TCA3388 Telephone Line Interface
Contents
1. MOTOROLA ANALOG IC DEVICE DATA SEATING PLANE NOT 1 2 3 4 oro 000 Y14 5M 1982 CONTROLLING DIMENSION INCH DIMENSION L TO CENTER OF LEAD WHEN FORMED PARALLEL DIMENSION B DOES NOT INCLUDE MOLD FLASH INCHES MILLIMETERS MIN MAX MIN MAX 1 010 1 070 25 66 27 17 0 240 0 260 6 10 6 60 0 150 0 180 3 81 4 57 0 015 0 022 0 39 0 55 0 050 BSC 1 27 BSC 0 050 0 070 1 27 1 77 0 100 BSC 2 54 BSC 0 008 0 015 0 21 0 38 0 110 0 140 280 3 55 0 300 BSC 7 62 BSC 15 15 0 040 1 01 z eo m o gt S ES MENSIONING AND TOLERANCING PER NSI Y14 5M 1982 ONTROLLING DIMENSION MILLIMETER MENSIONS A AND B DO NOT INCLUDE OLD PROTRUSION JAXIMUM MOLD PROTRUSION 0 150 006 PER SIDE MENSION D DOES NOT INCLUDE AMBAR PROTRUSION ALLOWABLE AMBAR PROTRUSION SHALL BE 0 13 005 TOTAL IN EXCESS OF D DIMENSION MAXIMUM MATERIAL CONDITION MILLIMETERS INCHES MN MAX MIN MAX 12 65 12 95 0 499 0 510 7 40 760 0 292 0 299 2 35 2 65 0 093 0 104 0 35 0 49 0 014 0 019 0 50 0 90 0 020 0 035 1 27 BSC 0 050 BSC 0 25 0 32 0 010 0 012 0 10 0 25 0 004 0 009 0 7 pe 72 10 05 10 55 0 395 0 415 0 25 0 75 0 010 0 029 SEZY as 2 ajoul ixjejojnjojojm gt 15 TCA3382. The input stage of Figure 9 consists of a current amplifier with transfer Ky an input impedance of 1 0 k RTXI plus an attenuator which reduces the signal current at high line currents AGC This attenuator can be switched on off via the microcontroller The input current lu within the telephony speech band is derived from the microphone signal according Vu Vu lu Amic Ru Big Ru With Vu signal of the microphone only loaded with RMic The overall gain from microphone to line ATx now follows as V ZO x Z A _ Line _ Ku X Line ie Vu Ru Zin j ZL ine Practically the gain can be varied only with Z0 Ru and RMic The TCA3388 offers the possibility to mute the microphone also called privacy mode by making the MUT Pin high During pulse dialing the microphone bias is switched off Pin Mic will be made high impedance shutting off the microphone dc current This reduces the current consumption of the circuit during pulse dialing TCA3388 Figure 10 Receive Part of the TCA3388 Zi R20 AA V V C17 Line e E te R19 MAN HYSO HYL IMP E TCA3388 E 1 gt gt 16V RXO2 _ J ve Vref Il I Cear Ge _ e ARAN B f i RLoad T CLoad Ge ms Line Mute O T 2VBeE vot AGC E ax Handset AAA RA l Earpiece SAI Gnd D Ri ji Line AN t RECEIVE SIDETONE
3. The receive part of the TCA3388 is shown in Figure 10 The receive signal is picked up by the amplifiers at the HYL HYS inputs These are the same amplifiers present in the dc loop of Figure 5 The signal is first converted to current by the transconductance amplifier with transfer Ge The multiplier placed after performs the line length AGC It switches over between the 2 signals at HYS and HYL according to the line current via a modulation factor m Afterwards the current is converted back to voltage via the external feedback network ZLoad The resulting voltage is available at output RXO1 and inverted at RXO2 From the diagram of Figure 10 the receive gain ARx can be derived as V RXO 1 1 A Gex R1 x Z xl RA Mine Load 2 With F aoa in case of 1 sidetone network and HYS connected to HYL or 1 _ R20 _ R19 Za RA m 1 Ri ze in case of 2 sidetone networks More information on ZH and the modulation factor m can be found under the sidetone characteristics The earpiece can either be connected as a single ended or as a differential load The above calculated gain is valid for the single ended case When connecting as a differential load the gain is increased by 6 0 dB The TCA3388 offers the possibility to mute the signal coming from the line to the earpiece This can be useful during pulse and DTMF dialing 10 When a transmit signal is transmitted to the line a part of the signal is retur
