User's Manual

HE910 Hardware User Guide
1vv0300925 Rev.9 – 07-02-2012
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 19 of 80
4 Hardware Commands
4.1 Turning ON the HE910
To turn on the HE910 the pad ON_OFF* must be tied low for at least 5 seconds and then
released.
The maximum current that can be drained from the ON# pad is 0,1 mA.
A simple circuit to do it is:
NOTE:
Don't use any pull up resistor on the ON_OFF* line, it is internally pulled up. Using pull
up resistor may bring to latch up problems on the HE910 power regulator and improper
power on/off of the module. The line ON_OFF* must be connected only in open
collector or open drain configuration.