Designing with PTC Resettable Fuses

[gtenrreiro]

Hi,

I want to use a PTC resettable fuse to limit the maximum current that might flow on a line.
The max current I want to pass is about 0.7A.
The fuse specs have two current parameters, there is a "hold current", and a "trip current".
The hold current is about half the trip current, or about 0.35A if I were to use a fuse with a 0.7A trip current.

My question is how to choose the proper fuse. Do I design for the trip current ? if so what happens in between the hold and the trip current? (since there is quite a gap).

I appreciate your help.

Thanks

 

[milind.a.kulkarni]

Re: Desiiigning with PTC Resettable Fuses

Generally protection design is made using safty factor .....so if you want to have hold current of 0.7a then you need to chose the trip current rating is safty factory * peak current in case you know the peak current or holding current....for electronic circuit generally the safty factor varies in the range of 1.3 to 2

Also please refer the link
- Resettable fuse - Wikipedia, the free encyclopedia

Good Luck