User's Manual
HC864-AUTO Hardware User Guide
1vv0300946 Rev.4 – 2012-12-27
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights
Reserved. Page 32 of 77
5.2.1.3. Battery Source Power Supply Design Guidelines
• 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 HC864-AUTO 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 HC864-
AUTO and damage it.
NOTE:
Do not use any Ni-Cd, Ni-MH, and Pb battery types directly connected with HC864-AUTO.
Their use can lead to overvoltage on HC864-AUTO and damage it. Use only Li-Ion battery
types.
• A Bypass low ESR capacitor of adequate capacity must be provided in order to
cut the current absorption peaks, a 100F tantalum capacitor is usually suited.
• Make sure the low ESR capacitor (usually a tantalum one) is rated at least 10V.
• A protection diode must be inserted close to the power input, in order to save
HC864-AUTO from power polarity inversion. Otherwise the battery connector
must be done in a way to avoid polarity inversions when connecting the battery.
• 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.