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INA2181-Q1: INA2181 failure mode need TI help to analysis

user6216182
Prodigy 60 points
Part Number: INA2181-Q1
Other Parts Discussed in Thread: INA2181, INA240

 Hi team:
Now we have problem at INA2818 application.

We use INA2181 for solenoid high side current amplifier at automotive product, the SCH like this.

The INA2181 have two failure modes:

  1. The output have 0.2V~0.8V offset voltage at the solenoid switch off status. This failure mode is our main problem. We have total 12pcs failure parts and all during sample building.

  1. The output voltage can't linear with input current, the input is 1.8A and the output is 0.8V. This failure mode is only one part at life testing. The solenoid is burning cause the driving current too high than needed.

 

Now we can reproduce the failures by ESD testing. But the failure mode is not same as our product. The ESD testing failure are combine 2 failures and only have failure 1(with offset output). You can find the result below, the INA2181 have 1V static output offset and not linear with input current at operating.

Could you pls help me to analysis the failure reason? And give me the troubleshooting suggestion. Thank you!

  • 0
    TI__Mastermind 30740 points

    Hi,

    To keep the same topology, I would suggest INA240 instead. You might want to fly wire some experimental boards to check out the results before committing to a PCB spin.

    INA2181 may not work well in the current configuration and that’s probably the reason for the high failure rate. If you only need to measure the active current and not the decay, then you can still use it. But need to move (it and Rshunt) to one of two locations: (1) between solenoid and positive terminal of the battery (high side sensing); or (2) between the switch and the battery negative terminal (low side sensing).

    Regards, Guang

  • 0 in reply to Guang Zhou
    Prodigy 60 points

    Hello:

    Do you means the INA2181 can't bear the soleniod reverse voltage during switch off? But now we have freewheeling diode to protect the reverse voltage. And we try to remove that diode also can't damage the INA2181, even the IN+ and IN- have 35V voltage.

    We are confuse for can't find any over range condition of INA2181. And a lot of failures are happened at sample building phase. That means the solenoid only active few times.

    Hope can get the details explaination for these failure modes and countermeasure.

    Thank you!

  • 0 in reply to user6216182
    TI__Mastermind 30740 points

    Hi,

    I don’t think over/under voltage is the problem. A more likely scenario is the fast common mode switching caused the problem.

    You may want to probe an INA2181 to see if the damage/degradation is permanent, such as a simple pin ohmic test compared with a known good unit. Also if witching to another part fixes the issue, it provides an indirect proof.

    Regards, Guang