Data Sheet AS2540 austriamicrosystems
Revision 3.1 Page 1 of 18
austriamicrosystems
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*#)
Applications
- Web Telephones
- Answering Machines
- Fax Machines
- Base Station of Cordless Telephones
- Hospital Communication Units
Key Features
- 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
Package
- 28 pin SOIC
- Dice-on-Foil
Block Diagram
LS
RO H
RO T
M1
M2
TI T
AGND
Line
LI
RI
STB
CS
CI
DPn
C1
C2
C3
R1
R2
MODE
RFD
-2d B
+6dB
+2dB
Mask
DTMF-
generator
DIALLER UART
ST
IT
SR
O
H
SR
O
T
SM
U
T
E
Dia
l
Dig
it
SM
A
S
K
SD
P
n
MO
RxD
TxD
VDD
EHS
MHS
VSS
OSC
Main Power Mode
LS
RO H
RO T
M1
M2
TIT
AGND
Line
LI
RI
STB
CS
CI
DPn
C1
C2
C3
R1
R2
MODE
RFD
-2dB
+6dB
+2dB
Mask
DTMF-
generator
DIALLER UART
ST
IT
SR
O
H
SR
O
T
SM
U
T
E
Dia
l
Dig
it
S
MA
S
K
S
DP
n
MO
RxD
TxD
VDD
EHS
MHS
VSS
OSC
Backup Mode
Remote Controlled Single-Chip-Telephone
AS2540
DATA SHEET (PRELIMINARY)