TPS563200 failure mode operation.

Jin-Suk Choi

Other Parts Discussed in Thread: TPS563200, TPS54202

Hi~

Customer made a TPS563200 board, input is 12V, output is 5V, load current is 40mA.

But IC always works like burst mode operation. When added additional load with electric load, IC didn't work like DCM or CCM, just increase burst mode interval.

Checked layout and it looks not bad, what case make IC works like burst mode?

Any advice will be welcome. (attached data)

Thanks.

over 9 years ago

0 JohnTucker over 9 years ago

TI__Guru**** 191445 points

Actually, the layout is not well optimized. The input capacitor return is not tightly coupled to the IC pin 1 GND. At higher output voltages, that type of bursting is more prevalent, but that is worse than what I have typically seen. If you increase the load above 500 mA, does the circuit work in normal CCM?

0 Eric Guo1 over 9 years ago in reply to JohnTucker

TI__Intellectual 2590 points

As John suggested, could you please try larger loading? such as 1A, 2A to see whether TPS563200 can enter CCM mode?
The device seems not stable and osscillation.

thanks!

0 Jin-Suk Choi over 9 years ago in reply to Eric Guo1

TI__Intellectual 2290 points

Hi~ Customer revised PCB layout but issue still exist. When increase load more than 300mA, it enters CCM mode as you suggested. Why TPS563200 is unstable under light load? And when I change device with TPS54202 which is same pinout with TPS563200, it works well. TPS563200 is weak in any noise?

0 JohnTucker over 9 years ago in reply to Jin-Suk Choi

TI__Guru**** 191445 points

That is not "unstable" but bursting during eco-mode. If the VFB voltage reaches the hysteresis voltage before the switch current drops to zer0 an additional pulse is added at the end. TPS54202 may be less susceptible to that effect.

0 Jin-Suk Choi over 9 years ago in reply to JohnTucker

TI__Intellectual 2290 points

Is there any solution to avoid bursting mode? Due to burst mode in light load, it cause inductor acoustic noise so failed at customer test. When I tried close cap at Vin, it was not effective. Let me have your solution not to enter burst mode.

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TPS563200 failure mode operation.