User's Manual

GE864- QUAD Har dwar e User Guide
1vv0300872 Rev.1 2010-04-02
- All Rights Reserved. Page 28 of 77
An example of linear regulator with 5V input is:
6.2.1.2. +12V input Sour ce Power Suppl y Design Guidelines
The desired output for the power supply is 3.8V; hence due to the big
difference between the input source and the desir ed output, a linear
regulator is not suited and shall not be used. A switching power supply
will be preferable because of its better efficiency especially with the 2A
peak current load represented by the GE864-QUAD.
When using a switching regulator, a 500kHz or mor e switching frequency
regulator is prefer able because of its smaller inductor size and its faster
transient response. This allows the regulator to respond quickly to the
curr ent peaks absor ption.
In any case the fr equency and Switching design selection is related to the
application to be developed due to the fact the switching frequency could
also generate EMC inter fer ences.
For car PB batter y the input voltage can rise up to 15.8V and this must be
kept in mind when choosing components: all components in the power
supply must withstand this voltage.
A Bypass low ESR capacitor of adequate capacity must be provided in
order to cut the cur rent absor ption peaks, a 100μF tantalum capacitor is
usually suited.