4. AM MOTOROLA Advance Information Telephone Line Interface The TCA3388 is a telephone line interface circuit which performs the basic functions of a telephone setin combination with a microcontroller and a ringer It includes dc and ac line termination the hybrid function with 2 adjustable sidetone networks handset connections and an efficient supply point FEATURES Line Driver and Supply DC and AC Termination of the Telephone Line Selectable DC Mask France U K Low Voltage Current Protection Adjustable Set Impedance for Resistive and Complex Termination Efficient Supply Point for Peripherals Hook Status Detection Handset Operation e Transmit and Receive Amplifiers e Double Anti Sidetone Network e Line Length AGC e Microphone and Earpiece Mute e Transmit Amplifier Soft Clipping Dialing and Ringing e Interrupter Driver for Pulse Dialing e Reduced Current Consumption During Pulse Dialing e DTMF Interfacing e Ringing via External Ringer Application Areas Corded Telephony Cordless Telephony Base Station Answering Machines Fax Intercom Modem This document contains information on a new product Specifications and information herein are subject to change without notice Order this document by TCA3388 D TCA3388 TELEPHONE LINE INTERFACE SEMICONDUCTOR TECHNICAL DATA 20 DP SUFFIX PLASTIC PACKAGE CASE 738 FP SUFFIX PLASTIC PACKAGE CASE 751D RXI TXI Mic LAO
5. Factor 12 5 0 uA mr 0 65 0 75 0 85 Variation with Line Length 12 30 HA Low Voltage Mode Internal Transconductance 12 3 0 uA Hybrid Weighting Factor 12 3 0 uA Variation with Line Length 12 30 A DISTORTION French Transmit 12 10 uA Receive 12 6 0 uA VE 700 mV VE 1250 mV NOTE VE is the differential earpiece voltage across Pins 19 and 20 MOTOROLA ANALOG IC DEVICE DATA TCA3388 AC ELECTRICAL CHARACTERISTICS continued TA 25 C Characteristic Symbol Min Typ Max Unit DISTORTION Low Voltage Transmit 12 10 uA Receive 12 6 0 uA NOTE V is the differential earpiece voltage across Pins 19 and 20 TYPICAL TEMPERATURE PERFORMANCE Characteristic Typical Value 25 C Typical Change 20 to 60 C Vcc Regulated Supply Pin 17 0 8 mV C Current Consumption at Pin 17 Pin PI High 400 pA 0 55 pA C Amplifier A8 Driver Slope 1 0 uA mV 0 0035 uA mV C Voltage on SAI Vc French 0 47 Vdc 0 35 mV C U K 0 70 Vdc VD French 0 49 Vdc U K 0 72 Vdc Internal Slope for Low Voltage Mode 125 mV uA 0 07 mV uA C Transmit Gain Ku0 12 5 dB 0 01 dB C Line Length Regulation AKu French 6 5 dB lt 0 3 dB Variation U K 6 5 dB lt 0 3 dB Variation L V 6 0 dB 0 05 dB C Internal Transconductance Geo 180 rA V lt 1 0 dB Variation Line Length Regulation AGe French 3 7 dB lt 0 5 dB Variation U K 3 5
6. LAI HYL HYS CM IMP SAO PIN CONNECTIONS RXO2 RXO1 Gnd Voc lret MUT PI HSO DCM SAI Top View ORDERING INFORMATION Tested Operating Device Temperature Range Package TCA3388DP ae see DIP 0 to 70 TCA3388FP SOIC Motorola Inc 1995 TCA3388 Simplified Block Diagram Line gt DC and AC Termination 3 ra Bo eas oe ape ae leo Aa oor a Handset DC Mask Generation anass AC Termination Supply Earpiece 2 4 Wire Conversion Stabilizer A Handset i Microphone Mic Line Driver Ria ee Microcontroller Interface o e E SS HA lm u A 2 u a D J SIE gt Line This device contains 1 911 active transistors MAXIMUM RATINGS Oooo o ACA i Mae Uni NOTE Devices should not be operated at or outside these values The Recommended Operating Limits provide for actual device operation RECOMMENDED OPERATING CONDITIONS Characteristic Symbol Min Typ Max Unit Operating Temperature Range TA 0 _ 70 C DC ELECTRICAL CHARACTERISTICS Ta 25 C Characteristic Symbol Min Typ Max VOLTAGE REGULATOR Regulated Supply at Pin 17 Icc 7 0 mA ICC 20 mA Icc 80 mA Current Consumption at Pin 17 Pin PI High DRIVER DC CHARACTERISTICS Available Curren
