process for Li Ion Batteries can be divided into 4 phases
41. ations need only few mW of power which can be directly drained from the GM862 GPRS pins provided a suited speaker is used This direct connect design is the cheaper and simpler solution and will be suited for the most of the earphone design requirements There s no need to decouple the output ear lines if a suited earpiece is connected For the last group the speakerphone a power amplifier is required to raise the output power up to 5 10W required in a car cabin application All the designs shall comply with the following guidelines e Where possible use a bridged earphone circuitry to achieve the maximum power output from the device e Keep the earphone traces on the PCB and wires as short as possible e If your application requires a single ended earpiece and you want a direct connection then leave one of the two output lines open and use only the other referred to ground Remember that in this case the power output is 4 times lower than the bridged circuit and may not be enough to ensure a good voice volume e Make sure that the earphone traces in the PCB don t cross or run parallel to noisy traces especially the power line e The cable to the speaker shall be a twisted pair with both the lines floating for the bridged output type shielded with the shield to ground for the single ended output type Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 36 of 63
42. aving 4mA e Average current during idle Power Saving disabled 17mA NOTE The average consumption during transmissions depends on the power level at which the device is requested to transmit by the network The average current consumption hence varies significantly Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 14 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit TIP The thermal design for the Power supply should be made keeping a average consumption at the max transmitting level during calls of 350mA rms Considering the very low current during idle especially if Power Saving function is enabled it is possible to consider from the thermal point of view that the device absorbs current significantly only during calls If we assume that the device stays into transmission for short periods of time let s say few minutes and then remains for a quite long time in idle let s say one hour then the power supply has always the time to cool down between the calls and the heat sink could be smaller than the calculated one for 350mA maximum RMS current or even could be the simple chip package no heat sink Moreover in the average network conditions the device 1 requested to transmit at a lower power level than the maximum and hence the current consumption will be less than the 350mA being usu
43. ction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 38 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit Some amplifier require a low impedance load at high frequency in order to avoid auto oscillation this can be made with a capacitor 100 in series with a resistor 150 When designing your application remember to provide an adequate bypass capacitor to the amplifier and place it close to the power input pin of the IC keeping the traces as short as possible 6 4 Hands Free earphone low power design The same design considerations made for the handset are valid for the hands free earphone the only difference is that the external ear audio output level from the GM862 GPRS is 6dB lower than the internal one so the gain of the amplifier must be 6dB higher to provide the same audio level 6 5 Car Kit speakerphone design For the car kit speaker phone function the power output requirement is usually at least 4W therefore an amplifier 15 needed to boost the GM862 GPRS output The design of the amplifier shall comply with the following guidelines e The input to the amplifier MUST be taken from the external audio path EAR_HF EAR HF of the GM862 GPRS because of its echo canceller parameters suited to a car cabin use e amplifier shall have a gain of 30 40 times 29 32 dB to provide the desire
44. d output power of 5 10W with the signal from the GM862 GPRS external audio output lines EAR HF e If the amplifier has a fixed gain then it can be adjusted to the desired value by reducing the input signal with a resistor divider network e The amplifier shall have a mute control to be used while not in conversation This results in two benefits eliminating the background noise when not in conversation and saving power e power to the amplifier should be decoupled as much as possible from the GM862 GPRS power supply by either keeping separate wires and placing bypass capacitors of adequate value close to the amplifier power input pins e The biasing voltage of the amplifier shall be stabilised with a low ESR e g a tantalum capacitor of adequate value 1 NOTE The GM862 GPRS audio path connected to the car kit hands free amplifier MUST be the external one EAR HF otherwise the echo cancellation will not be done due to the difference in the echo canceller characteristics of the GM862 GPRS internal audio path from the external audio path Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 39 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit An example of car kit amplifier schematic can be HIGH EXT EAR AMPLIFIER 1 1 1 1 1 E 1 TO SPEAKER 4 8 OH
