User guide

UC864-E/G/WD/WDU Hardware User Guide
1vv0300766a Rev.4
- 03/02/09
Reproduction forbidden without Telit Communications S.p.A’s. written authorization - All Rights Reserved. Page 17 of 78
4. Hardware Commands
4.1. Turning ON the UC864-E/G/WD/WDU
To turn on UC864-E/G/WD/WDU, 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 do it is:
4.2. Initialization and Activation state
Upon turning on UC864-E/G/WD/WDU, UC864-E/G/WD/WDU is not activated yet
because the boot sequence of UC864-E/G/WD/WDU is still going on internally. It
takes about 6.5 seconds to complete the initializing the module internally.
For this reason, it would be useless to try to access UC864-E/G/WD/WDU during a
Initialization state as below. To get stability, UC864-E/G/WD/WDU needs at least 6.5
seconds after the PWRMON goes High
ON/OFF
1 sec (at least)
PWRMON
2.27ms
Internal state
Initialization state Activation state
6.5 sec
ON#
Power ON impulse
GND
R1
R2
Q1