7. 1 0 _ 1 0 Mute Mode IMIH 10 10 DC MASK CHARACTERISTICS French Internal Slope RI 120 160 200 mV uA Voltage on SAI I2C 3 6 uA Vc 0 40 0 47 _ Vdc Voltage on SAI 12D 4 0 uA Vp _ 0 49 0 57 Vdc Delta Offset Voltage on SAI I2E 30 uA Ve Vp _ _ 30 mV U K Internal Slope RI 210 260 310 mV uA Voltage on SAI I2C 3 5 uA Vc 0 59 0 70 _ Vdc Voltage on SAI 12D 3 9 uA Vp 0 72 0 83 Vdc Delta Offset Voltage on SAI I2E 30 uA VE Vp _ 20 50 mV Low Voltage Mode Internal Slope Voltage on SAI I2C 13 uA Voltage on SAI 12D 15 uA Delta Offset Voltage on SAI I2E 20 uA Overvoltage Protection Threshold VI AI VSAO French and U K DC Masks Low Voltage DC Mask Protection Voltage Level VI A VSAO French and U K DC Masks Low Voltage DC Mask MOTOROLA ANALOG IC DEVICE DATA 3 TCA3388 AC ELECTRICAL CHARACTERISTICS TA 25 C Characteristic Symbol Min Typ Max Unit TRANSMIT MODE French and U K dB Maximum Transmit Gain 12 3 0 uA Kuo 11 25 12 5 13 75 Line Length Regulation 12 30 A AKu 5 5 6 5 7 5 Gain in Protection Mode 12 30 uA Kup 10 5 12 5 14 5 Low Voltage Mode Maximum Transmit Gain 12 3 0 uA Kuo 11 25 12 5 13 75 Line Length Regulation 12 8 2 uA AKu 4 5 6 0 7 5 Gain in Protection Mode 12 8 2 uA Kup 10 5 12 5 14 5 Gain Reduction when Microphone is Muted AKum 60 _ _ RECEIVE MODE French Maximum Internal Transconductance 12 3 0 uA Geo 150 180 210
8. 8 Motorola reserves the right to make changes without further notice to any products herein Motorola makes no warranty representation or guarantee regarding the suitability of its products for any particular purpose nor does Motorola assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability including without limitation consequential or incidental damages Typical parameters can and do vary in different applications All operating parameters including Typicals must be validated for each customer application by customer s technical experts Motorola does not convey any license under its patent rights nor the rights of others Motorola products are not designed intended or authorized for use as components in systems intended for surgical implant into the body or other applications intended to support or sustain life or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur Should Buyer purchase or use Motorola products for any such unintended or unauthorized application Buyer shall indemnify and hold Motorola and its officers employees subsidiaries affiliates and distributors harmless against all claims costs damages and expenses and reasonable attorney fees arising out of directly or indirectly any claim of personal injury or death associated with such unintended or unauthor
9. F zS 9 29 5 TaTTi e ezu L 3 lau 3 as Io ool yNo Mo ud a L oca ee as AA O 99 1J O O ani J O O asind 2 I l l Il IIT E y OOSH I ured WwSsuel T LH o a 1 9W O Am Lia els S gy O seva H 9 8 ue 44 D a J S8EEVOL Jw OJALO INA O L8 EWOL i Dine spa tree l ot je Sg r AA 4 pu p 3 LW JALG 9ur eouejeg auojapis un O E 13 mo Ll et t9 F3 szo x a sus vig O 19 uS go L A 6zu L l i el Oa AS e sa l tL u an Fea a TA P on UL n eun buoy rT eurquoyg lisence ey sus TE oz 111 i z L e O so aus Suu Bulu O A ina u O WN ps liza zH du vos A SOS 16 Hove sug Sate lao A a a ee pe J Lib J 12 Ae Ws J De SS St Luya Se cis JJ uonesiyddy eoid anp MOTOROLA ANALOG IC DEVICE DATA 12 TCA3388 Figure 14 List of Components for Typical Application TCA3388 Location Application ae on Board BasioLV Frames Remarks m ue A s L s DTMF Gain 470k Transmit Gain 39 k DTMF Gain lref Pin 16 ZO ZO Z1 Z1 Z2 Z2 Sidetone Bal Sidetone Bal Z21 PABX Mask Setting Mask Setting Mask Setting Pin 19 Stability Pin 20 Stability Z21 Transmit Gain VMic Line A B Line Driver Rec
