AS2540Q AMSCO [austriamicrosystems AG], AS2540Q Datasheet - Page 4

• Manufacturer Part Number: AS2540Q
• Description: Remote Controlled Single-Chip-Telephone
• Manufacturer: AMSCO [austriamicrosystems AG]

Data Sheet AS2540
Functional Description
Modes of operation
There are 4 possible modes:
Idle Mode
Manual hook-switch and electronic hook-switch (e.g. relay)
is open (MHS
the oscillator is stopped, signalling via the serial interface
is not possible.
Ringing Mode
AS2540 is supplied via the ring capacitor and external
path, manual hook -switch and electronic hook-switch is
open (MHS
valid incoming ringing is signalled via the serial interface to
the CPU. If the CPU does not reply the AS2540 switches
into backup mode and sends a ring melody to the MO
output.
Backup Mode
Manual hook-switch and/or electronic hook-switch is closed
(MHS
current, the oscillator is running, the keyscan is enabled
and the handset path is switched on, signalling via the
serial interface is possible. After AS2540 has started
dialling in backup mode, he must not be interrupted any
more in order to ensure consistent dialling. A mode
transition BM -> MPM is only possible before AS2540 has
started dialling digits independently.
Main Power Mode
Manual hook-switch and/or electronic hook-switch is
closed, AS2540 is supplied with line current (MHS
= logical 1), the oscillator is running, the keyscan is
disabled, AS2540 is controlled via the serial interface,
handset path or monitor path or modem path is on,
signalling via the serial interface is possible.
Select Operation Mode
Revision 3.1
Command Message
<SetHandsetPath>
<SetModemPath>
<SetMonitorPath>
EHS = logical 1), AS2540 is supplied with line
EHS = logical 0), the oscillator is running, a
EHS = logical 0), no ring signal is applied,
Switches ON
SROH
SROT & STIT
SROH & SROT
Switches OFF
SROT & STIT
STIT
EHS
Example Main Power Mode
Start-up in backup mode
As soon as AS2540 is supplied with line current, the
external V
VDD pin and after the V
operating level, the handset path of the speech circuit is
switched on. This off-hook status is also signalled to the
internal logic via the MHS or EHS pin in order to start the
pinscan and subsequently set the country specific modes.
Additionally a <LineEvent> message is sent to the CPU.
Start-up in ring mode
When a ringing signal is applied to the line, V
is charged up via an external path. After V
the operating voltage the oscillator starts and AS2540
discriminates the ring frequency. After a valid ring
frequency is applied on the RFD pin, the logic sends a
<LineEvent> message is sent to the CPU and a watchdog
timer is started. When the <LineEvent> message is not quit
by the CPU before the watchdog timer has finished the
countdown, AS2540 changes into backup mode and sends
out a melody via the MO pin.
DC conditions
The normal operating mode is from 15mA to 100mA. An
operating mode with reduced performance is from 5mA to
15mA. In the line hold range from 0mA to 5mA the device
is in a power down mode and the voltage at LI is reduced
to a maximum of 3.5V
Line
dd
capacitor will be charged up via the LI and
MODE
DP n
RFD
MHS
MO
EHS
C1
C2
C3
R1
R2
ST B
CS
CI
LS
LI
RI
Mask
DIALLER
-2dB
dd
austriamicrosystems
generator
DT MF-
voltage has reached the
UART
+ 6dB
+ 2dB
dd
ROH
ROT
M1
M2
T IT
AGND
has reached
RxD
T xD
VDD
VS S
OS C
dd
of AS2540
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