GE865 Hardware User Guide
1vv0300799 Rev.9 – 27-07-2009
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page 27 of 70
An example of linear regulator with 5V input is:
6.3.1.2 + 12V input Source Power Supply Design Guidelines
•
The desired output for the power supply is 3.8V, hence due to the big difference
between the input source and the desired 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 GE865.
•
When using a switching regulator, a 500kHz or more switching frequency regulator is
preferable because of its smaller inductor size and its faster transient response. This
allows the regulator to respond quickly to the current peaks absorption.
•
In any case the frequency and Switching design selection is related to the application to
be developed due to the fact the switching frequency could also generate EMC
interferences.
•
For car PB battery the input voltage can rise up to 15,8V and this should 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
current absorption peaks, a 100
μ
F tantalum capacitor is usually suited.
•
Make sure the low ESR capacitor on the power supply output (usually a tantalum one)
is rated at least 10V.
