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INA210: Product Selection and Inquiry

Ray Vincent Aranzaso
Genius 12765 points
Part Number: INA210
Other Parts Discussed in Thread: INA190

Hi,

Good Day. I have a customer who is working with current sense amplifier. Please see below the two queries of the customer for your reference. Thank you very much.

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I need your help in choosing the best chip to measure 10s of nanoamps as accurate as possible.

I watched your full series of current sense amplifiers and checked.

https://www.ti.com/amplifier-circuit/current-sense/overview.html

********************************************************************************************************************************************

The INA210 shunt resistor has high value as 50 Ohms.

Help me calculate the error curves, maximum shunt allowed to enter is 100 mOhm but this is not suitable for my design.

I need to use 50 Ohms, it is one of your chips that amplifies shunt resistor voltages to get currents.

But as per the calculator provides the maximum resistor allowed is 100 mOhm

Is it safe to exceed that number ?

Will it cause any problems if I use 50 Ohms as shunt resistor?

INA210 is a device that measures currents.

In order to be able to use it, I believe I should increase the resistance value.

********************************************************************************************************************************************

Best Regards,

Ray Vincent

  • 0
    TI__Mastermind 18750 points

    Ray, 

    The shunt range as well as other characteristics on the web calculator are limited to a generic range that provides useful information for all of our devices so that separate calculator does not need to be maintained for every device family. The use of a larger shunt may increase the error due to the bias currents of the device, but it certainly will not harm the device, and is a legitimate use case the customer can explore. If the customer wishes to generate error curves using a shunt of >100mΩ, I would recommend that they use the full error tool located in the INA210 product folder here. This tool will allow them to set the shunt to their desired levels and view their corresponding errors over range. 

  • 0 in reply to Carolus Andrews
    TI__Genius 12765 points

    Hi Carolus,

    Good Day. How about a current sense amplifier that measures 10s of nanoamps as accurate as possible? Does TI have a device for that specs? Please advise. Thank you very much.

    Best Regards,

    Ray Vincent

  • 0 in reply to Ray Vincent Aranzaso
    TI__Mastermind 18750 points

    Ray,

    At that level of current, the only current amplifier we have that could be considered would be the INA190, and even this device may not be sufficient based on their accuracy needs. Input bias currents of the amplifier chosen need to be much smaller in magnitude than the current of interest being measured. The bias currents of the INA190 are typically 500pA, with a worst case up to 3nA. If this is insufficient for the customer to meet their error targets, I would recommend they look for an instrumentation amplifier, or transimpedance amplifier solution. 

  • 0 in reply to Carolus Andrews
    TI__Genius 12765 points

    Hi Carolus,

    Good Day. Please see below the response of our customer to your reply. Thank you very much.

    The suitable value for the low current I am using was calculated as 10 Ohms, is it safe to use this calculated as shunt for the INA190 ?

    Best Regards,

    Ray Vincent

  • 0 in reply to Ray Vincent Aranzaso
    TI__Mastermind 18750 points

    Ray, this value should be fine. The size of the shunt should have no bearing on the safety of any of our products, but as I stated earlier, it may have effects on the accuracy due to the input bias currents. As the Ib of INA190 is typically 500pA, this effect is minimal and larger shunts are typically able to be used.