Hello,
I have a problem about output voltage regulation with the COT LM25085. It's about line regulation. When I exceed 14 V on Vin, my voltage ouput regulation (8V2) is bad for the same load. See different pictures attached. The problem is probably due to parasitic inductances but i'm not sure. I decided to add a resistor of 10 ohm in series with the pin which control the gate of the LM28085 and PFET gate. Now it works, I can exceed 16V. So it seems that the commutation was to fast and i think that there were spikes to high on my FB ripple (exceeding 1V575 as it is mentionned into the datasheet), in that case the LM25085 stop to regulate until the FB ripple go down to 1V25 something like this... My interpretation may be wrong, please tell me if iit's wrong.
I don't want to let my 10 Ohm resistors in series with the PFET gate. My layout doesn't allow me to do this. So i m asking if i can take a diode which would be slower ? Do you think it could help me ?
For information, the ripple injection configuration that i m using is the one with the RC integrator and the bypass capacitor.
Here are ripple @ different VIN :
15V
13V
14V
Thank you very much,
Have a nice day ! :)