10. French or U K mask is selected this transfer takes places for line currents of 30 mA to 40 mA depending on the components settings With the Startup and Low Voltage mask the transfer lies outside the normal operating range with line currents of 90 mA or more In most applications the transfer from region 1 to 2 takes place for line currents below 10 mA With proper settings region 4 is entered only during an overload condition In this mode the power consumption in the telephone set is limited In order to detect an overload condition the voltage between the Pins LAI and SAO is monitored When the voltage difference is larger than the threshold VClamp1 the protection is made active The relation for the line voltage VI p at this point is given as V Z0 LP Z21 Vclamp1 Vep VO2 When the protection mode is entered the line current is reduced to a lower value I P of E Vclamp2 VO1 VO2 LP R1 When the line voltage becomes lower than VI P the overload condition is removed and the TCA3388 will leave region 4 The current drawn from the line by the dc part is used to supply the TCA3388 and peripheral circuits The excess loop current is absorbed by the voltage regulator at Pin Vcc where a filter capacitor is connected The reference for the circuit is Pin Gnd Startup of the application is ensured by an internal startup circuit When the line current flows the hook status output pin HSO goes high This informs th
11. G PA AO Q SN TCA3388 Ri Line O ANN e MOTOROLA ANALOGQ IC DEVICE DATA 7 TCA3388 The TCA3388 offers the possibility to connect 2 sidetone networks Z1 and Z2 For correct dc operation the dc impedance of these networks must be equal When only 1 sidetone network is used Pin HYS has to be connected to HYL All formulas below are based on a single sidetone network so only Z1 appears When 2 sidetone networks are used Z1 has to be replaced by Z1 Z2 In region 1 the transfer of the amplifier G at the HYL HYS inputs equals zero The voltage difference between SAO and SAI will equal VO1 The slope RE1 of the VLine ILine characteristic will equal R m x i 20 E1 Z21 In region 2 the output current of the amplifier G will be proportional to the input current As a result the voltage between SAO and SAI will increase with the line voltage Speech signals on the line are of no influence on this because they are filtered out via capacitor C16 The slope RE2 of the VLine ILine characteristic will equal Res RI x 1 E2 R Zi 1 ZO In region 3 the output current of the amplifier G is kept constant As a result the slope in region 3 will equal the slope of region 1 The transfer from region 2 to 3 occurs at the point VLK ILK defined by VLK Z1 x l2CD 2 VBE VCD VO2 Z21 SF x z x 12CD 2 Vee Vep LK R1 V V With 12CD 26 12D and Vep 52 and 2 VBE 1 4 V V02 1 1 V When the
12. crophone will not be amplified to the line and signals from the line are not amplified to the earpiece The complete interfacing of the DTMF generator with the TCA3388 is shown in the typical application SUPPORT MATERIAL Brief description of the TCA3388 block diagram device data test diagram typical application User manual TCA3388 Extended description of the circuit and its concept adjustment procedure application hints and proposals Demonstration board Shows performance of the TCA3388 in its basic application TYPICAL APPLICATION The typical application below is based on the demoboard of the TCA3388 It contains the speech transmission part diode bridge hook switch and microcontroller interfacing The dc mask setting on the bottom left is given for France U K and Low Voltage applications The component values are given in the table of Figure 14 The line driver is extended with T1 D5 and R3 which increases the signal swing under low line voltage conditions Device Specification 11 TCA3388 A sail Cn 2 ules 89Al99917 Aj L X8vd Bumas ySEN pur O e e T O pug e i ZUS wus o so Sa 2 E oo L sn ZI
