# Blowing a Fuse to Permanently Disable Functionality

Certain electrical designs require permanently disabling hardware functionality on the fly. Sending an overcurrent to a weak fuse may be a method for accomplishing this, breaking the circuit in a particular region of a device. My questions are:

1. What are the potential risks caused by this process, assuming a fairly weak fuse?
2. Are there alternatives to this method for disabling functionality permanently?
• How permanent is permanent? If it's a discrete fuse, it can be replaced... – HikeOnPast Aug 16 '12 at 19:30
• Watch out. This method for disabling a disposable device by deliberately blowing a fuse has been patented some time in 2000s (not too long ago). Sorry, I can't find a pat# . In the patent, the method was geared towards preventing reuse of disposable medical applicators. – Nick Alexeev Aug 16 '12 at 20:05
• I'm curious: If one is able to send an overcurrent (to blow a fuse) on the fly, then can't one also instead turn off a load switch in the same place, or even switch a transistor OFF ? I mean, are there specific advantages to this proposed fuse method ? – boardbite Aug 25 '12 at 2:31

Risks include detonation of the device being used as the crowbar, if it absorbs too much energy from the short before the fuse opens. To avoid that, check the $I^{2}T$ rating of the fuse and of the device. If the $I^{2}T$ rating of the device is higher, it should not detonate before the fuse fails. You may need to use high-speed fuses, which may be difficult to find, depending on the voltages and currents involved.