PPTC (Resettable Fuse) Question

[Supercap2F]

Hey Everyone!!

I am thinking about adding a PPTC (resettable fuse) in to some of my circuits for safety reasons. On the data sheet for one it has the hold current and the trip current, I think I know what those terms mean but I'm not 100% sure. Can someone define them for me? And what is the schematic symbol for a PPTC? Is it just like a fuse?

Thanks
Dan

 

[KrisBlueNZ]

Hi Dan.

Generally, the hold current is the current below which the fuse is guaranteed to hold indefinitely, and the trip current is the current above which the fuse is guaranteed to open eventually or after a certain maximum time. But there are qualifications such as ambient temperature range.

Look on the manufacturer's web site for application notes. Bourns and Raychem have good info, but go for the manufacturer of your device.

 

[Supercap2F]

Generally, the hold current is the current below which the fuse is guaranteed to hold indefinitely, and the trip current is the current above which the fuse is guaranteed to open eventually or after a certain maximum time.

So if I have a circuit that drawing 0.6A max I should get a PPTC with a hold current of 0.6A?

Thanks
Dan

 

[KrisBlueNZ]

Yes. But READ THE MANUFACTURER'S DATA SHEET. The extra information in there may be important for your application.