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Variable power supply output protection

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crysti:
Hi guys!
What is the simplest output protection for reverse battery connection (blocking reverse input current) on 0-60V/5A variable power supply with two N-Channel transistors?

Example BJC polarity protector
  http://www.geofex.com/article_folders/cheapgoodprot.htm
Example single Mosfet protector
https://youtu.be/7Tk5ghH_U2s
Thanks in advance!

jonpaul:
séries and shunt diodes, eg Schottky,  inside feedback loop

j

David Hess:

--- Quote from: jonpaul on May 23, 2022, 08:02:55 pm ---séries and shunt diodes, eg Schottky,  inside feedback loop
--- End quote ---

That is how I do it.  At lower currents and voltage, a bipolar transistor can be used for lower voltage drop to do the same thing.

Some power supplies have a class-B or class-AB output so that they can also sink some current which helps keep the output voltage lower than the regulated voltage, but a series diode should still be used.

jonpaul:
Dave, fine HP, Lambda lab variable power supplies have such protection diodes.

Faults occasionally blow up the diodes but the power supplies survived.

One other protection is an overvoltage crowbar, with an SCR and Zener at gate, in shunt with the output.

Jon

crysti:
With diode protection power supplies not survives on reverse connection large capacity battery ex. >70Ah lead acid because sudden increase input current



--- Quote from: jonpaul on May 24, 2022, 05:31:18 am ---Dave, fine HP, Lambda lab variable power supplies have such protection diodes.

Faults occasionally blow up the diodes but the power supplies survived.

One other protection is an overvoltage crowbar, with an SCR and Zener at gate, in shunt with the output.

Jon

--- End quote ---

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