45. dification reserved page 41 of 63 Telit GM862 PCS GPRS GSM Hardware User guide It 2 1vv0300613 Rev ISSUE 4 10 02 04 7 3 Using the Alarm Output GPIO6 The GPIO6 pin when configured as Alarm Output is controlled by the GM862 GPRS module and will rise when the alarm starts and fall after the issue of a dedicated AT command This output can be used to power up the GM862 GPRS controlling microcontroller or application at the alarm time giving you the possibility to program a timely system wake up to achieve some periodic actions and completely turn off either the application and the GM862 GPRS during sleep periods drammatically reducing the sleep comsumption to few uA In battery powered devices this feature will greatly improve the autonomy of the device 7 4 Using the Buzzer Output GPIO7 The GPIO7 pin when configured as Buzzer Output is controlled by the GM862 GPRS module and will drive with appropriate square waves a Buzzer driver This permits to your application to easily implement Buzzer feature with ringing tones or melody played at the call incoming tone playing on SMS incoming or simply playing a tone or melody when needed by your application A sample interface scheme is included below to give you an idea of how to interface a Buzzer to the Vbuzz R112 4 7K a 5 1 0102 s2F BZ101 2 SOT 23 SMUS 1227 2907 1 2 d D101 b Q101 MCLA148 GPIO7 gt fea 50
46. e biasing can be 13 8 MIC Biasing HRegulstor Capacity multiply circuit TET 11 3 0 1 dv 1N y o GND C1 un ON OFF NC Cat a a as a aS a SS Ss a a a SS Se SS SS Electret microphone m gt 4 i snielded i To Mic Buffer amplifier ibd MIC i C3 j 220nF bl A we 9 ee 4 NOTE In the unbalanced application the capacitor C3 shall be 200nF otherwise the frequency response will be cut at low band frequencies down to 300Hz This capacitor can be placed close to the MIC pin EXT MIC or INT MIC depending on the audio path chosen or if possible it should be placed close to the shielded cable connector If the ground return path is well designed then it is possible to eliminate the C3 capacitor provided the buffer is close to the mic input 1 NOTE The cable to the microphone should be shielded 1 NOTE The microphone sensitivity changes with the value of R2 Usually the microphones characterized with 2kO biasing resistance so try to keep the value of R2 around 2 For mic characteristics refer to the manufacturer Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 28 of 63 Telit GM862 PCS GPRS
47. e users area DESCRIPTION EXTERNAL ACCESSORIES oan SOT 323 n EVK for GM862 S1 R507 Mobile Terminals S p A E Mod 067rev 0 03 01 ANNOTATION 5 PROJECT Deperini F AUX PINS STATE LEDS AND ON RESET BUTTONS 0603 SOT 323 WEs o YELLO 1 GREEN GPIO1 LED LY T670HK WAY YELLO Gd DL502 YELLOW STAT LED R506 LY T670HK pes DL501 fi 5 0603 2 STAT LED C 9 GPIO1 ical SOT 323 004 5D 006 10D WEs CAR STEREO GPIO GPRS CONNECTOR PL508 1615061 10F L505 LQG18HN39NJ00 PL503 1215061 02F 301101 z PROJECT HEET N SHEET DRAWIN DE ONE gt AXE DRAWN Serdi M 041201 EUER 2 oy 2 522 ii aren 0208 5 10 30208SE10944b VERIFIED Locatelli M Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 52 of 63 FORBIDDEN ALL RIGHTS RESERVED REPRODUCTION AND DISCLOSURE VIETATE TUTTI I DIRITTI RISERVATI RIPRODUZIONE E DIVULGAZIONE B 22222212221 5 22 22 52 54412 BALANGED MICROPHONE POLARIZATION J 3V_INT_MIC_BAL R601 MES 5 7 SN DECOUPLING CAPACITORS BC847BW 1 p C601 2 q 43V INT BAL 4 7uF 9 gt R616 43V INLAM BAL 5 o CONT R SO606 T 47K 01001 1944 2205 9 ER
48. ed shall be considered as mandatory while the suggested hardware configurations shall not be considered mandatory instead the information given shall be used as a guide and a starting point for properly developing your product with the Telit GM862 PCS GPRS GSM modules For further hardware details that may not be explained in this document refer to the GM862 PCS GPRS GSM Product Description document where all the hardware information 15 reported NOTE In this document all the hardware solution are referenced to the GM862 GPRS As a general rule since all the product line GM862 P CS GM862 GPRS GM862 GSM is pin to pin hardware compatible all these solutions apply also to the GM862 GSM and GM862 PCS except for the features not supported by these products NOTE The information presented in this document is believed to be accurate and reliable However no responsibility is assumed by DAI Telecom for its use nor any infringement of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under any patent rights of DAI Telecom other than for circuitry embodied in Telit products This document is subject to change without notice Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 4 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 2 Hardware Com
49. ed to that supply introducing the noise floor at the burst base frequency For this reason while a voltage drop of 300 400 mV may be acceptable from the power loss point of view the same voltage drop may not be acceptable from the noise point of view If your application doesn t have audio interface but only uses the data feature of the Telit GM862 GPRS then this noise is not so disturbing and power supply layout design can be more forgiving Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 15 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit e The PCB traces to the GM862 GPRS and the Bypass capacitor must be wide enough to ensure no voltage drops occur when the 2A current peaks are absorbed This is for the same reason as previous point Try to keep this trace as short as possible e The traces connecting the Switching output to the inductor and the switching diode must be kept as short as possible by placing the inductor and the diode very close to the power switching IC only for switching power supply This 15 done in order to reduce the radiated field noise at the switching frequency 100 500 kHz usually e The use of a good common ground plane is suggested e The placement of the power supply on the board should be done in such a way to guarantee that the high current return paths in the grou
