Precision shunt reference for the BOM
The Texas Instruments TL431BQLPME3 is a three-terminal adjustable shunt voltage reference that covers the classic TL431 function: set the output anywhere from 2.495 V up to 36 V with two external resistors. The ±0.5% tolerance at 25 °C means the reference voltage stays tight across the band — useful when the ADC or comparator threshold budget has no room for a sloppy bandgap. Rated for 100 mA continuous cathode current with a minimum operating current of 700 µA, it drives optocoupler LEDs, sets error-amplifier references in offline supplies, or biases a comparator threshold without starving the shunt.
Through-hole package and board fit
Housed in a TO-92-3 (TO-226AA) with formed leads, this is the classic three-lead transistor-style package that drops into 0.100-inch pitch plated-through holes. The supplier device package is TO-92-3 — same footprint as the standard 2N3904 or BC547, so the PCB layout is already a commodity. No reflow profile to manage; hand-solder or wave-solder as the assembly line prefers. Available in Cut Tape (CT) or Tape & Box (TB) — the TB option suits pick-and-place with tube-fed or tray-fed handlers that prefer the box format over reels. The base product number TL431 covers the full family; the BQLPME3 suffix flags the ±0.5% B-grade and the through-hole package.
ROHS3 compliant per the manufacturer's statement, so it passes the EU RoHS directive without exemption claims.