PSB4500

PSB4500 SIEMENS | Alldatasheet

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Features

@ Operation down to a dc line voltage of 1.6 V (excluding polarity guard) @ Anticlipping control circuit prevents signal distortion on the line in the transmit direction caused by large microphone signals or poor supply and load conditions @ Adjustable voltage regulator for line voltage drop @ Adjustable differential DC resistance @ Current supply for external components @ Input for DTMF signals with confidence tone @ Symmetrical high-impedance inputs (68 kQ) for dynamic, magnetic and piezoelectric microphones @ Asymmetrical high-impedance input (34 kQ) for electret microphones @ Wide setting range for microphone and earpiece amplifiers @ Receiving amplifier for magnetic, dynamic and piezoelectric earpieces @ Line loss compensation depending on line current @ Adaptable gain control @ MUTE input for DTMF dialing @ Power down input for pulse dialing or register recall @ Line loss compensation switchable from 3 dB to 6 dB (only for PSB 4500) @ Special microphone MUTE input (only for PSB 4501) @ Fulfills the high German PTT noise requirements 748

Anticlipping Control Function Clipping Anticlipping ToT oy | 4] ly im) La | Aa A) A (Pete eye pi | || | i He attK +{\\ MM me 1 a bite TT ret J Lo The diagram shows an input signal The PSB 4500/4501 processes controlled which generates a distorted output amplification so that a distortion-free signal signal with conventional speech circuits. with all harmonics is available at the output, having the same dynamic range like the input signal. When does the Anticlipping Control Affects? In poor feeding conditions, e.g. @ very low line current and long line cable, or @ two or more telephone sets in parallel operation and a long line cable, @ and high microphone level. The anticlipping contro! prevents the transmitted signal from being distorted when the signal is reaching the maximum linear range of the output stage. If any distortion (clipping) is , sensed by the peak detector, the gain of the microphone amplifier is reduced at once within a very short time constant to a non-distorting gain level - the PSB 4500/4501 remains in a reduced gain state. Without any loss, the output dynamic range is then equivalent to the input dynamic range. For a capacitor of C, = 470 nF the release time is approximately 6 ms for each 3 dB overdrive. Siemens Aktiengeselischaft 749

Anticlipping Control Circuit Ht wl ee eke oct -— 2 PE te (az p> Hey it | Pa | re % — HEF eet 2p EP Supoly ana ca ae | 9 ho 9 rae: Siemens Aktiengeselischaft 750

p PSB 4500 PSB 4501 Pin Configurations (top view) P-DIP P-DSO tines] Tce b aoc uneecfr LT zope to1cz 19 asc roi[]2 as} Jase 243 sees outs nv te2[]3 vf ]pes outs 16a nute Rosé 15 OTHE our-[]4 Xe me-cd7 uEae0 outs []s a6[ ]rure mice abo teers 125 tine ro[ | 15{ Jorme oe ee re 115 hee vac [}? 16[]ro mice []e af] tees (9 12{ Juine pescsor wore]? Lt Pin Definitions and Functions Pin No. Function

