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NOTE:
The electrical design for the Power supply should be made ensuring it will be capable of a peak
current output of at least 2 A.
The UE910-EUx variants are supporting EDGE class 33; the NAx variants support EDGE class
10.
5.3 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.
5.3.1 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
5.3.1.1 + 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 UE910, 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 UE910
from power polarity inversion.
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