How can TPS54350PWP oscilate at about 150Hz?

Jim Zheng

Other Parts Discussed in Thread: TPS54350

Dear Sir/Madam

I am troubleshooting a WiMAX product in a factory, and I meet a lot of units which output voltage only 1.1V(shall be 6V). I did some test for these units, and I draw the waveform in the schematic diagram. I think TPS54350PWP was forced into oscilating by some feedback loop, but I don't know which path will cause this kind result. Would you help me to analysis this circuit and give me some suggestion?Thank you very much!

Jim

over 14 years ago

0 JohnTucker over 14 years ago

TI__Guru**** 191445 points

That bitmap you posted is too low resolution. Can you possibly post in PDF format?

0 Jim Zheng over 14 years ago in reply to JohnTucker

Prodigy 30 points

Dear John Tucker

Thank you for your reply! I compressed the picture and attached it, it is a high resolution picture.

Best regards,

Jim1323.6V0A problem.rar

0 JohnTucker over 14 years ago in reply to Jim Zheng

TI__Guru**** 191445 points

The TPS54350 is definitely re-setting. It could be a fault condition but most likely it is either over current protection (most likely) or instability. Can you check the peak inductor current? the best way is to lift on side of the inductor and install a loop of wire sufficient to use a clamp on style current probe. I did not check your design calculations (you did not provide any) but the compensation values are in the range for typical circuits.

0 Jim Zheng over 14 years ago in reply to JohnTucker

Prodigy 30 points

Dear John Tucker

Thank you very much. I am troubleshooting technician in a manufacture factory. This product produces in my factory regularly. So I think it may be some part's parameters shift away from the normal values, and these shifts cause the circuit instable. I will test the failed units peak current at the inductor and tell you the test result. Thanks again!

Best regards,

Jim

Power management

Power management forum

How can TPS54350PWP oscilate at about 150Hz?