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TLE4275-Q1: Failure at -30V and 85°C

Arin Kudlacek
Prodigy 20 points
Part Number: TLE4275-Q1

I am using the TLE4275QKTTRQ1 on a product and it states that it is "Reverse-Polarity Proof" but we are seeing catastrophic failure at 85°C and -30V. I am using a 1uF ceramic cap on the input (pin 1) and 33uF tantalum cap on the output (pin 5).

I have removed everything from the regulator except for the two caps mentioned, so it is open load. When fed with -30VDC at 25°C the output is at -0.8V and it is drawing about 51mA. That makes PT = 30*0.051 = 1.53W which seems kind of high. Using the equation TJ = TA + RθJA × PT I get TJ = 85 + 32.8*1.53 = 135.184°C. I see that this is close to the absolute maximum of 140°C but should it be drawing that much power in reverse anyway? The catastrophic failure happens when I change polarities within a couple seconds which makes me believe that the inrush of the output capacitor is pushing it over the edge. Is this normal operation for the regulator to draw that much current in reverse? What can I do to remedy this problem?

Thanks,

Arin Kudlacek
Brand Hydraulics

  • 0
    TI__Mastermind 23361 points
    Hi Arin,

    I am seeing the absolute Vout range is from -1V to 16V. Reverse polarity protection means to protect the situations car battery's positive shorted to Vout of the LDO and battery's ground shorted to Vin. For a 12V car battery system, car battery can go from 9V to 14V. That's why Vout is rated up to 16V. As -30V is well beyond the absolute rating for the Vout pin, it's not surprising for you to see the device being permanently damaged.

    May I know your application case for me to understand why you would apply -30V on the Vout?

    Regards,
    Jason
  • 0 in reply to Jason Song
    Prodigy 20 points

    I am not talking about reverse polarity on the output, it is the input that is getting the reverse polarity. When VIN is -30VDC with respect to GND this regulator gets overheated and dies. From the datasheet it says that it has an absolute maximum range of –42 to 45V.

  • 0 in reply to Arin Kudlacek
    TI__Mastermind 23361 points
    Hi Arin,

    Please allow some time for us to investigate this issue.

    Regards,
    Jason
  • 0 in reply to Jason Song
    TI__Mastermind 23361 points

    Hi Arin,

    The absolute maximum voltage rating is only meant for transient performance and it's not meant for the device to operate constantly at non-operating voltages. When you apply -30V at the input, the part will be heated up quickly. The Tj could well beyond 140C and permanently damaged the device. Unfortunately we don't specify the behaviors of the device under this reverse polarity case.

    If your application requires more protections to this kind of situation. I would recommend consider automotive LDO with built-in latch mechanism and the ability to turn off itself when faulty conditions detected. You can consider TPS7B7701/02 to see if it will satisfy your needs.

    Regards,
    Jason Song