MC34118

The MC34118 voice switched speakphone circuit incorporates the necessary amplifiers, attenuators, level detectors, and control algorithm to form the heart of a high quality hands-free speakerphone system.

Features of the MC34118 are:(1)improved attenuator gain range: 52 dB between transmit abd receive; (2)low voltage operation for line-powered applications(3.0 V to 6.5 V); (3)4-point signal sensing for improved sensitivity; (4)background noise monitors for both transimit and receive paths; (5)microphone amplifier gain set by external resistors-mute function included; (6)chip disable for active/standby operation.

The absolute maximum ratings of the MC34118 can be summarized as:(1): supply voltage(pin4) is -1.0 Vdc to +7.0 V dc; (2): voltage at CD(pin 3), MUT(pin 12) is -1.0 Vdc to Vcc+1.0 Vdc; (3): voltage at VLC(pin 13) is -1.0 V dc to Vcc+0.5  Vdc; (4): voltage at TXI(pin 9 ), RXI(pin 21), FI(pin 2) is -0.5 Vdc to Vcc+0.5 Vdc; (5): storage temperature range is -65 to +150.