Hardware interfaces
Version 8 dated 15.03.00
18
Siemens Information and Communication Products
4.3.2
Power on/off
Note
:
1
) Level range: 0 < IGNITION < 6.2 V, (maximum voltage: +/-50 V). For additional information see
2
) See
Fig. 4-1 Timing of power on/off signals
case IGNITION > 2.7 V level = IGNITION – 0.7 V.
To turn on the M20, connect IGNITION to the voltage specified in the table above. The device will then keep running
even if a voltage < 0.6 V is applied to IGNITION or the device is left disconnected. To turn off the M20, use the corre-
sponding AT command (AT^SMSO, see Chapter
5.7 “Siemens-defined AT commands for enhanced functions” on page 111
Note
: if IGNITION is connected to a fixed voltage > 1.3 V, the M20 cannot be turned off with an AT command.
POWER_ON indicates that the microprocessor of M20 is supplied.
RES# level High indicates that the microprocessor of M20 is supplied and working.
Note
: RES# also can be used as 2.8 V reference level for applications of the M20.
For additional information, see
Fig. 4-1 Timing of power on/off signals
Fig. 4-1
Timing of power on/off signals
Signal
Function
I/O
Level
Comments
IGNITION
Switch on
I
1
)
IGNITION >2.7 V
for longer than 1 s switches on
POWER_ON
Power-on indicator
O
2
)
Load current < 300 uA
Note: may be unconnected if unused
RES#
Reset indicator
O
2.8V
Load current < 500 uA
Note: may be unconnected if unused
Uswitchon
IGNITION
t
2.8V
RES#
t
Uswitchon-0.7V
POWER_ON
t
2V typ.
300ms
duration > 1s