50. ed to the VBATT pins Charge input must fulfil charger line requests 50 pin Molex male connector PL103 to interface with the 5 862 5 directly e 30 pin Berg male connector PL101 to interface with a PCB developed by the user or the EVK board On this connector is available the complete audio path the serial port lines with full handshaking and the pins ON AXE RESET GPIOI and STAT LED Also the CHARGER IN pin can be available placing a ohm resistor e 18 pin ZIF female connector 5 101 for CMOS camera ON OFF button SW102 to power on and off the module GPIOI button SW101 for future applications e ed DL101 for device status indication 1 NOTE The Philips 74LVC1608GW must be placed close to the GM862 connector the length of the line between CAMERA connector and MOLEX 50 PIN of GM862 must be max 5cm anyway Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 45 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 9 Document Change Log Revision Date Changes ISSUE 1 18 10 02 ISSUE 2 29 01 03 Changed manufacturer into DAI Telecom ISSUEZ3 12 05 03 Par 4 1 RS232 Level translation updated Annex A EVK schematics changed into vector format images better resolution ISSUEZA Par 8 CAMERA added with Annex B EVB for camera support schematics R
51. egulator select GND SN xr Ig ee q meet aAa 3 7V l 4 e E 4 1 Wh JL Dl RR r Fo 1 BR ur 1215061 51 y k L201 0 C S L1 NS 1215061 03F Ne PL202 zal _ Get ik eee aa 7 E io 202 1201 T LTT3 4CR 4701 LIUM 9295 Te DO3316 poete A IMG l L uc H2V INPUT 104 iG ra 8 15 8V Vcc 1 9 Soon 207 206 D201 Tov 1 41 6 24 STPS140Z EN Ck STPS140Z oum R203 N SOD123 EEUU SOD123 io noMount YES 9993 CONTE s Mal 717 gt eno 0603 GND GND FIND G ee a ee EN TIAS TT R204 gt 4 7K e 5 0603 72 GN gt a m p Ww lt lt Egu CN a 12V input switching regulator Eg oc worry PATH home users area DESCRIPTION FILE NAME cs944b cir ell EVK for GM862 S1 Mobile Terminals S p A Mod 067 rev 0 03 01 mi ee FORM T 5V 12V INPUT POWER REGULATORS A3 PROJECT SHEETN OFSHEETS DRAWING CODE E Locatelli M
52. ent flow If the layout of the 1 not well designed a strong noise floor 15 generated on the ground and the supply this will reflect on all the audio paths producing an audible annoying noise at 216 Hz if the voltage drop during the peak current absorption 1s too much then the device may even shutdown as a consequence of the supply voltage drop TIP The electrical design for the Power supply should be made ensuring it will be capable of a peak current output of at least 2 A 3 2 General Design Rules The principal guidelines for the Power Supply Design embrace three different design steps the electrical design the thermal design the layout Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 9 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 3 2 1 Electrical design Guidelines The electrical design of the power supply depends strongly from the power source where this power is drained We will distinguish them into three categories e 45V input typically PC internal regulator output e 12V input typically automotive e Battery 3 2 1 1 5 input Source Power Supply Design Guidelines e The desired output for the power supply is 3 8V hence there s not a big difference between the input source and the desired output and a linear regulator can be used A switching power supp
53. eproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 46 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 10 Annex A EVK schematics Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 47 of 63 224 215 21 1 22 2 22 2 72 N o On SH e Sow CURRENT UNLIMITED 0 BATTERY CHARGER INPUT 6 Vcc 2 15 0502 a A 0104 3Fs ee i eee ee LE 71 BC857B VS WARNING Q101 i Care must be taken to ensure 3 that the right polarity in the 2 power input is respected ag DO NOT Supply power when the gt D Battery is not connected Otherwise GM862 be damaged Zz I rga o Ozm X MEAE Mr TV tr 5 N Aaa a 40 a CURRENT LIMITED LL D cr BATTERY CHARGER INPUT _ 7 12 4 5 10 Vcc FCMMO502 S0103 P a 90 z T 5 T 5 lt amp 4 vcc ACPR SENSE FAULT GATE NTC SHDN BAT TIMER GND 8 H115 Z Nc7 GND Bi Poids GND 1d 80 104 68nF X7R
54. erating Range Interface levels 2 8V CMOS Output low level 0 0 35V Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 17 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit The signals of the GM862 GPRS serial port are RS232 GM862 Name Usage Pin GPRS Pin Number Number 1 DCD 36 Data Carrier Detect Output from the GM862 GPRS that uart indicates the carrier presence RXD Transmit line see Note Output transmit line of GM862 GPRS x uart UART TXD Receive line see Note Input receive of the GM862 GPRS rx uart UART 4 DTR 43 Data Terminal Ready Input to the GM862 GPRS that controls the DTE READY condition DSR Data Set Ready Output from the GM862 GPRS that dsr_uart indicates the module is ready RTS Request to Send Input to the GM862 GPRS that controls rts_uart the Hardware flow control CTS Clear to Send Output from the GM8062 GPRS that cts_uart controls the Hardware flow control RI 30 Ring Indicator Output from the GM862 GPRS that ri uart indicates the incoming call condition j NOTE According to V 24 RX TX signal names are referred to the application side therefore on the GM862 GPRS side these signal on the opposite direction TXD on the application side will be connected to the receive line here named TXD rx uart of the GM862 GPRS serial port a
