How to design a driver that "withstand 300VAC Surge for 5 seconds"

2 posts / 0 new

Hi Experts,

I have seen LED drivers having this specification: "withstand 300VAC surge for 5 seconds"

How do they achieve this?

Mine is a constant current drive.

Current is 250mA.

LED driver is driven through AC mains of 230V/110V AC.

Output power = 18 watts.

Which MOV can do this work? Or is there any design that I should implement?

How to make a selection? any calculation sheet with an example will be of a great help.

Thank you,

Rahul Shah

Voltage step at 300VAC for 5 seconds is enough to stress the output diodes input capacitor and the power switch of the IC so therefore a proper design margin should be considered. As such specification, the design should have been considered this before building the board.

MOV is not recommended to absorb the energy for 5 seconds. Do not rely on this part, MOV is used for high frequency surge only.

First thing to clarify is the specification behavior at 300VAC. Is it allowed to turn-off or not. Defining it clear will yield an optimized design.

Assuming turn-off is not option then, consider normal operation at 300VAC. As such make sure no input OVP is activated at this condition, input capacitors and bridge rectifiers should be sized up according to this input voltage. Calculate also the Vds and Peak inverse voltage in the output diode depending on the topology. So normally a buck converter is an advantage on this application.