Microchip TC4420.

Easy to use, very robust.

Best regards,


Rubens
PY2RML

At 19:01 25/4/2007, you wrote:
>Hello all,
>
>I'm trying to minimize the losses in an H bridge for a 12V brush motor
>(>40A stall current). One thing I'm thinking of is replacing the p-channel
>high-side MOSFET with an n-channel MOSFET and the associated, more complex
>driver.
>
>I looked into what is available in form of ICs (like National LM9061 or
>Micrel MIC5021), and it seems to me they guarantee only gate-source
>voltages of 7V (LM9061) or even only 4V (MIC5021). Since most low Rdson
>MOSFETs require Vgs in the range of >10V for this to happen, and reducing
>Rdson is probably the main reason for using an n-channel MOSFET as
>high-side driver, I'm a bit stumped. I thought it was easier to find a
>MOSFET high-side driver that outputs a guaranteed Vgs of 10V or 12V
>floating over Vsource. 
>
>Am I missing something here?
>
>My current approach is to use a simple boost switcher to provide an
>auxiliary voltage that is guaranteed to be >12V over the board supply and
>then take it from there, with zeners and optos. It doesn't have to be
>terribly fast; I'm doing the PWM with the low side drivers -- but I need
>the lowest Rdson I can get, so I really need >12V Vgs. 
>
>Any better ideas?
>
>Thanks for hints, tips, pointers, (preferably constructive) criticism,
>anything at all... :)
>
>Gerhard
>
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