Good day everybody, I'm looking for advice on jitter related problem in several designs using TPS546C20A. My switch-node jitter is not only excessively high, but exhibits bimodal distribution pattern as if the regulator is changing between 2 duty cycles. Output ripple, regulation and transients seems to be fine. Efficiency is great too. It's just this strange jitter phenomena is happening on all my boards.
I've tried reducing loop bandwidth to 1/10 fsw and the jitter pk-pk reduced slightly, but the bimodal distribution pattern still remains. I've also tried adding as much input capacitance as I could (~1mF) and with 9V battery as a cleanest DC input source but to no avail. Knowing that with the input-feedforward feature, the jitter pk-pk also gets reduced when higher input is given, but there is still a bimodal distribution on the switch node jitter. Is there something I am missing here?
- Nominal input voltage: 7V
- Switching Frequency: 300kHz
- Output voltage (same issue on separate designs): 3.3V, 1.2V, 1.0V, 1.05V, 1.35V
- Target loop bandwidth: ~60kHz (need a higher crossover to meet transient load requirements)
No load
5A
