IL34118

The IL34118 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 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 tone from being attenuated by the Receive background noise monitor circuit of the IL34118. Also included are two line driver amplifiers 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 60 Hz noise in the reseive channel, or for other filtering functions. A Chip Disable pin permits powering down the entire circuit to conserve power on long loops where loop current is at a minimum.

The IL34118 may be operated from a power supply, or it can be powered from the telephone line, requiring typically 5.0 mA. The IL34118 can be interfaced directly to Tip and Ring (through a oupling transformer) for stand-alone operation, or it can be used in conjunction with a handset speech network and or other features of a featurephone.