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LMR10515: low temperature operation

SM
Expert 1730 points
Part Number: LMR10515

Hello,

            Following is our circuit to generate 3.3V from 5V. We are using a similar circuit to generate 1.2 and 2.5V also. The board is supposed to operate till -40 and so all the components chosen are of this range. 

    

The problem is as follows:

1) The regulators operate fine as the temperature is lowered (till -25C)

2) However when the board is powered cycled (OFF only for even a second), lower than -10C the 3.3V regulator's output is noisy and stays around 1.95V. 

3) Subsequently when  the temperature is increased to a little more than -10C then the regulator becomes alright. 

Please advise on what could be going wrong. The 1.2 and 2.5V regulators operate just fine and the loads are similar. 

Thank you for your help in advance,

  • 0
    TI__Expert 7595 points

    Hello user,

    Thanks for your question.

    Could you please provide the schematic and layout of you application? Maybe you already did that, but the system didn't uploaded your pictures correctly (please use the 'Insert file' button).

    To provide further support, it would be very helpful if you could send us the waveforms of VIN, SW, FB and VOUT at this working conditions:

    - startup, when device works correctly (> -10C, VOUT starting from 0V)

    - startup, when device doesn't works correctly (< -10C, VOUT starting from 0V)

    - steady state, when device doesn't works correctly (< -10C)

    Thank you,

    Stefano

    All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml).