TEA1118 and TEA1118A versatile cordless transmission circuits
Contents
1. 16 3 4 5 6 7891 2 3 4 5678910 f kHz Fig 32 DTMF gain versus frequency at different temperatures The input of the DTMF amplifier can handle signals up to 180 mVrms with less than 296 THD Fig 33 shows the distortion on line versus the rms input signal at lline 2 15 mA THD 10 T T Ri s L i i 7 4 Vin Vrms Fig 33 Distortion of the DTMF signal on line versus input signal 3 8 MUTE function TEA1118A only Principle of operation The mute realizes an electronic switching between the speech mode and the dialling mode If a high level is applied to the MUTE input both the transmit and the receive channels are disabled while the DTMF channel is enabled By applying a low level or leaving pin MUTE open the receive channel is enabled moreover if TMUTE pin level is low the transmit channel is also enabled The threshold voltage level is 0 68 V typically with a 29 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note temperature coefficient of 2 mV C Fig 34 shows the transmit gain reduction and MUTE input current versus MUTE input voltage Gvtx dB 8 2 V MUTE V Fig 34 Transmit gain and MUTE inpu2. Ad Hy bh 0 20 30 9 50 60 70 80 90 100 110 120 130 140 Tline mA Fig 12 Influence of Rslpe on the DC characteristics 3 1 2 Supply for peripherals This sub chapter concerns line powered applications which may not be usual for these ICs Principle of operation The supply voltage at pin VCC is normally used to supply the internal circuitry of the TEA1118 A However a small current can be drawn to supply peripheral circuits having VEE as ground reference The VCC supply voltage depends on the current consumed by the IC and the peripheral circuits as shown by the following formula VCC VCCO Rccint x Iqr Ip VCCO VLN Rec x lec Iqr internal current necessary to supply the receive output amplifier when there is AC signal Rccint Rcc internal equivalent impedance between VCC and VEE 16 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Rccint is the output impedance of the voltage supply point As can be seen from fig 7 the internal supply current Icc depends on the voltage on the pin VCC it means that the impedance of the internal circuitry connected between VCC and VEE is not infinite While supplying a peripheral circuit on VCC the Ip supply current flowing through the Rcc resistor decreases the value of the voltage on the pin VCC and then reduces the consumption So the impedance to use in combination with Ip and Iqr is not Rec but Rccint which
3. T 29 28 i 1 2 3 4 5 6 7 8 91 2 4 5678910 f kHz Fig 26 Receive gain versus frequency and temperature The maximum output swing QR depends on the DC line voltage the Rcc resistor the Icc current consumption of the circuit the lp current consumption of the peripheral circuits and the load impedance on QR The receiving input IR can handle signals up to 18 mVrms with less than 296 THD Fig 27 shows the distortion on QR when the limitation is related to the input voltage for a line current equal to 75 mA Fig 28 shows the distortion of the signal on QR as a function of the rms signal on QR with a load of 450 Q and a line current of 15 mA THD 0 3 Vrms Fig 27 Distortion on QR versus input signal on IR 25 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note THD 1 L 0 j nni 4 0 B P 8 E 45 Fig 28 Distortion on QR versus level with 450 load Fig 29 shows the noise on QR loaded with 150 Q psophometrically weighted P53 curve as a function of the line current This curve has been done with an open input IR With the antisidetone network connected to the input IR part of the transmit noise generated on the line will be added but thanks to the low transmit noise value the effect is negligible Vrms 60 5
4. 2 8 8 6 B5 7 vec lt Fig 7 lcc versus VCC Fig 8 shows the main voltages as a function of the line current 7 VLN Lie vec REG VREF d pr 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 Iline mA Fig 8 Main voltages versus line current 14 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Fig 9 shows the behavior in the low voltage area in line powered condition while fig 10 shows this behavior when the ICs are externally powered 4 i i vin 3 5 3 2 5 i 1 0 1 2 3 4 5 6 7 8 9 10 11 2 Tline mA Fig 9 Low voltage behavior in line powered conditions Vref 3 masa 2 5 tA TE T 0 4 S il 6 8 10 12 mA Fig 10 Low voltage behavior with external 3 3 V power supply Adjustments and performances The reference voltage Vref can be adjusted by means of an external resistor Rva It can be increased by connecting the Rva resistor between pins REG and SLPE see fig 11 or decreased by connecting the Rva resistor between pins REG and LN In case of line powered application it is not recommended to use the voltage reduction because it reduces the peripheral supply capabili
5. APPLICATION NOTE Application of the TEA1118 and TEA1118A versatile cordless transmission circuits AN96071 PHILIPS Philips Semiconductors D LI DS Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Abstract The TEA1118 and TEA1118A are bipolar transmission circuits for use in cordless telephone sets or answering machines They are part of TEA111x family A detailed description of the circuit blocks of the TEA1118 and TEA1118A and advices on adjustments are contained in this report Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note APPLICATION NOTE Application of the TEA1118 and TEA1118A versatile cordless transmission circuits AN96071 Author JM Malaurie Technical Marketing Telecom Products Caen France Keywords Telecom Demonstration Board TEA1118 TEA1118A Transmit DTMF Receive Date July 31st 1996 3 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Summary A detailed description of the blocks of both ICs TEA1118 and TEA1118A is given The possible settings to adjust the DC and transmission characteristics are explained The TEA1118 and the TEA1118A incorporate a transmit amplifier and a receive amplifier the TEA1118A incorporates also a DTMF amplifier An evaluation board for the TEA1118A which can be used for the TEA1118 is available The general not
6. VEE 5 ES 5 TX B 6 9 i 7 8 f AGC 8 1 1 LN Positive line terminal 2 2 SLPE Slope adjustment 3 3 REG Line voltage regulator decoupling 4 nc Not connected 5 4 TMUTE Transmit mute input 6 5 DTMF Dual tone multifrequency input 7 nc Not connected 8 6 MUTE Mute input 9 7 IR Receive amplifier input 10 8 AGC Automatic gain control 11 9 TX Inverting transmit input 12 10 TX Non inverting transmit input 13 11 VEE Negative line terminal 14 12 QR Receive amplifier output 15 13 GAR Receive gain reduction adjustment 16 _14 VCC Supply voltage for speech and peripherals Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 3 DESCRIPTION OF THE TEA1118 A All the curves shown in this section result from measurement of typical samples All the component names refer to the basic application of the ICs shown in fig 5 Vcc gt Cz Peripheral supply Rz Rec GND 100 uF Rtx2 Ctx1 TXA Rtx1 Rtx3 Ctx2 TXB TEA1118 A Cgar Cgars 100 pF Rgar Cear REC p i o MUTE MUTE O 4 TMUTE GAT TMUTE O DTMF SLPE VEE REG 100 nF Rgat Rslpe Cre 202 8 4 7 uF Fig 5 Basic application for measurements 12 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 3 1 DC characteristics and supply block Without influence on the DC characteris
7. Rast3 Zbal With the values used in this example it gives 32 dB at 1 kHz Zir is the receive amplifier input impedance typically 20 kO 3 9 2 Wheatstone bridge The conditions for optimum suppression are given by Zbal Rast1 Rslpe x Rec Zline Also for this bridge type a value for Zbal has to be chosen that corresponds with an average line length The attenuation of the received line signal between LN and IR is given by Vir Zir Rast Ra Zbal Zir Rast Ra Ra is used to adjust the bridge attenuation its value has no influence on the balance of the bridge 32 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 4 APPLICATION COOKBOOK In this chapter the procedure for making a basic application is given Reffering to fig 38 the design flow is given as a number of steps which should be made As far as possible for every step the components involved and their influence on every step are given Step _Adjustment DC setting Adjust the DC setting of the TEA1118 A to the local PTT requirements Voltage LN VEE This voltage can be adjusted by changing Vref increased up to 7 V witha resistor between pins REG and SLPE or decreased down to 3 V witha resistor between REG and LN DC slope The DC slope might be modified by changing the value of Rslpe this is not advised all gains are modified AGC characteristic is modified Suppl
8. Vrms Fig 18 Distortion on the line versus transmit signal at 5 dB gain on TEA1118 Fig 19 shows the distortion of the line signal versus the input transmit signal on the line at line current of 4 mA and nominal gain when the TEA1118 A are powered from an external 3 3 V power supply between VCC and VEE 20 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note THD 0 4 Vtrs Vrms Fig 19 Distortion of line signal at Iline 4 mA with external 3 3 V power supply Fig 20 shows the transmit noise psophometrically weighted P53 curve versus line current at nominal gain when a 200 resistor is connected between the inputs TX and TX Noise dBmp 82 70 75 Tline mA Fig 20 Transmit noise versus line current Fig 21 shows the common mode rejection ratio at 15 mA and at nominal transmit gain Two curves are present in this fig 21 the first one is the spectrum of the signal on pin LN when a transmit signal is applied on pin TX while pin TX is shorted to VEE the second one is the spectrum of the signal on pin LN when a transmit signal is applied on pins TX and TX shorted together Both signals are at 1 kHz the difference between the two curves gives the CMRR 21 Philips Semiconductors TEA1118 A versatile cordless transmission I
9. AND TEMPERATURE 2 2 2 12 2 2 2 020002020002204444444444444444 25 27 DISTORTION ON QR VERSUS INPUT SIGNAL ON 25 28 DISTORTION ON QR VERSUS LEVEL WITH 450 Q LOAD enne nene enne nenne ren 26 29 NOISEON O EE cans devs EXER EAE ved dave 26 30 AGC ON THE TRANSMIT GAIN VERSUS LINE CURRENT AND RAGC i 27 3K DIMECHANNEEOF THE TEA TTSA OE Feo GERE HER NES 28 32 DTMF GAIN VERSUS FREQUENCY AT DIFFERENT TEMPERATURES 00 29 33 DISTORTION OF THE DTMF SIGNAL ON LINE VERSUS INPUT SIGNAL ssseecccceecesssssecccceccceeeeuanseeccceeseuaaeseeeceeeeeeas 29 34 TRANSMIT GAIN AND MUTE INPUT CURRENT VERSUS MUTE INPUT 30 35 TRANSMIT AND RECEIVE GAIN REDUCTION IN MUTE CONDITION ON THE TEA1118A sene 30 36 TEA106x ORTEA111X FAMILY ANTI SIDETONE BRIDGE LEFT AND WHEATSTONE BRIDGE RIGHT 31 37 EQUIVALENT AVERAGE LINE IMPEDANCE eee eee eee 32 38 18 005 eer ooo Ere EE E Eee Pe E nt 36 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 1 INTRODUCTION The TEA1118 A offer all the transmit
10. Rcc Rp typically 620 15 5 Rgasint internal resistor realizing the current to voltage conversion typically 27 6 kQ with a spread of 15 Rrefint internal resistor determining the current of an internal current stabilizer typically 3 4 kQ witha spread of 15 correlated to the spread of Rgasint Zline load impedance of the line during the measurement a gain control factor varying from 1 at Iline 15 mA to 0 5 at Iline 75 mA when AGC function is applied see chapter 3 6 for details Using these typical values in the equation and assuming Zline 600 Q we find a gain equal to 18 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Gvtx 20 x log Avtx 11 8 atlline 15 mA The different gain controls AGC MUTE and TMUTE for TEA1118A only act on the transmit preamplifier stage modifying its transconductance Adjustments and performances On the TEA1118 only the transmit gain can be decreased by connecting a resistor Rgat between pins GAT and REG It can be adjusted from 11 dB to 5 dB to suit application specific requirements however this gain adjustment slightly increases the gain spread and affects the temperature coefficient due to matching between internal and external resistors Fig 15 shows the typicall curve of the transmit gain versus the external resistor Rgat The gain dependancy to this external Rgat resistor is given by the following equation
11. impedance between pins IR and VEE It is equal to 20 kQ with a maximum tolerance of 15 The ICs are able to drive loads down to an impedance of 150 As can be seen from fig 24 the receive amplifier itself is built up out of two parts a preamplifier which realizes a voltage to current conversion and an end amplifier which realizes the current to voltage conversion The overall gain Gvrx of the receive amplifier from input IR to output QR is given by the equation Gvrx 20 x log Avrx Avrx a x 1 21 x Rgarint Rrefint with Rgarint internal resistor realizing the current to voltage conversion typically 100 kQ with a spread of 15 Rrefint internal resistor determining the current of an internal current stabilizer typically 3 4 with a spread of 15 correlated to the spread of Rgasint a gain control factor varying from 1 at Iline 15 mA to 0 5 at Iline 75 mA when AGC function is applied see chapter 3 6 for details Using these typical values in the equation we find a gain equal to Gvrx 20 x log Avrx 31 dB atlline 15 mA The different gain controls AGC MUTE for TEA1118A only act on the receive preamplifier stage modifying its transconductance Adjustments and performances The receive gain can be decreased on the TEA1118 A by connecting a resistor Rgar between pins GAR and QR It can be decreased from 31 dB down to 19 dB to suit application specific requirements however this gain adjustment slightly
12. increases the gain spread and affects the temperature coefficient due to matching between internal and external resistors 31 dB of receive gain compensate almost typically the attenuation provided by the antisidetone network Fig 25 shows the typicall curve of the receive gain versus the external resistor Rgar The gain dependancy to this external Rgar resistor is given by the following equation Gvrx 20 log 1 21 x Rgarint Rgar Rrefint x o Gvrx dB ic GET nz ET I i 30 ZB RE ere C ES 25 20 15 10 5 0 10000 Rgarx kohms 1 1000 Fig 25 Receive gain versus Rgar connected between GAR and QR 24 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Two external capacitors Cgar connected between GAR and QR and Cgars connected between GAR and VEE ensure stability when the relationship Cgars gt 10 x Cgar is fulfilled The Cgar capacitor provides a first order low pass filter which cut off frequency is determined with Rgarint Rgar Fig 26 shows the frequency response of the receive amplifier at different temperatures Cgar 100 pF Cgars 1 nF 32 dB T T 75 C 31 25 1 25 C
13. receive and line interface functions required in cordless telephone sets or in answering machines They perform the interface between the line and the RF interface of a cordless telephone set or between the line and the codecs of a digital answering machine Furthermore the TEA1118A includes a DTMF amplifier for dialling The selection between the transmit amplifier and the DTMF amplifier is made with a MUTE or a TMUTE function The MUTE function switches off both the transmit and the receive amplifiers while the TMUTE switches off only the transmit amplifier both switch on the DTMF amplifier The TEA1118 is mainly dedicated to applications where DTMF is not necessary eg answering machine application or where DTMF is provided by some other part eg DECT application The TEA1118A is mainly dedicated to CTO base stations The report is divided into two parts the first part up to chapter 3 gives a detailed description of the different circuit blocks of the TEA1118 A including operating principles settings of DC and transmission characteristics and performances of the different functions the second part describes the consecutive steps to design and adjust applications using the TEA1118 A and introduces the demoboard Note the values of parameters given in this application note are as accurate as possible but please refer to the last product specification for final ones Philips Semiconductors TEA1118 A versatile cordless transmissio
