OV/OC Protection of DC Input

Circuit Protection of DC Input - OV/OC

Design Notes:

Protection Application:
For LCD back lighter and microprocessor power, a DC voltage (typically in the range of 5VDC to 18VDC) will be supplied. The electrical threats include lightning surges, ESD and overcurrent conditions (short circuit or overload).
Solution Description:
As shown at the left, a fuse or PTC can be used for short circuit and overload current conditions. For surge and ESD protection, TVS diode (e.g. P4KE or P4SMA series) can be used.
Companion Solutions:
Note that the magnitude of the surge transient should be understood as this can point to alternative solutions. For example, if more severe surges are expected, then C-III or UltraMOV varistors or higher-rated diodes (e.g. 600W, 1,500W) can be selected. If the only threat is expected to be ESD, then multilayer chip varistors can be selected.
Regulatory Issues:
If ESD is a concern, the IEC 61000-4-2 can be consulted to find information on the test method and transient waveform that should be used.
Unique Features:
Does not apply.
Application Warnings:
Does not apply.