Alan B. Pearce wrote:

>> but it seems the existing driver ICs don't match the majority of
>> existing low-Rdson MOSFETs.
> 
> What FET are you using that you need 12V anyway? All the low RDSon ones
> I have seen are speced at 10V.

I'm thinking of using the IRF2804. You're right that they are often speced
at 10V, but most of them have lower Rdson at higher values of Vgs. With the
exception of the Intersil drivers, the ones I found didn't even go that
far. 7V is not enough for low Rdson.

But you're also right that the difference between 10V and 12V or 15V is
usually not that significant (around 50mV Vds drop in this case), and I'm
thinking that 10V may be enough. 

Considering this, I've had another, closer look at the Intersil HIP408x
series, and they look interesting. They are the only ones I found so far
that talk a bit about their internal charge pump and even specify some of
its characteristics. However, I find it strange that the charge pump output
(probably as voltage increase over high-side source reference) can be
higher than the chip's supply voltage -- see figure 8 of the HIP4086
datasheet.

So now I'm trying to decide between either using the HIP4081, or using a
discrete charge pump and a few discrete components to drive the high side
statically and one of the common simple low-side drivers to drive the low
side with PWM.

Thanks to everybody for your help,
Gerhard

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