Its ±1% reference tolerance holds the output voltage tighter than the standard ±2% grade, which matters when the feedback divider in a switching supply or the threshold in an overvoltage comparator must stay inside a narrow window across temperature and load. Output is adjustable from a 2.495 V minimum up to 36 V, set by two external resistors. The 100 mA output current capability covers most auxiliary bias rails and optocoupler drive needs in offline flyback converters, while the 700 µA minimum cathode current sets the floor for the bias resistor — below that the device drops out of regulation.
Through-hole 8-DIP — board-fit and assembly
Housed in an 8-DIP (0.300", 7.62 mm) through-hole package with the supplier device package listed as 8-PDIP.
For new designs or a BOM that needs a second source, the base TL431 family has many pin-compatible variants from multiple manufacturers; the ±1% tolerance and 8-DIP package are the key matching parameters when selecting an alternate.