1 Positive line terminal

2 TG1 Transmitter gain adjustment

3 TG2 Transmitter gain adjustment

4 OUT — Inverting output, receiving amplifier

5 OUT + Non-inverting output, receiving amplifier

6 [RG __| Receiver gain adjustment

7 MIC — Inverting microphone input

8 MIC + Non-inverting microphone input

9 Reference current

10 Lage Adjustment of AGC-level (PSB 4500)

MMUTE Microphone MUTE (PSB 4501) 1 | tcc ___| Delay time const. of ACC

12 Negative line terminal

13 [IN __| Receiving amplifier input . 14 [PD _| Power-down input

15 Dual-tone multi-frequency input

16 MUTE input

7 Positive supply decoupling

18 [REG _| Voltage regulator decoupling

19 Automatic gain control input

20 [RDC _| Slope (de. resistance) adjustment Siemens Aktiengesellschaft 751

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Veg (17), Line + (1), RDC (20), Iner (9): DC Supply and Corresponding Control Pins The IC and its external circuitry are usually supplied from the telephone line. The PSB 4500/4501 generates its own supply voltage at V.< and regulates its voltage drop. External circuitry such as dialing components and microcontrollers are also supplied by Veg: A smoothing capacitor between Vc, and Line - is used to decouple the ac voltage of the supply. Another capacitor between REG and Line - decouples the internal voltage regulator. The internal reference current is adjusted by a resistor (3.6 kQ) between Iper and Line -. The DC current flowing into the circuit is determined by the exchange supply voltage Ve,on. the feeding bridge resistance Re,.,, the subscriber line DC resistance Rijn, and the DC voltage at the telephone set (see figure 3). tf the line current J,,,. exceeds the current I, + I, + 0.5 mA required by the IC and its peripherals (J,¢ ~ 1 mA), the voltage regulator diverts the excess current via Line +. The voltage regulator adjusts the mean voltage to Vone = Veer + Teoe X Ro = Veer + (ine — Toc — 0.5 x 10-3 — I.) x Ry. Veer is the temperature compensated voltage of 3.6 V, between Line + and RDC. R, is an external resistor between RDC and Line - with a preferred value of 20 Q. Changing R, influences the microphone gain, DTMF gain, the current dependent gain control charac- teristics, side tone, the max. output swing at Line + and the DC characteristic (particularly with low voltages). With Ipoc>> Ice +0.5 MA +J,, the static behavior of the IC is similar to a 3.6 V voltage regulator diode with an internal resistance R,. in the audio frequency range the dynamic impedance equals Ry, since Ri, OF Ry,>>R,. Ry, is an external resistor, by means of which the internal reference voltage can be adjusted. If Ry, is connected between pins Line + (1) and REG (18), the reference voltage Vecr is reduced. If Ry, is connected between pins REG (18) and RDC (20), the reference voltage Veer is increased. The corresponding equivalent circuit diagram is shown in figure 3. Siemens Aktiengesellschaft 754

i Figure 3 June pono-n oo 1 et Ze RyRy lly? 1 [7 TO R sR, | Henn $ al , 5 R 5 3 ay 3 ia t> i« ae | 2 q l OO | a Rei =Re > | I 2 / 2 ms | Loo ed Vina 3 oP T2/tine- * Ra2) g G & =| Pee Lesa 0p Equivalent de and impedance circuit of PSB 4500/4501 Note ') R,, connected between pin 18-1 reduces the DC voltage drop across the circuit. Veer = 1.3 V + (Pyare) 1116.3 kA) x 0.14 mA 2) Ry, connected between pin 18-20 increases the DC voltage drop across the circult Veer = 2.93 V +21200 VOQ/(Ryaie-20) !1 31.6 kQ) The current available from Vo, to supply external circuitry depends on the external compo- nents and on the line current. Figure 8 shows this current for Vo > 2.2 V (min). With the MUTE input in the LOW state and the receiving amplifier in operation, the supply current available for peripherals is further decreased. If the current on the telephone line falls below 9 mA, the reference voltage is automatically adjusted to a lower value (typ. 1.6 V at 1 mA) (see figure 4). This enables several sets to be operated in parallel down to a minimum DC line voltage of 1.6 V (excluding polarity guard) with slightly reduced performance. At line currents lower than 9 mA the circuit operates with limited transmit and receive levels. Siemens Aktiengesellschaft 755

