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BL34018 Dataheets PDF



Part Number BL34018
Manufacturers SHANGHAI BELLING
Logo SHANGHAI BELLING
Description high quality hands free speakerphone system
Datasheet BL34018 DatasheetBL34018 Datasheet (PDF)

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 backg.

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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/stand by operation. Linear Volume Control Function. 3. BLOCK DIAGRAM http://www.belling.com.cn -1Total 16 Pages 8/15/2006 Wrote by 2006 BL34018 4. PIN CONFIGURATIONS Pin 1 2 Name RR RTX Description A resistor to ground provides a reference current for the transmit and receive attenuators. A resistor to ground determines the nominal gain of the transmit attenuator. The transmit channel gain is inversely proportional to the RTX resistance. Input to the transmit attenuator. Input resistance is nominally 5.0 k ohms. Output of the transmit attenuator. The TXO output signal drives the input of the transmit level detector, as well as the external circuit which drives the telephone line. Input of the transmit level detector. An external resistor ac coupled to the TLI pin sets the detection level. Decreasing this resistor increases the sensitivity to transmit channel signals. Output of the transmit level detector. The external resistor and capacitor set the time the comparator will hold the system in the transmit mode after speech ceases. Input of the receive level detector. An external resistor ac coupled to the RLI pin sets the detection level. Decreasing this resistor increases the sensitivity to receive channel signals. Output of the receive level detector. The external resistor and capacitor set the time the comparator will hold the system in the receive mode after speech ceases. Microphone amplifier input. Input impedance is nominally 10 k ohms and the dc bias voltage is appro.


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