HE910 Hardware User Guide
1VV0300925 Rev. 32 Page 46 of 111 2019-11-25
An example of switching regulator with 12V input is in the below schematic:
Figure 5-2 switching regulator
5.3.1.3. 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 cel power to the Telit HE910 module.l battery
type is suited for supplying the power to the Telit HE910 module.
Warning
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 the HE910 and
damage it.
NOTE:
DON'T USE any Ni-Cd, Ni-MH, and Pb battery types directly
connected with HE910. Their use can lead to overvoltage on the
HE910 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 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
HE910 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.
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