13. dB lt 0 5 dB Variation L V 5 7 dB 0 04 dB C NOTE Temperature data is typical performance only based on sample characterization and does not provide guaranteed limits over temperature PIN FUNCTION DESCRIPTION Pin Symbol Description 1 RXI Earphone Amplifier Input x s ow oes x m um __ j 19 RXO1 Earphone Amplifier Output 20 RXO2 Earphone Amplifier Inverted Output MOTOROLA ANALOG IC DEVICE DATA 5 TCA3388 DESCRIPTION OF THE CIRCUIT Concept With a TCA3388 a microcontroller and a ringer a basic telephone set can be built according to the concept depicted in Figure 1 In off hook position the application is in speech mode The line current flows through transistor T2 and supplies the externals microcontroller at the supply point Vcc which is stabilized by the TCA3388 The Viine lline characteristic is adjusted by the external components ZO Z1 Z21 and R1 which are in a regulator loop acting on transistor T2 The ac impedance is generated in a similar way The handset can be connected directly to the TCA3388 Via a logic level interface the microcontroller drives the TCA3388 to perform the DTMF pulse dialing The user keyboard has to be connected to the microcontroller In on hook position a ringing melody can be generated with a ringer application The block diagram of the TCA3388 in Figure 2 shows the basic blocks of the device plus the essential external components Fi
14. e microcontroller that the set is off hook When the line current is no longer present the pin will go low again Because the line current is monitored and not the line voltage also an interrupt of the exchange can be recognized AC CHARACTERISTICS Impedance In Figure 6 the block diagram of the TCA3388 performing the ac impedance is depicted As can be seen it is partly common with the dc mask block diagram The part generating the dc mask is replaced by a dc voltage source because for ac this part has no influence Figure 6 AC Stage of the TCA3388 Line O Ny z R5 o l TCA3388 ce LAI l Lao T3 me Gy SAO hi Gnd l p w l y vo 0 SAI R1 Line MN When calculating the ac loop it can be derived that the set impedance Zin equals V _ Line _ z0 ZO z tine _ p4 1 40 m1 x 20 In lane 221 221 As can be noticed the formula for the ac impedance Zin equals the formula for the dc slope in regions 1 and 3 However because for the dc slope the resistive part of ZO and Z21 are used the actual values for Zin and the dc slopes do not have to be equal A complex impedance can be made by making either Z0 or Z21 complex When ZO is made complex to fit the set impedance the transmit characteristics will be complex as well The complex impedance is therefore preferably made via the Z21 network Because Z21 is in the denominator of the Zin formula Z21
15. eive Gain DTMF Gain Transmit Gain Transmit Gain C7 Pin 17 220 u Voc 10 V C8 DTMF Gain 10n C10 ZO _ 4 7n 330 p C11 zi 220p 120p 150p C12 Z2 _ 82p 150 p C13 Z21 470 p C14 Sidetone Bal 470 p Stability C15 Sidetone Bal _ 470 p 470 p Stability C16 Pin 8 680 n 680 n 22u DC Mask C17 Sidetone Bal 680 n MOTOROLA ANALOG IC DEVICE DATA 13 Location on Board Mask Setting Pin 19 Pin 20 Mask Setting Pin 17 TCA3388 Figure 14 List of Components for Typical Application TCA3388 Basic L V Application Remarks Stability Stability 10u 10V Close to Pin Transmit Gain 10u MMe 10 V Pin 2 4 7 n Pin 16 1 0n Line Driver Line Driver Line Driver Bridge Line Driver 14 MPSA92 MJE350 MPSA42 4 x 1N4004 1N4004 PNP HV PNP HV NPN HV HV Signal MKP1V270 Sidac MOTOROLA ANALOG IC DEVICE DATA TCA3388 OUTLINE DIMENSIONS DP SUFFIX PLASTIC PACKAGE CASE 738 03 ISSUE E oT SEATING PLANE ol D 20 PL pe gt e y 20 PL NOTES 1 DIMENSIONING AND TOLERANCING PER ANSI 2 3 4 lt gt 0 25 0 010 0 25 0 010 A Ka Salle 20x D FP SUFFIX PLASTIC PACKAGE CASE 751D 03 ISSUE E 0 010 0 25 0 010 0 25 40
