CH1786 Family of Ultra Small 2400bps Modems
Contents
1. Name Type Characteristic Value SPK O DF Minimum Load 3000 Maximum Capacitive Load 0 01y Output Impedance 100 Output voltage 2 54 1 6V D C Offset 20mV 2003 Cermetek Microelectronics Inc Page 16 Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Table 12 CH1786 Pin Functions PACKAGE CONNECTION TABLE PIN NO FUNCTION PIN NO FUNCTION 1 RING 12 VID 2 TIP 13 DTR 3 RXA 14 DSR 4 TXA 15 RI 5 SPK 16 CTS 6 NC 17 DCD 7 NC 18 HS 8 SLEEP 19 VCC 9 NC 20 GND 10 TXD 21 RST 11 RXD 22 NC CH1786 A oe BOTTOM VIEW SIDE VIEW 0 015 SIDE VIEW Except CH1786LCNE CH1786NE CH1786LCNE CH1786NE 0 010 and CH1786NH and CH1786NH Only 1 All dimensions are in inches 2 Case dimensions are nominal 0 02 inches 3 Pin length is nominal 0 03 inches 4 Cermetek recommends that 0 04 inch diameter plated through holes are used with 0 060 inch diameter pads 5 Pin spacings are nominal 6 The CH1786LCNE CH1786NE and CH1786NH case has four 15mil round 15mil high standoffs on the bottom of the package Figure 8 CH1786 Physical Dimensions 2003 Cermetek Microelectronics Inc Page 17 Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Table 13 Summary CH1786 Family of Products2. 2003 Cermetek Microelectronics Inc In the event repairs are ever needed on the insert your product name they should be performed by insert your company name or an authorized representative of insert your company name For information contact insert your company address DEFAULT STATUS PERFORMANCE AND SPECIFICATIONS The following is a summary of the Default Configuration Profile installed by Cermetek Microelectronics Incorporated prior to delivery of the CH1786 Async mode selected 2400bps Bell 212A operation at 1200bps Even parity Auto answer enabled Disabled on CH1786NH Command echo ON All result codes enabled extended Wait for dial tone before dialing 22 seconds Detects busy signal Full word result codes Pulse dial make break ratio 239 61 DSR enabled Modem enabled DTR Disabled on CH1786NH DCD enabled Disabled on CH1786NH Speaker enabled but off when receiving carrier Speaker volume set to medium Local modem will grant RDL request from remote modem Guard tones disabled Minimum DTR pulse width 20 1 seconds Ring count 201 CH1786 Escape code character 243 Carriage return character 213 Line feed character 710 Back space character 08 Duration of wait for dial tone 202 seconds Duration of wait for carrier after dialing 30 seconds Duration of dial pulse comma 02 seconds Carrier detect response time 0 1 seconds Escape code guard time 1 second Length of use after comma 2 0 secon
3. product s user manual FOR YOUR USER S MANUAL The FCC Part 68 rules require the following or equivalent be provided to the end user of equipment containing a DAA Type of Service The insert end product name is designed to be used on standard device telephone lines It connects tot he telephone line by means of a standard jack called the USOC RJ 11C or USOC RJ45S Connection to telephone company provided coin service central office implemented systems is Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems prohibited Connection to party lines service is subject to state tariffs Changes in Attestation Procedure for Plugs and Jacks Name of applicant attests that the network interface plugs or jacks used on this equipment comply with and will continue to comply with the mechanical requirements specified in Part 58 sub part F specifically the dimensions tolerances and metallic plating requirements The compliance of these connectors will be assured by purchase specifications and incoming inspection Documentation of such specifications and or inspections will be provided to the FCC within 30 days of their request for the same Telephone Company Procedures The goal of the telephone company is to provide you with the best service it can In order to do this it may occasionally be necessary for them to make changes in their equipment operations or pro
4. 1200 or 300bps and parity odd even mark space or none via a host initiated training sequence This training also sets the speed of the data for originate calls The CH1786 will automatically adjust to the originators speed when answering calls The CH1786 matches the host s parity when it returns status messages to the host During a data connection however the modem passes parity through without interpretation or alteration Sleep Mode To minimize power consumption the CH1786 includes a power down feature called Sleep Mode When activated the CH1786 will automatically enter Sleep Mode after 0 to 254 seconds of inactivity The inactivity delay is selected using the ATS24 command The CH1786 is delivered from the factory with a 5 second inactivity delay enabled i e ATS24 5 The CH1786 returns to normal operation when a ring signal is received or Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems upon an input low signal on the TXD pin ATS24 255 disables the Sleep Mode and is the default if no value is set in register S24 A SLEEP output signal is available to control power to external devices In Figure 6 a FET controlled by the SLEEP signal turns of the external speaker amplifier when the CH1786 enters Sleep Mode n Sleep Mode power is reduced to approximately 50 of normal operating power Guard Tone A guard tone of 550 Hz or 1800 Hz can be g
5. 408 752 5004 CERMETEK WEB SITE http www cermetek com EMAIL sales cermetek com iModem Network WEB SITE http www imodem net or https sunnyvale imodem net 2003 Cermetek Microelectronics Inc Page 18 Document No 607 0004 Revision L1 06 03 erlgum This datasheet has been downloaded from www EEworld com cn Free Download Daily Updated Database 100 Free Datasheet Search Site 100 Free IC Replacement Search Site Convenient Electronic Dictionary Fast Search System www EEworld com cn All Datasheets Cannot Be Modified Without Permission Copyright O Each Manufacturing Company