55. g g g gg me E E ee car cp ee ar ec a a RC 211 600 101 800 m Ld qe emn em si pu bend pep nds qe oom pet up ot er m 801 800 001 900 qe Be EEN ol mulco ll 200 js SN 1S ie ae n is N E mE 1 Lot pt tt 4 Fi4 SS E 1 I e T y 88 A ___ X Q Z gt Q a 1 S sisSricc ages 8 952889556 Hoon 5555 26 z 1 1 M 1 1 1 Nadadiddod ALVIAIA AYNSOTOSIG ANY ANOIZVOTINAIG 3 ANOIZNGOUdIY Q3AH3SH SLHDIY TIV IL VAH3SIH I ILLAL 22 page 51 of 63 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved ALL RIGHTS RESERVED REPRODUCTION AND DISCLOSURE FORBIDDEN VIETATE TUTTI I DIRITTI RISERVATI RIPRODUZIONE E DIVULGAZIONE 1 lt 4 3 7 3 7V
56. harging phase since the battery at this point 1s fully charged and the process may stop after the final charge The maintenance charge provides an additional charging process to compensate for the charge leak typical of a Li Ion battery It is done by issuing pulses with a fixed time length again few hundreds of ms and a duty cycle around 5 or less Last but not least in some applications it 1 highly desired that the charging process restarts when the battery 1s discharged and its voltage drops below a certain threshold As you can see the charging process 15 not a trivial task to be done moreover all these operations should start only if battery temperature is inside a charging range usually 5 C 45 For these reasons it 15 preferable to use a dedicated charge controller IC again there are a multitude of them from the simplest constant current constant voltage regulator eliminating the qualification and maintenance phases to the more complex 4 phases controller NOTE For all the threshold voltages of the charging process and timeouts refer to your battery 1 manufacturer Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 13 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 An example of battery charger can be CURRENT wer BATTERY CHARGER INPUT _ 2 4 5 10 0103
57. in 6 through 50 circuits TE bea Be bs i heb rad TWH yee in 0 53 1 77709600 2 mmodated FFC FPC Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 44 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit NOTE GM862 PCS is 100 pin to pin compatible with previous GM862 models Therefore in order to connect the camera to the standard 50 pins Molex industrial connector some pins will dual function GPIO pins except for GPIO1 as usual GPIO operations or CAMERA support See Molex PIN OUT described in the GM862 PCS Product description 1 NOTE The CMOS camera must be removed when the GPIO pins are used for I O purpose 9 3 EVB for camera support In order to interface the Telit GM862 PCS with a CMOS camera Telit has developed an evaluation board The EVB is provided by e Opin Berg male connector PL201 and RS232 level translator that allows a direct connection to the PC To switch on the level translator a jumper shall be set on PL203 e 12 pin Berg male connector PL202 to supply the GM862 PCS mounted on the EVB The input source power should be in the range 4 5 V 12V Charge line is also provided in case a Li Ion battery 15 connect
58. ine TXD rx uart of the GM862 GPRS is NOT internally pulled up with a 1 resistor so there may be the need to place an external 47KO pull up resistor either dtr uart and RTS rts uart input lines are not pulled up internally so an external pull up resistor of 47KO may be required A power source of the internal interface voltage corresponding to the 2 8VCMOS high level 15 available at the PWRCTL pin on the connector whose absolute maximum output current is 1 A maximum of 9 47 KO pull up resistors can be connected to the PWRCTL pin provided no other devices are connected to it and the pulled up lines are GM862 GPRS input lines connected to open collector outputs in order to avoid latch up problems on the GM862 GPRS Care must be taken to avoid latch up on the GM862 GPRS and the use of this output line to power electronic devices shall be avoided especially for devices that generate spikes and noise such as level translators digital ICs or microcontrollers failure in any of these condition can severely compromise the GM862 GPRS functionality NOTE The input lines working at 2 8VCMOS can be pulled up with 47KO resistors that can be 22 connected directly to the PWRCTL line provided they are connected as in this example NO OTHER devices should be powered with the PWRCTL line otherwise the module functionality may be compromised Reproduction forbidden without DAI Telecom written authorization A
59. lines should be used where possible as inputs to the power amplifier This ensures a higher common mode rejection ratio reducing the GSM current busts noise on the speaker output In this case the EAR MT lines from the GM862 GPRS should be AC coupled with a capacitor of 100nF It is always desirable to have a mute control on the amplifier in order to turn it off while the device is not sending signal to the output in this manner the amplifier background noise which may be audible during idle conditions is cut off A principle schematic may be Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 37 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 7 P H3 eg E el Caen EAR QUT 4 Cu T LX cus MT cr YCC D GND Li H5 uF nM END GND The resulting gain and high pass cut can be obtained with the formula R3 Gain R2 1 Hz 2n R3 C4 And an example of internal Ear amplifier is INTERNAL EAR AMPLIFIER o x sm mee m TO SPEAKER 27 58 EAR zz um Lu 1 m TAF m FROM GM862 ceat CB22 I aw EE oe PL803 i i 1215051 03F D P i _ MUTE CONTROLLED sa lsa 3 atways 0603 507 do AMPLI POWER CONTROL Reprodu