14. 0 MA 20 4 ai E E xa 4 15 20 25 30 35 40 45 50 55 60 65 70 75 Tline mA Fig 29 Noise on QR 3 6 Automatic gain control Principle of operation The TEA1118 A perform automatic line loss compensation The automatic gain control varies the gain of the transmit and receive amplifiers in accordance with the DC line current To enable this AGC function the pin AGC must be connected to the pin VEE For line currents below a current threshold Istart typically 25 mA the gain control factor a is equal to 1 giving the maximum value to the gains Gvtx and Gvrx If this threshold 26 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note current is exceeded the gain control factor a is reduced and then the gains of the controlled transmit and receive amplifiers are also reduced When the line current reaches an other threshold current Istop typically 63 mA the gain control factor is limited to its minimum value equal to 0 5 giving the lower value to the transmit and receive controlled gains The gain control range of both amplifiers is typically 5 8 dB which corresponds to a line length of 5 km 0 5 mm twisted pair copper with an attenuation of 1 2 dB km The attenuation is correlated to the current lagc sunk at pin AGC when this current is lower than typically 5 pA the gains are maximum when this current is higher than typicall
15. 000100000000114 15 11 INFLUENCE OF AN RESISTOR BETWEEN REG AND SLPE ON VLN AT 15 eene 16 12 INFLUENCE OF RSLPE ON THE DC CHARACTERISTICS i 16 13 EQUIVALENT SET IMPEDANCE E EE 17 ERANSMERCHANNEEL ti E RI rio 18 15 TRANSMIT GAIN VERSUS RGAT CONNECTED BETWEEN GAT AND REG 19 16 TRANSMIT GAIN VERSUS FREQUENCY INFLUENCE OF TEMPERATURE 000 19 17 DISTORTION ON LINE VERSUS TRANSMIT SIGNAL AT NOMINAL GAIN ON 1118 20 18 DISTORTION ON THE LINE VERSUS TRANSMIT SIGNAL AT 5 DB GAIN ON TEA1118 20 19 DISTORTION OF LINE SIGNAL AT ILINE 4 MA WITH EXTERNAL 3 3 V POWER SUPPLY LL 21 20 TRANSMIT NOISE VERSUS LINE CURRENT ccccccccesssssecccececcesscsssececcccceesaueseecceeeseeuueseeccceeessuaesseececeessauaesesseeececeeeeaas 21 21 COMMUN MODE REJECTION RATIO ON TRANSMIT ccccccccsssseseccccecccusseuesseecccceeesauseceecccceesauaeseeecceeeesuanseeecceeessaannens 22 22 TRANSMIT GAIN AND TMUTE INPUT CURRENT VERSUS TMUTE INPUT VOLTAGE LL 22 23 TRANSMIT GAIN REDUCTION IN TMUTE CONDITION 1 2 000060000000000000000045 000000 23 24 RECEIVE CHANNEL ue NIMM E m rA SEO 23 25 RECEIVE GAIN VERSUS RGAR CONNECTED BETWEEN GAR AND QR rra 24 26 RECEIVE GAIN VERSUS FREQUENCY
16. Cs Application Note REF 0 DBM x OFFSET 0 HZ 10 DRESY RANGE 0 DBM B1 4 DB secs LI START 0 HZ STOP 5 000 0 HZ RBW 30 HZ VBW 100 HZ ST 11 2 SEC Fig 21 Common mode rejection ratio on transmit 3 4 TMUTE function TEA1118A only Principle of operation The transmit mute function realizes an electronic switching between the transmit amplifier and the sending DTMF amplifier This function disables the transmit channel to provide a kind of privacy function and at the same time enables the DTMF channel if needed for some specific applications this function has no effect on the receive channel If a high level is applied to the TMUTE input the transmit channel is disabled while the DTMF channel is enabled by applying a low level or leaving pin TMUTE open if MUTE pin level is low the transmit channel is enabled The threshold voltage level is 0 68 V typically with a temperature coefficient of 2 mV C Fig 22 shows the transmit gain reduction and TMUTE input current versus TMUTE input voltage dB IgA 20 144 y 10 N 12 0 i 20 i j E ES 75 25 C 25 40 6 50 A 60 2 70 11 50 4 6 8 12 8 1 0 2 1 v 0 204 6 12 14 16 18 Fig 22 T
17. Gvtx 20 x log 0 016 x Rgasint Rgat Rrefint x Ri Zline Rslpe x o Gvtx dB 12 10 100 1000 10000 Rgat kohms 0 Fig 15 Transmit gain versus Rgat connected between GAT and REG A capacitor Cgat can be connected between pins GAT and REG of the TEA1118 to provide a first order low pass filter which cut off frequency is determined by the product Cgat x Rgasint Rgat Fig 16 shows the typical frequency response of the transmit amplifier without filter of the TEA1118 A Gvtx dB Fig 16 Transmit gain versus frequency influence of temperature 19 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Fig 17 shows the distortion of the signal on the line as a function of the transmit signal at nominal DC settings and for a line current of 15 mA for TEA1118 A while fig 18 shows this distortion versus the input transmit signal when the transmit gain is reduced to 5 dB on the TEA1118 THD 4 2 75 5 15 1 125 15 175 2 225 15 3 Vln Vrms Fig 17 Distortion on line versus transmit signal at nominal gain on TEA1118 A THD 96 0 132 1 3 Vtrs
18. TEA1118A 36 VCC GND Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 6 ELECTROMAGNETIC COMPATIBILITY As no common international specification exists for RFI immunity and as different assembly methods may lead to different solutions only some advices can be provided It is advisable to take care of the impedance of the GND the smallest is always the best This means that the GND VEE trace must always be as large as possible the best is to have a second layer dedicated to this purpose TX TX inputs may also be sensitive RF signals entering these pins would be amplified Care has to be taken with the lay out of the transmit amplifier which is also helpfull for the noise providing a good decoupling to GND A low pass RC filter may be added at the input of the amplifier Low impedance capacitors in parallel with the electrolythic one between VCC and GND as well as in parallel with the Creg capacitor may help Usually a low impedance capacitor connected between LN and GND helps for the conducted interferences but this capacitor is in parallel with the impedance network of the apparatus so its value must be small enough In general when connections are coming from external environment e g TXP TXM A B on the demoboard it is better to filter the RFI signal before it influences the close environment of the TEA1118 A e g action of C1 C2 C11 on the demoboard 37 Phili
