The ±0.5% B-grade — why it matters for your rail
The TL431BQLPM is onsemi's B-grade adjustable shunt voltage reference, offering ±0.5% initial tolerance on the 2.495 V internal reference — a meaningful step up from the standard TL431's ±2.2% or even the ±1% A-grade. That tighter band means you can hold a 5 V or 12 V rail to within 25 mV without external trimming, which simplifies the BOM in precision supplies, isolated flyback feedback loops, and comparator threshold circuits. The adjustable output spans from the 2.495 V minimum up to 36 V, set by two external resistors. Cathode current sits at just 700 µA typical, while the shunt can sink 100 mA — enough to drive an optocoupler LED directly or bias a pass transistor.
Temperature range and package — industrial and retrofit ready
The TO-92-3 through-hole package (TO-226AA with formed leads) is the classic three-lead transistor outline. It's still the go-to for high-vibration assemblies, point-to-point wiring, or retrofitting older boards where an SMD footprint isn't available. The formed leads drop into standard 0.1-inch pitch holes and solder easily by hand or wave.
This is a current-production part you can qualify into a new design without worrying about a forced respin. The base product number TL431 has been in continuous manufacture for decades across multiple vendors, so the supply base is broad — onsemi, TI, ST, NXP all make pin-compatible versions. The BQLPM suffix is onsemi's own ±0.5% TO-92 variant.
If you're filling a BOM line or building a prototype run, submit an RFQ and we'll return a firm price and lead time from our multi-source channel. The ±0.5% grade is less commonly stocked than the standard ±2.2% TL431, so confirming availability before committing the line is the right move.