6. Dial amp V View Active Configuration Qn Result Code Display Option amp Wn Store Active Profile Sn Select an S Register amp Yn Recall Active Profile Sn Write to an S Register amp Zn Store Telephone Numbers Sn Read an S Register Percent Function Vn Result code Form Option Commands Xn Result Code Set Call Progress Dn DTMF Attenuation Option J Load Secondary Factory Escape Code Sequence Pause Defaults Pause Returns Last addressed S Register PHONE LINE CONNECTION GUIDELINES Yn Long Space Disconnect Option 1 The CH1786 must be mounted in the final Fn On Line Echo character Option assembly such that it is isolated from exposure to Z Reset any hazardous voltages within the assembly 2003 Cermetek Microelectronics Inc Page 10 Adequate separation and restraint of cables and cords must be provided Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems 2 10 Figure 6 The circuitry from the CH1786 to the telephone line interface must be provided in wiring that carries no other circuitry other than that specifically allowed in the FCC rules such as A and A1 leads Connection to phone line should be made through an RJ 11C jack PCB traces from the modem s RING and TIP pins to the RJ 11C jack must be 0 1 inch spacing or greater to one another and 0 2 inch spacing or greater to all other traces The traces should have a nomi
7. Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Table 8 CH1786 Electrical Specifications Parameter Description Min Typ Ma Units Vec Positive Supply Voltage Noise less than 50mV 4 75 5 0 5 V Icc Off Hook Nominal Operating Current when modem is OFF Hook 50 7 mA Icc On Hook Nominal Operating Current when modem is ON Hook 25 50 mA lccep Power Down Current 10 mA Vin High Level Input Voltage 2 V Vit Low Level Input Voltage 0 3 0 8 V lin Input Leakage Current TXD DTR RTS 15 A uA lio Leakage Current DCD HS RXD SLEEP DSR 10 uA Cp Capacitive Lead TXT DTR RST 10 pF VT Positive Hysteresis Threshold for RESET pin 2 5 V VT Negative Hysteresis Threshold for RESET pin 1 8 V Von High Level lou 0 5mA 2 4 V VoL Low Level lo 1 6mA 0 6 V Test conditions VCC 5V 10 Temp 0 C to 70 F unless otherwise stated Output Load 50 pF one TTL Table 9 CH1786 Electrical Specifications Parameter Minimum Typical Maximum Units Comments Off Hook Impedance 20 Ohms Trans Hybrid Loss 25 dB 600 Ohm RXA TXA Ring Voltage Loop 110V 250V Vop On 48VDC line voltage for sustained periods Line Loop Current Off 20 100 mA Hook Return Loss 1000Hz 15 dB 600 Ohm Ring Frequencies 40 Hz Receiver Insertion Gain 0 5 0 0 0 5 dBm 600 Ohm Data Mode Transmit Power 9 5 dB First Char
8. Model Summary of Features Operating Temperature CH1786 Full function Voice Inject NVRAM FCC Part 68 approved UL 1950 0 C to 70 C Listed Hermetic CH1786ET Full function Voice Inject NVRAM Zero Power Option FCC Part 68 40 C to 85 C Approved UL 1950 Listed Hermetic CH1786FX Full function FAX Voice Inject NVRAM FCC Part 68 approved UL 0 C to 70 C 1950 Listed Hermetic CH1786FXNE Full function FAX Voice Inject NVRAM FCC Part 68 approved UL 0 C to 70 C 1950 Listed Non Hermetic CH1786LC Full function Voice Inject FCC Part 68 Approved UL 1950 Listed 0 C to 70 C Hermetic CH1786LCNE Full function Voice Inject FCC Part 68 approved UL 1950 Listed 0 C to 70 C Non Hermetic CH1786NE Full function Voice Inject NVRAM FCC Part 68 approved UL 1950 0 C to 70 C Listed Non Hermetic CH1786NH Full function FCC Part 68 Approved Non Hermetic Listed UL 1950 0 C to 70 C Cermetek reserves the right to make changes in specifications at any time and without notice The information furnished by Cermetek in this publication is believed to be accurate and reliable However Cermetek assumes no responsibility for its use or for any infringements of patents or other rights of third parties resulting from its use No license is granted under any patents or patent rights of Cermetek Printed in U S A 406 TASMAN DRIVE SUNNYVALE CA 94089 LOCAL 408 752 5000 TOLL FREE 1 800 882 6271 FAX
9. The ring signal is typically 20 to 30 Hz and is on for 2 seconds and off for 4 seconds Although not TTL compliant the RI pin can nonetheless be utilized to activate external circuitry including the external RST pin When using the RI pin it is recommended that a Schmitt Trigger or the Isolated Envelope Detect Circuit in Figures 3 or 5 be placed between the RI pin and the external load Power Supply The CH1786 modem module is a complex set of sub systems During the course of Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems normal operation the CH1786 decodes analog signals from the telephone line that are in the millivolt range Steps must be taken by the user to guarantee that power supply noise on all supply lines including ground does not exceed 50 mV peak to peak Any frequency between 20 kHz and 150 kHz must be less than 500 micro volts peak If necessary use dedicated power and ground planes Failure to provide such operating conditions could cause the CH1786 to malfunction or to function erratically The CH1786 requires a single 5V 5 supply It is recommended that by pass capacitors be placed on the power supply as close to the modem s supply input as practical Its recommended a 10 uF Tantalum capacitor in parallel with a 0 01 pF ceramic capacitor be used Voice DTMF Tone Injection Port The CH1786 provides two pins to allow the user to share
10. enabled with the Xn command Where n 0 1 2 3 4 establishes the result codes allowed by the user XO Result Codes 0 1 2 3 4 allowed X1 Result Codes 0 1 2 3 4 5 10 allowed X2 Result Codes 0 1 2 3 4 5 6 10 allowed X3 Result Codes 0 1 2 3 4 5 7 10 allowed X4 Result Codes 0 1 2 3 4 5 6 7 10 allowed The CH1786 is factory set to X4 which allows all result codes MODEM STATES The CH1786 can be in either command mode or data mode When the modem is idle it is in command mode by default and will recognize commands When data transmission is in progress the CH1786 is in the data mode state and will not recognize commands To force the CH1786 to recognize commands the host must send an escape sequence to the CH1786 forcing it out of data mode and into command mode Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems ANALOG VOICE RXA lt t INJECTED SIGNALS TXA TELEPHONE LINE OPTIONAL PHONE CONTROL VOICE DATA RELAY SPEAKER CONTROL NOTE SPEAKER CONTROL AND PHONE CONTROL ARE ANCILLARY CIRCUITS V 24 SHOWN ELSEWHERE IN THIS DATA SHEET EIA 232 D SIGNAL GND MUST BE CONNECTED TO INTERFACE RI EARTH GROUND EXTERNAL RESET Isolated envelope ring detect Figure 5 CH1786 Application Diagram 2003 Cermetek Microelectronics Inc Page 6 Document No 607 0004 Revision L1 06 03 Cermetek
11. must adjust its rate or terminate the call Table 1 indicates the connection rate that will result when the calling modem s Initial Trained Rate and the answering modem s Initial Trained Rate are different NOTE A 2400 baud connection rate will only result if both modems are initially set at 2400 baud Zero Power Mode CH1786ET only If an application calls for zero power during standby periods the power may be switched off using external circuitry and then reapplied when the CH1786 s RI 2003 Cermetek Microelectronics Inc Page 3 pin becomes active The CH1786ET products can thus be powered down to zero Table 1 Connection Rates Connection Rate Resulting When Calling Modem Initial Rate Is Answering Modem Initial Trained Rate 300 1200 2400 CH1786ET PD UL 22K ENVELOPE RING DETECT Figure 3 Zero Power Operation Referring to Figure 3 the controller activates the relay switch supplying power 5V to the CH1786ET In this configuration the ring signal is used to wake up the CH1786ET when the CH1786ET is in the power down state The pins of the CH1786ET will be in an undefined state when power is switched off This must be taken into consideration to assure that no unwanted signals are presented to the CH1786ET during power down Ring Indicator RI The RI pin follows the frequency of the ring signal and toggles low when the CH1786 detects an incoming call
12. submitting the final end product to an independent test house or consultant for evaluation The test house or consultant then forwards the test results and applicable documents to the regulatory agency Call Cermetek for a list of suggested consultants Non Volatile RAM NVRAM The NVRAM present on the CH1786 is sufficient to store up to two user customized modem configurations The AT amp Wn command will store the active modem configuration in the selected NVRAM locations by specifying an n of 0 or 1 The AT amp Yn command selects the modem configurations to be automatically recalled and made active upon a reset or power up The ATZn command immediately recalls and activates a stored configuration Refer to Tables 4 5 and 6 for storable S Registers and available commands The NVRAM can save up to four telephone numbers with up to 36 digits or modifiers in each telephone number The AT amp Znzs command will store s the telephone number dial string The individual NVRAM telephone number storage locations are selected by specifying an n of 0 1 2 0r 3 The ATDTS n command will cause the modem to dial the stored telephone number in location n NVRAM is not available on the CH1786LC or CH1786NH 2003 Cermetek Microelectronics Inc Page 2 SUPPORT FEATURES AT Command Set A 40 character command line is supported The command line starts with AT and may contain standard or enhanced commands The commands are compatible with EIA Doc
13. the telephone line interface associated with the modem for voice and DTMF applications Figure 4 contains a schematic indicating one possible configuration for voice tone utilization WARNING The CH1786 has been FCC Part 68 approved as a data modem only Utilization of the Voice DTMF Tone Port requires further registration FCC will require that the system including the CH1786 and the handset or DTMF transceiver adhere to Part 68 rules Voice Tone Injection is not active on CH1786NH Typically voice communication would precede data communications For this case the following commands should be used to configure the CH1786 Refer to Figure 4 TI TLC274 OR EQUIV RXA CH1786 MECHANICAL RELAY ONLY A ZERO IMPEDANCE SWITCH MAY REPLACE THE RELAY AND TRANSISTOR CIRCUIT 2N2222 Figure 4 Voice Tone Injection Enter ATSOZ CR Result OK 2003 Cermetek Microelectronics Inc Disables auto answer Enter ATS72255 CR Disables data carrier time Result OK out Enter ATS102255 CR Disables lost carrier time Result OK out The following command sequences illustrate implementation of common Voice Tone Port applications 1 To answer a voice call a Enter ATH1 lt CR gt Result OK b Drive V INJ HIGH to activate relay c Begin voice conversation 2 To switch to data mode a Drive V INJ LOW b At the originate modem Enter ATX1 lt CR gt Result OK 3 To disconnect hang up a
14. C 25 Delay to DTR Framing S27 Bit Mapped Options Register FRT n Receive Test Data S28 Bit Mapped Options Register FTTn2m Transmit test Data Note Table 6B Dial Modifiers Summary In Tables 4 5 6A 6C an signifies parameters that Dial Modifiers Function are stored in NVRAM upon receipt of the amp W P Pulse Dial command The CH1786LC CH1786LCNE R Originate Call in Answer CH1786NE and CH1786NH do not contain NVRAM Mode and therefore do not support data storage after T Touch Tone Dial power down A detailed definition of all commands W Wait for Dial Tone and registers is available from Cermetek Return to Idle State Microelectronics Inc Refer to Cermetek Document Wait for Quiet Answer AT Commands and S Registers Reference Guide or Command access our website at www cermetek com Flash Hook Paul Table 5 CH1786 AT Command Set Summary 0 9 Dial Digits Characters Basic Function A B C D Commands AT Attention Code Table 6C Ampersand and Percent Commands A Answer command Ampersand Function Al Repeat last Command Commands BN Communications Standard Option amp Cn Data Carrier Detect Option D Dial Command amp Dn Data Terminal Ready Option E Off Line Character Echo Option amp F Load Factory Defaults Hn Switch Hook Control Option amp Gn Guard Tone Option Ln Speaker Volume Option amp Pn Make to Break Ratio Section Mn Speaker Control Option amp Sn Data Set Ready Option On On Line Command amp Tn Test Command Option P Pulse
