PBL3781/02N

PBL3781 ERICSSON | Alldatasheet

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Technical content

tronic telephones. The circuits are designed to operate at low supply voltages, down to OC. 1.3 V, making them usable when connected in parallel with other telephones, «AG voltage swing down 10 0.4 V. A differential-input microphone amplifier, permits the use of a dynamic microphone. ; . for automatic loop loss compensation. toe even at low supply vokages electret buffer amplifier or pulse dialler. impedance to the line + Balanced receiver output stage. transducers and battery feeding systems. power dissipation. Figure 1. Functional diagram. oO |

(C1 = 1uF when aia oes used. a Figure 3. Test setup with rectifier bridge. Figure 4. PBL 3781 with external compo- 4 mie “t=° | nents for test circuits in figures 2 and 3.

1 CT> > > Aa = 752 R14= 900 Q (3781)

ERICSSON 2 PBL 3781, PBL 3781/02

Electrical Characteristics

Tage = 25°C. Measured using test circuit of fig. 1 and 2 without artificial cable, unless otherwise noted Ret Parameter fig) Conditions Min We Max Unit DC-characteristics Line voltage, V_ R, = 47 ohm 2 | =2.5mA 13 v 2 1 =10mA 33 v 2 |, = 100 mA 85 v R, = 75 ohm 2 1, =25mA 15 v 2 | =10 mA 35 v 2 |= 100 mA 13 v Maximum Transmitting gain,V,, V,_ 20x'? log (V2/V3), f= TkKHz —

2 R, = Oohm, R, = 0 ohm, 87 cr)

R, =, R, = 47 ohm

2 R, = 900 ohm, R, = 0 ohm, 62 8

Transmitting gain .V,, V, 20x" log (V2/V3) f= 1 kHz, (adjustable with R2 & R3)

2 R, = 0 ohm at 43 45 0B

2 R, = 400 ohms 435 455 475 dB

2 R, = 900 ohms 46 48 50 a8

Transmitting gain, range of regulation 2 f= 1 KHz. R, = 0 to 900 ohms 3 5 7 a Transmitting frequency response 2200-3400 Hz es ee Maximum receiving gain,V,.V, ~~~ 20x" log (V4NV1), f= 1 KHz a — _

2 R, = Oohm, R,, == 8 4B

R900 0h, ger BB Receiving gain,V,, V, 20+ 10 log (V4/Vi) f= 1 kHz, (Adjustable with R10) 2 R, =Oohm 18.5, 16.5 14.5 dB

2 R, = 400 ohms 16 14 12° dB

2 R, = 900 ohms 4135 115 95 GB

Receiving gain range of regulation 2 t=1kHz,R, =0to 9000hms _ 3 5 7 xe | Receiving frequency response 2200-3400 Hz A ee ee Input impedance microphone amplifier 2.4 f= 1 kHz 25.8 ohms Transmitter dynamic output level, V, 2800-3400 Hz, THD £2 %, |, = 20-100 mA 15 Vo, Figure 5. DC-current to external micro- a OT TO

PBL 3781, PBL 3781/02 ERICSSON 2 Ret Parameter fig Conditions tin we Max Unit Transmitter maximum output level, V, 2 200-3400 Hz, =O0100MA,V,=01V. 35. SSS Receiver output impedance 2.4 ik 6 (+370) ‘ohms Receiver dynamic outputlevel,V, —=«2-~=S=«00-3400 Hz, THD © 2%, 1, =20-100mA 0.5 Vee Receiver maximum outputlevelV, <3 200-3400 Hz, =0-100mA,V,=050V.. 1 Vay Transmitter noise level, V,_+=S*<C«*CS*«é *SpOMICWEGHted =—OOSOSCS~SsSt relative to 1 V,.4,R, =0 -70 3B Receiver noise levelV, —~—~=~=~=S*«*CS*S*«C ig ted, relative to

1 Viqqs With artificial cable: -80 0B

0-5km, = 0.5mm 0-3 km, O = 0.4 mm DC current to extemal microphone —=<C*~*SC‘<«‘zé NS TOM TI top amplifier, ly. |, = 10-150 mA, DC-current at pin 300 HA Mute current, |. a =ieis0mA SO a Warning: It is important to use a receiver which is not too sensitive. Otherwise the internal clipping will not function properly, and acoustic shocks may cause permanent damage to the human ear. 5-48

