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INA212: Multiple failed ICs in current monitoring set-up

Neil McKee
Prodigy 20 points
Part Number: INA212

Hello,

I have designed a test set-up to monitor the current draw from multiple devices for a period of time.The INA212 is in parallel with an 18V supply to the device and powered from a separate 5V supply. Circuit below.

I have had multiple ICs fail, some with the output measuring low / almost nothing and some with the output being equivalent to the in+ and in-, in these cases around 15-20 ohms is can be measured between the in+ and output. 

I am measuring an LED flash which will have an average of around 10uA with a peak of around 200uA for 10ms. 

Are these ICs particularly sensitive to any certain environment? or any known environment which can cause these ICs to fail.

ESD precautions have been taken during the installation. 

Full part number of part in use - INA212AIDCKT

Any information or advice would be greatly appreciated. 

Kind Regards,

Neil 

 CurrentMonitor

  • 0
    TI__Mastermind 24615 points

    Hello Neil,

    Thank you for using the TI forums. I noticed that you are using the A version of the INA212. With this version, it is possible that your device’s internal ESD structures are being damaged by a large input transient. If this is the case, switching to the B or C version of the INA212 should fix your problem. Section 7.4.5 of the datasheet goes over this in more detail:

    Also, you may want to note that the INA212 has a typical input bias current of 28µA as shown in the data sheet:

    This input bias current will dwarf your 10µA current that you are trying to measure, and may significantly impact accuracy at that level.

  • 0 in reply to Mitch M
    Prodigy 20 points

    Hi Mitch,

    Thank you for the detailed reply. 

    In an attempt to combat the input transient I have been powering off the 5V IC supply then the 18V supply to the UUT when adding or removing connections, similarly when powering up I have been powering the 18V on waiting for a few seconds and then applying the 5V IC supply incase of any initial rush of current. This does not seem to be a solutions though as we have still had some ICs fail. 

    We may have to change the current set-up to the B or C version of the component or adding the external filtering recommended in the datasheet.

    To combat the bias current we having been measuring the 'offset' of each IC with no load and subtracting from any measurements taken. Do you know if this value is stable for each IC once measured with no load?

    Any further advice or recommendations would be greatly appreciated. 

    Kind Regards,

    Neil 

  • 0 in reply to Neil McKee
    TI__Mastermind 24615 points

    Hello Neil

    Just so you know, as long as the INA212 has a path to ground, the transient on the input pins can still damage the internal ESD structures even if the device is not powered on. Because of this, I still recommend using the B or C device.

    Your measured ‘offset’ of each IC should be relatively stable, but change primarily with the input bias current. As shown below in Figure 13 from the datasheet, the input bias current is fairly stable over temperature, but you may want to note that the input bias current for the IN+ and IN- input terminals will vary with changes in VSENSE. For more information on how the input bias current is affected by a change in VSENSE, please refer to session 8 of the “Getting Started with Current Sensing Video Training Series” titled “Understanding Filter Related Errors” which can be found at this link: https://training.ti.com/getting-started-current-sense-amplifiers-session-8-understanding-filter-related-errors?cu=456802.