INA231: INA231

Hello,

What condition is the INA231A in when having this happen? What is Vs, Vcm, and Vsense? Could you provide more detail on the testing sequence being done?

Is there a specific test that this happens after? Are you able to pass some testing and then one particular test breaks the devices?

Regards,

Cas

INA231 was used to test Vbus and Vsense, and Rsense was selected as one of 5mohm, 10mohm and 100mohm。The schematic diagram is shown below。Vs=3.3V, MUC obtains Vbus&Vsense data in ADC register through IIC.We tried to measure the instantaneous voltage of Vs at the beginning of power supply. The maximum voltage read by oscilloscope is about 3.9V, conforming to the range of 2.7V to 5.5V specified in the Datasheet.We also tried to input 4V voltage through the left side of R131, the voltage source and ina231 common ground.Unfortunately, the Bus voltage was readed by MCU through ADC was still 81.9V.As I described earlier, ina231 suddenly broke during use. I tried several methods but could not locate the problem…

Hello,

What are you doing with the IN- pin of the INA? Is the shunt connected when applying 4V to the IN+ pin?

Regards,

Cas

What are you doing with the IN- pin of the INA?   -----------To Connenting GND

Is the shunt connected when applying 4V to the IN+ pin? --------------NO

Hi Alex,

what happens when you connect IN+ and IN- both to Vbus during the testing? I ask, because the INA231 is expecting a voltage drop between these to inputs of less than 82mV.

Kai

I know the INA231 is expecting a voltage drop between these to inputs of less than 82mV，I also never connect IN+ and IN- both to Vbus during the testing；When we test the phenomenon that Vbus returns 81.9V, we try to input 4V from IN+ while IN- connects to GND for debugging.By doing this, the INA should normally return a value of 4V for Vbus, but unfortunately it still returns a value of 81.9V

Hi Alex,

I would take a fresh INA231, connect IN+, IN- and BUS directly VS and try again. If the problem still persists, the I2C communication could be incorrect.

Kai

Hello,

Kai mentioned a great test to conduct. If you see a failure here it would be the I2C communication.

alex.cao said:

1. Vbus returned correct value at the beginning of ADC chip test, and 81.9V appeared in subsequent Vbus test (the actual voltage range of the device under test did not exceed 0-28v specified by ADC).

I may have misunderstood your test procedure before. You are initially testing the INA231 with current running through a shunt and everything seems fine then you change something. This subsequent Vbus test is a different test? What has changed from the initial working test?

When conducting the above test is the Power supply (and load if high side) GND the same as INA231 GND?

Regards,

Cas

Yes, I also replaced it with a new INA231, after which the Vbus and vshunt tests returned correct values.However,I would like to know the reason for the phenomenon I described before, For example, is it due to improper use or electrostatic breakdown? Or is INA231 damaged internally? I will use a lot of INA231 to detect the Vbus and Vshunt of different devicesin the future .At present, INA231 has a high probability of sudden damage during use. I don't know why Vbus and Vshunt are suddenly abnormal, which will cause serious quality defects to our products.

Hi Alex,

the main reason why a INA231 becomes damaged is that an input signal violates the absolute maximum ratings: The input pins -simulataneously or individually- must not go below -0.3V or above +30V. This can easily happen when the input lines are too long and wiring inductances cause inductive kickbacks. Of course, any other inductance intendedly or unwantedly added at the wrong place can cause destroying inductive kickbacks. Sometimes people mount a choke between the signal ground of INA231 and the shunt ground or power ground to isolate the grounds in the hope to make the circuit more immune against EMI. Never do this! There must always be a very short and very low impedant connection between the signal ground of INA231 and the shunt ground or power ground.

Can you tell more about your application? Is any cabling involved at the inputs of INA231? Can you show a schematic?

The more infos -> the more help

Kai

Hello,

As Kai mentioned without detail on what you are doing we can only speculate based on the common issues we have seen in the past. 

Also if you are not flexible in changing of test procedures or circuit, knowing more about the overall scope and circuit could lead us to help you protect the INA231 from this. For example with clamping of the common mode (if this is actually the problem). These protection methods will add some error but may help with creating a more robust solution. 

Regards,

Cas

Hello, I've been busy lately, so no updates. As for the schematic diagram and PCB, I am sorry that I cannot provide them due to the company's confidentiality regulations. Today, we tried a new method to test INA231. We tested the leakage current of each pin by applying a voltage of 3.3V to each pin of INA231. The test results are shown in the picture. The blue "OK" line represents a good chip, and the red line represents an 81.9V chip in the test.From the graph, the three pins of VS, A1 and SCL should be problematic,but I don't know what causes this phenomenon. Please review these reports and help analyze what causes the damage of ina231. Thank you very much.

Hello,

I will look into this in the mean time I will send you a private message with my email.

Regards,

Cas