Hi,
I am using TPS40210-HT in a flyback converter, which has been tested in openloop successfully. However, when the loop is closed, the circuit never starts up.
VDD is measured to be 12V, the switching frequency is about 70kHz, DIS/EN pin has been grounded.
The GDRV output is completely low. As the datasheet describes, the minimum on time is 300ns. But this minimum length of pulse is not observed.
An additional comment is that the loop compensation is done by an external opamp. The voltage on COMP can vary between 0.05V and 0.45V. Is this limited window of voltage going to cause any issues?
Thank you in advance.