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TL431: TL431BQPK‘ Vref is not in SPEC.

user6380661
Prodigy 20 points
Part Number: TL431

TL431BQPK‘s Vref is not in SPEC. In fact, the Vref is only 4.443V, it is below the Min 4.483V that define in the datasheet.Exchange the Part to another TL431BIPK, the Vref is in SPEC.Can you explain Why for this? 

  • 0
    TI__Mastermind 19580 points

    Hi,

    Can you share the exact schematic you are using to test the device?

  • 0 in reply to Marcoo Z
    Prodigy 20 points

    Hi,Marcoo Z.

    Because of some reasons, I can't provide schematic.

    I want to find out why the performance of tl431bqpk and tl431bqpk of the same circuit is significantly different, and tl431bqpk is lower than the specification definition of 4.383v.

  • 0 in reply to user6380661
    TI__Mastermind 19580 points

    The TL431BQ has a VREF of 2.495V at 25C. The VKA can be varied with external resistors. If the voltage is not correct, I would check the REF pin voltage. If the REF pin voltage is not correct then you need to check the biasing conditions. I would also look at the output with a scope to make sure the device is stable.

    I would review the app note below to see if the output error was calculated correctly. The app note also covers how different errors affect the TL431.