TPS62233 DRY does not work anymore - Power management forum - Power management

Hmm, this is strange but it is even stranger that you have some output voltage. Have you confirmed that the IC is not switching?

Could any other rail in the system be applying a voltage to the output? This is typically where some residual voltage might be coming from.

You could retest your setup on the EVM to rule out a board layout weakness.

0 Julian de Groot over 12 years ago in reply to Chris Glaser

Prodigy 20 points

Hello Chris,

Yes, it is a strange problem indeed, I already tried many things, I measured with an oscilloscope and can confirm that the IC is not switching, it is really a DC voltage coming out. It is also no residual voltage at the output, because when I briefly short the output voltage to GND and then release it, the voltage will come back to 0.112V. We got 3 units back from the field suffering this problem. It seems that the converter is locked or hanging in some mode. I tested the first 2 units and the only solution is removing the battery. The third unit is still kept in this situation so I can perform some tests or actions, but no succes this far. Also the 2 units that had this problem are now functioning perfect again, I can not generate this fault on them again. I thought maybe the battery is malfunctioning so I soldered a new battery parallel to the attached one and then remove the "old" battery, the problem was still there. Really a strange problem. I also noticed that when heating the PCB with a hairblower, the voltage is increasing to 0.25V and when cooling down the voltage decreases.

0 Chris Glaser over 12 years ago in reply to Julian de Groot

TI__Guru**** 150650 points

Since you are experiencing filed failures, it is best if you work with your local TI or disti FAE to debug your issues. They can review your whole system, design, board layout, use cases, etc. to see what might be causing this. It is also possible that the failing devices are damaged somehow, so they can help determine this as well.

0 Chris Glaser over 12 years ago

TI__Guru**** 150650 points

Hi Francois,

Would this happen to be the same issue as this thread: http://e2e.ti.com/support/power_management/non-isolated_dcdc/f/196/t/251546.aspx

If so, I will merge these threads and direct you, as well, to your local FAE.

0 Francois Adams over 12 years ago

Prodigy 15 points

We have a battery powered application with a TPS62233 with VIN (VBAT)=4.09V, MODE=GND, EN=VIN and Vout(VREG_SYS_3V)=0.2V (on SW and behind inductor).

When we cycle the input i.e. off then on, we have Vout=3.3V.

We do not know in which state the TPS62233 is when Vout is stuck at 0.2V; we see no evidence of switching activity.

We found 4 of these cases up till now; do you have a clue what can cause this behaviour?

When our design/layout causes this what can be the mechanism, we basically use the standard circuit of page 1 of the datasheet.