User's Manual

HE920 Hardware User Guide
1vv0301014 Rev.9 – 2014-01-23
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Reserved. Page 30 of 84
4.4. Hardware Unconditional Restart (RESET)
To unconditionally restart HE920, the pad RESET* must be tied low for at least 200
milliseconds and then released.
A simple circuit to do it is:
NOTE:
Do not use any pull up resistor on the RESET* line or any totem pole digital output. Using
pull up resistor may bring to latch up problems on the HE920 power regulator and improper
functioning of the module. The line RESET* must be connected only in open collector
configuration.
TIP:
The unconditional hardware Restart must always be implemented on the boards and the
software must use it as an emergency exit procedure.
RESET#
Unconditional Restart
impulse
GND