PBL3853

Product Summary

The PBL3853 is a biopolar integrated speech circuit with specific parameters making it highly suitable to be used as a line interface and speech circuit in a telephone line powered electronic payphone. Emphasis has been put on low current consumption in the IC thus facilitating that a greater part of the available line current can be used to power other electrical functions in the design. From a minimum line current of 16 mA, 12 mA at 4.5 V can be used to power auxiliary functions. The PBL3853 can optionally create an active impedance towards the telephone line, set by external passive components, to reduce the current consumption for the transmitted signal. The PBL3853 is designed to be used with a low impedance dynamic microphone but can be used with an electret type as well. The receiver drives a low ohm dynamic transducer directly. External clamping diodes are required on the receiver output. Both transmitter and receiver can be muted separately (receiver cut off). Line length regulation of the gain is possible in both receiver and transmitter. The PBL3853 is also possible to use the circuit without regulation. Payphone tones and confidence tone in the receiver at DTMF dialling can be injected directly into the receiver amplifier where their levels are not affected by line length regulation and without the signal going out on the line. All pin numbers refer to DIP package unless otherwise noted.

Parametrics

PBL3853 absolute maximum ratings: (1)Line voltage, VL: 22 V; (2)Continous operating line current, Tamb=70℃, IL: 130 mA; (3)Input voltage, all inputs, Vpinx: -0.5 to Vpin4+0.5 V; (4)Operation temperature, Tamb: -20 to +70℃; (5)Storage temperature, Tstg: -55 to +125℃.

Features

PBL3853 features: (1)Low own current consumption; (2)Can operate both with active and passive impedance towards the line; (3)Derives a high current from the line for auxiliary functions, 12 mA at 16 mA line current; (4)Separate mute inputs for transmitter and receiver (receiver cut off); (5)Line length regulation possible (line loss compensation; (6)Comes in 18 pin DIP and 20-pin SO package; (7)High line current operation, max. 130mA; (8)Especially suitable for payphone applications; (9)DTMF - confidence tone input; (10)Excellent RFI performance.

Diagrams