60. ll Right reserved Right of modification reserved page 22 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 5 Microphone The microphone circuitry 15 the more noise sensitive and its design and layout must be done with particular care 5 1 Microphone line Characteristic and requirements Telit GM862 GPRS provides two audio paths for the microphone and the earpiece the internal and the external audio paths Only one of the two paths can be active at a time and it 1s selectable by hardware line AXE or by AT command The audio characteristics of the two paths are slightly different and this should be kept in mind when designing The internal audio path should be used for handset function while the external audio path is suited for hands free function car kit Both microphone paths from the Telit GM862 GPRS are balanced and the OEM circuitry should be designed balanced to reduce the common mode noise typically generated on the ground plane however for particular OEM application needs also an unbalanced circuitry can be used The microphone input lines characteristics are internal microphone path e line coupling 100nF cond e line type balanced e differential input resistance 25kO e line nominal sensitivity 50 mVrms e input voltage 360 mVims e microphone nominal sensitivity analog gain suggested 45 249 e echo canceller type
61. ly will not be suited because of the low drop out requirements e When using a linear regulator a proper heat sink shall be provided in order to dissipate the power generated A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption peaks close to the GM862 GPRS a 100uF tantalum capacitor is usually suited e Make sure the low ESR capacitor on the power supply output usually a tantalum one is rated at least 10V e protection diode should be inserted close to the power input in order to save the GM8062 GPRS from power polarity inversion An example of linear regulator with 5V input 15 15v input linear regulator 3 8 OUT LT152BLrO 5w INPUT H Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 10 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 3 2 1 2 12V input Source Power Supply Design Guidelines The desired output for the power supply is 3 8V hence due to the big difference between the input source and the desired output a linear regulator is not suited and shall not be used A switching power supply will be preferable because of its better efficiency especially with the 2A peak current load represented by the GM862 GPRS When using a switching regulator a 500Khz switching frequency regulator is preferable beca
62. m _ wid 0 L603 158 INT MIC SELECTION lox J LQG18HN39NJO0 39nH x LQG18 Here SO602 LGK2009 0201 C607 C616 9 inF SINGLE ENDED INTERNAL MIC ons Dus LGK2009 02 73V INT MIC SINGLE U603 Ou noy 5 5 BS Sse 2 G G OF Res Kc DEI 43V INT MIC SINGLE R621 T INT MIC ia 5 ST is 2 10K 0603 A R617 43V MIC EE C631 F HANDSET V125 Baie 0833 R620 ioo SO603 980 16V 95001 6881 E 16V 5 0603 5 SIGNAL FILTERING 0603 0603 BOOT RX dE A GND E L606 LQG18HN39NJOO hs ee GPIO L605 004 50 005 7 LQG18HN39NJOO LQG18 L604 MICR LOG18HN39NJOO _ 004 3D 008 10B LQG18 621 619 620 623 BN 3 MEDIEN COG COG X7R X7R X7R 50V 50V 50V 50V 50V 50V DESCRIPTION N G chi Nb 4 PATH home users area B UT Jele EVK for GM862 S1 Mobile Terminals S p A E Mod 067 rev 0 03 01 ANNOTATION PROJECT Deperini F ELE INTERNAL MICROPHONE SECTION ee qme SHEETN OFSHEETS DRAWING CODE MICROPHONE POLARIZATION REGUL
63. mands 2 1 Turning ON the GM 62 GPRS To turn on the GM862 GPRS the must be tied low for at least 1 second and then released The maximum current that can be drained from the ON pin is 0 1 mA A simple circuit to do it is ON RI _ L LI Ql Power ON impulse OND AN NOTE don t use any pull up resistor on line it is internally pulled up Using pull up resistor 27 may bring to latch up problems on the GM862 GPRS power regulator and improper power on off of the module The line must be connected only in open collector configuration NOTE In this document all the lines that are inverted hence have active low signals are labeled with a 57 name that ends with or with a bar over the name TIP To check if power has raised it is possible to monitor the START line when this line goes high the module is powered on but before it remains on the device needs other 900 ms for software startup Hence check the START line and 900 ms after its transition to high it is possible to release the pin For example l Let s assume you need to drive the ON pin with a totem pole output of a 3 5 V microcontroller OUTI Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 5 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 ah E ul
64. maximum battery voltage 1s never exceeded otherwise the battery may be damaged and even explode Moreover for the constant voltage final chargers the constant voltage phase final charge must not start before the battery voltage has reached its maximum value otherwise the battery capacity will be highly reduced The final charge can be of two different types constant voltage or pulsed The constant voltage charge proceeds with a fixed voltage regulator very accurately set to the maximum battery voltage and hence the current will decrease while the battery 1s becoming charged When the charging current falls below a certain fraction of the fast charge current value then the battery 1 considered fully charged the final charge stops and eventually starts the maintenance pulsed charge process has no voltage regulation instead the charge continues with pulses Usually the pulse charge works in the following manner the charge 1 stopped for some time let s say few hundreds of ms then the battery voltage will be measured and when it drops below its maximum value a fixed time length charging pulse is issued As the battery approaches its full charge the off time will become longer hence the duty cycle of the pulses will decrease The battery is considered fully charged when the pulse duty cycle 15 less than a threshold value typically 1046 the pulse charge stops and eventually the maintenance starts The last phase 1s not properly a c
