Power Mosfet Gate drivers

[sameer_baveja]

Hi,

I am trying to find out some "practical" architectures for power mosfet gate drivers. Can anyone please point me to useful links on this topic?

Thanks in advance
Sameer

 

[dick_freebird]

With so many of them already out there, why would you want
to design another one?

Notice the "Similar topics:" --->

 

[sameer_baveja]

Thanks for your reply. I am not trying to design a "new" one. I just want to look at various architectres and pick up the one which will suit me best.
Can you please point me to the papers relevant to the gate drivers?

Cheers!

 

[DaMoose]

really your gonna want to use a transformer or the "floating gate driver IC"

that are Quote " readily available and out there "

what the IC's are doing is simple
they employ a switched capacitor voltage generator...
that creates a floating dc supply you can bias against the Source .

with a Nfet in the High side driver position it's Source is a "Moving Target"
so fixed biasing is not optimal..

and thats why the transformer and the gate driver IC ROCK !

 

[j_writer]

Regarding MOSFET drivers, it can be hard to get the big picture. Some factors that make a difference are:
- Will your topology require a low side or high side MOSFET or both?
If you use a high side FET, here are some further questions...
- Will the FET be N-channel or P-channel?
- Can you generate your own bias voltage (used to switch the high side gate, usually 12-20 Volts). With a P channel FET, bias can be easily generated with a zener.
- If your high side driver is N channel, you might you prefer a MOSFET driver IC that generates it own high side bias, like the FAN7382. This is called "bootstrapping" in the data sheets and it has its own complications, like duty factor and startup issues. See Fairchild app note AN-6076 for more info.
- You will probably need opto-isolation if your high side driver is at a higher voltage than your control circuit.
- Are your power voltages generated directly from the AC mains ("offline" application)? If so, you may need to isolate both your high and low side drivers from your control circuit.
- If you generate your own bias supply, you can use a simpler driver IC with just a totem pole output, like a FOD3150 or equivalent. You would apply the bias to the Vcc and Vee terminals that drive the totem pole.
- What is the sense of the driver output - in other words, will the power FET turn on in the absence of a drive signal (not good).

I hope these points are useful. I would like to see a web page with this information and some links to app notes from various manufacturers. Also, a list of the most common FETs and driver ICs would be useful.

Attached is part of AN-6076 that shows some high side driver topologies. As you can tell, the high side is the issue. Driving a low side N channel device is usually easily done with a chip like a FOD3150 or equivalent.

Check out a couple of threads:
1) my previous post on understanding MOSFET driver ICs

2) a post on driving a P channel MOSFET


Plus I'm sure there are more. Hope this helps.