The SL34118 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.

• Improved Attenuator Gain Range: 52 dB Between Transmit and
   Receive
• Low Voltage Operation for Line-Powered Applications (3.0-6.5 V)
• 4 Point Signal Sensing for Improved Sensitivity
• Background Noise Monitors for Both Transmit and Receive Paths
• Microphone Amplifier Gain Set by External Resistors - Mute
   Function Included
• Chip Disable for Active Standby Operation
• On Board Filter Pinned-Out for User Deined Function
• Dial Tone Detector to Inhibit Receive Idle Mode During Dial Tone
   Presence