MOSFET based switching for battery power

Thread Starter

chaitannya

Joined Apr 10, 2018
15
Hello Everyone,

I want to design a circuit similar to this one, which can switch to battery power in case of mains failure.
My requirement is very simple. Here's a simple battery charging circuit, driven by 5V supply.
I would want the 3.3V regulator to be driven by 5V supply in case there is power & through Vbat in case of power failure.

The one question I have about the reference circuit is that it shows 12V supply to the gates, in my case the supply would be from Vbat which is like 3V - to 4.2V. The datasheet shows the G-S voltage to be 9V

Regards,
Chaitannya
 

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Thread Starter

chaitannya

Joined Apr 10, 2018
15
OK,
This should work, that was the first thing I had thought of but the only conern is, is it used in practical circuits. Are their any disadvantages of using it over MOSFET.

Regards,
CHaitannya
 

danadak

Joined Mar 10, 2018
3,873
Yes, MOSFET circuits can get close to 0 Vdc drop across them, incrementally
giving you a little more battery/circuit lifetime. Also they can exhibit more isolation
when off depending on device used.

Regards, Dana.
 
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