19. ation in this report for both ICs is TEA1118 A Note The information presented in this document does not form part of any quotation or contract is believed to be accurate and reliable and may be changed without notice No liability will be accepted by the publisher for any consequence of its use Publication thereof does not convey nor imply any licence under patent or other industrial property rights Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note CONTENTS T INTRODUC TO N creen 7 2 BLOCK DIAGRAMS AND PINNINGS i 8 3 DESCRIPTION OF THE TEATT118 A netten deat eni 12 3 1 DC characteristics and supply nnns 13 9 1 1 DG Characteristics rod ew cg e neu 13 3 1 2 Supply for peripherals ii 16 3 2 Set impedance 2cn CE 17 3 9 Transmit amplifler 2c or an 18 3 4 TMUTE f nction TEATTTSA only iere eterne hee ene eae 22 3D REGCIVE AMPI dare m 23 3 6 Automatic gairnicornitrol ioi Gai eee edie 26 3 7 DTMF amplifier TEA1118A 9 27 3 8 MUTE function TEA1118A 29 3 9 Anti sidetone ane a De a Os dada dale date do bute 31 3 9 1 TEA106x TEA111x family 31 3 9 2 Wheatstone brid
20. e circuit is composed of Rcc Zline Rast1 Rast2 Rast3 Rslpe and Zbal Maximum compensation is obtained when the following conditions are fulfilled Rslpe x Rasti Rec Rast2 Rast3 6 k Rast2 x Rast3 Rslpe Rast1 x Rslpe Zbal k x Zline The scale factor k is chosen to meet the compatibility with a standard value of capacitor for Zbal In practice Zline varies strongly with line lenght and line type Consequently the value for Zbal has to be chosen to fit with an average line length giving acceptable sidetone suppression with short and long lines The suppression further depends on the accuracy with which Zbal equals this average line impedance Example Let s optimize for a theorical equivalent average line impedance shown in Fig 37 31 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 1265 0 210 0 140 nF Fig 37 Equivalent average line impedance For compatibility of the capacitor value in Zbal with a standard capacitor value from the E6 series 220 nF k 140 220 0 636 For Rast2 a value of 3 92 kQ has been chosen So using the previous equations we can calculate Zbal Rast1 Rast3 We find Rast1 130 kQ Rast3 390 Q and for Zbal 130 Q in series with 220 nF 820 Q The attenuation of the receive line signal between LN and IR can be derivated from the following equation Vir Vin Zir Rast2 Rast1 Zir Rast2 If Rast2 gt gt
21. ed by a complex network see fig 5 Rcc Rz Cz The DC resistance which influences the value of VCC becomes Rcc Rz 17 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 3 3 Transmit amplifier Principle of operation In fig 14 the block diagram of the transmit amplifier of the TEA1118 A is depicted E TE M M MEE TEA1118A only Bs D 2221 GAT TEA1118 only TX Vu LN Rp rc Rgasint Rec Rexch EN n Rd REG SLPE Creg 4 Cexch Fig 14 Transmit channel The transmit amplifier has symmetrical high input impedances typically 64 2 times 32 between pins TX and TX with maximum tolerances of 15 The input of this transmit amplifier is able to handle AC signals up 900 mVrms with less than 2 total harmonic distortion As can be seen from fig 14 the transmit amplifier itself is built up out of two parts a preamplifier which realizes a voltage to current conversion and an end amplifier which realizes the current to voltage conversion The overall gain Gvtx of the transmit amplifier from inputs TX TX to output LN is given by the following equation Gvtx 20 x log Avtx Avtx 0 016 x Rgasint Rrefint x Ri Zline Rslpe with Ri the AC apparatus impedance
22. ficial inductor of the voltage stabilizer MUTE input of the TEA1118A TMUTE input of the TEA1118A transmit channel Demoboard of the TEA1118A Receive amplifier output pin of the TEA1118 A Resistor to adjust the sidetone bridge attenuation Antisidetone resistor Filter capacitor of the equivalent inductor connection pin of the TEA1118 A Bridge resistance of exchange Radio Frequency Interference 39 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Rgar External resistance to reduce receive gain of TEA1118 A Rgarint Internal resistance 100 kQ which sets the receive gain Rgasint Internal resistance 27 kQ which sets the transmit gain Rgat External resistance to reduce transmit gain of TEA1118 Rp Internal resistance between LN and REG SLPE Slope input pin of the TEA1118 A THD Total Harmonic Distortion TX TX Transmit amplifier input pins of the TEA1118 A VCC Positive supply of the TEA1118 A VEE Ground reference of the TEA1118 A Vin DC voltage between LN and VEE Vref Stabilized reference voltage between LN and SLPE Vslpe DC voltage level between SLPE and VEE Zir Input impedance of the receive amplifier of the TEA1118 A Zbal Anti sidetone network Gain control factor of the AGC 40
23. ge nett 32 4 APPLICATION COOKBOOK eret pn nior Denuo nap tace dnd erase dada 33 5 EXAMPLE OF APPLICATION 12 ie tcoce cater a 35 6 ELECTROMAGNETIC COMPATIBILITY in 37 ididd edle M 38 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note LIST OF FIGURES FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG FIG k TRATII S BEOCKDIAGRAM sibili 8 2 a ASS ASBEOCKCDIAGRAMR S Saia Rini 9 10 A DEAL ES AMPINNIINGS eG BE S Me M EON 1 3 5 5 CURE EORR ER RR Eb 12 6 DC CHARACTERISTICS CONFIGURATION 2 000 13 ICGVERSUSINC lla RU ge ae A E 14 8 MAIN VOLTAGES VERSUS LINE CURRENT uenit aeee E E E E N EEE EEE E E 14 9 LOW VOLTAGE BEHAVIOR IN LINE POWERED 15 10 LOW VOLTAGE BEHAVIOR WITH EXTERNAL POWER 8 2 1 22 20 002 0000000000000
