austriamicrosystems
Telephone Line Interface and
Speakerphone Circuit
AS2523, AS2524, AS2524B
Key Features
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DATA SHEET
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.
Line/Speakerphone circuit on a 28-pin CMOS-IC, simple
inventory: same die for AS2523/24 and AS2523/24B
Serial I/F on AS2523, parallel I/F on AS2524
Enhanced voice switching
Background noise monitoring
Tx- and Rx-gain programmable on AS2523 only
Digital volume control of Rx signals on AS2523 only
DC characteristic programmable on AS2523 only
Dual softclipping in handset mode on AS2523 only
Dual softclipping in handsfree mode on AS2523 only
Loudspeaker amplifier for loudhearing and handsfree
Supply voltage generation for external circuitry
Automatic line loss compensation on AS2523 / 24B only
Real and complex impedance selectable by external
components
Side tone adaptation selectable by external components
Unique EMC performance
Operating range from 15mA to 100mA (down to 5mA
with reduced performance)
Few external components
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
Revision 1.13
Page 1 of 19
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
