Description.
PBL 38541 is a monolithic integrated speech transmission circuit for use in electronic telephones or in any other line interface application. High settable supply current for auxiliary functions, up to 6.0 mA (at high line currents). The circuit is designed to accomodate either a low impedance dynamic or an electret microphone. Microphone can be muted separately. Payphone signaling and DTMF dialling tones have a separate input that is controlled by a mute signal.

Key features.
• Minimum number of external components, with two filtered DCsupplies, 7 capacitors and 11 resistors.
• Easy adaption to various market needs.
• Mute control input for operation with DTMF - generator.
• A separate signaling input for payphone and DTMF tones controlled by mute.
• Transmitter and receiver gain regulation for automatic loop loss compensation.
• Extended current and voltage range 4 - 130 mA, down to 2 .2V.
• Differential microphone input for good balance to ground.
• Balanced receiver output stage.
• One stabilized DC - supply for low current CMOS diallers and or electret microphones. One settable current limited supply with 6 mA max. current.
• Short start up time.
• Excellent RFI performance.
• 18 - pin DIP and 20 - pin SO packages.