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10% Failure of INA214A in new design

Dave Chapman
Prodigy 20 points

Hi,

I hope someone may be able to help?

We have been using INA214A for about 2 years and have been pleased with the device performance and reliability.

We have recently launched a new product with a slightly different design and have seen a 10% failure on the first batch of 200 PCB's.  

The application is a DC current monitor for a caravan / motorhome control system, with this particular sensor monitoring the charging current from a solar panel / regulator.  

The INA214A should give a 0V output at 0A, but when the failure occurs we see a permanent 3.4 to 3.6A  reading (even with no connection to the shunt resistor).  The failure is permanent and does not reset after a power down.

The shunt resistor is 0.002R giving a full-scale range of 0 to 25A with our application working in the range of 0 to 10A, so the above failure equates to the output being stuck at about 0.7V.

Our design is made up of 2 PCB assemblies plugged together, with the shunt resistor on one (power) PCB and the monitoring and micro-controller on the other PCB.

I have pasted our schematic  below for reference.

After looking into the problem my initial thoughts are that some form of transient is damaging the device, and that a possible move to INA214B may resolve the problem, but I would really appreciate other peoples views as I am no expert.

 Basic schematic.pdf

  • 0
    TI__Expert 4595 points

    Hi Dave,

    You may be right about large input tranisient causing this permanent damage. You can try the suggestions in 8.4.5 section in the datasheet for improving transient robustness. INA214B devices are certainly less sensitive to these tranisients compared to the A devices. If large input transients are the reason for these failure then certainly B devices may work better. Please also look into this TI design for more information on improving tranisient robustness for current shunt monitors.

    TIDA-00302 - Transient Robustness for Current Shunt Monitor

  • 0 in reply to Rabab Itarsiwala
    Prodigy 20 points

    Hi Rabab,

    Thanks for your reply.  I'm happy moving forward to incorporate the changes in 8.4.5 and also change the device to the B version, but I would like to better understand what is actually causing the damage?

    What I omitted from my earlier post was that we also use an INA213A on the same PCB arrangement for measuring battery current.  In this circuit we have the reference held at 2.5V (via the recommended Op-amp circuit) giving a +/- 24A scale.  This circuit has the same physical design with the shunt resistor on one PCB and the rest of the circuit on the other.  We have not seen any failures of this device, even though the shunt side of the circuit is almost identical to the circuit using the INA214A.

    We have good ESD protection on the PCB's in transit from the PCB assemblers, and assemble them into our product in a safe area, so I don't think handling is causing the failures.

    Do you have any further thoughts or ideas as to how I could identify the cause?

    Thanks,

    Dave.

  • 0 in reply to Dave Chapman
    TI__Expert 4595 points
    Hi Dave,Thank you for your patience over the holiday weekend.
    Have you tried INA213A in this exact setup? Switching to INA214B may be another way since those devices were designed for this purpose. Since fast transients are the cause for these latchup failures, if you have the capability to monitor the input for these fast transients.