Siemens AC75, Hardware Interface Description, Page: 88 / 120

AC75 Hardware Interface Description
Strictly confidential / Preliminary
s
AC75_HD_V00.202 Page 88 of 120 27.04.2006
Function Signal name IO Signal form and level Comment
Power
indicator PWR_IND O V
IH
max = 10V
V
OL
max = 0.4V at Imax = 2mA
PWR_IND (Power Indicator)
notifies the module’s on/off
state.
PWR_IND is an open
collector that needs to be
connected to an external pull-
up resistor. Low state of the
open collector indicates that
the module is on. Vice versa,
high level notifies the Power-
down mode.
Therefore, the pin may be
used to enable external
voltage regulators which
supply an external logic for
communication with the
module, e.g. level converters.
Ignition IGT I
Internal pull-up: R
I
≈ 30k
Ω
, C
I
≈ 10nF
V
IL
max = 0.8V at Imax = -150µA
V
OH
max = 4.5V (V
BATT+
)
ON
~~~
|____|
~~~
Active Low
≥
400ms
This signal switches the
mobile on.
This line must be driven low
by an open drain or open
collector driver.
Emergency
reset
I Internal pull-up: R
I
≈ 5k
Ω
V
IL
max = 0.2V at Imax = -0.5mA
V
OH
min = 1.75V
V
OH
max = 3.05V
Signal
~~~
|______|
~~~
Pull down
≥
10ms
Reset or turn-off in case of
emergency: Pull down and
release EMERG_RST. Then,
activating IGT for 400ms will
reset AC75. If IGT is not
activated for 400ms, AC75
switches off.
Data stored in the volatile
memory will be lost. For
orderly software controlled
reset rather use the
AT+CFUN command (e.g.
AT+CFUN=x,1).
This line must be driven by
open drain or open collector.
If unused keep pin open.
Power-on
reset
EMERG_RST
O Internal pull-up: R
I
≈ 5k
Ω
V
OL
max = 0.2V at I = 2mA
V
OH
min = 1.75V
V
OH
max = 3.05V
Reset signal driven by the module:
VEXT
EMRG_RST
appr. 120ms
(see also Figure 5 and Figure 6)
Reset signal driven by the
module which can be used to
reset any application or
device connected to the
module. Only effective for
120ms during the assertion of
IGT when the module is about
to start.