LE910C1 Hardware User Guide
1VV0301298 Rev. 1.08 - 2017-11-14
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6.2. General Design Rules
The principal guidelines for the Power Supply Design embrace three different design steps:
• Electrical design
• Thermal design
• PCB layout
6.2.1. Electrical Design Guidelines
The electrical design of the power supply depends strongly on the power source where this power
is drained. Power sources can be distinguished by three categories:
• +5V input (typically PC internal regulator output)
• +12V input
• Battery
6.2.1.1. + 5V Input Source Power Supply – Design Guidelines
• The desired output for the power supply is 3.8V. So, the difference between the input
source and the desired output is not big, and therefore a linear regulator can be used. A
switching power supply is preferred to reduce power consumption.
• When using a linear regulator, a proper heat sink must be provided to dissipate the power
generated.
• A bypass low ESR capacitor of adequate capacity must be provided to cut the current
absorption peaks close to the LE910C1 module. A 100 μF tantalum capacitor is usually
suitable (on both VBATT and VBATT_PA together).
• Make sure that the low ESR capacitor on the power supply output (usually a tantalum one)
is rated at least 10V.
• A protection diode must be inserted close to the power input to protect the LE910C1
module from power polarity inversion.
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