Adjustable shunt regulator with a ±0.5% ceiling
It provides a 2.495 V reference voltage at the cathode when the reference pin is tied to the cathode, and can be set to any higher voltage up to 36 V with two external resistors. The ±0.5% tolerance on the reference voltage is the B-grade precision tier — tighter than the ±1% TL431A and the ±2% TL431C, making it the choice for designs that need better than 1% initial accuracy without moving to an expensive bandgap reference.
The 100 mA output current rating sets the maximum continuous current the shunt can sink while maintaining regulation. In a typical shunt regulator configuration, the series resistor from the supply to the cathode must be sized so that the cathode current stays above the 600 µA minimum and below 100 mA across all load and line conditions. If the load draws more than 100 mA, the cathode voltage rises and regulation is lost — the design needs a higher-current shunt or a series-pass transistor. The 600 µA minimum cathode current is the other boundary: below this the internal gain drops and the output voltage drifts off the programmed setpoint.
If the board sits in an unheated enclosure or near a motor drive that pushes the ambient above 70°C, step up to the TL431BID or TL431BQ variants in the same SOIC-8 footprint.
SOIC-8 — the footprint that fits everywhere
The 0.154-inch body width and 1.27 mm pin pitch are compatible with two-layer PCB layouts — no via-in-pad or microvia needed. The tape-and-reel and cut-tape options cover both production reels and prototype quantities.