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TPS3803: TPS3803-01 Question phenomenon that IC is broken.

Bob Lee62837
Mastermind 7230 points
Part Number: TPS3803
Other Parts Discussed in Thread: TPS3700,

Dear support member,

My customer used TPS3803-01.

There was a phenomenon that IC is broken.
I have a question.

（Specification condition）
Specification condition put minus 6V in VDD and It is a circuit that detects -5.317 to -5.686V.


（Question）
Q1.
Is there a problem with the circuit diagram below?

Q2.
Are there any problems with the specification conditions?
VDD：-6V
SENSE　Voltage：-5.317～-5.686V

When the IC is broken
The reset continued and the resistance between SENSE pin and GND was smaller than the normal resistance.

Q3
Is there anything I can think of as a cause?

Best regard.
Bob Lee.



  • 0
    TI__Genius 9375 points

    Bob,

    The TPS3803-01 is not a device meant to manage negative voltage rails, and we direct customers to use the TPS3700 for that reason. I believe that the TPS3803 is not functioning correctly most likely due to parasitics and ESD protection inside the device. The application needs to be able to clamp the logic level low to ~0 V to be able to provide a logic level high to monitor a negative voltage rail.

    We have an app note on this very subject, and I suggest you take a look: Using the TPS3700 as a Negative Rail Over- and Undervoltage Detector

    Thanks,

    Abhinav.

  • 0 in reply to Abhinav.Sharma
    Mastermind 7230 points

    Dear Abhinav.Sharma,

    Thank you very much for reply.

    By the way, using TPS3803-01 on the same board, we are sensing by inputting plus 5 V to VDD.


    (As usage)
    The device on the positive 5V side is used as a reference for GND.
    The device on the minus 6V side is used minus as a standard.

    （Question)
    Q1
    Is it possible that current flows 5V⇒GND⇒-6V in such usage and it is broken?

    Q2
    As 5V⇒GND⇒-6V current flows path,
    Is there any possibility of breaking beyond the maximum rated voltage ?


    Best regard.
    Bob Lee.

  • 0 in reply to Bob Lee62837
    TI__Genius 9375 points
    Bob,

    I'm a little confused by your questions, but what I can say is: the ESD diodes internal to the device most likely prevent the IC from managing negative rails properly. The 5V->GND->-6V path may cause issues, but I don't think it is the primary reason this device is malfunctioning. Your use of connecting the positive 5V to GND also may not be functionally supported.

    I highly suggest you take a look at the TPS3700, it is a device we push for negative rail detection for a reason, and it should benefit you greatly here.

    Thanks,
    Abhinav.
  • 0 in reply to Abhinav.Sharma
    Mastermind 7230 points

    Dear Abhinav.Sharma,


    Thank you very much for reply.


    Best regard.
    Bob Lee.