What are the ways to test a switching IC TOP266EG with a multimeter?

I want to check it if it is damaged or not.

Link to the datasheet: https://www.alldatasheet.com/datasheet-pdf/pdf/663154/POWERINT/TOP266EG.html

Here is the DATASHEET picture:

Here is the appearence of IC:

 

You can't really do any meaningful tests of that IC with a multimeter.
The IC needs to be in an operating circuit and observed with an oscilloscope.

 

If it has failed, the the MOSFET usually failed short circuit. If you find a low resistance between the D and S terminals, then it is dead.
It will probably look like a silicon diode between S and D.
In fact, if you find a low resistance between any two terminals, then it is probably dead.
But you can’t assume that if there is a high resistance between D and S that it’s going to work.

 

If it has failed, the the MOSFET usually failed short circuit. If you find a low resistance between the D and S terminals, then it is dead.
It will probably look like a silicon diode between S and D.
In fact, if you find a low resistance between any two terminals, then it is probably dead.
But you can’t assume that if there is a high resistance between D and S that it’s going to work.

what do you mean by " But you can’t assume that if there is a high resistance between D and S that it’s going to work. " ??

 

what do you mean by " But you can’t assume that if there is a high resistance between D and S that it’s going to work. " ??

Simply that if you DO measure a low resistance between D and S you know it has failed, but the converse is not necessarily true.