Hello.
I`m using NB671.
Condition : Vin = 12V, Vout = 5V.
Measuring the VCC pin of the NB671 shows a sawtooth waveform as shown below.
Please help how can I solve this problem.
You don’t have the feedforward cap from the output to the FB node. COT schemes seem to need these the data sheet schematics show 220pF. Also your PG pullup is 10k the reference shematics show 100k. I would just take it out to start.
Dear Jshannon.
Thanks for your reply.
I’ve used the same circuit for other boards, but I’ve never had this problem before.
I’ve already checked what you said, but the problem hasn’t improved.
I would like to know which point of NB671 can affect the internal regulator.