Mosfet driver IC's

[hairylee]

Hi,
Why does everyone seem to have an unhealthy liking for the gate driver IC's. Is it just down to simplicity of design?

[classd4sure]

They can simplify things but I believe they can also be prohibitive, mainly they are not a plug in solution and should not be viewed as such, they need some pampering.

There's really no reason to hate them either, they can be made to work. I believe manufacturers typically dislike them because they can build their own at a small fraction of the cost.

[fredos]

Commercial Driver IC are just good for ''standard'' design. If you need something better tahn comercial, or with exotic fuctions, forget this!

By the way, commercial driver IC is always cheaper than discret drive...Sory for your dream classd4sure!

Fredos

www.d-amp.com

[classd4sure]

Guess it depends on the discrete driver. In simplest form a few transistors and a few diodes... hard to get any cheaper than that right?

[Lars Clausen]

Chris: I would sure like to see how you would propose a discrete circuit that works as fast as a driver IC. Especially with low cost standard components. Delay and rise times are critical.

Look at this scope shot, showing a 120V jump (1:10 probe) in under 10 nS, using a commercial driver IC.



I have been working on beating this performance for years without finding a good discrete solution. Let alone cheaper. So your ideas would be very interesting

[classd4sure]

Kind of puts words in my mouth. I'm not saying such a simple driver can do the job at high voltage/high speed, but for typical class d at lower voltage I'm positive it's cheaper to use a few transistors than a driver IC, especially when you start burning them out, so I don't think "always cheaper" can really apply.

When I come up a better discrete version for highpower/speed though, be happy to sell it to you

[Lars Clausen]

OK, i wish you good luck!

Anyway i dont think the price of the driver solution, be it IC or discrete is of any significance, because it's only a small fraction of the whole circuit. And they roughly balance.

But if higher performance could be achieved with a discrete solution, i don't think anybody would mind an extra cost involved

[classd4sure]

Still working on it Spice sucks I need a scope.

Say Lars, have you heard of hitting the gate with a sub nano pulse? Just curious.

[Lars Clausen]

No, i haven't heard about that.

[IVX]

Very good, and i guess, cheap discrete driver is does exist! And it's UcD again. So UcD400 switching for 120v/20nS. For true-virtual comparison several drivers, we would be try to fit THD figures by the loop gain multiplier to the zero feedback state. E.g. UcD400@10w 30db THD=.007%, then THDopenloop=.007*31.6=.22%, for 100w .02*31.6=.63% etc. Anybody ready?