User's Manual

LE910 V2 HARDWARE USER GUIDE 1VV0301200 Rev.2 Preliminary • 2015-08-04 23 of 81
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4.3 General Design Rules
The principal guidelines for the Power Supply Design embrace three different design steps:
 the electrical design
 the thermal design
 the PCB layout.
4.3.1 Electrical Design Guidelines
The electrical design of the power supply depends strongly from the power source where this power is drained. We
will distinguish them into three categories:
 +5V input (typically PC internal regulator output)
 +12V input (typically automotive)
 Battery
4.3.1.1 +5V Source Power Supply Design Guidelines
 The desired output for the power supply is 3.8V, hence there's not a big difference between the input
source and the desired output and a linear regulator can be used. A switching power supply will not be
suited because of the low drop out requirements.
 When using a linear regulator, a proper heat sink shall be provided in order to dissipate the power
generated.
 A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption
peaks close to the Module, a 100μF capacitor is usually suited.
 Make sure the low ESR capacitor on the power supply output rated at least 10V.
An example of linear regulator with 5V input is: