TLV9061: Output difference

Hello Yue,

Thank you for your question.  To help you further with this issue, I have some follow-up questions.

Could you please explain what is the input voltage/current at both inputs or provide a waveform?

Also, do you know what is being measured in the top two images?  Is the equipment somehow measuring voltage?  The voltages the customer is seeing are 2.6V and 3V, but I am not sure what is being showed in those images (numbers do not match).

Does the customer have a more zoomed in image of the output waveforms?  It is very hard to see any difference when the scope is set to 5V/division.

Lastly, are all the failures the exact same failure or are some different?

Regards,

Daniel

Daniel,

please see below capture file for your question 1.

for the top two images, it is the ADC reading of  TLV9061's output voltage. for example : 3.3V is 4096, 3V is  3696, 2.6V is 3310. 

and yes, all the failures are the same, NG device's reading is about 3310, 2.6V.

I can try to ask them to provide a more clear waveforms tomorrow.  please help to suggest what other test can be done to locate the issue . thanks 

Hi Yue,

Thank you for your response here.  How much voltage do they typically see across R213?  Is it about 75mV?

Are the amplifiers all being tested on the same board or are they being tested on different boards?  It is important to rule out variation in component values as a factor, especially when measuring such a small current.

If the customer really wants to try something, I would suggest trying to change the passive components.  Use the same values, simply change the units.  See how big of a difference is created.  You can try changing the resistors of the difference amplifier, but the most important resistor will be R213.

Regards,

Daniel

Daniel,

They tested on the same board and  the symptom was following device.  just wondering if there are any differences between devices could cause such a huge voltage deviation.   

Yue,

It could be the distribution of a device parameter.  However, if devices were having this type of issue I would expect to see a range of failing values.  For example, devices might test at 3V, 2.9V, 2.8V, 2.7V, etc.  Instead, the customer is seeing all the devices passing at 3V or failing at 2.6V.

I would recommend asking the customer to test at the inputs of the op amp.  See if you can measure pins 1 and 3 of the op amp.  The customer can also try measuring at I224 and I231.  Try to testing the voltages for 3 passing units/boards and 3 failing units/boards.  This will give us a better idea of where the error may be introduced.

Regards,

Daniel

Hello Yue,

Have you received any feedback from the customer?

Regards,

Daniel

Daniel,

I'll visit them in these days, will get back to you soon. thanks. 

Hi Yue,

maybe a soldering issue arround the shunt? Can you show a photo of the PCB?

Kai

Hello Yue,

Very well.  Please let me know if the customer needs any further assistance.

Regards,

Daniel

Daniel,

I verified on our EVM, after AABB test, dIdn't reproduce their issue. They will keep monitoring this issue. I'll close this thread first.  thanks for your suggestions. 

Yue,

Very well.  Please let me know if any more help is needed.

Regards,

Daniel