15. Cermetek microelectronics CH1786 Family of Ultra Small 2400bps Modems INTRODUCTION The CH1786 family of modems are a full function FCC Part 68 approved 2400bps modem These modems provide a fast easy and flexible way to integrate a modem into any OEM product while utilizing the minimum amount of PCB space 1 01 x 1 27 x 0 52 The CH1786 family only requires two external interfaces a CCITT V 24 serial interface that can be routed directly to a UART and a Tip and Ring interface which goes directly to an RJ 11 jack for the PSTN line connection The CH1786 can be controlled with industry standard AT commands and hence is compatible with available industry communication software All CH1786 modems support asynchronous operation at 2400bps 1200bps and 300bps to both Bell and CCITT standards The resident PSTN line interface or Data Access Arrangement DAA while being FCC approved is also Canadian DOT approvable and can be approved in other countries that require 1500VAC RMS isolation requirements per UL 1950 Edition 3 The CH1786 family of modems operate off a single 5 volt supply The low power operation and automatic standby mode make these modems ideally suited for portable equipment In addition their small physical size affords maximum flexibility in equipment design CH1786 SERIAL V 24 INTERFACE TELEPHONE LINE INTERFACE MODULATION DEMODULATION SPEAKER INTERFACE Figure 1 Functional Block Diagr
16. Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Table 2 CH1786 Pin Descriptions PIN NAME TYPE FUNCTION 1 RING O RING Directly connects to the telephone line s Ring lead through a user supplied RJ 11C jack 2 TIP 1 0 TIP Directly connects to the telephone line s Tip lead through a user supplied RJ 11C jack 3 RXA O ANALOG VOICE INJECTED Receive Signal Let float if not used Not active in CH1786NH 4 TXA ANALOG VOICE INJECTED Transmit Signal Let float if not used Not active in CH1786NH 5 SPK O SPEAKER Audio output for speaker See speaker control schematic in Figure 6 6 NC No connection 7 NC No connection 8 SLEEP O SLEEP A LOW indicates CH1786 is in low power idle mode Used to control power to other devices See Figure 6 Register S24 is the sleep timer register When the CH1786 is inactive for a period of time specified by 824 the CH1786 will power down by about 50 of its normal operating power During power down all I O lines become undefined The CH1786 products are shipped from the factory with a 5 second inactivity timer ATS24 5 enabled 9 NC No connection 10 TXD TRANSMIT DATA Serial Transmit data input Marking or a binary 1 condition is transmitted when a HIGH is asserted 11 RXD O RECEIVE DATA Serial Receive data output Received marking or binary 1 condition is indicated by HIGH 12 V D O VOICE DATA Used to switch between teleph
17. The SO register controls the number of rings that must occur before the modem answers a call The register may range in value from 0 to 255 S0 0 DO NOT ANSWER TELEPHONE S0 1ANSWER ON RING 1 S0 2ANSWER ON RING 2 S0 3ANSWER ON RING 3 S0 255 ANSWER ON RING 255 When SO is set to 0 the modem will not auto answer The Serial Interface Lines The CH1786 supports a full EIA 232D V 24 serial interface Signal levels are TTL rather than EIA 232D level compatible which allows direct connection of the CH1786 to the host UART without the need for level translation circuitry See Table 2 for a complete pin description The CH1786 is controled by sending it serial commands over TXD and it s status determined by monitoring the serial status messages returned on RXD DTR is optionally used to reset terminate calls or return CH1786 to command mode All other serial interface lines may be utilized for the convenience of a particular application but are not required by the CH1786 Unused outputs from modem should be left unconnected Unused inputs should be set to the proper logic level See Table 2 Fax Modes The CH1786 Product Family supports Send and Receive FAX The modes and rates are determined by the AT F commands Refer to Table 6A FAX modem processing CCITTV 29 CCITTV 27 and CCITT V 21 recommendations All modulation wave form spectrum and data processing functions conform to the appropriate specifications is expli
18. a certified independent lab to verify compliance For Canada use either 10Q resistors carbon film or SMD parts 1 8 watt minimum as described in paragraph B above 2 Over Voltage and Lightning Protection A Surge Protection is provided by internal circuitry contained within all CH1786 Products except the CH1786NH see Figure 7 No additional external components are required to maintain conveyed FCC Part 68 approval for al CH1786 Products excluding the CH1786NH 2003 Cermetek Microelectronics Inc OPTIONAL EXTERNAL OVER VOLTAGE AND SURGE PROTECTION FUNCTION OVER VOLTAGE AND LIGHTNING CURRENT LIMIT All CH1786 Modems Except CH1786NH BUT REQUIRED FOR CH1786NH PSTN Line Interface for all CH1786 Products Page 13 B For CH1786NH the required surge protection identified as D1 in dashed Box 2 must be supplied externally The purchaser must include some form of surge protection as described herein to maintain conveyed FCC Part 68 approval C In most environments 2 suppressors are adequate environments use an external device with an earth ground terminal surge For severe 3 terminal 3 EMI RFI Suppression No external EMI RFI noise suppression circuitry is required to maintain conveyed FCC Part 68 approval However additional suppression if required for other reasons may be added as described below in Sections 3A 3B without adversely affecting FCC Part 68 approval A To provid
19. acter After Reset 0 5 1 0 5 sec Delay Inter Character Delay 20 50 msec Between all command characters Command Delay 100 200 msec Between all AT commands Minimum Reset Pulse 10 msec If user supplied Duration 2003 Cermetek Microelectronics Inc Page 15 Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Table 10 Other Performance Specifications Parameter Minimum Typical Maximum Units Comments Tone 2 Harmonic 35 dB HYB enabled into 600Q Distortion DTMF Twist Balance 3 dB DTMF Tone Duration 50 255 ms 95ms default Pulse Dialing Rate 8 10 20 pps 10pps default Pulse Dialing Make 39 61 US Canada default Break Pulse Dialing Make 33 67 UK Hong Kong Break Pulse Interdigit Interval 700 3000 ms 789ms default Guard Tone Frequency 550 Hz Referenced to High Channel Transmit Guard Tone Amplitude 6 dB Referenced to High Channel Transmit Guard Tone Frequency 1800 Hz Referenced to High Channel Transmit Guard Tone Amplitude 9 dB Referenced to High Channel Transmit High Channel Transmit 1 dB Referenced to Low channel Amplitude Guard tone enabled Guard Tone 2 40 dB Harmonic Distortion Call Progress 120 620 Hz Passband Frequency Wait Time for Dial tone 2 255 Sec Two second default Return loss 1000Hz 30 dB T 6000 2 16 UF Table 11 Analog Characteristics
