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Power

PolyFuse / PPTC

Polymeric Positive Temperature Coefficient fuse
Resettable fuse — opens on overcurrent, resets when it cools.

How it looks

Drawing: this is not on CORE3588, so it is drawn
5 V inPolyFuseboard
A resettable fuse in series with the supply. CORE3588 uses a different part for this job: an electronic fuse chip (U1, see VIN).

How it works

TOO MUCH CURRENT5 V inboardPolyFusenormal: low resistance, current flowsPolyFusea short downstream: too much current, the fuse heats upPolyFusehot: its resistance shoots up, current drops to a tricklePolyFusefault removed, it cools down and conducts again

Where it fits

It protects against too much current; a TVS diode protects against too much voltage. It sits right after VIN.

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