Dear Expert
We used TI's power chip LM20133 in one of our projects, which utilized the function of external input frequency synchronization (SYNC pin).
We are currently encountering a problem during testing. Please help consult TI to answer the reason and provide countermeasures. Thank you.
The problem is as follows:
At high temperatures, the input frequency of SYNC does not match the actual switching frequency, resulting in slight deviation and phase shift.
At room temperature, it is normal.
From the test waveform above, it can be seen that the phase of SYNC and the phase of the switch are stable at room temperature. At high temperatures, there is drift between the phase of SYNC and the phase of the switch.
The frequency of SYNC input is 800KHz. The circuit design diagram is as follows:
