Circuit Protection of DC Input - OV/OC
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).
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.
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.
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.