User's Manual

Telit GE863-QUAD / GE863-PY

Hardware User guide

1vv0300697, Rev. ISSUE#0, - 21/11/05

3.2.1 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

3.2.1.1 + 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 GE863-QUAD, 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 GE863-

QUAD from power polarity inversion.

An example of linear regulator with 5V input is: