HE920 Hardware User Guide
1vv0301014 Rev.9 – 2014-01-23
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Page 32 of 84
4.6.
Summary of Turning ON and OFF the module
Below chart describes the overall sequences for Turning ON and OFF.
NOTE:
Do not use any pull up resistor on the SHDN* line nor 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 SHDN* must be connected only in open collector
configuration.
The SHDN* is generating an unconditional shutdown(power off) of the module without an
automatic restart.
The module will shutdown, but will NOT perform the detach from the cellular network.
To proper power on again the module please refer to the related paragraph (“Turning ON the
HE920”)
TIP:
The unconditional hardware shutdown must always be implemented on the boards and should
be used only as an emergency exit procedure.