a ‘Side-Tone Suppression An anti-side-tone network consisting of R,//Zyine, Ro, Rss Re Ry and Z,,, (see figure 15a/b) ‘suppresses the transmitted signal in the earpiece. The following conditions have to be fulfilled to achieve maximum compensation: Re/Rs = Re/Ry a) Zoai = (Rr/Rs) Zune (2) Fixed values must be chosen for R,, Rz, Rs and Re to fulfill condition (1), provided that Ry <<IR, + Zea! (3) R, UI Zgu<<Re (4) ‘and with (2) in (4) Re >>RyX Zrnel (Ri + Zuine)) (6) The value of Zyq, has to correspond to a standard capacitor of the E6 or E12 series. In practice Zyn. varies strongly with line length and cable type, therefore a mean value should be selected for Zp, The side-tone suppression also depends on how well Zpai/(R7/R,) equals the mean line impedance. The anti-sidetone network (see figure 15a/b) attenuates the signal from the line by 32 GB. Attenuation over the audio frequency rang is nearly linear. The conventional Wheatstone bridge can be used as an alternative to the above described special bridge. Both bridges may be used with a resistive or a complex impedances. Gcc(11): Anti-Clipping Control (ACC) In poor feeding conditions, e.g. @ very low line current and long line cable or @ two or more telephone sets in parallel operation and a long line cable @ and high microphone level The anticlipping control prevents the transmitted signal from being distorted when the signal is reaching the maximum linear range of the output stage. If any distortion (clipping) desensed by the peak detector (threshold level), the gain of the microphone amplifier is reduced at once within a very short time constant to a non-distorting gain level - the PSB 4500/4501 remains in a reduced gain state. Without any loss, the output dynamic range is then equivalent to the input dynamic range. How long the circuit remains in this reduced transmitting condition, is dependent on the overdrive condition. For a capacitor of C, = 470 nF the release time is approximately 6 ms for each 3 dB overdrive, respectively for each 3 dB gain reduction. This release time is proportional to the value of C, at pin 11 {taoc), because it will be recharged by an internal current source. Siemens Aktiengesellschaft 757

MUTE (16): MUTE Input A HIGH level enables the DTMF input and inhibits the microphone and receiving amplifier inputs. With LOW level or open circuit the same occurs vice versa. Switching the MUTE input causes negligible clicking in the earpiece and line. When Voc drops below 2 V, the IC is always in the speech condition, independent of the dc level applied to the MUTE input. MMUTE (10) (PSB 4501 only): Microphone MUTE Input A LOW level at the MMUTE pin (or connection to GND/Line —) inhibits the microphone input, but has no influence on the receiving amplifier, the received signal can be heard normally in the earpiece. HIGH level or open MMUTE pin provides the normal function in the transmit direction. When Vcc drops below 2 V, the MMUTE-attenuation will be reduced. DTMF (15): DTMF Input When the OTMF input is enabted, dialing signals can be transmitted on the telephone line. The voltage amplification from pin DTMF to pin Line + is typ. 26 dB and varies with R, ‘as well as with the microphone amplification. The dialing signals can be faintly heard in the earpiece (confidence tone). IN (13), OUT + (5), OUT — (4), RG (6): Receive Amplifier input and Outputs, Amplifier Adjustment The receive amplifier has one input IN and two complementary outputs OUT+ (non- inverting) and OUT— (inverting). Both outputs may be operated in symmetrical or asym- metrical mode, depending on the sensitivity and type of the earpiece (see figure 14). Amplification from IN to OUT+ is typ. 31 dB. This is sufficient for magnetic or dynamic earpieces of low impedance. These earpieces are suitable for asymmetrical operation. Using both outputs enables differential drive, and amplification is increased by 6 dB. Differential drive should be chosen if the earpiece impedance exceeds 450 Q (high- impedance dynamic, magnetic or piezoelectric earpieces). The maximum output voltage of the receiving amplifier depends on the voltage at Voo. The max. output voltage in speech condition is higher than during continuous wave drive, since with continuous wave drive Vc, is lower due to the increased current consumption of the output stage than in speech condition with varying amplitude. The receiving amplification for asymmetrical mode can be adjusted between 20 dB and 39 dB. For symmetrical mode the adjustment range is between 26 dB and 45 dB to permit the use of less sensitive transducers. Two external capacitors C,= 100 pF and C,=10x C,=1nF are required to ensure stability. A first-order low-pass filter is obtained with a larger value of C,. The cut-off frequency is determined by the time constant R, x C,. Siemens Aktiengeselischaft 758

