Dear team
Now I use TPS54140A to design a DC-DC power supply system with isolation, the schematic is as attached.
The resistance of RT is about 412KΩ, from the equation 7 in datasheet we know that the frequency should be 301kHz. But from the oscilliscope we find that the frequency is about 140kHz, about the half of what we set.
Can you explain or advise what should be modified in my circuit?
The INPUT typical value is 12V, while the output VCC13) value should be 12V with Imax=1A , but when I run the system, the Vout (VCC13) will decrease to 8V or even less. I think if the frequency problem is solved, then this problem will be solved,too.
more information of my design:
we use the oscilliscope to measure the pin1 and pin4 of T404, which is a transformer and the turns ratio of the transformer is about 1:2. the inductance of the transformer is about 16uH.
Thanks
btw,
