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Electronic DC Fuse - Simple Two Transistor Circuit 2016-04-07


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crutschow submitted a new article:

Electronic DC Fuse - Simple Two Transistor Circuit - Electronic Fuses eliminate fuse replacement and current-limit short-circuit power dissipation

An electronic fuse eliminates fuse replacement in case of an overload and does not dissipate any power under short-circuit conditions as a current-limiter circuit would.
Shown below is a two transistor (one PNP BJT and one P-MOSFET) version of a DC, high-side electronic fuse for positive voltages.
Reversing the transistor polarities to NPN and N-MOSFET would give a high-side fuse for negative voltages.

Q1 monitors the voltage across the shunt resistor R1. When the current increases so that...
Read more about this article...

Tony Stewart

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ETO has a bug on links in discussions.

This is a classic method called fold-back current limiting. Some have smart auto-retry for recovery.

Murphy's Law states ... that a fuse designed to protect a transistor will have the the transistor blow open to protect the fuse.

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