a AGC (19), Lacc (10), (Laac Only for PSB 4500): Automatic Gain Control input Connecting a resistor R, between AGC and Line - enables automatic line loss compensa- tion (current dependent AGC). The automatic gain control varies microphone and receive gain according to the de line current. For the PSB 4500 the control range can be switched from 3 dB to 6 dB by connecting pin 10 (Lagc) to ground. For 3 dB control range this pin should be left open. The PSB 4501 has a fixed 6 dB control range. Switching affects only the slope of the attenuation dependent on the line current; it has no influence on the AGC threshold. A control range of 6 dB corresponds to a line length of 5 km for a twisted cooper pair cable of 0.5 mm diameter, a dc resistance of 176 Q/km and an average attenuation of 1.2 dB/km. Resistor Ry should be chosen with regard to the exchange supply voltage and its feeding bridge resistance (see figure 9 and table 1). The start end of the AGC range depends on the line current, its ratio does not depend on R,. If AGC is not required, the AGC inputs should not be connected. In this case microphone and receive amplifiers are operated at maximum gain. PD (14): Power-Down Input During pulse dialing or register recall the line is interrupted, consequently the speech circuit and external components are not supplied from the line during this period. These gaps have to be bridged by the charge stored in the smoothing capacitor C,. Applying HIGH level to the PD input reduces the supply current required by the IC from 1.1 mA to typ. 55 pA. This reduces also the required value of the capacitor C, needed to supply the circuit during line interruption. In addition, a HIGH level at PD disconnects capacitor C, at REG from the IC, with the result that the voltage stabilizer has no switch-on delay. As a consequence, the IC has no influence on the current waveform during pulse dialing or register recall. If the power down function is not required, the PD pin may be left unconnected. Siemens Aktiengeselischaft 759

Limiting values in accordance with the absolute maximum system (IEC 134) parameter em ame me — a Positive line voltage (continuous) Vine v Repetitive line voltage during switch-on or line interruption Vine v Repetitive peak line voltage Mine v t/p=1ms/58;R.9=13Q Rp = 202 (see figure 15a, b) Line current [fine [440 | ma Voltage on all other pins v, Vec+0.7 | Vv ~Y, 07 v ‘Storage temperature range Tat 125 °C Operating ambient temperature range Ta 75 °c The maximum ratings may not be exceeded under any circumstances, not even momentarily or individually, as permanent damage to the IC will result. Siemens Aktiengesellschaft 760

Tine = 11 to 140 MA; Viing- = 0 V, f = 800 Hz; T, = 25°C; unless otherwise specified Parameter lama [safe Tae Unit Supply: Line+ and Vcc (pins 1 and 17) Voltage drop over circuit; between pin 1 and Pin 12 = Vine; microphone inputs open Lune Mine Kae) v Iine= 4 mA Vine 1.75 2.0 2.25 v Thine= 7A Vusne 2.25 28 3.35 v Tine = 11mA Vine 3.55 38 4.05, v Tune = 18 mA Vine 3.65 39 4.15 v Tine = 100.-ae, Vino 49 5.6 BS v Tine 140 mA } a Vine 75) |v Variation with temperature I=15mA AViine/AT | -3 mv/K Voltage drop over circuit with external resistor Aya; Tine = 15. MA Rya (in 1 to pin 18) = 68 kQ Vine 3.4 37 v Ava (Bin 18 to pin 20) = 39 kG Vine 42 48 v Supply current Ic¢; current into pin 17 PD = LOW (pin 14); Voc = 2.8 V Toc mA __PD=HIGH (pin 14); Voc=2.8V Tec HA Current available from pin 17 to supply peripheral cricuits; Teme = 15 MA; Voc 2 2.2 V; MUTE = HIGH Ip 13 17 mA Microphone Inputs MIC+ and MIC— (pins 7 and 8) Input impedance Differential (between pins 7 and 8) 12s 545 68 kQ Single ended (pin 7 or w.r.t. Line—) IZs/ 27 34 kQ Common-mode rejection ratio koun a en) Voltage amplification . (from pin 7-8 to pin 1); Tine = 15 MA; Ry = 68 KQ Avs 51 52 eB Variation with frequency f= 300 Hz to 3400 Hz AAg/St |-05 | £02 a8 Variation with temperature Icing = 50 MA; Ty =—25 to 75°C AAg/AT tb.n, dB Siemens Aktiengesellschaft 761

