Data Sheet AS2540
austriamicrosystems
austriamicrosystems
DATA SHEET (PRELIMINARY)
Remote Controlled Single-Chip-Telephone
AS2540
General Description
The AS2540 is a CMOS integrated circuit that
incorporates a speech circuit (line-adaptation, 2/4-wire
conversion, separate Rx- and Tx-amplifiers for handset
and modem), MF dialler, ring frequency detector, ring
melody generator and a two wire serial interface. It
shall act as an a/b-line-powered device in order to
interface a main-powered CPU to the analogue
telephone line.
AS2540 can operate in a so-called mainpower mode
and in a backup mode. During mainpower mode, a
watchdog timer is running on AS2540, which has to be
reset via the serial interface, which is connected to the
CPU through opto-couplers. During backup mode (=
The main-power failure or SW engine problem),
AS2540 can operate as an independent basic MF
dialler (digits 0-9*#)
Key Features
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Line Interface, Speech Circuit, MF Dialler and Tone Ringer
on a 28 pin CMOS chip
Programmable via 2-wire serial interface
(UART 9600 baud, 8N1)
Watch dog timer for Backup Mode
Additional input for modem transmit path
Additional output for modem receive path
CMOS for high EMC immunity
Low Noise (max. –72 dBm)
Operating range from 15mA to 100mA (down to 5mA with
reduced performance)
Soft clipping for handset operation to avoid harsh distortion
Line loss compensation selectable by pin option
Real and complex impedance selectable by external
components
Side tone adaption selectable by external components
Ring frequency discrimination
3-tone ring melody generator
Applications
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Web Telephones
Answering Machines
Fax Machines
Base Station of Cordless Telephones
Hospital Communication Units
Package
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28 pin SOIC
Dice-on-Foil
Block Diagram
Main Power Mode
Line
LS
LI
+ 6dB
Backup Mode
Line
LS
LI
+ 6dB
RI
SB
T
-2d B
+ 2d B
ROH
ROT
M1
M2
RI
SB
T
-2dB
+ 2d B
ROH
ROT
M1
M2
CS
Mask
CS
Mask
T
IT
CI
DPn
DT
MF-
generator
T
IT
CI
AGND
DPn
DT
MF-
g enerator
AGND
SMUT
E
S
MASK
S
MAS
K
SMUTE
SROH
SROH
SROT
S
DPn
S
DPn
Dia l
Dig it
Dial
Digit
ST
IT
SROT
ST
IT
RxD
RxD
DIALLER
C1
C2
C3
R1
R2
MODE
UART
T
xD
C1
C2
C3
R1
R2
MODE
VDD
DIALLER
UART
T
xD
VDD
RFD
MO
EHS
MHS
VS
S
OS
C
RFD
MO
EHS
MHS
VS
S
OSC
Revision 3.1
Page 1 of 18
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
