TS34118

The TS34118 Voice Switched Speakerphone Circuit incorporates the necessary amplifiers, attenuators, level detectors, and control algorithm to form the heart of a high quality hands-free speakerphone system. Included are a microphone amplifier with adjustable gain and MUTE control, Transmit and Receive attenuators TS34118 which operate in a complementary manner, level detectors at both input and output of both attenuators, and background noise monitors for both the transmit and receive channels. A Dial Tone Detector prevents the dial being attenuated by the Receive background noise monitor circuit. Also included are two line drive amplifiers TS34118 which can be used to form a hybrid network in conjunction with an external coupling transformer. A high-pass filter can be used to filter out 60Hz noise in the receive channel, or for other filtering functions .A Chip TS34118 Disable pin permits powering down the entire circuit to conserve power on long loops where loop current is at a minimum.

The TS34118 may be operated from a power supply, or it can be powered from the telephone line, requiring typically 5.0mA. The TS34118 can be interfaced directly to Tip and Ring (through a coupling transformer) for stand-alone operation, or it can be used in conjunction with a handset speech network and/or other features of a feature phone