Tune = 11 to 140 MA; Vine = 0 V, f= 800 Hz; T, = 25°C; unless otherwise specified Limit Values Parameter [in [we max] unt Dual-Tone Multi-Frequency input DTMF (pin 15) io mpedance [la] [ws [mr [sa Voltage amplification (from pin 15 to pin 1); Tune = 15 MA; Ry = 58 KQ Ava 26 27 dB Variations with frequency f= 300 Hz to 3400 Hz SA, fAt +02 |os Cl) Variation with temperature : Ting = 50 MA; Ty = 25 to 75°C SAyg/ AT £02 a8 Transmitting gain TG1 and TG2 {pins 2 and 3) Amplification variation with Ry 4Ag 0B (connected between pins 2 and 3), transmitter amplifier ‘Transmitting Amplifier Output Line+ (pin 1) (figure 6a, b) Output Voltage at /,,,.= 15 mA; R, = 68 kQ. Threshold level; dha. $ 2% Yingems) v (see also figure 11) Distortion at 10 dB overdrive rot % Distortion at 15 dB overdrive rot % Threshold level (Rs = 68 KO) Tine = 7 MA; hor S 2% Viinegrms) 09 v Thine = 4 MA; dio S 2% Viinoorms) 0.45 v Attack time for ACC; Cy = 470 nF ms Release time for each 3 dB overdrive; Cg = 470 nF ms Noise output voltage Thing = 15 A; Ry = 68 KO;

200 Q between pins 7 and 8;

psophometrically weighted (P53 curve) -72 dBmp Siemens Aktiengeselischaft 762

Tope = 11 t0 140 MA; Ying = 0 V, f= 800 Hz; T, = 25°C; unless otherwise specified Receiving Amplifier Input IN (pin 13) Input impedance [Zs | [ies [2 [22 | Ka Receiving Amplifier Outputs OUT+ and OUT— (pins 5 and 4) Voltage amplification from pin 13 to pin 4-5 Tune = 18 MA; Ry = 100 kQ single ended; R, = 300 Q | (from pin 13 to pin 4-5) Ae 30 31 aB differential; R, = 600 Q (from pin 13 to pins 4-5) Ava 36 37 08 Variation with frequency, f= 300 Hz to 3400 Hz AA, /At £02 B Variation with temperature Iune = 50 MA; Ta =—25 to 75°C SAyg/AT £02 ae Output voltage at I, = 0; dot = 2%; ‘sine-wave drive; Ry = 100 kQ. single-ended; R, = 150 Q Voems) 025 «| 029 v differential; R, = 450 Q Votems) 045 = | 055 v differential; C, = 47 nF (100 Q series resistor); f= 3400 Vous) 0.65 0.80 v Output voltage at I, = 0; dix = 10%; sine-wave drive; Ry = 100 k&2; RL=150Q Tine = 4 mA 15 mv June = 7 MA Vous) 130 mv Noise input voltage Thine = 15 MA; Ry = 100 kQ; pin 13 open psophometrically weighted (P53 curve) single-ended; R, = 300 Q Vogema) Hv differential; A, = 600 Q Vert) uv Recelving Gain RG (nin 6) | | ft ‘Amplification variation with Ry (connected between pins 6 and 5), receiving amplifier aB Siemens Aktiengesellschaft 763

Tung = 11 t0 140 MA; Vine = 0 V, f = 800 Hz; T, = 25°C; unless otherwise specified Limit Values Parameter Symbol | min. _| typ. max. | Unit MUTE input (pin 16) Input voltage | / HIGH Vos 15 | Veo v Low Ve 03 v input current [twre | fe ts Tw Reduction of voltage amplification from MIC + (pin 7} and MIC — (pin 8) to Line + (pin 1) MUTE = HIGH Avs 70 a8 . Voltage amplification from DTMF (pin 15) to OUT + (pin 5) or OUT— (pin 4) | MUTE = HIGH; | single-ended load R, = 300 Q Avs | +21 -19 -17 3B Power-Down Input PD (pin 14) Input voltage HIGH Yun Veo v Low Mi 03 v MMUTE input (pin 10), only PSB 4501 HIGH Yes Voc v Low Vie 03 v Input current, ing = 15 MA Junaure pA Tawren | 3 A Reduction of voltage amplification from MIC + | {pin 7) and MIC (pin 8) to Line+ (pin 1) | MMUTE = LOW bAvs 70 4B Automstic Gain Control Input AGC (pin 19) | Controtiing the gain from pin 1 to pins 4-5 and the gain from pins 7-8 to pin 1, Rg= 110 kQ {between pins 19 and 12) ‘Amplification control range fixed for PSB 4501 | Avg -6 aa ‘Amplification control range for PSB 4500 with Lago = Vuine— Ava | 6 «B with Lago = open | -3 a8 Highest line current for maximum amplification | J.ine | 22 mA Highest line current for minimum amplification | June 60 mA Siemens Aktiengesellschaft 764