65. nd plane are not overlapped to any noise sensitive circuitry as the microphone amplifier buffer or earphone amplifier e The power supply input cables should be kept separate from noise sensitive lines such as microphone earphone cables Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 16 of 63 J wa Telit GM862 PCS GPRS GSM Te It Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 4 Serial Port The serial port on the Telit GM862 GPRS is the core of the interface between the module and OEM hardware Several configurations can be designed for the serial port on the OEM hardware but the most common are RS232 PC com port microcontroller UART 2 8V Universal Asynchronous Receive Transmit microcontroller UART 5V or other voltages different from 2 8V Depending from the type of serial port on the OEM hardware a level translator circuit may be needed to make the system work The only configuration that doesn t need a level translation is the 2 8V UART The serial port on the GM862 GPRS is a 2 8V UART with all the 7 RS232 signals It differs from the 5232 the signal polarity RS232 is reversed and levels The levels for the GM862 GPRS UART are the CMOS levels Absolute Maximum Ratings Not Functional Input level on any 0 3V 3 75V digital pin when on Input voltage on 0 3V 3 0 V analog pins when on Op
66. nd viceversa for RX TIP For a minimum implementation only the TXD and RXD lines can be connected the other lines can i be left open provided a software flow control is implemented The signals in the UART connector on the EVK are Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 18 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 4 1 RS232 level translation In order to interface the Telit GM862 GPRS with a PC com port or a RS232 EIA TIA 232 application a level translator 1s required This level translator must invert the electrical signal 1n both directions change the level from 0 3V to 15 15V Actually the RS232 UART 16450 16550 16650 amp 16750 chipsets accept signals with lower levels on the RS232 side EIA TIA 562 allowing for a lower voltage multiplying ratio on the level translator Note that the negative signal voltage must be less than and hence some sort of level translation 1s always required simplest way to translate the levels and invert the signal 15 by using a single chip level translator There are a multitude of them differing the number of driver and receiver and in the levels be sure to get a true RS232 level translator not a RS485 or other standards By convention the driver 1s the level translator from the 0 3V UART level to the RS23
67. oblem it is preferable to set the gain of the microphone 10dB lower with respect to the calculated value for a nominal sensitivity The corresponding reduction in signal level will be compensated by an increased voice volume of the talker which will speak louder because of the ambient noise For the headset we shall distinguish two different types the headsets having the microphone sustained close to the mouth and the headsets having the microphone on the earpiece cable same considerations for the additional voice attenuation due to the distance from the microphone and the noise pick up can be made for the headset having the microphone on the earpiece cable while the other kind of headset shall be threaten as an handset For example With the external mic having the suggested nominal sensitivity 45dByrms pa at the normal spoken conditions 4 7dB at 7 cm from the mouth of the talker and with a further attenuation of 20dB due to the distance from the microphone about 50 cm At that acoustic pressure the voltage output from the microphone is Voltage Output dB 45 4 7 20 69 7 dByrms corresponding to Voltage Output 10 997 3 3 104 by having the microphone gain set to 10 dB corresponding to 5 times the signal in the nominal conditions on the input external mic pins of the GM662 GPRS will be Voltage 9 GM662 GPRS 3 3 10 3 1 MV us Hence in these conditions the
68. oller uP OUT2 gt RESET Bc E cs B alT 323 IFS M m He 6 gt Jnoconditional rower inpulse Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 8 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 3 Power Supply The power supply circuitry and board layout are the most important part the full product design and they strongly reflect on the product overall performances hence read carefully the requirements and the guidelines that will follow for a proper design 3 1Power Supply Requirements The GM862 GPRS power requirements are Nominal Supply Voltage 3 6 V e Max Supply Voltage 4 2V e Supply voltage range 3 4V 4 2V e Max Peak current consumption impulsive 1 9 e Max Average current consumption during transmission rms 350 mA Average current during Power Saving 4 mA e Average current during idle Power Saving disabled 17 mA The GSM system is made in a way that the RF transmission 15 not continuous else it 15 packed into bursts at a base frequency of about 216 Hz the relative current peaks can be as high as about 2A Therefore the power supply has to be designed in order to withstand with these current peaks without big voltage drops this means that both the electrical design and the board layout must be designed for this curr
