User's Manual

LE920A4 HW User Guide Hardware Commands
Doc#: 1VV0301261 Turning off the Module
Rev. 4.3 Page 51 of 123 2017-12-07
5.3.3. Unconditional Hardware Reset
To unconditionally restart the module, the RESET_N pad must be asserted low for a
period of 500-2000 milliseconds and then released.
Figure 7 shows a simple circuit for this action.
Figure 7: Circuit for Unconditional Hardware Reset
For keeping backward compatibility to LE920, it is recommended to prepare an alternate
connection of the RESET_N pad also to Pad AP1 while keeping Pad AN8 as the default
connection as is shown in Figure 8.
Figure 8: Alternate Connection of RESET_N Pad
LE920A4
AP1
AN8
DNP
0 Ohm
RESET#
NOTE:
In general, using RESET_N is not recommended.
The Unconditional Hardware Reset must always be implemented on the
boards, but the software must use it only as an emergency exit procedure,
and not as a normal Reset operation.
NOTE:
Do not use any pull-up resistor on the RESET_N line or any totem pole
digital output. Using a pull-up resistor may cause latch-up problems on the
module’s power regulator and improper functioning of the module. The
RESET_N line must be connected only in an open-collector configuration.