PSB 4500: Test Circuit for Defining Voltage Amplification of MIC+ and MIC— and DTMF Inputs Voltage amplification is defined as: A,,= 20 Ig V)/V,. For measuring the amplification from MIC + and MIC— the MUTE input should be LOW or open, for measuring the DTMF input MUTE should be HIGH. Inputs not under test should be open. Re Tune 62a Yec Tine == 100 pF IN out- [és . MIC+ our 600 2 ol | “ Mic- []

6 PSB 4500 nto ©

100 pF | DIME RG GlanFT 140 maT ch) 162 G a7 PO heel ‘100pF tacc_Line- REG AGC ner _ROC| Q he 9 ‘ G sy; (? d seiiurl |e [Jaékalle6a = Gone ‘Siemens Aktiengesellschaft 765

PSB 4501: Test Circuit for Defining Voltage Amplification of MIC+ and MIC — and DTMF Inputs Voltage amplification is defined as: Ay; = 20 log V/V. For measuring the amplification from MIC+ and MIC— the MUTE input should be LOW or open and the MMUTE input should be HIGH or open, for measuring the DTMF input MUTE should be HIGH. Inputs not under test should be open. Tage Wa 1 Vic Tine+ == 100pF IN our- ‘| . Mice 5 Llebon outs rho | wl PSB 4501 a ‘ot ‘Sl ote 2 Glink 7 140ma' ace) ° MUTE ,o 66K 162 G 7 po tec ‘Hook MUTE Line- REG AGC rer _ ROC, 2) fe ° LG G Siemens Aktiengesellschaft 766

PSB 4500: Test Circuit for Defining Voltage Amplification of the Receiving Amplifier Voltage amplification is defined as: Aya= 20 log V/V. R ly Lie 7 1 Vec Tine 100 pF 43N our-+ Spc Lge es * 5 out.| % ‘ - Hin Se

4 PSB 4500 10 to C)

‘WO pF 45] RG) CO ae toye DIME rei Glink] 140A | 16tyure t Rs 162 G SO tbl o5 treet 100 pF tus Line REG AGC ner __ ROC 10 18 9

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¢ yell) [Pabi0 - 20 nF Siemens Aktiengesellschaft 767

PSB 4501: Test Circuit for Defining Voltage Amplification of the Receiving Amplifier Voltage amplification is defined as: A,,= 20 log V/V. Ri Keine 6208 . | Vec Tines == 100pF wy our-|¢ a f [lz [ ]éoo.0 MICs 5 our.| 7 ia 4 me psp 4501 , Ge J air F100 pF RG 10 to " clnope Some Toil THT tomak | mute 162 G 14] iS) PD hace ‘100pF MMUTE Line- REG AGC ner __ROC, nC) 9 ° LG a: G LIYE [Je [sexe he ‘Tone Siemens Aktiengesellschaft 768

Typical Current /, Available form V,, for Peripheral Circuitry with Voltage at Voo22.2V Curve (a) is valid when the receiving amplifier is not driven or when MUTE = HIGH, curve (b) is valid when MUTE = LOW, MMUTE is open and the receiving amplifier is driven; Vous) = 150 mV, R, = 150 Q asymmetrical. The supply possibilities can be increased simply by setting the voltage drop over the Circuit V,j9 to a higher value by means of resistor Ry, (18-20). mA i a » PED re} et phe eee b iW petcqccksn \\ 4 pr He at tt a Us} rr a j.- bop fede ah Nj. nen peti thi j ° 1 2 3 av ~ eK | Siemens Aktiengesellschaft 769

a Figure 9 Variation of amplification with line current with R, as a parameter B ° Cus Reco BA\\NNEEE EEE Avs X NY ROAR AN Y T 1 wt AAA 7ae COT Ry=202 a LT TTT | 6 ao se oe

