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ATL431: Reference Current

mark stavropoulos
Prodigy 30 points
Part Number: ATL431

What is the statistical distribution of reference current?  The data sheet lists it as 30nA typical and 150nA max, but is there a distribution curve of Iref?  Is 150nA the 6Sigma maximum?  What would be the 6 Sigma minimum?

  • 0
    TI__Mastermind 19370 points
    Hi Mark,

    We cannot give the distribution data out. Typically the maximum is the 6 sigma of the typical + some guardband so you can use this assumption but I cannot give out the amount of guardband.

    -Marcoo
  • 0 in reply to Marcoo Z
    Prodigy 30 points
    What bounds the lower limit? TI spec's a typical but no minimum. How does one take into account the reference current contribution on the low end?
  • 0 in reply to mark stavropoulos
    TI__Mastermind 19370 points
    Hi Mark,

    Since the minimum is missing from the datasheet, it means we do not spec that so we do not measure that value during final test. We make sure that it does not exceed the EC table maximum.

    -Marcoo
  • 0 in reply to Marcoo Z
    Prodigy 30 points
    Marcoo,

    I will repeat my question then, what bounds the lower limit? You may not test it during final test but there must be some value. I have to design a circuit based on the ATL431 that regulates a voltage. I need to know the upper and lower limits of the regulator voltage. This depends on the upper and lower limits of the ATL431 voltage AND reference current since the current flows through the feedback resistors connected to the reference pin. Since you won' tell me a minimum and you won't tell me the distribution, how do I know what the minimum voltage of the regulator will be? Do I assume zero for the minimum?

    Mark
  • 0 in reply to mark stavropoulos
    TI__Mastermind 19370 points
    Hi Mark,

    The minimum current to the device would be the current the pin needs to operate. In this case it would be the current into the error amplifier of the ATL431 through the VRef pin. From my experience a good lower bound for this pin would be current Fig 2. I have not seen the current go any lower than this. I would say use this value as the lower bound for any calculations.

    -Marcoo