What this shunt reference does that the standard TL431 doesn't
The TL431BCDCKR is a precision adjustable shunt voltage reference from the TL431 family, but with a tighter ±0.5% tolerance than the standard ±2% or ±1% grades. That half-percent matters when you are setting a 2.495 V reference for an ADC or a 5 V rail supervisor and cannot afford to trim every board.
This part is fine for a benchtop power supply, a home appliance control board, or an office router. Do not spec it for a motor drive enclosure or an outdoor telecom cabinet where the ambient hits 85°C — the reference drifts and the cathode current minimum of 600 µA may not hold regulation at temperature extremes.
SC-70-6 package — tiny but reworkable
The SC-70-6 (also known as SOT-363) is a 6-pin surface-mount package about 2 mm × 2.1 mm. No hidden leads under the body — the pins are on the sides, so orientation is obvious once you see the pin-1 mark. If you are swapping this in the field, bring a hot-air station or a really steady hand; the pad pitch is tight.