Description
TELEFUNKEN microelectronic’s low voltage speech and ringer interface circuit, U4037B performs all necessary speech, line interface functions and the tone ringer required in an electronic telephone set. The circuit is line powered and contains all components necessary for amplification of signals and adaption to the line. The power supply of U4037B provides the MCU during the ringing and the speech mode.

Features
Speech Circuit
● Adjustable dc characteristic
● Symmetrical input of microphone amplifier
● Receiving amplifier for dynamic or piezo-electric earpieces
● Automatic line loss compensation
● MCU controlled earphone gain 8 dB
● Anti-clipping in transmit direction

Tone Ringer Interface
● Adjustable volume via 2 bit D/A converter
● Adjustable threshold
● MCU power supply

Benefits
● Low number of external components

Applications
    Standard, telephones, fax machines