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polarity protection with diode between vcc and gnd

Is it OK to do it like on the picture.
To protect circuit from power connector inserted the wrong way.
I'm thinking of this solution a voltage drop wouldn't be good.
Power is supplied by a common benchtop DC power supply, current limited to 200mA.
 

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Harald Kapp

Moderator
Moderator
It is o.k. if the diode can withstand the power dissipation produced by the current (approx. 140 mA @ 200 mA).
An even better protection scheme would include a fuse between the diode and the positive input. That way the fuse will blow if wrong polarity is applied, thereby protectiong the circuit completely.
 
Battery driven equipment can often run on lower than the nominal voltage. I would try a diode in series with the supply and see it it works satisfactorily.

There is a cunning circuit using a FET which is only turned on with the right polarity. I have never tried this.
 
Is it OK to do it like on the picture.
To protect circuit from power connector inserted the wrong way.
I'm thinking of this solution a voltage drop wouldn't be good.
Power is supplied by a common benchtop DC power supply, current limited to 200mA.
Dont use this topology because you risk shorting and burning your psu if inserted the wrong way.
Better use a fuse in serries as suggested before or place the diode on one of the rails with correct direction.
as for the above circuit i have also never used it.
 
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