BL34018

www.DataSheet4U.com BL34018 1. GENERAL DESCRIPTION The BL34018 Speakerphone integrated circuit Incorporates the necessary amplifiers ， attenuators ， and control functions to produce a high quality hands free speakerphone system． Include are a microphone amplifier， a power audio amplifier for the speaker， transmit and receive attenuators，a monitoring system for background sound level，and an attenuation control system which responds to the relative transmit and receive levels as well as the background level．Also included are all necessary regulated voltages for both internal and external circuitry， allowing line-powered operation (no additional power supplies required)．A chip select pin allows the chip to be powered down when not in use．A volume control function may be implemented with an external potentiometer．BL34018 applications include speakerphones for household and business use，intercom systems，automotive telephones，and others． 2. FEATURE Voice switched speakerphone circuit. All necessary level detection and attenuation controls for a hand-free telephone included. Background noise level monitoring with long time constant. Background sound level compensation for transmit and receive levels as well as the background level. Wide operating dynamic range through signal compression. On-chip supply and reference voltage regulation. Power audio amplifier for typical 100mW output (into 25 ohms) with peak limiting for speaker to minimize distortion. Chip Select pin for active/st...