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LP2992 ON/ OFF Threshold Variation Over Temperature

Richard Elmquist
Mastermind 45250 points
Other Parts Discussed in Thread: LP2992

The data sheet gives a minimum voltage to turn the device on at 1.6V over-temperature. It also lists a typical value of 1.4V.

I have a customer who is asking if we have any data on the variation of this threshold over temperature (especially between 0C and 70C).

Do we have a histogram or anything similar of this specification that would show the variation over the requested temperature range?

I understand that we have specified the minimum, but they have an issue with this input voltage and need to do an analysis of possible failure based on the voltage that they have present to turn the device on.

Thanks for your help with this!

Richard Elmquist

  • 0
    TI__Mastermind 22610 points

    " ... Do we have a histogram or anything similar of this specification that would show the variation over the requested temperature range? ..."

    No. However, since the on/off pin voltage directly drives the base of a PNP transistor it may be safe to presume that the threshold moves by 2 mV/C

    A bigger issue is that the LP2992 on/off circuitry does not have the typical on-or-off behavior. Rather, there is a rather wide range where Vout tracks against the on/off pin voltage.

    This means that if on/off voltage is between 1.6V and 150mV, it is very likely that the output voltage will not be zero (off), and will not be at the rated Vout either.

    Below is chart for LP2992-5.0 vs a slow falling-rising Von/off. Note that Vout is at full rated 5V only when Von/off is above about 1.5V. If Von/off is at 1V, Vout is at about 3.5V, certainly not fully off, or fully on. I believe that the LP2992 datasheet has a 'CAUTION' regarding Vout behavior with the on/off pin biased between the min/max limits.

  • 0 in reply to Donald Jones
    TI__Mastermind 45250 points

    Donald,

    Thanks for the detailed response!

    I will let you know if the customer has any further questions.

    Thanks again.

    Richard Elmquist