Other Parts Discussed in Thread: UCC5350, ATL431
Hi
I am using UCC5350 in 3 phase bridge circuit , sadly i decided later in the project to use isolated Bipolar dc/dc converter (+15/-9) for gate drive supply 15 connected to VDD and -9 to VEE and Switch-node will connect to 0v pin of the DC/DC converter. Now the problem is that this gate driver is not optimized for bipolar supply and UVLO is too low. Since I bought a large quantity and i cannot change the gate driver , I have to implement UVLO externally especially for turn On voltage (+15v) or for the total voltage (15+9=24v).
1. Do you have any suggestion on a simple circuit other than using ATL431 and its derivatives?
2. What would be better , using ATL431 to control p-channel mosfet to turn off Gate driver supply OR using ATL431 to control an opto coupler which controls a buffer or AND gate to disable PWM inputs ?
3. What would be better monitoring the Total output of dc/dc converter , or just the positive voltage ? I am worried that switch node undershoot and noise could cause false triggering ATL431.
4. Can I add Capacitor and is there a limit on maximum value near Feedback/Ref pin of ATL431 ? the goal is to filter the switching noise and prevent false triggering .
thanks