UC864-E Hardware User Guide
1vv0300766a Rev.1 - 31/01/08
An example of linear regulator with 5V input is:
5.2.1.2 + 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
•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.
•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. The same consideration has to be applied to the voltage peaks that in a Car Application could rise to 100V.
•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 on the power supply output (usually a tantalum one) is rated at least 10V.
•A spike protection diode should be inserted close to the power input for Car applications, in order to clean the supply from spikes.
•A protection diode should be inserted close to the power input, in order to save
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