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Hi Ti team,
I have build a board with TPS40428 and 2x CSD95378B for evaluation, using 12V input to provide 1V output, design reference from PMP9444
but now my system have 2 issues
1/ OVF are easily triggered when enable TPS40428
2/ Sometimes TPS40428 can operate normal, but it usually shut down within 5min
I have probed Vout and FB found they usually give a lot of ripples before OVF shutdown
Should I change the R/C value in the loop compensation circuit?
Thanks a lot.
Alex
/cfs-file/__key/communityserver-discussions-components-files/196/TPS40428_5F00_output_5F00_OVF.pdf
Hello,
I'm looking into this issue and get back with you tomorrow.
Regards
Hello,
The circuit is oscillating and the compensation loop needs to be modified. Compensation network R70 = 360K is very large and C41 = 4.7pF is very small. Are these the correct value? My quick suggestion is to change R70 to 20K and C41 to 1000pF and give it try. These value may stabilize the loop and you can measure the loop across R68. Please let me know if it works by changing R70 and C41.
Regards, Mahmoud
Hello,
Thanks for the reply.
I have changed the circuit to your suggested value and the circuit working much better now. Thanks a lot.
I am new to building power circuit, do I using the loop calculation table wrong?
Regards,
Alex.