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In a small device (direct current). What is the simplest and efficient solution for over voltage protection?

Regards

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    \$\begingroup\$ The simplest solution is to provide no protection and throw it away if it fails. \$\endgroup\$ – The Photon Mar 7 '17 at 19:50
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    \$\begingroup\$ A warning sticker is pretty simple. \$\endgroup\$ – PlasmaHH Mar 7 '17 at 19:50
  • \$\begingroup\$ For an actual solution, let us know what the usual operating voltage and current are, and how it might be connected that would produce overvoltage. \$\endgroup\$ – The Photon Mar 7 '17 at 19:51
  • \$\begingroup\$ Zener diode maybe... \$\endgroup\$ – Robert Endl Mar 7 '17 at 19:54
  • \$\begingroup\$ @ThePhoton You can also short all inputs and outputs properly to ground. That will save the throw-away. (save, re-use, recycle :-) \$\endgroup\$ – skvery Mar 7 '17 at 20:12
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For constant over-voltage, not a transient, a crowbar circuit. It consists of a series fuse and a zener diode from the power line to ground or return line. An over voltage condition would cause the zener to conduct as a low impedance path cauing the fuse to open up and disconnect the circuit from the offending voltage source to the circuit.

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For a simple MOSFET device with Current Limit, Overvoltage protection, ESD protection, and thermal shutdown detection, you would simply use comparators and zener diodes. Some additional pin on a chip might be required sometimes like a Current Sense pin (CS) or a Fault reporting pin (FLT).

Note that a simple Zener diode is used to prevent inductive kick back on the MOSFET.

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But make sure to read the datasheet to see how the faults are usually reported. It could be via serial communications, a dedicated pin, or by simply shutting down the device. You can shutdown a device if it goes into Thermal Shutdown. The temperature difference would be taken by a comparator (in voltage of course), and when the hysteresis of the comparator is back under the threshold, the device would be operational again.

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https://www.sunpower-uk.com/glossary/what-is-over-voltage-protection/ This is a simple overview of a crow bar circuit. I think it is really simple solution.

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  • \$\begingroup\$ Nice suggestion. Perhaps it would be useful to specify that, for such circuits, for restarting the circuit after an overvoltage it is needed the intervention of an operator, since the current limiter must interrupt the circuit in order to turn off the SCR. \$\endgroup\$ – Daniele Tampieri Oct 22 '18 at 5:32

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