L
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 – 2013-05-
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 38 of 76
5.2.1.3.
Battery Source Power Supply Design Guidelines
x
The desired nominal output for the power supply is 3.8V and the maximum
allowed voltage is 4.2V, hence a single 3.7V Li-Ion cell battery type is suited for
supplying the power to the Telit LE920 module. The three cells Ni/Cd or Ni/MH
3.6 V Nom. battery types or 4V PB types must not be used directly since their
maximum voltage can rise over the absolute maximum voltage for LE920 and
damage it.
NOTE:
Do not use any Ni-Cd, Ni-MH, and Pb battery types directly connected with LE920. Their use
can lead to overvoltage on LE920 and damage it. Use only Li-Ion battery types.
x
A Bypass low ESR capacitor of adequate capacity must be provided in order to
cut the current
x
Make sure the low ESR capacitor (usually a tantalum one) is rated at least 10V.
x
A protection diode must be inserted close to the power input, in order to save
LE920 from power polarity inversion. Otherwise the battery connector must be
done in a way to avoid polarity inversions when connecting the battery.
x
The battery capacity must be at least 500mAh in order to withstand the current
peaks of 2A; the suggested capacity is from 500mAh to 1000mAh.