0 ED 40 60 80 100 120 140 mA

Values of resistor R, for optimum line loss compensation, for various usual values of exchange supply voltage V,,.., and exchange feeding bridge resistance Resch Rexen (Q) [oo [oo] ao | Tao Re (kQ) ‘| a [| wo | to [oat | ee Siemens Aktiengesellschaft 770

The line output signal of a kHz burst signal on R, = 600 Q at [jing = 7 mA by a microphone input level of 2 mV (lin. range) and an overdrive level of 20 mV (overdrive nearly 20 dB) es | bj in NENMEM NE y AY yy tp | | = [aviolv | OSms/DIV | Siemens Aktiengesellschaft 7

Line voltage V_,. <., and THD as a function of the microphone input level “ne 2755806 -! of the slope for the linear range with the slope corresponding to the limited MTDUt €ve cetermines the threshold level. From this point the gain will be reduced - it is = overenve mode. . % o— eee 30 R= 6BKD;G, = 4ID AF; Ry = 600K FT EE aH tapes tot t +t = Hd ; Bassi Fee i [| {threshold Level sat tyemal-t ee F jp econ TF SSS SE so Zee t—}—} eH [TT ATT 35, Z _ rT Oe Pett} | Ai iil AAT SSS SS Sere fe eee aes ARS

005 YAH

Siemens Aktiengeselischaft 772

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Component | Function and Note Recommended Value Ry determines and dynamic resistance of the speech circuit | 620Q R= RVMRind Run (1) where Ri, = 18 kQ is a equivient internal resistance between Line + and REG Ry, = external resistor between Line + and REG if the voltage drop across the circuit has been reduced R, with C, provides a smoothed voltage Vcc for the IC itself and for the peripheral circuits (I,); R, determines the differential dc-resistance of the speech 2009 circuit Rec-a = Re and affects the voltage drop across the circuit Vines = Veet + Re (tine-Loc—LintLp) (2) where V,.; = reference voltage (= 3.6 V for [ing 211 mA) Tone = line current Tog = 1 mA Tye = 0.5 MA I, = current for external circuits It also determines the microphone gain (see note to R3) and influences the gain-contro! characteristics; Rs determines the voltage gain in transmit direction; 68 kQ for test- the gain for the microphone signal is condition Ay=1.356x 2% x aye) @) R. x Ry where R, = determined by (1) R, = line termination resistance-load at Line + during measurement 1.= 3.47 kQ is the dynamic resistance of the internal circuitry the gain of the DTMF dialing signal is 26 dB lower then that of the microphone amplifier. The gain can be set over a range of + 8 dB by means of Ry between 25 kQ and 180 kQ Siemens Aktiengeselischaft 775

‘Component | Function and Note Recommended Value Ry determines the gain in receiving direction; the gain of the | 100 kQ receiving amplification (between IN and the symmetrical outputs OUT + and OUT -—) is given by R. Zz, Aas = 2.628 x x ——t_ (4) Ry Z;+2r, where Z, = impedance of the earpiece 1, = 4 Qis the output impedance of the receiving amplifier. The gain can be adjusted over a range of + 8 dB by means of R, between 40 kQ and 250 kQ. Rs Re, Ro Rn Zoo) determines with R,, Rp and Z.ine the 130 kQ R, anti-side-tone network and attenuates the receiving 3.9 kQ 6 signal before it gets to the receiving amplifier. . R, Optimum anti-side-tone performance is given by 3902 Zea Zou = x Zine (6) | 1300 +820 Q// R, 220 nF the attenuation of the received signal is vy RUR, IN MMRe © Vines Rs + (RY/Re) where R, = input impedance of the receiving amplifier (21 kQ) R,=R, given by (1) The attenuation in a practical circuit is about 32 dB Re determines the line current start-point where the gain 100 kQ of both microphone and receiving controller amplifier decreases as a function of increasing DC-line current. Tistan = 4.5 x 10-8 x —* ) The line current end-point to start-point given by ratio is approximately constant “9 95 joan If pin 19 is open the AGC is inoperative. Siemens Aktiengesellschaft 776