16. gure 1 Telephone Concept with TCA3388 la Hookswitch Zi Zo T2 Z21 Vcc oO A B Ringer TCA3388 L Micro Handset O R1 AA Gnd Figure 2 Block Diagram of the TCA3388 with Essential Components Line lt o z C1775 S21 n C16 20S ee L R19 R20 221 R12 ANNAN 7 6 8 10 5 9 16 la PHYS HYL Ocm sao LA QIMP QI rk P C20 ref Ay axo TT T cC OF DC Mask Generation bo ae AC Termination Supply 17 Of 2 4 Wire Conversion Stabilizer R6 20 Line Length AGC References Gnd pe RXI Protection lt 07 QI Mute AGC 16 R9 G ee Ol Mute AGC i Micro Interface Mic Hook Detect Me PABX 3 TCA3388 L es A E a SAI DCM HSO Pl 11 12 141 15 Z pom R22 To From Microcontroller Line lt AAA R1 MOTOROLA ANALOG IC DEVICE DATA TCA3388 DC CHARACTERISTICS AND STARTUP The dc mask has the general form as depicted in Figure 3 The TCA3388 offers the possibility to adjust the dc Figure 4 Selection of the Country Mask via Pin DCM characteristics of all 4 regions via mask selection a
17. he gains are nominal When the line current has increased above I start MOTOROLA ANALOG IC DEVICE DATA with a current IL range the gain is reduced by 6 0 dB Due to the general characteristics of the line AGC curve the gain will be decreased further for higher currents For France and U K the line AGC will be active in region 3 of the dc characteristics The IL start is approximately equal to the ILK The range is calculated from I _ Z1 x I2R 12CD Lrange Re3 For Low Voltage mask the line AGC is active in region 2 DIALING Pulse dialing is performed by making pin PI high As a result the output LAO goes low and the loop will be disconnected Internally the current consumption of the circuit is reduced and the current through the microphone is switched off DTMF dialing is performed by supplying a DTMF signal current to Pin LAI This is the same node where the microphone signal currents are internally applied Therefore for the DTMF gain the same formulas apply Because the microphone preamplifier is bypassed there is no influence on DTMF signals by the line length AGC A DTMF confidence tone can be generated on the earpiece by injecting a signal current at the RXI pin Because only the earpiece amplifier itself is used there are no effects from AGC or hybrid switchover For correct DTMF dialing the pin MUT has to be made high This mutes both the microphone and earphone preamplifier In this way signals from the mi
18. ized use even if such claim alleges that Motorola was negligent regarding the design or manufacture of the part Motorola and M are registered trademarks of Motorola Inc Motorola Inc is an Equal Opportunity Affirmative Action Employer How to reach us USA EUROPE Motorola Literature Distribution JAPAN Nippon Motorola Ltd Tatsumi SPD JLDC Toshikatsu Otsuki P O Box 20912 Phoenix Arizona 85036 1 800 441 2447 6F Seibu Butsuryu Center 3 14 2 Tatsumi Koto Ku Tokyo 135 Japan 03 3521 8315 MFAX RMFAX0 email sps mot com TOUCHTONE 602 244 6609 HONG KONG Motorola Semiconductors H K Ltd 8B Tai Ping Industrial Park INTERNET http Design NET com 51 Ting Kok Road Tai Po N T Hong Kong 852 26629298 AA MOTOROLA 0 TCA3388 D
