TPS61099: Output of TPS610994 is 5.5V.

Hi Ishiwata,

the error can be removed if toggling the EN logic. to avoid enter such issue, you can try to add RC delay to the EN pin with 10ms constant time.

Hi Jasper

Thank you for your reply.
The EN and VIN are separated and input to the EN from another power supply.
I entered EN after entering VIN, but OVP occurs.

The waveform received from the customer is attached.
EN is input after the rise of VIN.

Best Regards,
Ishiwata

Hi Ishiwata,

the waveform looks strange. did the issue find in every system board? 

Hi Jasper,

No, not all.
Of the eight boards customer created, two have this issue.

Best Regards,
Ishiwata

Hi Ishiwata,

is it possible that the FB pin not well solder? and the device trigger OVP. 

please measure the ESD diode of the FB pin of the failure unit and good unit.

Hi Jasper,

Thank you for your answer.

Since it is a BGA package, it could not be visually confirmed.
As a test, I installed a voltage divider resistor on the FB line.

No abnormal output was confirmed, and a stable voltage was output.
However, the output voltage was not as shown in the data sheet.

I think the cause is the comparator of the FB, but what do you think?

Best Regards,
Ishiwata

Hi Ishiwata

are you using the TPS61099 or TPS610994? TPS610994 is a fixed 3.3V VOUT device. external feedback resistor doesn't impact the VOUT of the device.

please measure the ESD diode of the FB pin of the failure unit and good unit as in the blog. remove the feedback resistor firstly. 

https://e2e.ti.com/blogs_/b/powerhouse/posts/tips-in-debugging-a-boost-converter 

Hi Jasper,

I think so too that the FB terminal does not affect VOUT because TPS610994 is a 3.3V fixed product.
However, it was confirmed that the actual evaluation results had an effect.

To confirm the failure of the FB pin.
I think it is possible to measure the voltage drop by applying a voltage to the FB pin and measuring the voltage from the VIN, but is my understanding correct?

Best Regards,
Ishiwata

Hi Ishiwata-san,

it seem the IC was damaged or it is not well soldered. the device has >400us delay before ramping up the 3V. that is also not correct behavior

sorry, but i'm not sure which voltage drop do you want to measurement 

Hi Jasper-san,

Thank you for your reply.

Soldering was fine.
Therefore, we have informed the customer that the IC may be damaged.
I would like to observe the progress.

Thank you very much for your support.

Best Regards,
Ishiwata

Hi Jasper-san,

I told the customer that the device may be damaged.
It will be Close once.
Thank you for your support.

Best Regards,
Ishiwata