Help understanding datasheet please

Thread Starter

EricSutton

Joined Oct 7, 2018
37
Hi, I was told THIS "High-Side Or-ing FET Controller" would be a good way to switch between 2 power supplies. I am having trouble understanding exactly what this does from the datasheet.

I would like to use this part in this format (taken from the datasheet, I want to use 2 power supplies)
upload_2019-5-14_21-47-11.png

From the pin functions it states:
upload_2019-5-14_21-48-6.png
My question is about the IN and OUT pins. It states that IN is connected to the source and OUT is connected to drain.
upload_2019-5-14_21-49-44.png
Since it is an N-Channel MOSFET, I am understanding this as current is going INTO the power supply. Is this correct? If so this is not what I want.
 

DickCappels

Joined Aug 21, 2008
6,650
Yeah, the messed up on the type of MOSFET.

The circuit simulates two ideal diodes with very low forward drop (depending upon the specific MOSFET and current).

The two ideal diodes are OR-connected similar to the diode circuit below (ORing two power supplies to automatically switch in a battery) so the one with the highest input voltage is turned on. If both inputs are equal they both turn on.
upload_2019-5-15_14-38-33.png
 

Thread Starter

EricSutton

Joined Oct 7, 2018
37
So the way this work is whichever power supply is at a higher voltage is the one that will be used to supply the load with power? What if I would like to use one battery until it is dead then switch to the other. Is this the right device for doing that?
 
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