2

4741C–CORD–11/05

U4090B-P

1.

Description

The microcontroller-controlled telephone circuit U4090B-P is a linear integrated circuit for use in

feature phones, answering machines and fax machines. It contains the speech circuit, tone

ringer interface with DC/DC converter, sidetone equivalent and ear protection rectifiers. The cir-

cuit is line powered and contains all components necessary for amplification of signals and

adaptation to the line.

An integrated voice switch with loudspeaker amplifier allows loud-hearing or hands-free opera-

tion. With an anti-feedback function, acoustical feedback during loud-hearing can be reduced

significantly. The generated supply voltage is suitable for a wide range of peripheral circuits.

Figure 1-1.

Block Diagram

MC with

EEPROM/

DTMF

Audio

amplifier

Speech

circuit

Voice

switch

Tone

ringer

Loudhearing

and

Tone ringing