Revision 1.13

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Key Features

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Line/Speakerphone circuit on a 28-pin CMOS-IC, simple

inventory: same die for AS2523/24 and AS2523/24B

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Serial I/F on AS2523, parallel I/F on AS2524

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Enhanced voice switching

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Background noise monitoring

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Tx- and Rx-gain programmable on AS2523 only

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Digital volume control of Rx signals on AS2523 only

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DC characteristic programmable on AS2523 only

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Dual softclipping in handset mode on AS2523 only

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Dual softclipping in handsfree mode on AS2523 only

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Loudspeaker amplifier for loudhearing and handsfree

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Supply voltage generation for external circuitry

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Automatic line loss compensation on AS2523 / 24B only

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Real and complex impedance selectable by external

components

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Side tone adaptation selectable by external components

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Unique EMC performance

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Operating range from 15mA to 100mA (down to 5mA

with reduced performance)

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Few external components

General Description

AS2523/24 is a CMOS integrated circuit that incorporates

DC and AC line adaptation (DC-mask and synthesized AC-

impedance of 1000Ω) as well as a speech circuit with

softclipping, line loss compensation and Rx-volume control

for handset and handsfree operation. It shall act as an a/b-

line powered device, which is controlled by a CPU via a

serial interface on AS2523 or a standard dialler via a

parallel interface on AS2524 and AS2524B.

Applications

Enhanced handsfree feature phones with CallerID and

extended displays. The AS2524 and AS2524B are

developed to interface with common Taiwanese dialers.

Package

Available in 28-pin SOIC or die

Block Diagram

Telephone Line Interface and

Speakerphone Circuit

AS2523, AS2524, AS2524B

DATA SHEET