20. am of CH1786 The CH1786 comes with FCC Part 68 approval and is shipped from the factory with an FCC Part 68 label indicating the registration number and ringer equivalent This label should be prominently displayed on the end product 2003 Cermetek Microelectronics Inc Page 1 FEATURES e Supports Standards 212 and Bell 103 FCC Part 68 approved and DOT CSA CS 03 Part approvable UL 1950 and CSA C22 2 950 Listed UL File Number E104957 AT Command structure with extensions 1500 VAC RMS isolation barrier minimum 2122V peak surge protection minimum Single 5 volt operation Low power operation with automatic reduced power standby mode e Automatic adaptive equalization Size 1 01 x 1 27 x 0 52 nominal NVRAM allows storage of custom configurations and telephone numbers CCITT V 22bis V 22 Bell and fixed compromise CH1786 FAMILY CH1786 NVRAM Voice Inject Hermetic Operating Temperature 0 C to 70 C CH1786ET NVRAM Voice Inject Hermetic Operating Temperature 40 C to 85 C CH1786NH Non Hermetic Operating Temperature 0 C to 70 C LE BING Ry 11 TIP Jack TP gy RING Jack OPTIONAL PHONE TELEPHONE _ LINE CH1786 2N2222 VID pin is used to create a separate port for telephone connection sharing of the tip and ring lines V D is TTL compatible lo 1 6mA Vo 0 4v and is active during data connection thereby isolating the telephone from
21. cedures If theses changes might affect your service or the operation of your equipment the telephone company will give you notice in writing to allow you to make any changes necessary to maintain uninterrupted service In certain circumstances it may be necessary for the telephone company to request information from you concerning the equipment which you have connected to your telephone line Upon request of the telephone company provide the FCC registration number and the ringer equivalence number REN both of these items are listed on the equipment label The sum of all of the REN s on your telephone lines should be less than five in order to assure proper service from the telephone company In some cases a sum of five may not be useable on given line Consult your telephone provider If Problems Arise If any of your telephone equipment is not operating properly you should immediately remove it from your telephone line as it may cause harm to the telephone network f the telephone company notes a problem they may temporarily discontinue service When practical they will notify you in advance of this disconnection If advance notice is not feasible you will be notified as Soon as possible When you are notified you will be given the opportunity to correct the problem and informed of your right to file a complaint with the FCC Contact your local telephone service provider if you have nay questions about your phone line
22. citly defined in Table 4 CH1786 Register Summary Register Function S0 Ring to Answer On S1 Ring Count S2 Escape Code Character S3 Carriage Return Character S4 Line Feed Character S5 Back Space Character S6 Wait for Dial tone S7 Wait for Data Carrier S8 Pause Time for Comma Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Table 4 CH1786 Register Summary Table 6A FAX Command Set Summary Continuation FAX Command Function Register Function FCLASS n Select Service Class S9 Carrier Detect Response Time F lt command gt Report Active Configuration S10 Lost Carrier to Hang up Delay F lt command gt Report Operating Capabilities S11 DTMF Dialing Speed FAA n Data Fax Auto Answer 12 Escape Code Guard Time FF Enhanced Flow Control S14 Bit Mapped Options Register FTS n Stop Transmission and Wait S16 Modem Test Options FTSM n Transmit Data 21 Bit Mapped Options Register FTH n Receive Data 22 Bit Mapped Options Register FTH n Transmit Data with HDLC 23 Bit Mapped Options Register Framing 24 Sleep Mode Inactivity Time FRH n Receive Data with HDL
23. d ATO lt CR gt guard time The guard time is set by register 12 The escape character code is set in register S2 At power up the guard time is set to 1 second minimum AT COMMAND APPLICATIONS and the escape character is set as There is no Dialing A Phone Number The Dial command takes minimum delay between characters but the maximum the form Dn where n is a string of characters In the delay is set by register S12 simplest form n will be only the digits of the phone number to be dialed The CH1786 will stay off hook with its carrier on after Example Dial number the escape sequence is received It will return an OK Enter ATD1234567 lt CR gt 2003 Cermetek Microelectronics Inc Page 8 Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Result OK In response to this command the CH1786 dials the telephone number 123 4567 and then waits for a carrier from the distant modem If no carrier is detected within a given time the default time is 30 seconds the CH1786 automatically releases the line and sends a NO CARRIER result code If a carrier is detected the CH1786 gives a CONNECT result code and goes on line permitting communication with the distant modem The Dial Command may also be issued without a telephone number ATD causes the modem to pick up the telephone line without dialing a number Pause During Dialing When placing a call fr
24. ds Last carrier to hang up delay 0 1 seconds DTMF interdigit delay 20 1 seconds DTMF Attenuation 4dB Sleep mode inactivity time 5 seconds Long space disconnect disabled Document No 607 0004 Revision L1 06 03 C Figure 7 1 ermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems l INTERNET MODEM AND OR DAA EMURFI SUPPRESSION Currently Limiting PSTN Protection Line Device Currently limiting devices are mandatory to meet UL safety standards To maintain conveyed FCC Part 68 approval the current limiting components identified as F1 and F2 in dashed Box 1 must also survive FCC Part 68 surge testing Refer to Cermetek Application Note 126 Supplemental PSTN Line Protection for more details Refer to Application Note 130 Summary of Recommend Suppliers for a list of suppliers and associated part numbers A A Polyfuse rated at 0 15 amps is preferred because it resets automatically upon removal of the current flow Non resettable devices are also acceptable Refer to Application Note 130 for a complete list of recommended vendors and associated part numbers B Resistors 10Q carbon film or 1 8 watt minimum may be used in Canada as Canada has no requirements that PSTN equipment be operational after a Type B surge test C Although CSA CS 03 Part 1 Canada follows the requirements of FCC Part 68 USA Cermetek recommends contacting DOT Canada and or
