Hardware Development Guide of Module Product
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MF206A
Figure 4–4 LDO Power Supply
4.5
PCB Layout Guideline of Power Supply
As seen on the electrical design guidelines the power supply shall have a low ESR capacitor on the output to cut
the current peaks and a protection diode on the input to protect the supply from spikes and polarity inversion.
The placement of these components is crucial for the correct working of the circuitry. A misplaced component
can be useless or can even decrease the power supply performances. The users of ZTEWelink modules should do
as the following guidelines in the process of power supply PCB line designing:
The use of a good common ground plane is suggested.
The placement of the power supply on the board should be done in such a way to guarantee that the high current
return paths in the ground plane are not overlapped to any noise sensitive circuitry as the microphone
amplifier/buffer or earphone amplifier.
The power supply input cables should be kept separate from noise sensitive lines such as
microphone/earphone/RF cables.
The Bypass low ESR capacitor must be placed close to the ZTEWelink module power input pads, or in the case
the power supply is a switching type it can be placed close to the inductor to cut the ripple provided the PCB
trace from the capacitor to the module is wide enough to ensure a dropless connection even during the 2.5A
current peaks.
The protection diode must be placed close to the input connector where the power source is drained.
The PCB traces from the input connector to the power regulator IC must be wide enough to ensure no voltage
drops occur when the 2.5A current peaks are absorbed. Note that this is not made in order to save power loss but
especially to avoid the voltage drops on the power line at the current peaks frequency that will reflect on all the