SGLS302G March 2005 – May 2020 TL431-Q1 , TL432-Q1
PRODUCTION DATA.
Refer to the PDF data sheet for device specific package drawings
In this application, the TL43x-Q1 requires an input resistance in addition to the reference current (IREF) to ensure the device is in the proper operating regions while turning on. The actual voltage seen at the REF pin is
VREF = VIN – IREF × RIN. Because IREF can be as high as 4 µA, TI recommends using a resistance small enough to mitigate the error that IREF creates from VIN.