24. in parallel with the transmit gain resistor between TEA1118 pins REG and GAT form a low pass filter The receive gain of the application has to be adjusted preferably after the output QR nevertheless it is possible to reduce the receive gain with the resistor Rgar A capacitor in parallel with the receive gain resistor between TEA1118 A pins QR and GAR form a low pass filter stability is ensured with capacitor Cgars gt 10 x Cgar between pins GAR and VEE TEA1118A only DTMF gain DTMF The DTMF level on line must be adjusted before entering pin DTMF It is selected with a high level either on pin TMUTE or on pin MUTE 34 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 5 EXAMPLE OF APPLICATION A demo board 0M4789 is available as the TEA1118 A may be used in various applications this demo board includes only the TEA1118A with its basic environment Replacing the TEA1118A by a TEA1118 may make it usable also for the evaluation of the TEA1118 which offers the possibility to reduce the transmit gain Fig 38 gives the basic application of the TEA1118 A On this schematic the capacitors connected with doted lines and the resistors drawn with dotted lines are indicated for RFI immunity purpose 35 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Cz 01 1118 TEA1118T Fig 38 Basic application of the
25. include in parallel the impedance of the internal circuitry connected between VCC and VEE For a line current equal to 15 and Rcc equal to 620 this Rccint impedance is 550 Q As VCC is limited to a minimum value to ensure correct operation Ip will be limited to a maximum value Adjustments and performances As the impedance connected between LN and VCC also determines the set impedance the easiest way to increase the current capability of the supply point VCC is to increase the reference voltage Vref by connecting a resistor Rva between pins REG and SLPE see 3 1 1 3 2 Set impedance Principle of operation The ICs behave like an equivalent inductance that presents a low impedance to DC Rslpe and a high impedance Rp to speech signals Rp is an integrated resistance in the order of 15 5 kQ 15 It is in parallel with the external RC realized by Rcc and Cvcc Thus in the audio frequency range the apparatus impedance called set impedance is mainly determined by the Rcc resistor Fig 13 shows an equivalent schematic for the set impedance LN Rec VCC Leq Creg X Rslpe X Rp Rp internal resistor Cvcc 100 VEE Fig 13 Equivalent set impedance Adjustments and performances When decreasing the reference voltage Vref a resistor is connected between LN and REG in parallel of Rp see fig 13 so slightly modifying the impedance If complex set impedance is required the Rcc resistor resistor is replac
26. n To avoid the transmit signal to come back with a too high level in the receive channel the anti sidetone circuit uses the transmit signal from pin SLPE which is in opposite phase to cancel the transmit signal at the IR input of the receive amplifier The anti sidetone bridge already used for the TEA106x or the TEA111x families or a conventional Wheatstone bridge as shown in fig 36 may be used for the design of the anti sidetone network Fig 36 Wheatstone bridge left and TEA106x orTEA111x family anti sidetone bridge right The TEA106x or TEA111x family anti sidetone bridge has the advantage of a relative flat transfer function in the audio frequency range between the input IR and the output QR both with real and complex set impedances Furthermore the attenuation of the bridge for the receive signal between pins LN and IR is independent of the value chosen for Zbal after the set impedance has been fixed and the condition shown in equation 6 is fulfilled Therefore readjustment of the overall receive gain is not necessary in many cases Compare to the previous one the Wheatstone bridge has the advantages of needing one resistor less anda smaller capacitor in Zbal But the disadvantages include the dependence of the attenuation of the bridge on the value chosen for Zbal and the frequency dependence of that attenuation This requires some readjustment of the overall receive gain 3 9 1 TEA106x or TEA111x family bridge The anti sideton
27. n ICs Application Note 2 BLOCK DIAGRAMS AND PINNINGS Fig 1 shows the block diagram of the TEA1118 fig 2 shows the block diagram of the TEA1118A the pinnings are shown in fig 3 and 4 GAR QR low voltage circuit Fig 1 TEA1118 block diagram Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note VCC LN REG AGC circuit low voltage circuit SLPE Fig 2 TEA1118A block diagram Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note NGG LN VCC la SLPE GAR QR REG QR TEA1118M ee GAT VEE i nc TX id nc TX AGE IR AGC IR Fig 3 TEA1118 pinnings TEA11I8MPIN_TEA1118TPIN__NAME DESCRIPTION 1 Positive line terminal 2 2 SLPE Slope adjustment 3 3 REG Line voltage regulator decoupling 4 4 GAT Transmit gain reduction adjustment 5 5 nc Not connected 6 6 nc Not connected 7 nc Not connected 8 nc Not connected 9 7 IR Receive amplifier input 10 8 AGC Automatic gain control 11 9 TX Inverting transmit input 12 10 TX Non inverting transmit input 13 11 VEE Negative line terminal 14 12 QR Receive amplifier output 15 13 GAR Receive gain reduction adjustment 16 14 _VCC _Supply voltage for speech and peripherals Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 0 14 a VCC E 13 GAR 14 12 QR 4 1118 4 TEAJIISAT
