Bourns SinglFuse FAQ

Fuses can be confusing, here are some frequently asked questions on Bourns SingleFuse’s.

Is it necessary to derate a fuse for different temperatures?
Yes, it is necessary, there is a derating chart that is found on every datasheet. Fuses have different current carrying capabilities at different temperatures, the derating factor must be taken into account during the design stage.

How should one select the proper fuse amperage?
The fuse rating should be selected based on 125% of the circuit’s full load current.

What is the maximum voltage a fuse can operate under?
The Vmax rating of the fuse is the maximum rating, and the voltage should never exceed this limit.

What is the resistance tolerance?
The typical resistance tolerance value is provided on every data sheet, which is measured at a current level of less than 10% of the rated current.

Is there any indication to show when the fuses are activated to open?
The resistance of the fuse, when measured will show an open circuit. Otherwise, there may be a small puff of smoke that will show when the fuse has opened.

What is opening time versus fault current chart?
This is dynamic as the higher the current, the faster the device will open. A chart illustrating this is provided on every datasheet.

What is the comparison between a SinglFuse™ device and a TeleFuse™ device?
Both are one-time fuses and both are surface mount devices. The telecom fuse is designed for telecom signal lines (e.g. tip & ring) while the SinglFuse™ device is designed for a wider spectrum of applications.

Why would an application use a SinglFuse™ device instead of a Multifuse® Resettable fuse?
Multifuse® products are resettable fuses and SinglFuse™ products are one-time acting fuses. Some applications require a physical break in the circuit if a short circuit arises without the circuit resetting and continuing to operate. In this case, a SinglFuse™ device can be used. In applications where the circuit is to be protected from an overcurrent event and then continue operating after the event, a Multifuse® resettable fuse will be used.

What is the shelf life of a SinglFuse™ fuse?
If stored properly, shelf life is at least 2 years.

We also have a part number breakdown listed here: Bourns SinglFuse Part number breakdown

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