SLVS543R August 2004 – October 2023 TL431 , TL432
PRODUCTION DATA
TL431 requires an input resistance in this application in order to source the reference current (IREF) needed from this device to be in the proper operating regions while turing on. The actual voltage seen at the ref pin will be VREF=VIN-IREF*RIN. Since IREF can be as high as 4 µA it is recommended to use a resistance small enough that will mitigate the error that IREF creates from VIN.