🚀 go-pugleaf

So I would have thought that this would be a simple problem but the more 
information I get the more I get confused......


I want to PWM a whole lot of LEDs. The current consumption of the bank of 
LEDs is in the order of 15 Amps, at 12V.

For reasons I won't go into, my only option is to use a high side mosfet.

I have chosen an N-channel MOSFET (IRL3803) mainly because of its huge 
current capability and very low on resistance of 7 milli ohms.

I am hoping to use PWM at a reasonably high frequency, say 20khz or higher, 
and I want to use an efficient MOSFET driver IC that is designed for the 
job.

I understand that to switch an N channel mosfet on the high side of the 
supply line, I have to drive the gate with 10V **more** than the supply 
voltage. This is correct yes?

This is where the question comes in. I am looking at the option of using the 
IRS2001 to switch the high side fet. But looking at the datasheet, I am 
confused. How can the  IRS2001 generate a voltage greater than VCC without 
actually being connected to the high side voltage????? There is no talk of a 
charge pump in the description and in any case it does not know what 
potential the fet is connected to..

Maybe it is not suitable for my application as the IRS2001 seems to be used 
for switch mode power supplies? I can't make sense of the first diagram on 
the datasheet.

here is a link to the datasheet:

http://www.irf.com/product-info/datasheets/data/irs2001spbf.pdf



OK so if the above IC is not suitable, I have been looking at the MAX621.

http://datasheets.maxim-ic.com/en/ds/MAX620-MAX621.pdf

This one looks to be more straight forward. But I'm not sure how this IC 
will go with 20Khz switching. There are many **low side** mosfet drivers 
that are in the 2 to 7 amp range to ensure that the mosfets are hard on or 
hard off within a few nS. This one doesn't look like it will do anywhere 
near that switching current.


Any other ideas for a high side N channel driver IC that packs a punch?