s ERICSSON % PBL 3781, PBL 3781/02 Pin Descriptions Ref. fig 3 and 5. DIP S10. Name Description +1 4 4k Output of the DC-regulator and transmit amplifier. This pin is connected to the line through a polarity guard diode bridge. 2 2 70 Output of the transmit amplifier. This pin is connected to a resistor Fé of 47 ohms to 100 ohms to -L, which sets the DC series-resistance of the circuit. The output has a low AC output impedance, and the signal is used to drive a sidetone balancing network RS, R7, RB and C2. 3.3 «+47 Input of the transmit amplifier. 45,5 1 The negative power terminal, connected to the line through a polarity guard diode bridge. 12,13 6 6 + This pin is the positive power supply terminal for most of the circuitry inside the PBL 3781 (about 1 mA current consumption). The majority of the line current however, passes through the TO and +L pins (see above). The +C pin shall be connected to a decoupling capacitor, C4 of 47 to 150 uF. 7 7° GR This pin is control input for the gain regulation circuitry. 8 8 MUTE The MUTE input which requires min. 100 A, to mute the microphone and receiver amplifiers. 9 13 MO Output of the microphone amplifier. When electret microphones are used, this pin can be connected as a current generator output. See functional description for pins 10 and 11 below. 1014 Mit Inputs of the microphone amplifier. The input impedance at these pins is approx, 2.5 kohms. Connecting 1 15) M2 pins 10 and 11 to pin 6, (+C) switches pin 9 (MO) to a current generator output, that sources about 300 WA for an external electret buffer amplifier. 14 18 Al Input of receiver amplifier. Input impedance is approx. 35 kohms. 45,16 19,20 RE1, RE2 Receiver amplifier output. The output is intended to drive low impedance receivers.

49 NC Not connected

10,11 12,16 - Figure 6 Pin configuration. 16 -pin DIP and 20-pin SO package. 1 [a] RE 2 acl ‘7 foree TO 2 pa RE To [i RE1 e fa RI q Rl Ne @| [ia] Nc ty lig] -L 18 Hal NC ia A +cH fe] Mi2 +c [i] Mi 2 GR [Mt cr Fa nat Mute [5] [3] MO Mute [3] [5] MO ne [a ane NC NC 891048A 5-49

The OC-regulator determines the opposite in phase from the transmit signal DTMF or pulse dialler circuit. from a bandgap reference, which provides 2nd sidetone cancellation occurs. Only 4. Impedance to the line. for temperature-stable DC-characteristics. the receive sora isleft atthe input ofthe 5 6. characteristics. bridge) drops below 2.5 Volts, the circuit _iS regulated with the line length. The and frequency response. Amicrophone amplifier with a down to 150 ohms,3781/02 down to 200 frequency response. microphones. oo . determined by R14 in parallel with C5. from the circuit). The transmit output over the world. Adaptation to different circuit inside PBL 3781, PBL 3781/02. Figure 7. Basic application for 48V/2 X 400 ohms battery feeding system and dynamic microphone and receiver.

the supply voltage at pin 6. C5 should be _ratio between R14 in parallel with the line network respectively. the V-I curve. For line currents above 10 gain is therefore enough to enable an the side-tone network is given below. volts. necessary to utilize the current generator find an optimum solution. 47 to 100 ohms depending on the battery ‘Automatic gain regulation circuitry in Point in most cases. voltage gain. A differential input stage regulation curve to get a correct compen- balancing network. common mode rejection. stems. The slope of the curve is determi- receiving gain.

3 Side-tone cancellation occurs at the 18 is approximately 35 kohms, A balan-

g | | Battery feed £ correct driving impedance. Figure 8. Typical gain regulation curve. DTMF circuit operates in parallel with the

Figure 9. Typical tone-dialling telephone for 48V 2x200Q battery feeding system. Figure10.Typical pulse-dialling telephone for 48V 2x200Q battery feeding system.

s ERICSSON & PBL 3781, PBL 3781/02 speech circuit, consuming a stand-by Pulse dialling telephone the telephone line supplies a small current of less than 250 uA. When a key Figure 10 shows a 10 number amount of current to retain the memory. closure is sensed, the speech circuit is memory telephone, using a minimum Since the line current passes through muted, and a tone pair is generated directly mer of components. the speech network during dialling, the on the line, Resistors RH and RL are used The current generator output at pin Pulses wit be monitored in the receiver. to set the output levels of the DTMF- @ of the PBL 3781 PBL 3781/02 and pin However, by adding two balancing generators. A reduced tone level is monito- 43 of the PBL 3781/02 SO is used to resistors of 47 kohms at the receiver red in the receiver during cating feed the pulse dialler during oft-hook, __utPut terminals, this effect is minimized. When using a generator, ¢ i a stablived cappy votage may be derived Dund ov-hook, @ 10 Mahm resistor io from pin 6 of the PBL 3781,PBL 3781/02. A The tones can be fed directly o the transit Ordering Information amplifier input as indicated in figure 7. The Package Temp. Range Pert No. mute input requires a minimum of 100 uA. Plastic DIP -20 to +70°C PBL 3781N Plastic DIP -20 to +70°C PBL 3781/02N Plastic S/O -20 to +70°C PBL 3781/0280 5-53