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LM26480-Q1: How to test UV thresholds for bucks output rails

Part Number: LM26480-Q1

Customer's safety team came back to me with some technical questions as shown below : 

-          we would like to measure/verify threshold levels for UV detection at Buck1 and buck2 output. Moreover in data sheet there’re only typical values (92% and 82%), is there a specific reason why there’s not min/max values, is it just “simulated “values ? Does it mean these thresholds are not tested in production …??? Do you still have some histograms to provide in order to have an idea what could be min/max values …?


-          Can you propose a setup to measure these thresholds on the bench please ?

Thanks in advance for your support.

Best regards

  • Jean-Jacques,

    If you dig a little deeper you will see that it says "Comparator Trim" on page 19 of the datasheet. The usage of the word trim suggests that the comparators are fine-tuned during production and the typical value is accurate at room temp 25C before leaving the factory.

    The absence of Min/Max values simply means that there is not a guaranteed value across temperature.

  • Thanks a lot for feedback. But even if thresholds are trimmed at production, we should have a min/max value in DS as it's for every LDO, buck, offset for opamps, etc .... which are also trimmed at production.

    Moreover, second part of the message was how to measure these thresholds on the bench, do you have a setup to propose please ?

    Best regards

  • On the bench, I would measure with the following setup:

    • Trigger on nPOR falling edge
    • DC coupling with offset = VBUCKx
    • Vertical scale = 10mV or 20mV (highest resolution possible)
    • Test by shorting the output to GND

    When nPOR is low, then you found the voltage at which the comparator trips on the falling edge.

    It is harder to measure the rising edge due to the delay.