User's Manual

MC55/56 Hardware Interface Description
Confidential / Preliminary
s
MC55/56_hd_v03.00 Page 76 of 104 16.08.2005
Function Signal name IO Signal form and level Comments
Ignition /IGT I
R
I
 100kΩ, C
I
 1nF
V
IL
max = 0.5V at Imax = -20µA
V
Open
max = 2.3V
ON
~~~
|____|
~~~
Active Low ≥ 100ms
Input to switch the mobile
ON.
The line must be driven low
by an Open Drain or Open
Collector driver.
Emergency
shutdown
(Watchdog)
/EMERGOFF I/O
R
I
22kΩ
V
IL
max = 0.5V at Imax = -100µA
V
Open
max = 2.73V
Signal
~~~
|______|
~~~
Active Low ≥ 3.2s
Watchdog:
V
OL
max = 0.35V at I = 10µA
V
OH
min= 2.25V at I = -10µA
f
O
min = 0.16Hz
f
O
max = 1.55Hz
This line must be driven by
an Open Drain or Open
Collector driver.
Emergency shutdown
deactivates the power
supply to the module.
The module can be reset if
/IGT is activated after
emergency shutdown.
To switch the mobile off
use the AT^SMSO
command.
To avoid floating if pin is
high impedance, use pull-
down resistor tied to GND.
See Chapter 3.3.2.1.
/EMERGOFF also
indicates the internal
watchdog function.
If unused keep pin open.
V
OL
max = 0.2V at I = 1mA
V
OH
min = 2.35V at I = -1mA
V
OH
max = 2.73V
Synchroni-
zation
SYNC O
1 Tx, 877µs impulse each 4.616ms and
2 Tx, 1454µs impulse each 4.616ms, with
300µs forward time.
Indicates increased current
consumption during uplink
transmission burst. Note
that timing is different
during handover.
Alternatively used to
control status LED (see
Chapter 3.12.2.2).
If unused keep pin open.