Other Parts Discussed in Thread: PMP8803
I borrowed from the original circuit using TPS23753 to 5V output, I want to change to 12V output, the original circuit is as shown below, the reference circuit is shown in Figure 2 or the link (ie development board: PMP8803)
We borrowed the existing PCB board to replace the corresponding transformer, optocoupler and other materials according to the BOM of PMP8803, but after the replacement, we found that the 12V output is unstable.After testing, we found that the 48V power supply is unstable and the 12V output is unstable. The 48V voltage waveform is as shown below.
This problem has plagued us for a while and has not been resolved. Do you have any ideas?
I have done a few tests:
Confirm that the resistance of the DEN pin is 24.9K.
The resistance of the CLS pin is changed to 1.24K or 90Ω without change.