25. e adequate EMI RFI suppression the capacitor inductor network contained in dashed Box 3 should be located as close to the RJ11 Jack as possible Further this network should be provided with an excellent ground path to the chassis B Capacitors C1 and C2 should not exceed 0 005uf They must have a rating of 1 5KV and typically are 0 001uf 20 Inductors L1 and L2 may be either individual inductors or a dual inductor Refer to Application Note 130 for a complete list of recommended vendors and associated part numbers For UL applications choose capacitors and inductors that are UL 1950 listed The actual values of the components used may vary depending on the end product design Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Table 7 CH1786 System Data Mode Compatibility Specifications Parameter Specification Parameter Specification Asynchronous 2400 1200 600 bps character Receive Carrier Originate 2400Hz 7Hz asynchronous Frequencies Answer 1200Hz 7Hz 0 300 bps asynchronous V 22 bis V 22 212A Asynchronous Speed TXD may differ 4196 2 5 Bell 103 Answer space 2020Hz Range from modem output Offsets 7Hz will be corrected by adding Answer mark 2225Hz deleting stop bits 7Hz Originate space 1070Hz 7Hz Originate mark 1270Hz 7Hz Asynchronous Format 8 9 10 bits including start Rece
26. enerated at 6 dB or 9 dB below the transmit level respectively by using the amp Gn command Refer to Cermetek AT Commands and S Registers reference Guide or the Cermetek web site at http www cermetek com Answer Tone A CCITT 2100 Hz or Bell 2225Hz answer tone is generated depending on the selected configuration Refer to Cermetek AT commands and S Registers Reference Guide or the Cermetek web site at http Awww cermetek com Data Encoding The data encoding conforms to CCITT recommendations V 22bis or V 22 or Bell212A or 103 depending on the selected configuration Refer to Cermetek AT commands and S Register Reference Guide or the Cermetek web site at http Awww cermetek com Line Equalization Transmitter and receiver digital filters compensate for delay and amplitude distortion during operation on nominal phone lines In addition automatic adaptive equalization in the receiver minimizes the effects of inter symbol interference Transmission Speed In normal operation the originating modem initiates the call and attempts to connect to the answering modem at a speed established by the originating modem s controller prior to call initiation This is referred to as the Initial Trained Rate Upon receiving the call the answering modem will attempt to connect to the originating modem at its Initial Trained Rate If these two rates are identical the connection is made If the speeds differ the answering modem
27. for 200ms after reset has been initiated to allow the CH1786 time to properly reconfigure Training the Modem Each modem must be trained to match its host s speed and parity so that it is able to recognize serial asynchronous commands sent to it by the host s is UART The host must retrain the modem each time a reset pulse is applied on RST or after a RESET serial command has been issued Modem Training Command Sequence The CH1786 is trained by sending it the following sequence Enter AT lt CR gt Result OK Where A and T may be either upper or lower case but must be the same case lt CR gt represents carriage return The AT sequence is referred to as an attention sequence The CH1786 will respond with one of the following status messages depending on whether it is optioned for Terse abbreviated or Verbose English status messages Result 0 lt CR gt Terse or Result lt CR gt lt LF gt OK lt CR gt lt LF gt Verbose Where lt CR gt represents carriage return ASCII 13 or HEX OD lt LF gt represents line feed ASCII 10 or HEX 0A After responding with an OK the CH1786 is in idle mode and is ready to accept additional commands An alternate attention sequence A may be sent which behaves much like the AT sequence except that it causes the previously entered command specified with an AT prefix to be executed When given both the AT and A must be in upper case ASCII No carriage return is needed for t
28. he A command THE COMMAND FORMAT Typical commands consist of three elements the attention sequence the commands themselves and a terminating carriage return AT commands lt CR gt Where AT represents attention sequence Commands represents command strings 2003 Cermetek Microelectronics Inc Page 5 lt CR gt represents carriage return ASCII 13 or HEX OD When entering commands to the modem the backspace character control H ASCII 8 or HEX 08 may be used to edit mistakes AT and A may not be edited Multiple commands may be placed in the command line A command line may be as long as 40 characters excluding the letters AT By way of example the command below instructs the CH1786 to configure itself to not echo characters when in command mode EO and then put itself in answer mode A Enter ATEOA CR Result OK AT Command Set The available command set is divided into four types of commands dial modifiers basic commands ampersand and percent commands Refer to the complete list in Table 5 AT Command Data Rate With the serial interface the rate is speed sensed for parity and format THE STATUS MESSAGES The CH1786 responds with a status message after each command is executed This status message may either be a single digit followed by a carriage return or a carriage return and line feed with a message in English followed by a carriage return and line feed The basic status code subsets are
