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PDF AS2540 Data sheet ( Hoja de datos )
| Número de pieza | AS2540 | |
| Descripción | Remote Controlled Single-Chip-Telephone | |
| Fabricantes | austriamicrosystems AG | |
| Logotipo |  |
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Data Sheet AS2540
austriamicaursotrsiaymsitceromsysstems
Remote Controlled Single-Chip-Telephone
AS2540
DATA SHEET (PRELIMINARY)
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
Line
Main Power Mode
LS
LI
RI -2dB
STB
CS
Mask
CI
DPn
DTMF-
generator
+ 6dB
+ 2d B
ROH
ROT
M1
M2
TIT
AGND
Line
Backup Mode
LS
LI
RI -2dB
STB
CS
Mask
CI
DPn
DTMF-
g enerator
+ 6dB
+ 2d B
ROH
ROT
M1
M2
TIT
AGND
C1
C2
C3
R1
R2
MODE
RFD
MO
EHS
MHS
DIALLER
UART
RxD
TxD
VDD
VSS
OSC
C1
C2
C3
R1
R2
MODE
DIALLER
RFD
MO
EHS
MHS
UART
RxD
TxD
VDD
VSS
OSC
Revision 3.1
Page 1 of 18
1 page  
Data Sheet AS2540
austriamicrosystems
The DC characteristic is determined by the voltage at LI
pin and a 30Ω resistor between LI and LS pin. It can be
calculated by the following equation: VLS = VLI + ILine *
30Ω. The t.m. voltage at the LI pin is 4.5V. The calculation
leads to the following DC resistances: 330Ω to 75Ω at line
currents from 15mA to 100mA.
2/4 wire conversion
AS2540 has a built-in dual Wheatstone bridge with one
common ground. This provides a maximum of
independence of AC impedance and side tone from each
other. One can adapt side tone without changing the AC
impedance.
A1=3.4/3.5
A2=-0.4
AC impedance
The ac impedance of AS2540 is set to t.m. 1000Ω. With
the external capacitor at CI pin it can be programmed
complex. With a parallel impedance at the LS pin it can be
programmed to 600Ω.
Side Tone
A good sidetone cancellation can be achieved by using the
following equation:
ZBAL/ZLINE = 10
Transmit path
The gain of the M1/M2 —> LS transmit path is set to 38dB
for ac-impedance 1000Ω. The input is differential with an
impedance of 25kΩ. The soft clip circuit limits the output
voltage at LS to 2Vp. The attack time is 30µs/6dB and the
decay time is 20ms/6dB.
The gain of the TIT —> LS transmit path is set to 8dB for
ac-impedance 1000Ω. The input is single ended with an
impedance of 25kΩ. The soft clip circuit is not active for
this input. The dynamic range of this path is 2.5Vp at LS.
Receive path
The gain of the LS —> ROH receive path is set to 2dB for
ac-impedance 1000Ω. The receive input is the differential
signal of RI and STB. During DTMF dialling a MF comfort
tone is applied to ROH which is -30dB relative to the line
level. The soft clip circuit limits the output voltage at ROH
to 1Vp. It prevents harsh distortion and acoustic shock.
The gain of the LS —> ROT receive path is set to 0dB for
ac-impedance 1000Ω. The receive input is the differential
signal of RI and STB. The soft clip circuit is not active for
this output.
Modescan
The DTMF-level on the line and the function of the line loss
compensation can be selected with the connection of the
MODE-pin to the keyboard matrix. The MODE-pin is
scanned once after each OFF-Hook transition.
PIN
MODE
PIN PIN PIN
C1 C2 C3
R1 1 2 3
R2 4 5 6
789
*0#
c1 C2 C3
PIN
R1
PIN
R2
C3 C2 C1 R2 R1 LLC Dtmf Level
45mA-75mA
-6dBm
X X 45mA-75mA
-8dBm
X 45mA-75mA -10dBm
X
20mA-50mA
-6dBm
X
20mA-50mA
-8dBm
XX
20mA-50mA -10dBm
XX
No LLC
-6dBm
XX
No LLC
-8dBm
XXX
No LLC
-10dBm
X indicates connection to pin mode
Revision 3.1
Page 5 of 18
5 Page 
Data Sheet AS2540
austriamicrosystems
Electrical characteristics
Electrical characteristics are measured with the Test Circuit application. Typical mean values will not be tested.
Absolute maximum ratings
Positive Supply Voltage
Input Current
Input Voltage (LS)
Input Voltage (LI, CS)
Input Voltage (STB, RI)
Digital Input Voltage
Electrostatic Discharge (HBM 1.5kΩ-100pF)
Storage Temperature
-0.3V <= VDD <= 7V
+/- 25mA
-0.3V <= Vin <= 10V
-0.3V <= Vin <= 8V
-2V <= Vin <= VDD+0.3V
-0.3V <= Vin <= VDD+0.3V
+/- 800V
-65°C to +125°C
Recommended operating conditions
Supply Voltage (generated internally)
Oscillator Frequency
Resonator Murata CSA 3.58MG312AM
Operating Temperature
3.6V <= VDD <= 5V
3.58MHz
-15°C to +60°C
DC characteristics
ILine=15mA w/o operation of SI through optocouplers, unless other specified
Symbol Parameter
Conditions
Min Typ Max Units Test
IDD Operating Current
Speech Mode
Speech Mode with SI
MF Dialling
LD Dialling, VDD=2.5V
Ring Mode, VDD=2.5V
3 5 mA Y
5 mA N
4 mA N
200 µA N
300 µA N
VLI Line Voltage
15mA<=ILINE<=100mA
4.2 4.5 4.8
V
Y
IOL Output Current, Sink CS,
DPn, MO
VOL=0.4V
TXD VOL=10mA
1 mA N
10 mA N
IOH Output Current, Source MO
VOH=VDD-0.4V
-1 mA N
Revision 3.1
Page 11 of 18
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet AS2540.PDF ] | |
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