Herbert,

This is what I meant:

        -----C---------
        |             | HIGH
 +V-----------AK---AK---SIDE
     |     |     |      DRIVE
     D     D     |      SUPPLY
    GN     NG    C
     S     S     |
     |-----+-----|
     |     |    LOAD
     |     |-----|
     D     D
    GN     NG
     S     S
     |     |
GND---------

I hope the art comes out okay.

Yes, you are correct.  The high side drive supply would be higher than 
the 540s could tolerate and you'd certainly have to manage that.  Of 
course, you should be managing that anyway if you've got a 24 to 48V 
main supply rail.

Dave

Herbert Graf wrote:

>On Thu, 2004-11-04 at 12:01, David Minkler wrote:
>  
>
>>Herbert,
>>
>>Can you bootstrap a charge pump off the output of your bridge?  It's 
>>just a few diodes and caps.
>>
>>Dave
>>    
>>
>
>Hmm, I'm not exactly sure what you mean, but if I'm thinking of the
>right thing I don't believe so.
>
>The parts I'm using are IRF540s, they need about 7V to turn completely
>on (I'd prefer more, just to be sure). The major sticking point in the
>absolute MAX Vgs is +/-20V, and a charge pump would double the voltage,
>meaning it's too high a Vgs.
>
>Again, I may not be picturing correctly what you mean, so please correct
>me if I'm wrong. Thanks, TTYL
> 
>-----------------------------
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>http://repatch.dyndns.org:8383/pic_stuff/
>
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