User's Guide

LE920A4 HW User Guide Hardware Commands
Doc#: 1VV0301261 Unconditional Hardware Reset
Rev. 4.7.1 Page 52 of 124 2019-11-21
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 9 shows a simple circuit for this action.
Figure 9: 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 below figure.
Figure 10: 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.
NOTE:
Asserting t
RESET
low for period longer than 2000 milliseconds will cause the
module to shut down.