Circuit protection for DC input current - overvoltage and overcurrent
For LCD back lighter and microprocessor power, a DC voltage (typically in the range of 5VDC to 18VDC) will be supplied. Electrical threats include lightning surges, electrostatic discharge, and overcurrent conditions (short circuit or overload).
As shown on the left, a fuse or PTC can be used for short circuit and overload current situations. For surge and ESD protection, TVS diode (e.g. P4KE or P4SMA series) can be used.
Note that when considering alternative solutions, the magnitude of the transient surge amplitude should be taken into account. For example, if the inrush current is too large, C-III or UltraMOV varistors or more powerful diodes (such as 600W, 1,500W) can be used. If the only threat is from electrostatic discharge, then multi-layer chip varistors are an option.
If you need to consider electrostatic discharge, you can refer to IEC 61000-4-2 for test methods and transient waveform information that should be used.
Characteristics: Not applicable.
Application warning: Not applicable.