austriamicrosystems
Telephone Line Interface and
Speakerphone Circuit
AS2522B
Key Features
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DATA SHEET
General Description
AS2522 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. Furthermore the AS2522 incorporates a
DTMF, FSK transmitter, single tone and ringer tone
generator.
AS2522 allows to use an off-the-shelf microprocessor
without special blocks and functions for telephone
applications. DTMF, FSK transmitter, single tone and ringer
tone generator can be controlled via the serial interface as
well as the gain settings in handset and handsfree mode.
Line/Speech circuit, DTMF dialer, FSK transmitter and
tone ringer on a 32-pin CMOS-IC
Enhanced voice switching
Background noise monitoring
DTMF tone generator
FSK Transmitter V.23, BELL202, V.21, BELL 103
Ringer tone programmable
Tx- and Rx-gain programmable
Digital volume control of Rx signals
DC characteristic programmable
Dual softclipping in handset mode
Tx-softclipping in handsfree mode
Common monitor amplifier for loudhearing, handsfree
and ringing
Supply voltage generation for external circuitry
Automatic line loss compensation (LLC)
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.
Package
Available in 32-pin TQFP
Block Diagram
Revision 3.4
Page 1 of 19
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
