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INA199: INA199A1DCKR damaged.

jiayu Chen
Prodigy 45 points
Part Number: INA199

I have a product use the INA199A1DCKR to check the current.  after the PCBA done and the hardware QC pass (contain the current check), it work normal, but when it ship it to our client, there are 2pcs PCBA has the issue, it cause by the INA199A1, the  IN- to GND forward voltage is 0.144 V，and the IN+ to GND forward voltage is 0.7 V. I think it may damaged when it transporting or assembling, may caused by ESD?  The schematic is according to the ddatasheet.,the battery is 7.4V.  Is it has some problem on my designed? I hope you can  give me some feedback, thank!

  • 0
    TI__Mastermind 25045 points
    Hello Jiayu,

    If your INA199 device functioned properly before you sent it to your client, and afterwards it did not function, I too would suspect improper handling (ESD or some other issue). Your supply voltage (3.3V) and common mode voltage (7.4V) are both within the recommended operating conditions. However, could you provide some more details on the load in series with your shunt resistor?
  • 0 in reply to Patrick Simmons
    TI__Mastermind 25045 points

    Hello Jiayu,

    Someone from my team has pointed out to me that the A version of the INA199 does not have the most robust ESD protection.  It is possible your client may have applied transients that exceed A version's ESD cell specifications.  Fortunately our B and C versions of the INA199 have more robust ESD cells.  More information on this particular issue can be found on https://e2e.ti.com/support/amplifiers/current-shunt-monitors/w/faq/3187.what-is-the-difference-between-the-ina199a-ina199b-and-ina199c-devices and https://e2e.ti.com/support/amplifiers/current-shunt-monitors/f/931/p/410196/1456777  

  • 0 in reply to Patrick Simmons
    Prodigy 45 points

    Hello Patrick

    Thank your feedback. Series with the shunt resistor contain  a MOS and a small value resistor，it is less than 1KHz frequency to control the MOS, according to the resistor specification, the circuit instantaneous current may up to 28A, and the average is about 12A.

  • 0 in reply to jiayu Chen
    TI__Mastermind 25045 points
    Hello Jiayu,

    I still suspect that some transients are causing the A version's ESD structures to latch. However, have you been able to do any tests with the B or C versions in your system? Also do you have any additional details on how your client may have used your hardware differently?
  • 0 in reply to Patrick Simmons
    Prodigy 45 points

    Hello Patrick,

    The latest test result, if the INA199A1 damaged, it does not cause the circuit short,but it cause the leakage current, before the battery drain to 0V, it seem work normal, we will do more test about the damaged unit. but when the battery drain 0V, we can not charge it. so the may not our client operation error，it may damage when we solder battery or after. We now are looking forward some way to found which unit's current sensor is damaged, because we already Mass production. I hope your team can give some suggestion or feedback. Thank you very much !

  • 0 in reply to jiayu Chen
    TI__Mastermind 25045 points
    Hello Jiayu,

    So one possible explanation why it worked for you yet broke when your client received the board may be the following. I suspect you tested your board with a power supply, which potentially was current limited or may have had a slow slew rate, thereby it fell well within the A1 ESD specs. However, when your customer applied the battery it dumped the max current into VBAT trace much more quickly, latching the the ESD cells.

    Alternatively if you did test yours with a battery. It is possible that you did not test enough units to see this issue. Not all devices are exactly the same due to small manufacturing variances and some may actually perform better than others with respect to this ESD protection. So it is possible that the few working units you tested before shipping out may have actually been the higher performers of your batch of samples.
  • 0 in reply to Patrick Simmons
    Prodigy 45 points
    Hello Patrick,
    This issue happen on soldering the battery, it damage the sensor,our battery not use connector . Will use the B version to replace the issue component, but do not know if damage the B version or not , Do you know some way to avoid it ?
  • 0 in reply to jiayu Chen
    Prodigy 20 points
    Patrick,
    Any updates from your side? I work alongside Jiayu and am very vested in this project.

    As Jiayu said, we current suspect the issue coming from when we solder on the 7.4V battery. We are thinking a surge is causing damage to the sensor. Do you have reason to believe the Version B or Version C chip would perform better in this regard? If not, do you have any suggestions for another chip or perhaps a way to protect this chip better?

    Thank you for all your help.
  • 0 in reply to Zach Bielak
    TI__Mastermind 25045 points

    Hello Jiayu, Zach,

    The ESD protection of the B and C version is supposed to better and thus I would expect it to perform better.  However, you still may need additional external protection in the form of a TVS or a large lossy capacitor between the battery and the INA199.  If you decide to use a TVS, its placement or layout needs to be carefully addressed.  The following article, provides some information on good TVS layout practices: http://www.ti.com/lit/an/slva680/slva680.pdf.

  • 0 in reply to Patrick Simmons
    Prodigy 20 points

    Patrick,

    Thank you so much for your assistance. We will look into both of these options and hope they solve the issue. Thank you!