19. n the line current and the factor m is depicted in Figure 11 Figure 11 Modulation Factor m as a Function of Line Current m A 1 0 0 5 ILine 0 ILstart Lm ILstop For low line currents below lLstart thus long lines the factor m equals 1 This means the hybrid network ZHL is fully used For high line currents above IL stop thus short lines the factor m equals 0 This means the hybrid network Zs is fully used Both networks are used 50 for the intermediate line current llm The switch over between the 2 networks takes place in region 3 for the French and U K mask and in region 2 for the Low Voltage mask LINE LENGTH AGC The TCA3388 offers the possibility to vary the transmit and receive gain over line length in order to compensate for the loss in gain at longer line lengths In the block diagrams of the transmit and receive channels Figures 9 10 the line AGC is drawn The line AGC can be switched off by connecting a 150 kQ resistor between HSO and Gnd In this case the transmit and receive gain are lowered by 2 0 dB with respect to the value calculated in the formulas above The line AGC characteristics for both transmit and receive channel have the general shape depicted in Figure 12 Figure 12 General Line AGC Characteristics Gain i A Gain Nominal Gain 1 L Lstart Nominal _ l Gain range Reduced Gain gt ILine ILstart ILrange For low line currents and thus long lines t
20. nd Ipem HA hardware adjustments A FR The selection of the 3 masks France United Kingdom 14 H and Low Voltage can be done via the ZDCM network at Pin UK Z DCM as shown in Figure 4 For French and U K masks the 11 EA region 3 with the high slope is within the normal dc feeding a conditions For Low Voltage mask the region 3 will be outside V I this and the dc mask is mainly determined by regions 1 4 a and 2 iz l Voom 0 0 5 20 25 30 32 DeM Figure 3 General Form of the DC Mask of the TCA3388 VLine ZpoM for the L V U K and FR Mask A DCM VCC DCM DCM O O O R23 56k VLP o e R24 L C21 R25 L C018 47k T 10u 10M T 470n V eres Sr K LV U K FR Vic t 0 gt Line The capacitor in the U K network is to ensure a stable selection of the mask during all working modes and ILC ILP IK IvLP transitions The capacitor in the French network is used to Region 1 Startup Low Line Current High Slope Create a startup in L ow voltage Mask Region 2 Mid Range Line Current Low Slope The adjustment possibilities will be discussed below with Region 3 High Line Current High Slope the aid of the block diagram of Figure 5 Region 4 Overload Protection Figure 5 DC Part of the Block Diagram of the TCA3388 Line O Y ce mel a z Zi o l EFI J tev S20 2L CM R5 lf l ls me Ovcc 4 e Z21 LAI LAO P lo T Sl S Lo ie al gt ES Bar O G H S f Sx ti x
21. ned to the receive channel due to the architecture of the 2 to 4 wire conversion of the hybrid During transmit the signal on the line will be lLine x ZLine During receive the signal on the line will be lLine x Zin When replacing Zin in the formula for the receive gain it follows that the signal on the earpiece output due to a sending signal on the line will be Vear 1 1 Ge x R1 x Z x VLine transmit Load ZH ZLine In applications with 1 sidetone network where HYS is connected to HYL it follows 1 _ R20 1 Z4 R1 x Z1 ZuL ZH has to be chosen according the average line impedance and the average linelength of the countries involved in the application A complex sidetone network can be made via a complex Z1 which is preferred above making R20 complex The coupling capacitor C17 in series with R20 is meant only to block dc For applications with 2 sidetone networks it follows 4 _ R20 on R9 _ z UBA ee Dex z2 m m 1 3 HL HS The ZH thus exists as ZHL for long lines with low line currents and as Zys for short lines with high line currents This can be useful in applications such as DECT and handsfree where the sidetone has to be minimized to reduce the effect of delayed echoing and howling respectively The TCA3388 will automatically switch over between the 2 hybrid networks as a function of line current This is expressed in the MOTOROLA ANALOG IC DEVICE DATA TCA3388 factor m The relation betwee
