MC33219A

The Motorola MC33219A Voice Switched Speakerphone Circuit incorporates the necessary amplifiers, attenuators, level detectors, and control algorithm to form the heart of a high quality handsfree speakerphone system. Included are a microphone amplifier with mute, transmit and receive attenuators, a background monitoring system for both the transmit and receive paths, and level detectors for each path.
An AGC system reduces the receive gain on long lines where loop current and power are in short supply. A dial tone detector prevents fading of dial tone. A Chip Disable pin permits conserving power when the circuit is not in use. The volume control can be implemented with a potentiometer.
The MC33219A can be operated from a power supply, or from thetelephone line, requiring typically 3.2 mA. It can be used in conjunction with a variety of speech networks. Applications include not only speakerphones, but intercoms and other voice switched devices. The MC33219A is available in a 24 pin narrow body DIP, and a wide body SOIC package.