Description.
PBL 38573 is a monolithic integrated speech transmission circuit for use in electronic telephones. It is intended specially for telephone lines with constant current feed. Maximum line current less than 130 mA in DIL package (100 mA in SO package). It is designed to accomodate either a low impedance dynamic or an electret microphone. A signal summing point at the transmitter input is available for DTMF dialler- and possible monitor or handsfree signals. An available internally preset line length compensation can be adjusted or shut off in low gain mode with external resistors.

Key features.
• Minimum number of external components for function,with one filtered DC-supply. 6 capacitors and 10 resistors.
• Easy adaption to various market needs.
• Mute control input for operation with DTMF - generator.
• Transmitter and receiver gain regulation for automatic loop loss compensation. Disconnectable.
• Extended current and voltage range 5 - 130mA (DIP), down to 2 V.
• Differential microphone input for good balance to ground.
• Balanced receiver output stage.
• Stabilized DC - supply for low current CMOS diallers and electret microphones.
• Short start up time.
• Excellent RFI performance.
• In 14- pin DIP and SO packages.