I have a question about high-side switching a load using an p-channel MOSFET.
I'm using the following configuration to control the backlight brightness of a LCD panel:
Q1 = N-channel logic level MOSFET so it can control the p-channel MOSFET using a microcontroller.
Q2 = SI2319DS p-channel MOSFET
Now because the backlight has a very specific voltage range (between 29,5V to 30,2V) I want to calculate the voltage drop over the source-drain terminals of Q2.
The datasheet of the SI2319DS states that for a Vgs of -10V Rds(on) is about 65 mΩ. This would mean that my voltage drop would be: Vds(drop) = 65 mΩ * 120 mA = 8 mV.
Is this really the case? it seems so low.