We have used this part for 3 years now for a PCB in full production.
In the latest fab run of boards, these devices seem to be regulating to a FB=0.803 V instead of FB=0.765.
The timing of the regulator period is about 714 ns with a high time of 450ns. (63% duty cycle)
At first I thought the Inductor, or the feedback resistors are wrong so they have been replaced.
Our circuit was designed for 11.8 V (19V input) with feedback 14.7k (1%) and 1.02K (1%).
Other components (Cin=0.1uF & 22uF), L=33uH, CB = 0.22uF, Diode (STPS2200U), (Cout=22uF & 22uF)
The regulator output voltage for these recent boards is in the range of 12.35 V to 12.46 V. This is too high for components on the board.
We have 100 boards, and the are all the same. 6 months ago we built 200 of such boards and they are all consistently less than 11.9V.
What could be wrong?
