INA220: The value of Reg0x00 was changed during running

Hi Nick,

Thank you for using the TI E2E Forums.
Would you be able to clarify whenever the two devices which are experiencing the issue are permanently showing a different value for REG0x00 (after a reset operation/power up) or whenever this happens during the course of normal device operation? If the later would you be able to provide us with some more details on how these are being tested and whenever the fault can be reproduced using TI INA220EVM?

Does the issue persist if the affected device(s) is (are) replaced or moved into a different PCB?
Lastly, would you be able to provide some plots showing the waveforms and timing used on the SMBUS?

Hi Carlos,

   The reg0x00 of these two devices changed when they were working normally. The customer found the current value of one device stopped update during normally working,and check the register found reg0x00 was set to 0x00(original is 0x399F) which mean the device is in trigger mode. The value when reg0x00 was changed in second device is not clear,the phenomenon was the device update incorrect current value.

    The issue is hard to duplicate,customer run the first issue device for about one month on their board,but the issue didn't appear again.

     I will check with them for SMBUS waveform.Could you help suggest what test should customer do if they meet similar issue again?

Best Regards,

Nick Dai 

Hi Nick,

Thank you for providing additional information. Let me summarize it to make sure I understood the information correctly:

The device was working normally and the customer wasn't touching REG 0x00. At some point the device failed to update the values via SMBUS.

I need some clarification: When you say stopped updating, do you mean, the device stopped providing readings via SMBUS, or do you mean the customer was changing some other register values and a subsequent read shown that the write wasn't completed successfully?

In regards to the SMBUS I want to make sure there is no corruption, that there is no other device pulling the SCL line low and that the pull ups are adequate to raise the bus voltage in a reasonable time at the frequency used. I would like to see a complete read/write event, with the plot showing the SCL and SCK lines using an oscilloscope (not a logic analyzer!)

I also need to understand how many boards are affected and whenever these devices worked normally after the issue was experienced and powered was cycled or if they are permanently showing this issue. If the later, we may be able to perform some testing with the failed devices.

Hi Carlos,

  The stopped updating is because when reg0x00=0x399F of INA220 in  normal work which mean continuous mode.When Reg0x00 was changed to 0x00 in unknow reason,the device was in trigger mode.So the customer always got same value because there was no trigger happen.

  I will ask the customer to provide the waveform of SMBUS.

 Currently,only two board report this issue. One board can't duplicate the issue after reset. The customer keep the failure condition on another board,but they can't open their module,so the only thing they can do is reading back the register. Do you have any idea?

Best  Regards,

Nick Dai

Ni Nick,

Thank you for your reply.
I understand the change in behavior. I am now trying to understand what conditions caused REG0 value to change and the nature of the fault (If it was permanent with the affected devices or if it happened randomly within a sample of all the devices).

Would you be able to clarify how many boards are affected and whenever these devices worked normally after the issue was experienced and powered was cycled or if they are permanently showing the different value after a restart or after the correct value is programmed/loaded to REG0?

hi Nick,

Can I know did you find the root caused of the issue at the end?
One of my customer also facing some issue but I am not sure if there are the same issue.
The INA220 initially work fine but after sometime like a few weeks or months, it will freeze and go low on the data signal line and it needs a reset (power cycle) in order to bring it back to work.
Hope you can share your experience.

Best Rgds,
Kpk

hi Nick,

No issue. I have advise end customer to do soft reset periodically with Bit15.
This will buy them time to do deep observation on the issue.

Best regards,
kpk

Hi Nick,

Thank you for the follow up on this matter.