Reverse Battery Protection?

Thread Starter

brightnight1

Joined Jan 13, 2018
81
I'm sure it depends highly on the application, current, etc, but for a low power device like a PIR circuit, what are some of the ways you could implement components so that a circuit would be protected if a battery was plugged in backwards? (besides making it impossible to plug the battery in backwards). A diode perhaps?
 

BR-549

Joined Sep 22, 2013
4,928
The battery compartment and terminals usually take care of that.

Polarity is usually protected for aux pwr connections.
 

dendad

Joined Feb 20, 2016
4,110
If there is voltage headroom, a simple series diode will suffice.
For high current devices, a series fuse followed be a reverse diode to blow the fuse on reverse volts is pretty common.
And a lot of boards use a FET as above.
 

crutschow

Joined Mar 14, 2008
29,500
The FET has the advantage of a very low forward-drop, equal to the circuit current times the FET on-resistance, as shown in Bordodynov's simulation.
This is a consideration if you want the battery to last the maximum time.
 

AnalogKid

Joined Aug 1, 2013
9,956
The 1.2 ohm resistor represents a 10 A load on the circuit after the MOSFET switch. The software likes to have something there for some of its calculations.

ak
 
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