Schematic wasn't attached. Attach it and I'll look. I've
done several of these, as robotics motors.

--Bob

Wouter van Ooijen wrote:

>I designed my first P/N FET H-bridge. Gif attached (Olin warning: you
>will have to zoom in). It sort of works. The GP4/5 pins are used to
>select backward or forward (switch the P-fet on, release the lock on the
>opposite N-fet), the GP2 pin (PWM out) is used to switch the N-fet. The
>resistor and R-zener dividers (I don't have the zeners yet, so the 15V
>zeners are now 4k7 resistors) are required to keep the gate voltage
>below 20V with the input voltage of 24V. 
>
>So far so good, but while testing with just a pair as LEDs as load to my
>surprise the P-fet that is supposed to stay off gets moderately hot!
>When its feed resistor is disconnected from the ULN2003 it stays hot, so
>it is not ULN leakage. 
>
>Changing the P-FET gate divider to 2k2 seems to solve the problem, but I
>don't feel comfortable when a problem goes away for an unknown reason.
>Can someone explain what's going on?
>
>Wouter van Ooijen
>
>-- -------------------------------------------
>Van Ooijen Technische Informatica: www.voti.nl
>consultancy, development, PICmicro products
>docent Hogeschool van Utrecht: www.voti.nl/hvu
> 
>
>  
>


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