User's Manual

LE920 Hardware User Guide
1vv0301026 Rev.8 2015-01-03
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
Reserved. Page 29 of 88
4. Hardware Commands
4.1. Turning ON the LE920
To turn on LE920, the pad ON# must be tied low for at least 1 second and then released.
The maximum current that can be drained from the ON# pad is 0.1 mA.
A simple circuit to power on the module is illustrated below:
4.2. Initialization and Activation state
Upon turning on LE920 module, The LE920 is not activated yet because the boot sequence of
LE920 is still going on internally. It takes about 10 seconds to complete the initializing the
module internally.
For this reason, it would be useless to try to access LE920 during the Initialization state, as
shown below. To reach full stability, The LE920 needs at least 15 seconds after the
PWRMON goes High to become operational by reaching the activation state.
During the Initialization state, any kind of AT-command is not available. DTE must wait for
the Activation state before communicating with LE920.