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Original question:

INA282: Measurement of voltage and current

INA210: Measurement of voltage and current

Silvia Luevano Cerda
Prodigy 60 points
Part Number: INA210
Other Parts Discussed in Thread: INA190EVM, , INA190

Hello,

I just began to use theINA210 using the configuration of the INA190EVM. I have a questions to confirm that everything is  set correctly.

1.I create a new combination for the INA 210 according to the schematic INA210

With he same values as in your EVM  but i need to calculate the R81 value. The voltage  for the unit is 14V the current to measure is 0.03 mA to .100mA.   we want to measure something for .100mA should be something like 4 volts with a steps of 100mV for less current. if this possible. I assume also the power up for INA210 should be 5V, is that correct.

thanks in advance

Silvia.

  • 0
    TI__Mastermind 23325 points

    Hello Silvia,

    With such low currents, I do not think you should proceed with the INA210.  The reason is that the device's input bias current can create a large error.  I illustrate the concept below.  In this case you have 30uA load that passes through 4.9 ohm which would be the system in this case.  Then I have a 100mohm shunt that was meant to be used for the current measurement.  In parallel with this shunt is the input bias current source, which actually siphons off my load and generates a Vsense voltage that would produce a very confusing result if I did not know better.   If you are going to measure in the microamp range, you should stick with our INA190.  The INA190's input bias current is in the nA range.  As for calculating the shunt you would do 4V/Gain/0.100mA.  500 V/V will give you the most resolution and the smallest shunt.

  • 0 in reply to Patrick Simmons
    Prodigy 60 points

    Hello Patrick,

    My real problem I cannot get this INA190 in Romania, the suppliers we had in company does not use this part number so that's why I move to someone that seems similar.

    I can ask other way around. Can I do a Threshold?.  to detect only something behind  100uA should be OK?

    This circuit will be in a test box, so I don need a lot of them and I have to assembly manually. That's why I use the SC70 6 pin package.

    For the test I perform is only important that the current should be less than 100uA.

    Thanks in advance.

    Silvia.

  • 0 in reply to Silvia Luevano Cerda
    TI__Mastermind 23325 points
    Hello Silvia,

    If you design your shunt monitor such that the INA210 device output is 4V at 100uA, then your shunt will be 200 ohms and the Vsense will be 20mV at 100uA. This will lead to less than a 1% error and therefore the INA210 should be able to pretty accurately indicate whether your load is greater than 100uA. This also should not damage the device if 100uA is temporarily exceeded as the Vsense max is 26V, well above the max vsense generated by your max expected load.