22. t at LAO 14 uA Source Current 45 70 100 Sink Current 100 70 45 Amplifier A8 Driver Slope s8 0 7 1 0 1 2 uA mV LAO Voltage PI High 14 100 A VLAO gt 270 mV Internal Offset Pins 5 to 10 VO1 VO2 30 80 140 mV SPEECH AMPLIFIERS IMP Voltage Pin 9 Closed Loop VIMP z 1 6 Vdc Earpiece Amplifier DC Bias Rext 100 kQ Vdc RXI Pin 1 VRXI E 1 6 RXO1 Pin 19 VRXO1 1 7 E RXO2 Pin 20 VRXO2 1 45 Offset VRxO1 VRXO2 Voffset _ 0 25 0 70 2 MOTOROLA ANALOG IC DEVICE DATA TCA3388 DC ELECTRICAL CHARACTERISTICS continued TA 25 C Characteristic Symbol Min Typ Max SPEECH AMPLIFIERS HYL and HYS DC Bias Voltage Normal Mode _ 2 4 _ PI High _ 1 4 _ Microphone Amplifier DC Bias at TXI _ 1 45 _ Saturation Voltage at Mic 1 0 mA _ 250 300 Leakage Current into Mic 3 7 V ILeak _ _ 2 0 HOOK STATUS OUTPUT Pin 13 High Level Voltage 5 0 uA Load Current Off Hook Vga Max VHSOH 2 7 2 9 Vdc Maximum Load Current HA Normal Mode IHSOL 5 0 PABX Mode IHSOH 20 _ Low Level Voltage 5 0 uA Load Current VSAI 5 0 mV Normal On Hook VHSOL PI High VHSOLPI Time Delay from On Hook or Off Hook TDel _ 3 5 _ ms PULSE INPUT Pin 14 Input Impedance DC Bias Voltage Input Current Make Phase Break Phase MUTE INPUT Pin 15 Input Impedance _ 160 _ DC Bias Voltage _ 1 4 _ Input Current Speech Mode IMIL
23. uA V Line Length Regulation 12 18 uA AGe 2 95 3 7 4 45 dB Hybrid Weighting Factor 12 18 uA mr 0 4 0 5 0 6 Line Length Regulation HYS Vcc 12 9 0 A AGe 1 5 2 1 2 5 dB Protection Mode 12 18 uA Gep 145 185 230 uA V U K Maximum Internal Transconductance 12 3 0 uA Geo 150 180 210 uA V Line Length Regulation 12 18 uA AGe 2 8 3 5 4 3 dB Hybrid Weighting Factor 12 13 uA mr 0 4 0 5 0 6 Line Length Regulation HYS Vcc 12 9 0 uA AGe 1 4 1 9 2 4 dB Protection Mode 12 18 uA Gep 145 185 230 uA V Low Voltage Mode Maximum Internal Transconductance 12 3 0 uA Geo 150 185 210 uA V Line Length Regulation 12 8 0 uA AGe 4 2 5 7 7 2 dB Hybrid Weighting Factor 12 7 0 uA mr 0 5 Line Length Regulation HYS Vcc 12 4 0 uA AGe 3 0 dB Protection Mode I2 8 0 uA Ge 145 185 230 uA V Earpiece Gain Reduction when Muted AGem 60 dB TRANSMIT PABX MODE French and U K dB Transmit Gain 12 3 0 uA KPABX 9 25 10 5 11 75 Variation with Line Length 12 30 uA AKPABX 0 5 _ 0 5 Low Voltage Mode dB Transmit Gain 12 3 0 uA KPABX 9 25 10 5 11 75 Variation with Line Length 12 30 A AKPABX _ 0 5 0 5 RECEIVE PABX MODE French Internal Transconductance 12 5 0 uA GPABX 120 145 170 uA V Hybrid Weighting Factor 12 5 0 uA mr 0 8 0 9 1 0 Variation with Line Length 12 30 uA AGPABX 0 5 0 5 dB U K Internal Transconductance 12 5 0 uA GPABX 120 145 170 uA V Hybrid Weighting
24. will not be a direct copy of the required impedance but a derivative of it Figure 7 gives this derived network to be used for Z21 MOTOROLA ANALOG IC DEVICE DATA TCA3388 Figure 7 Derived Network for Z21 in Case of Complex Set Impedance Ry Ry SAO WWA LAI Ra Sw S m m Cb gt Cw Gnd Ry R1 x Z0 2 Ra Ry R1 R1 x ZO Ra R1 Rw 4 R Ra Rp R1 ER x Cp Cw Ri x ZO TRANSMIT When a current is injected on Pin LAI via the loop depicted in Figure 6 a signal is created on the line In this way the microphone signals and DTMF signals from an external source are transmitted It can be derived that the signal voltage on the line VLine depends on the signal current injected in LAI IL AI according to 20 x Zi ine x lt gh a Zin ZLine V l Line With this relation a simplified replacement circuit can be made for the transmit amplifier see Figure 8 Here the product of aj and ZO is replaced by one voltage source Figure 8 Replacement Diagram for the Transmit Amplifier Zin NNV O MOTOROLA ANALOG IC DEVICE DATA The microphone signal current is derived from the microphone signal according to the schematic in Figure 9 Figure 9 Microphone Amplifier Input Stage PSSS O Voc TCA3388 F RMic C Mic Ru Cu ly Line AGC HIM gt TXI RTXI DI Ku gt Ial Handset Mic Microphone Mute
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