69. or multiply circuit For example a circuit for the balanced microphone biasing can be 9 By 317 MIC MIC Biasing Regulator Gapacity multiply circuit Lem om o d 4V R2 JK Nt Electret micropnane GNO 0402 TEE MICH lt 1 To MIC Buffer amplifier MK 4 i lt R3 7 NOTE In the balanced application the resistors R2 and R3 must have the same value to keep the circuit balanced NOTE The microphone sensitivity changes with the value of R2 and R3 Usually the microphones are characterized with 2kO biasing resistance so try to keep the sum of R2 and R3 around 2kO Refer to your microphone manufacturer for the mic characteristics Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 27 of 63 p Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 5 3 2 Unbalanced Microphone biasing The unbalanced microphone biasing voltage should be obtained from a dedicated voltage regulator in order to eliminate the noise present on the power lines This regulator can be the same for all the audio paths The microphone should be supplied from a capacitor multiply circuit For example a circuit for the unbalanced microphon
70. output and therefore the buffer has to gain 24 db The corresponding values for the resistors on the buffer could be if we keep the input resistance R604 R606 gain R603 gain R605 15 10 150 The commercial values of 150kO amp IOkO are then chosen As a consequence the values of the capacitors C636 and C637 shall be 636 637 1 2p 8000 R606 132 10 F A commercial value of 100pF is then chosen Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 30 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 5 4 2 Buffered Unbalanced Single Ended Mic A sample schematic for a buffered unbalanced single ended microphone can be SINGLE ENDED MICROPHONE BUFFER 10 dB 13v EXT MIG SINBELE 3V EXT MIGC SINGLE GM862 i 3 DECOUPLING M MIC TO MIC TO GM862 MIC 33v EXT MIC SINBLE 701 D 3955 GM862_MIC 43v EXT MIC SINGLE 4 o i ix id n720 1 NK 40K a B C g GND Mm 5 amp a T 0603 M sa 0603 C a F C725 C720 715 100nF oles 100nF Y5V i 15V 5 0603 DU 0603 0603 END END END The schematic does not include the required mic biasing circuitry For the biasing the same circuit as seen before can be used to be no
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72. pically generated on the ground plane and to get the maximum power output from the device however for particular OEM application needs also a single ended circuitry can be designed The GM862 GPRS speaker output lines characteristics are internal speaker path EAR EAR MT e line coupling DC e line type bridged e speaker impedance operating conditions 16 5 1kHz minimum load impedance 150 e signal bandwidth 150 8000 Hz 3 dB e maximum differential output 850 MV ms e rated output power 10 mW e maximum power output 30 mW e volume level steps SW 2 dB e number of volume steps SW 10 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 34 of 63 Telit Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 external speaker path EAR EAR HF e line coupling e line type e speaker impedance operating conditions e minimum load impedance e signal bandwidth e maximum differential output e rated output power e maximum power output e volume level steps SW e number of volume steps SW The v 1 2 audio output characteristics are internal external ear single ended e line coupling e line type e speaker impedance operating conditions e minimum load impedance e signal bandwidth e maximum output e maximum power output e
73. rough a series resistor R718 of 470KO freq Hz For example Let s assume you have a microphone with these characteristics sensitivity 45 dByrms pa and you want to use it in the external mic audio path With the mic having nominal sensitivity 454 at the normal spoken conditions 4 7dB but at 50 cm from the mouth of the talker an additional 20 dB loss shall be considered At that acoustic pressure the voltage output from the microphone is Mic Voltage Output dB 45 4 7 20 69 7 dByrms corresponding to Mic Voltage Output 10 7 20 3 3 10 Vis in order to have a signal of 1 10 dB lower than the nominal input for the GM amp 62 GPRS external mic path on the GM662 GPRS internal mic inputs then the buffer must have a gain of Voltage 9 GM6862 GPRS intmic Mic Voltage Output 1 10 3 3 10 4 3 Hence in these conditions the signal level on the input pins of the internal mic of the GM862 GPRS is 10 dB 3 times higher than the microphone output and therefore the buffer has to gain 10 db To calculate the resistor values it must be kept in mind that balancing the line will double the signal and hence already add 6 dB therefore the buffer must gain only 1 5 times The corresponding values for the resistors on the buffer could be if we keep the input resistance 10 R711 gain R708 I 5 10 15 R719 gain 1 R720 1 5 1 10 5
74. signal level on the input pins of the external mic of the GM amp 62 GPRS is 10 dB 5 times lower than the nominal as suggested The microphones usually need a biasing network that provides the necessary DC current to the mic this will be explained further on In the EVK all the microphone input jacks have the hot wire connected to the central pole Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 25 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 5 2 General Design Rules There are several configurations for the audio path but the most effective difference is between balanced and unbalanced microphone It is highly recommended to keep the whole microphone path balanced even if this means having 2 wires connecting the microphone instead of one needed plus ground in the unbalanced case The balanced circuitry is more suited because of its good common mode noise rejection reducing the 216 Hz burst noise produced during the GSM transmissions e Where possible use balanced microphone circuitry Keep the microphone traces on the PCB and wires as short as possible e f your application requires an unbalanced microphone then keep the lines on the PCB balanced and unbalance the path close to the microphone wire connector if possible e For the microphone biasing voltage use a dedicated voltage reg