29. ically sealed except the CH1786LCNE CH1786NE and CH1786NH and will not be harmed by industry standard wave soldering processes Cermetek recommends against exposing the non hermetic CH1786LCNE CH1786NE and CH1786NH to aqueous based rinsing processes Socketing The socketing approach to mounting eliminates cleaning and desoldering concerns When the socket is used it must make a solid connection to all pins Failure to do so will cause unreliable or intermittent operation Also steps should be taken to assure that the module remains tightly seated in the socket during shipping Cermetek recommends using Sockets from Samtec See Application Note 130 Summary of Recommended Suppliers FCC REGISTRATION All products in the CH1786 family are registered with the FCC Federal Communications Commission under Part 68 To maintain the validity of the registration you must serve notice to the end user of the products of several restrictions the FCC places on the modem and its use In addition to restriction notification the FCC requires that Cermetek make all repairs to all products in the CH1786 family If repairs are necessary after installation of the CH1786 in the end product and the end product has been delivered to the end user the end product must be returned to the end product supplier where the CH1786 can be removed and then forward to Cermetek for repair The following notice is recommended and should be included in the end
30. ing at 2400bps 19 VCC POWER SUPPLY 5 volts 5 Note Noise should be less than 50mV peak to peak 20 GND GROUND Note Noise should be less than 50mV peak to peak 21 RST RESET Active HIGH This input must be asserted HIGH for at least 10 ms to reset the modem RESET is then returned LOW for normal operation If no system reset is available let this pin float to enable internal reset 22 NC No connection required For CH179X or CH2056 compatibility connect to GND or use as an active LOW input for request to send RTS functionality for CH179X 2056 products Note 1 If VCC has a slow power up ramp time the internal reset may be ineffective 2 Do not drive LED s directly from any output Use Buffers Table 3 Summary of Result Codes and Meanings Result Codes Status Message Meaning 0 OK Command Executed 1 CONNECT Carrier detected at 300bps 2 RING Ring Detected 3 NO CARRIER Did not detect carrier 4 ERROR Entry error 5 CONNECT 1200 Carrier detected at 1200bps 6 NO DIAL TONE Off hook but no response after 5 seconds 7 BUSY Busy signal detected 10 CONNECT 2400 Carrier detected at 2400bps The escape sequence consists of a guard time a status message when it is ready to accept period where no characters are sent to the modem commands The CH1786 may be put into data mode followed by 3 escape characters followed by another by issuing the comman
31. iver OFF to ON threshold 43 stop parity Sensitivity dBm ON to OFF threshold 48 dBm Telephone Line Interface Two wire full duplex over Billing Delay 2 0 to 3 0 seconds Ta 25 C public switched network On chip hybrid and billing delay timers Modulation V 22 bis 16 point QAM at 600 Hysteresis 2 dB minimum baud V 22 and 212A 4 point DPSK at 600 baud 103 Binary phase coherent FSK Self Test Pattern Alternate ones and zeros Line Fixed compromise Generator and error detector to be used Equalization equalization transmit along with most loopbacks A Adaptive equalizer for number indicating the bit PSK QAM receive errors detected is sent to DTE Transmit Carrier Originate 1200Hz x 0196 Diagnostic Local analog loopback Frequencies V 22 bis Answer 2400Hz 01 Available Local analog loopback V 22 212A Remote digital loopback Request remote digital loopback Local interface loopback modem with self test Bell 103 Originate space 1070Hz Call Progress With speaker or quiet screen 01 Tones Detected messages No dial tone Originate mark 1270Hz busy ring back modem 01 answer tone and voice Answer space 2020Hz Computer IBX PC XT AT bus 01 Interface compatible with an Answer mark 2225Hz 8250 16450 16550A UART 01 as a Serial controller 2003 Cermetek Microelectronics Inc Page 14 Document No 607 0004 Revision L1 06 03 Cermetek
32. nal width of 0 020 inches or greater The RING and TIP PCB traces should be as short as possible and oriented to prevent coupling other high speed or high frequency signals present on the host circuit PCB No additional circuitry other than that shown in Figure 7A or 7B may be connected between the modem module and the RJ 11C jack Doing so will invalidate the FCC approval The CH1786LC CH1786LCNE and CH1786NH only requires external surge protection see Figure 7B This is mandatory to maintain FCC Part 68 conveyed approval The CH1786 the RJ 11C jack the interfacing circuitry and all PCB traces in between must be contained on a PCB with a 94 V 0 flammability rating The supplied FCC registration label must be applied visibly on the outside of the product The product s User Manual must provide the user with instructions for connection and use as recommended in the FCC Registration Section below VNO300L 2N7000 Speaker Control Circuit Optional to allow for call progress monitoring 2003 Cermetek Microelectronics Inc CH1786 HANDLING AND ASSEMBLY RECOMMENDATIONS The CH1786 contains static sensitive components and should only be handled by personnel and in areas that are properly protected against static discharge The two recommended mounting techniques for physically connecting the CH1786 to a PCB are discussed below Direct Soldering The CH1786 may be wave soldered All CH1786 products are hermet
33. om an office with a telephone connected to a PBX it may be necessary to dial an access code usually the digit 9 to get an outside line Inserting a comma in the telephone number instructs the modem to pause for a specific length of time The factory set default pause time is 2 seconds Example Dial 9 pause dial number Enter ATDT9 1234567 lt CR gt Result OK Multiple commas may be used to generate integer multiples of the specified delay time Originate a Call in Answer Mode The D command forces the modem into originate mode To call an originate only modem dial the number and set the modem to answer mode via the R command reverse originate This is done by including an R at the end of the telephone number Example Change modem from original only to answer mode ATDT1234567R lt CR gt OK Enter Result Multiple commas may be used to generate integer multiples of the specified delay time Redial Last Number The repeat command is a convenient way to execute the previously entered command line Example Use A the repeat command to redial the last telephone number dialed Enter Al Result ATDT1234567R lt CR gt Previous command OK line executed Return to Command State Use to return to command mode offer dialing Example Touch tone dial 9 pause dial number return to Command 2003 Cermetek Microelectronics Inc Page 9 Enter Result ATDT9 1234567 CR OK Automatic Answering
