Problem with feedback circuitry in PWM IC SG3525

[basit.abs]

I m using PWM IC sg3525
but problem is this that whwn i use feedback circuitry one phase leg get destructed the mosfet i m using is 2907
have any body a solution for this................?

 

[dick_freebird]

Inverter

I don't think those old PWMs have much for anti-shoot-through
and maybe there's something going on that makes cross-
conduction happen. For example a synchronous-rectified design
that lets the negative undershoot exceed -0.7V will light
up the body diode / BJT and it could fail to turn off in time
for the next edge (a MOSFET on resistance problem, becomes
a destructive problem).

If you get trouble when the loop is closed, start by opening
the loop and try to drive it into failure while observing the
kind of things that yield clues (Vds, Id, gate terminals as
indicators of cross-conduction, etc.). There must be a steady-
state or oscillatory condition of failure and you work forward
to where you can replicate it at will, and then backward to
the root cause.

 

[prathamesh_d2001]

Re: Inverter

I am facing problem for feedback loop while using the Gate Driver IC's for H Bridge devices. Earlier we used to have TTL where multiple supplies and Grounds with respect to them were created and feed back loop was operating directly taking reference from output. Now that the driver IC ground and Push Pull Section Negative (HV-) is same point, I am finding it difficult to get the reference directly from output. Can somebody help me with that ?

 

[kabiru]

Re: Inverter

Hi, i think the problem you are facing now is due to crossconduction try and use a dead time network b4 the gate of your mosfets.This drop the duty cycle to 49%.

 

[prathamesh_d2001]

Re: Inverter

the gate pulse is of 50% duty cycle and 50Hz..but if the ground for HV- and gate Driver IC is one and the same then I cannot take the direct signal from the output for negative side, i will need either a opto IC or some other isolation. I will send the diagram over it by tomorrow so that my problem will be clear.

 

[kabiru]

Re: Inverter

Hi, i think the ground has nothing to do with your output and normaly inverter circute shared the same ground, any way you can post your diagrams.

 

[prathamesh_d2001]

Re: Inverter

Thanks Kabiru..i will need to draw the circuit, then i will post it..