Component | Function and Note Recommended Value Ry determines the current in an internal current-stabilizer. 3.6 kQ No alternative value is permissible. Cc, smoothing capacitor for the supply voltage at Voc of 100 pF the IC itself — (see also note to R,). Cc, smoothing capacitor decoupling the AC-signal from the 4.7 pF DC regulation part Cy is necessary for ensuring the stability of the transmitting 100 pF amplifier. i In combination with R, it operates as a first-order low-pass filter in sending direction with a cut-off | frequency determined by the time-constant R, x C3. on is necessary to ensure the stability of the receiving 100 pF amplifier where the time constant R, x C, corresponds with the cut-off frequency of a first-order low-pass filter Cs decouples the AC-signal for the receiving amplifier. 100 nF Cy determines the release time of the circuit after an over- | 470 nF | drive condition in the transmit direction (turns out). The release time for each 3 dB overdrive, respectively | with gain reduction, is approximately 6 ms. The capacitor will be recharged by an internal current source. | [om is necessary for the stability of the receiving amplifier. 1nF The value of C, must be 10 x C,. Rua affects the DC voltage drop across the circuit (see figure 3). Ry, connected between — Line + and REG decreases the voltage drop 68 kQ Veet = 1.3 V + (Ryac-say lH 16.3 kQ) x 0.14 mA Veet (Ry, = 68 kQ) ~ 3.15 V — REG and ROC increases the voltage drop 39 kQ Vet = 2.93 V +21200 VO/(Ryar6-20) 31.6 kQ) Veer (Ryan = 39 kQ) ~ 4.2 V. Zo is a balancing network from the anti-side-tone circuit. See also R,, Re, Ry. Siemens Aktiengesellschaft 777

Typical application of the PSB 4500, shown here with a piezoelectric earpiece and DTMF dialing. The bridge to the left, the Z-diode and Rj, limit the current into the circuit and the voltage across the circuit during line transients. Pulse dialing or register recall require a different protection arrangement. By means of resistor Ry (Rig.20) the dc line voltage can be set to a higher value. The AGC range is 6 GB if pin 10 (Lagc) is connected to ground and 3 GB if pin 10 is open. Figure 15a a Re s e2x19- ce heal 7 fe 17 ‘te ft 3,q tines cs 2% Won ayy . Hour Une PSB 4500 le_| oe mute Control me a6 | cecuts Soe “i

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Typical application of the PSB 4501, shown here with a piezoelectric earpiece and DTMF dialing. The bridge to the left, the Z-diode and R,, limit the current into the circuit and the voltage across the circuit during line transients. Pulse dialing or register recall require a different protection arrangement. By means of resistor Ry, (Rie.20) the DC line voltage can be set to a higher value. _ ‘Switch S between pin 10 and line represents the MMUTE key. Figure 15b Ry rR (] [ana ao r Dou Bas G& u 7 (ae) 3fin Lines Voc KR one Line Ie Sone PSB 4501 ‘6 rope wre} Control a af | ews ssa fa o| falc | ! eure ROC 1TG1 162! REG AGC Jew Line- at ye [we |e fe 39m | G s 1009F ah af [Jesu [30 [I [Sex0) | Siemens Aktiengesellschaft 780

Typical Application (simplified) a) DTMF dialing circuit implemented with CMOS circuit PSB 8593 The dashed lines show an optional flash (register recall by timed loop break) b) Application circuit with pulse and DTMF bilingual dialer PSB 8510. ne . 1 RSH | it tee Lid ome forme H ose PtP ome one |, FERRE radi 4500 lal PSB K—ftetstc] f4 freee, ( | plac 8593 Etetatal tt r Th Line hs L ( Telephone seeszo12 thr a ~ L | Lines Vee Mec O om orm manatee radle ‘ (lefstcl Sonace a | pln.’ 8 e510 [Loft] t4 TI Line _ vs —- 0 Teiephone pswesroray Siemens Aktiengeselischaft 781