34. one and modem line use In a typical application V D active HIGH opens the normally closed voice injection relay and disconnects the handset from the telephone line HIGH indicates the CH1786 is off hook and online Therefore this pin also reflects the state of the off hook relay of the CH1786 See Figure 2 13 DTR DATA TERMINAL READY Active LOW Switching off DTR can either return modem to command state disconnect phone call or reset modem DET should be set LOW when not used 14 DSR O DATA SET READY LOW indicates handshaking with a remote modem is in progress and or the data carrier of a remote modem has been detected 15 RI O RING INDICATION This signal follows the frequency of the ringing signal and is normally about 20 to 40 Hz for 2 seconds on with 4 seconds off 16 CTS O CLEAR TO SEND No connect if not using the FAX option Reserved for flow control when using FAX option CTS only active on CH1786 when S24 255 17 DCD O DATA CARRIER DETECT LOW indicates a data carrier from a remote modem is detected Must be enabled using the amp C1 command 2003 Cermetek Microelectronics Inc Page 7 Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Table 2 CH1786 Pin Descriptions Continuation PIN NAME TYPE FUNCTION 18 HS O SPEED INDICATION HIGH speed select output A low on this pin indicates the modem is operat
35. the tip and ring lines Note the relay chosen must meet the appropriate regulatory agency requirements Figure 2 Voice Data Port Control Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems DESCRIPTION OF FUNCTIONAL BLOCKS AND DISCUSSION OF BASIC OPERATIONS Figure 1 contains a functional block drawing of the CH1786 The CH1786 is a highly integrated full function modem comprised of a modulator demodulator controller NVRAM and an FCC Part 68 approved and UL 1950 CSA C22 2 950 listed PSTN line interface Modulation Demodulation and Modem Controller These functions are provided by a monolithic modem integrated circuit This IC has built in facilities to accommodate integrated AT command control and contains the necessary resident interfaces for general communication and routing to the DAA Telephone Line Interface or DAA The CH1786 family of modems is designed to meet 1500VAC RMS isolation and provide 2122V peak surge protection Consequently the CH1786 satisfies U S FCC Part 68 and DOT CSA CS 03 Part Canadian requirements and will meet other international approval agency requirements that specify these levels of isolation With the exception of the U S most countries including Canada require submission of the final product or system containing the CH1786 to the appropriate governing regulatory agency for approval Typically this is accomplished by
36. ument TR302 2 88 08006 Serial Host Interface The serial interface is a V 24 EIA 232 compatible interface Ten Bits total 1 start bit 1 stop bit and eight data bits which can be either eight bits with no parity or seven odd or even with parity The start bit is LOW going RXD and TXD data is non inverted See pin description in Table 2 Speaker Interface The SPK output reflects the receiver analog input and provides a signal that can be used to monitor call progress The SPK signal can drive a 300 O load directly Typically the SPK signal is input into an audio power amplifier and the amplifier in turn drives the speaker coil The speaker is activated with the ATMn command The speaker volume is adjusted using the ATLn command where n is 0 1 2 0r 3 Increasing numbers correspond to higher volume Figure 6 indicates one method of driving an external 8 O speaker Phone Control Cermetek s CH1786 contains a pin called Voice or Data V D The V D pin toggles high when the modem goes off hook This pin can be used to activate a relay which can switch a telephone on or off the Tip and Ring incoming PSTN lines This feature allows any telephone associated with the CH1786 to be disconnected when a data call is in progress thereby preventing the data from being disturbed by an inadvertent telephone pick up See Figure 2 Speed and Parity Selection Prior to call initiation the host controller trains the modem to the host speed 2400
37. voice call or a data call a Enter ATH lt CR gt Result OK 4 Toplace acall to 1234567 using the CH1786 s DTMF tone generator a Enter ATDT1234567 CO CR Result OK b Drive V INJ HIGH MODEM CONTROL The CH1786 modem may be controlled by sending serial ASCII command sequences The commands are sent to the modem serially on the TXD pin After execution of a received command the modem returns a serial status message that can be read on pin RXD This message indicates command completion status Refer to Table 3 for a complete list of status messages INITIALIZING THE MODEM Before commands may be sent to the CH1786 the CH1786 must be initialized Initialization is a two step activity consisting of 1 Hard Reset This is accomplished by applying a hardware reset pulse to pin RST or by switching the power off and then back on 2 Initial modem training The CH1786 must be trained to the host s speed 2400 1200 300bps and parity odd even mark space or none These activities are briefly described below Document No 607 0004 Revision L1 06 03 Cermetek Microelectronics Inc CH1786 Family of Ultra Small 2400bps Modems Reset Upon applying power to the CH1786 the CH1786 automatically generates an internal reset pulse The user may also reset the modem externally by applying a high going reset pulse to the RST pin for at least 10ms after the 5V power supply has stabilized Delay sending commands to CH1786
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