User's Manual

Table Of Contents
MC46 Hardware Interface Description
DRAFT
MC46_HD_V02.8xb Page 32 of 98 21.08.2003
3.3.2.2 Maximum number of turn-on / turn-off cycles
Each time the module is shut down, data will be written from volatile memory to flash
memory. The guaranteed maximum number of write cycles is limited to 100.000.
3.3.2.3 Emergency shutdown using /EMERGOFF pin
Caution: Use the /EMERGOFF pin only when, due to serious problems, the software is
not responding for more than 5 seconds. Pulling the /EMERGOFF pin causes
the loss of all information stored in the volatile memory since power is cut off
immediately. Therefore, this procedure is intended only for use in case of
emergency, e.g. if the host controller experienced a watchdog reset and
afterwards MC46 fails to shut down properly or fails to respond.
The /EMERGOFF signal is available on the board-to-board connector. To control the
/EMERGOFF line it is recommended to use an open drain / collector driver. To turn the GSM
engine off, the /EMERGOFF line has to be driven to ground for ³ 3.2s.
Figure 6: Deactivating GSM engine by /EMERGOFF signal
BATT+
Internal reset
/EMERG-
OFF
Controlled by external application
max. 3.2s
/IGT
VDD
How does it work:
· Voltage V
batt+
is permanentl
y
applied to the module.
· The module is active while the
internal reset signal is kept at
high level.
During operation of MC46 the
baseband controller generates
watchdog pulses at regula
r
intervals.
Once the EMERGOFF pin is
grounded these watchdog
pulses are cut off from the
power supply ASIC. The powe
supply ASIC shuts down the
internal supply voltages o
MC46 after max. 3.2s and the
module turns off.
Consequently, the output
voltage at VDD is switched off.
Controlled by MC46 software