75. st be tied low for at least 1 second and then released The same circuitry and timing for the power on shall be used The device shuts down after the release of the ON pin TIP To check if the device has powered off the hardware line START should be monitored When START goes low the device has powered off 2 2 1 2 Hardware Unconditional shutdown To unconditionally turn OFF the GM862 GPRS the pin RESET must be tied low for at least 200 milliseconds and then released The maximum current that can be drained from the pin is 0 15 mA A simple circuit to do it is d Lo LI Unconditional Power OFF impulse RESET Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 7 of 63 Telit GM862 PCS GPRS GSM Te IC Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 NOTE don t use any pull up resistor on the RESET line nor any totem pole digital output Using pull J up resistor may bring to latch up problems on the GM862 GPRS power regulator and improper functioning of the module The line RESET must be connected only in open collector configuration f TIP The unconditional hardware shutdown should be always implemented on the boards and software should use it as an emergency exit procedure For example 1 Let s assume you need to drive the RESET pin with a totem pole output of a 3 5 V microcontr
76. ticed that the capacitor C3 on the unbalanced biasing circuit 1s not anymore needed if this Buffered design 15 used Two different configurations are used one inverting and the other not inverting hence an additional 6dB 2 times gain is achieved by doubling the mic signal path The gain of the not inverting buffer is given by the formula R719 R720 and hence it cannot be less than In the example shown the gain of the not inverting buffer is 1 5 While the gain of the inverting buffer 15 given by the formula Gain 1 4 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 31 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit As shown in the balanced buffered mic the gain adjustments can be done by changing R719 R720 and R708 R711 and as a consequence the capacitors C726 and C727 The bandwidth 3dB is given by the approximated formula considering C725 gt gt C726 1 1 27 R719 726 2 RT11 C727 The buffer bandwidth at 3dB shall 8kHz Note that the biasing of the operational amplifier is given for the inverting amplifier by the series divider R714 R715 The 100nF capacitor C719 15 needed to filter the noise that could be coupled to that divider For the not inverting operational the biasing is given by a different divider R715 R717 with the capacitor C720 and th
77. ulator and a capacitor multiply circuit e Make sure that the microphone traces in the PCB don t cross or run parallel to noisy traces especially the power line e If possible put all around to the microphone lines a ground trace connected to the ground plane by several vias This is done in order to simulate a shielded trace on the PCB e The biasing circuit and eventually the buffer can be designed in the same manner for the internal and external microphones 5 3 Microphone Biasing The electret microphones usually need a biasing voltage to work properly Refer to your microphone provider for the characteristics required NOTE The microphones have a hot wire were the positive biasing must be connected usually it is lt indicated by a sign or a red point If the polarity of the bias is reversed then the microphone will not work properly For this reason be sure to respect the mic biasing polarity Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 26 of 63 Telit GM862 PCS GPRS GSM Hardware User guide 1vv0300613 Rev ISSUE 4 10 02 04 Telit 5 3 1 Balanced Microphone biasing The balanced microphone bias voltage should be obtained from a dedicated voltage regulator in order to eliminate the noise present on the power lines This regulator can be the same for all the audio paths The microphone should be supplied from a capacit
78. use of its smaller inductor size and its faster transient response This allows the regulator to respond quickly to the current peaks absorption For car PB battery the input voltage can rise up to 15 8V and this should be kept in mind when choosing components all components in the power supply must withstand this voltage A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption peaks a 100uF tantalum capacitor is usually suited Make sure the low ESR capacitor on the power supply output usually a tantalum one 15 rated at least 10V For Car applications a spike protection diode should be inserted close to the power input in order to clean the supply from spikes A protection diode should be inserted close to the power input in order to save the GM862 GPRS from power polarity inversion This can be the same diode as for spike protection An example of switching regulator with 12V input is t12V INPUT 12 input switching regulator BAT62 OeW 0204 5020 89 3 8V OUTPUT 2 07202 C207 206 24 2 40uF gt 1 D203 Y b STPS140Z CONT C2048 Mark GND 24 25v 35v 1 BnF 500123 0503 CONT E 2 Boy BNO CAID 0503 GND GND NNN D03316 Reproduction forbidden without DAI Telecom written authorization All Right reserved Right of modification reserved page 11 of 63 Telit GM862 PCS GPRS GSM H

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