WE865-DUAL HW User Guide
1vv0300787
Rev. 1 - 03/10/08
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved
page 18 of 48
4.2.2 +12V input source
Due to the big difference between the input source and the desired output voltage, a linear voltage
regulator is not suited and not recommended. A switching power supply will be preferable because of
its better efficiency especially in presence of peak current load.
When using a switching regulator, 500 kHz switching frequency (or more) is preferable because of its
smaller inductor size and its faster transient response. This allows the regulator to respond quickly to
any current peak absorption.
A protection diode should be inserted close to the power input, in order to save the WE865-DUAL from
power polarity inversion. This can be the same diode as for spike protection.
The figure below shows a possible solution for the switching power supply. It must be taken into
consideration that the switching power supply performances strongly depend on the layout design.
