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UA78M-Q1: Problem with low temperature operating condition

Elio Barsetti
Prodigy 10 points
Part Number: UA78M-Q1


Hi,

I'm using the UA78M33QDCYRG4Q1, there isn't a lot of information about the recommended operating temperature in the datasheet but what I could found was -40 to 125 degrees C.

For my application, I found out the regulator isn't working properly at around -25 degrees C.

I get this problem on 10+ units.

I supply the regulator with a proper 5V and my application doesn't draw more than 100mA from the 3.3V regulator. 

I'm pretty sure my problem comes from the regulator because when my PCBA is around -25 degrees C all my power lines are working except the 3.3V from the regulator.

When I start to heat the regulator only, it will start working when the temperature reach around -5 to 0 degrees C.

Does TI has more information on the temperature characteristic of this product?

Tank you

Elio

  • +1
    TI__Expert 4120 points

    Hey Elio,

    We do not have any more characteristic information to share for this product.

    Could you explain in more detail what you mean by the LDO and LDO power line not working properly? 

    Could you share a scope shot of Vin, Vout, and Iout at 25C, 0C, and -25C? I think It is possible the device is going into dropout so if it is at all possible, please try to test with a larger supply voltage. 

    Thanks,

    -Jimmy