hip4081 problem power supply

hi everyone

I want to do a ciruit that produce a voltage from -70 to +70.
so I decide to use the h bridge with a LC filter.
and this is the general purpose by hip comany:

the values of components is :
* diode mur130
*capacitor 100nF
*resistor Hdel and Ldel = 200K
* mosfet irf520

As you can see, 2 pins of control :BLI and ALI ( A & B) and disable pin
the 3 will be controlled by a pic microcontroller :


the A and B are pwm controlled by the variable resistor on RA0

if value of res <50% output from 0 to -70
else from 0 to +70

but they don't produce an output together .
and the dis is 0 (active) when pin_c0 is 1

the load is :



the unpredictable thing is when i connect the 12V and 5v no problem

but when i connect the 70v supply the hip will burn(supply on the board)

but if i connect a 30v from my variable generator no problem and i take an output on Rload form -30 to +30

i can't resolve this problem what about you ? please let me know

thanx

i have seen nightmares using this IC . and some times nice results . but what i have concluded is that since this IC has internal charge pump and due to design issues it is very sensitive to voltage spikes . and operating at near maximum voltage rating (70v , maximum is 80) is not recommaned , i think the maximum i would use with this IC is 48 v .. i would also recommand using the IR2110 or similar ICs these half bridge ICs so you will need 2 of these but can operate up to 600v .

another thing watch out for voltage rating of capacitors , mosfets etc and make sure they are at least 2x time 70v for safe operation. inaddition try increasing the value of bootstrap capacitor to 0.47uF or 1uF ...

hope this helps

hi Mr Electro nS

thanx for your help and i will try what you suggested, and i hope this will work fine.

does anyone have another reply about this problem.

please help me to know

thanx