User's Manual

GE864

GE864GE864

GE864-

-QUAD Automotive V2 Hardware User Guide

QUAD Automotive V2 Hardware User GuideQUAD Automotive V2 Hardware User Guide

QUAD Automotive V2 Hardware User Guide

1vv0300840 Rev.3 2010-04-08

6.3.

6.3.6.3.

6.3. General Design Rules

General Design RulesGeneral Design Rules

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.

6.3.1.

6.3.1.6.3.1.

6.3.1. Electrical Design Guidelines

Electrical Design Guidelines Electrical Design Guidelines

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

6.3.1.1.

6.3.1.1.6.3.1.1.

6.3.1.1. + 5V input Source Power Supply Design Guidelines

+ 5V input Source Power Supply Design Guidelines + 5V input Source Power Supply Design Guidelines

+ 5V input 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 GE864-QUAD Automotive V2, 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 protection diode should be inserted close to the power input, in order to save

the GE864-QUAD Automotive V2 from power polarity inversion.