Choosing MOSFET for reverse polarity

Other Hardware General Electronics
1

Hi,
I work on a project and I need protection to avoid reverse polarity, but I block on some point usually I use prefabricated modules but in this case it will not work because of the space available, I want to use a P channel mosfet but I can find some documentation on which mosfet to use in my case the project and powered with 2x18650 in series 8.4v and has a load that can go from 10 to 20 ampere pulsed, for what I understand the mosfet must have an RDS (on) as low as possible but none of the documentation that I find informs me if it is necessary that there is a value other than RDS (on) which matters because of my load if you could help me on what I really need to worry about the characteristics of my mosfet for my project

ps: I also use a BQ25887 to charge the batteries in question so if it discharges a little too much I need that the charger can recharge them

2

The Rds(ON) must be quoted for the voltage you intend to drive it at (or lower). In your case, 5 volts would be normal.
Clearly the absolute maximum ratings must not be exceeded.
Also the maximum Vgs must be high enough, otherwise you need an additional zener diode and resistor.

Here is an example of one which appears to match your requirements (but may be physically too big or the package may not be good for you)

STL62P3LLH6

https://www.st.com/resource/en/datasheet/stl62p3llh6.pdf

3

thank you very much for your help and sharing of knowledge, normally this one should pass by compacting a little otherwise I would look for another now I know the rules :wink: