User's Guide

HE863 Family Hardware User Guide
1vv0300891 Rev.5
- 2011-03-18
Reproduction forbidden without Telit Communications S.p.A’s. written authorization - All Rights
Reserved. Page 31 of 89
5. Hardware Commands
5.1. Turning ON the HE863
To turn on HE863 Family, the pad ON/OFF# must be tied low for
at least 1 second and then released.
The maximum current that can be drained from the ON/OFF# pad
is 0.1 mA.
A simple circuit to do it is:
NOTE:
The HE863 Family turns fully on by supplying power more than
3.2V to the VBATT pads because of the first connect power on
feature. This feature could be done only when Vbatt equals to
almost 0V at the beginning. Normally the high value capacitor
will be mounted on Vbatt line so the user should have a wait
enoughly since vbatt is disabled till the remaining voltage on
Vbatt is fully dischaged in order to do re-start by this
feature.
Because the discharge time depends upon the capacitance on
Vbatt in the application it should be definitely considered in
the application side.
HE863 Family has dozens uF on Vbatt line inside.
5.2. Initialization and Activation state
Upon turning on HE863 Family, HE863 Family is not activated
yet because the boot sequence of HE863 Family is still going
on internally. It may take more than about 10 seconds to
complete the initializing the module internally.
For this reason, it would be useless to try to access HE863
Family during Initialization state as below. To get the