Telit Wireless Solutions GM862-GPS - Manual (Page 14)

GM862-GPS Hardware User Guide
1vv0300728 Rev. 0 - 27/04/06
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved page 14 of 55
An example of switching regulator with 12V input is:
3.2.1.3 Battery Source Power Supply Design Guidelines
• The desired nominal output for the power supply is 3.8V and the maximum voltage allowed is
4.2V, hence a single 3.7V Li-Ion cell battery type is suited for supplying the power to the Telit
GM862-GPS module.
The three cells Ni/Cd or Ni/MH 3,6 V Nom. battery types or 4V PB types MUST NOT BE USED
since their maximum voltage can rise over the absolute maximum voltage for the GM862-GPS and
damage it.
NOTE: DON'T USE any Ni-Cd, Ni-MH, and Pb battery types. Their use can lead to overvoltage on the GM862-GPS
and damage it. USE ONLY Rechargeable Li-Ion battery types.
• A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current
absorption peaks, a 100μF tantalum capacitor is usually suited.
• Make sure the low ESR capacitor (usually a tantalum one) is rated at least 10V.
• A protection diode should be inserted close to the power input, in order to save the GM862-GPS
from power polarity inversion. Otherwise the battery connector should 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.