The cathode current can go as low as 600 µA, so it works in low-bias circuits where every microamp counts. Output current capability is 100 mA, limited by the shunt topology and package thermal resistance — in an 8-SOIC at 70°C ambient, the usable continuous current is lower than the absolute-maximum figure; the reference design on page 7 of the datasheet walks through the resistor divider and stability capacitor selection.
Obsolete — sourcing plan
TL431BCPSR carries an obsolete lifecycle status from Texas Instruments. For a new design, consider the active TL431BIDR (same ±0.5% tolerance, same pinout, SOIC-8) or the TL431AIDBZR (SOT-23-3, smaller footprint). Both are current-production and pin-compatible where the package matches.
What the ±0.5% tolerance buys you
The ±0.5% initial tolerance (B-grade) means the reference voltage at the REF pin is within 2.495 V ±12.5 mV at 25°C. For a 5 V output supply using a 1 kΩ / 1 kΩ divider, the output spreads less than ±25 mV — enough to hold a 3.3 V rail within ±1% without trimming. Temperature drift is not listed in this record, but the TL431B family typically drifts 30–50 ppm/°C over 0°C to 70°C. If the application stays inside that range, the reference holds accuracy without calibration.