High side driver - how to use...

[Armagdn03]

Hello

I am trying to use a high side driver to convert a PWM signal into something useful to drive a power mosfet. I have had a little trouble trying to find info out there on how typical setups go. From what I understand I use a high side since my power supply is a battery and the pwm supply microcontroller switches the positive terminal on an off.

I would like a power output from the mosfets to be somewhere in the order of 100 - 120 amps continuous (this is a large safety margin of what I will really need) and am considering using two mosfets in parallel for power dissipation reasons. (I understand that its no problem using one driver for two mosfets, however I do not know if this is advantagious.)

Could anybody send me some wiring diagrams or info that I could read up on this subject. I am happy to do the learning myself, just need somewhere to start.

 

[Sceadwian]

High side drivers need their gate issolated, or a voltage up converter stage because voltages higher than the supply are needed to turn the Mosfet on. Pulse transformers are useful if the switching rate is decent or you have a real low gate capacitance, for low speed switching you can use photo voltaic issolators. That's a lot of current to be switching though, you're going to want more than one FET and good heatsinks as well. Driving Mosfets at that power level is troublesome though because you need to keep the FET out of it's linear range, or it'll meltdown.

 

[Blatman Bond]

High Side Driver

Understanding high side driver is about how to make higher voltage supplies for Vgs and a voltage level shifter. They are typically same with low side drivers.

There are two different types of high side driver. Bootstrapped driver and isolated driver.

Drivers with bootstrap are used for repetitive synchronous switching (buck converter, class-D amplifier, PWM with D<100%, etc)
If we need to switch-on the high side mosfet for long time, we can used the 2nd type of driver with isolated supply voltage. this mean two batteries or generate it with transformer.

there are popular technique to bootstrap the voltage using diode and capacitor.

 

[Blatman Bond]

If you are new to driving mosfets, this article might will help you.
"GATE DRIVE DESIGN FOR LARGE DIE MOSFETS"
Just download this pdf here :
https://www.electro-tech-online.com/custompdfs/2007/06/2001APR20_AMD_AN1PDF.pdf