28. nd VEE 13 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note The DC line current Iline flowing into the apparatus is determined by the exchange supply voltage Vexch the feeding bridge resistance Rexch the DC resistance of the telephone line Rline and the voltage across the apparatus including diode bridge Below a threshold line current Ith typically equal to 7 5 mA the internal reference voltage generating Vref is automatically adjusted to a lower value down to an absolute minimum voltage of 1 6 V In this range the shape of the curve giving Vref versus line current is slightly different if VCC is used to supply peripheral circuits or if the TEA1118 A are supplied from external supply This means that more sets can operate in parallel or that for very low voltage feeding bridge the line current has a higher value For line currents below this threshold current the TEA1118 A has reduced sending and receiving performances This is called the low voltage area The internal circuitry of the TEA1118 A is supplied from pin VCC In line powered application this voltage is derived from the line voltage by means of a resistor Rcc and must be decoupled by a capacitor Cvcc Fig 7 shows the IC current consumption Icc as a function of the VCC supply voltage Tec mA 18 75 C OE M ND care Ten TAE eee
29. ps Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 7 REFERENCES 1 TEA1118 A Versatile cordless transmission circuit Device specification 2 TEA1118 A Line Interface Demonstration Board USER MANUAL of OM4789 report n CTT96001 3 Philips Semiconductors SEMICONDUCTORS FOR TELECOM SYSTEMS IC03 38 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note APPENDIX LIST OF ABBREVIATIONS AND DEFINITIONS A B AGC BRL DTMF EMC GAR GAT GND Gvmf Gvrx Gvtx IC lcc lline Islpe Istart Istop Ith k Leq MUTE TMUTE OM4789 QR Ra Rast REG Rexch RFI Line terminals of application example Automatic Gain Control line loss compensation Balance Return Loss matching between the apparatus impedance and a reference Dual Tone Multi Frequency ElectroMagnetic Compatibility Receive gain adjustment pin of the TEA1118 A Transmit gain adjustment pin of the TEA1118 Ground DTMF amplifier gain Receive gain Transmit gain Integrated circuit Current consumption of the TEA1118 A Line current Current consumption of the peripherals Internal current consumption fromVCC of the receive amplifier Receive amplifier input pin of the TEA1118 A Part of the line current flowing through SLPE pin Start current of the AGC function Stop current of the AGC function Threshold current of the low voltage part Scale factor of anti sidetone network Arti
30. ransmit gain and TMUTE input current versus TMUTE input voltage Adjustment and performances Fig 23 shows the transmit amplifier gain reduction at Iline 15 mA for an input signal of 1 kHz Two curves are present on this fig 23 the first one shows the spectrum of the signal on the line when a signal is applied on the transmit inputs and when TMUTE is at a low level the second one shows the same signal when pin TMUTE is at a high level The difference between the two curves at this frequency gives the gain reduction 22 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note REF D DBM OFFSET D HZ 19 pany 2 RANGE 0 DBM 80 7 DB START 0 HZ STOP 5 009 0 HZ 30 HZ VBW 100 HZ ST 11 2 SEC Fig 23 Transmit gain reduction in TMUTE condition The TMUTE function works down to a voltage on VCC equal to 1 6 V below this threshold the transmit amplifier stays always enabled independently of the TMUTE input level The maximum voltage allowed at pin TMUTE is VCC 0 4 V 3 5 Receive amplifier Principle of operation In fig 24 the block diagram of the receive amplifier is depicted MUTE Rgarint iv E dM 2 DTMF Fig 24 Receive channel 23 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note The receive amplifier has an a symmetrical high input
31. t preamp from receive TMUTE Fig 31 DTMF channel of the TEA1118A The DTMF amplifier has an a symmetrical high input impedance of 20 between pins DTMF and VEE with maximum spread of 15 The DTMF amplifier is built up out of three parts an attenuator by a factor of 10 a preamplifier which realizes the voltage to current conversion and the same end amplifier as the transmit amplifier No AGC is applied to the DTMF channel The overall gain Gvmf of the DTMF amplifier from input DTMF to output LN is given by the following equation with Gvmf 20 x log Avmf Avmf 0 032 x Rgasint Rrefint x Ri Zline Rslpe Ri the AC apparatus impedance Rcc Rp typically 620 Q 15 5 kQ Rgasint internal resistor realizing the current to voltage conversion typically 27 6 kQ with a spread of Rrefint internal resistor determining the current of an internal current stabilizer typically 3 4 kQ with a spread of 15 correlated to the spread of Rgasint Zline load impedance of the line during the measurement Using these typical values in the equation and assuming Zline 600 we find a gain equal to Gvmf 20 x log Avmf 17 4 dB 28 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Fig 32 shows the frequency response of the DTMF amplifier at 15 mA and different temperatures Gdtmf dB 18 759 25 C 25 C
32. t current versus MUTE input voltage Adjustments and performances Fig 35 shows the transmit and receive amplifier gain reduction at Iline 15 mA for an input signal of 1 kHz Two curves are present on these graphics the first one shows the spectrum of the signal on the line or on QR when a signal is applied on the transmit inputs or respectively on IR and when MUTE is at a low level the second one shows the same signal when pin MUTE is at a high level The difference between the two curves at this frequency gives the gain reduction REF D DEM 10 DB DIV RANGE 0 DBM T T OFFSET O HZ REF O DBM 80 7 DB OFFSET O HZ 10 DB DIV RANGE 0 DBM 93 9 DB ENS PM ees ee MM START O HZ RB 30 HZ VBW 100 HZ STOP 5 000 0 HZ START 0 HZ STOP 5 000 0 HZ ST 11 2 SEC RBW 30 HZ VBW 100 HZ ST 11 2 SEC Fig 35 Transmit and receive gain reduction in MUTE condition on the TEA1118A The MUTE function works down to a voltage on VCC equal to 1 6 V below this threshold the transmit and receive amplifiers stays always enabled independently of the MUTE input level The maximum voltage allowed at the MUTE input is VCC 0 4 V 30 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note 3 9 Anti sidetone network Principle of operatio
33. tics except a slight difference at very low line current the TEA1118 A can be used in two different supply configurations they can provide supply to peripheral circuits like any IC from the TEA111x family of line interfaces or they can be externally supplied if an external power supply is available 3 1 1 DC characteristics Principle of operation The ICs generate a stabilized voltage called Vref between pins LN and SLPE This reference voltage typically 3 35 V is temperature compensated The voltage at pin REG is used by the internal regulator to generate the stabilized Vref voltage and is decoupled by a capacitor Creg connected to VEE For effective operation of the apparatus the TEA1118 A must have a low resistance to the DC current and a high impedance to speech signals The Creg capacitor converted into an equivalent inductance see set impedance section realizes this impedance conversion from its DC value Rslpe to its AC value Rcc Rz Cz in the audio frequency range The DC voltage at pin SLPE is proportional to the line current This general configuration is shown in fig 6 Fig 6 DC characteristics configuration The ICs regulate the line voltage between pins LN and SLPE the voltage on pin LN can be calculated as Vin Vref Rslpe x Islpe Islpe Iline Icc Ip lin lline line current Icc current consumption of the IC supply current for peripherals Current consumption between LN a
34. ty To ensure correct operation it is not advised to adjust Vref at a value lower than 3 V or higher than 7 V the maximum operating voltage of 12 V must be guaranteed by the application These adjustments will slightly affect a few parameters there will be a small change in the temperature coefficient of Vref and a slight increase in the spread of this voltage reference due to matching between internal and external resistors Furthermore the Rva resistor connected between REG and LN will slightly affect the apparatus impedance see section set impedance 15 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note VLN V 8 foi 7 5 j 7 6 5 Li BEN BEI 6 J ss _ 5 4 ll 3 5 Hae pt LJ LU i 5 10 100 1000 10000 Rva kohms Fig 11 Influence of an Rva resistor between REG and SLPE on Vin at 15mA The DC slope of the voltage on pin LN is influenced by the Rslpe resistor as shown in fig 12 The preferred value for Rslpe is 20 changing this value will affect more than the DC characteristics it also influences the gains the AGC characteristics the maximum output swing on the line and the low voltage threshold Ith Vin V Bo nu T
35. y 13 A the gains are minimum This current is proportional to the voltage between pins SLPE and VEE There is an internal resistor which sets Istart and Istop adding one externally in series between pins AGC and VEE reduces lagc and increases the values of Istart and Istop Adjustments and performances The ICs are optimized for use with an exchange supply voltage of 48 V a feeding bridge of 2 x 300 Q and the line previously described In order to fit with other configurations a resistor Ragc can be inserted between pins AGC and VEE This Ragc resistor increases the two threshold currents Istart and Istop Fig 30 shows the control of the transmit gain versus the line current for different values of Ragc When no AGC function is required the AGC pin must be left open then the control factor a equals to 1 and both controlled gains are at their maximum values AGC dB T T T T T E A 0 a i d 4 f li 2 3 m E te 4 No WA Noo 5 6 I rer m 4 0 10 20 30 40 50 60 70 80 90 100 Tline mA Fig 30 AGC on the transmit gain versus line current and Ragc 3 7 DTMF amplifier TEA1118A only principle of operation In fig 31 the block diagram of the DTMF channel of the TEA1118A is depicted 27 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note from transmi
36. y point VCC In line powered applications depends on the values of Vref and the resistive part of the impedance network Rcc Rz External power supply can be applied Artificial inductor Its value can be adjusted by changing the value of Creg a smaller value speeds up the DC current shape during transients but decreases the value of the inductance and then affects the BRL Impedance and sidetone After setting the required set impedance the sidetone has to be optimized using the sidetone network in order to minimize the loop gain in all line conditions AGC can be adjusted at that step Application impedance The BRL is adjusted with the impedance network connected between LN and VCC Rec Rz Cz Sidetone Adjust Zbal Rbal1 Rbal2 Cbal according to the line characteristics AGC Internally defined the characteristics Istart and Istop can be shiftted to higher line currents with an external Ragc resistor connected between AGC and VEE 33 Philips Semiconductors TEA1118 A versatile cordless transmission ICs Application Note Step _Adjustment TEA1118 A transmit and receive gains Transmit gain Receive gain The transmit gain of the application has to be adjusted preferably before entering pins TX TX for the TEA1118 A For the TEA1118 only it is also possible to reduce the transmit gain with the resistor Rgat Ctx1 Ctx2 and TX TX input impedance form a high pass filter A capacitor Cgat
Download Pdf Manuals
Related Search