Part of the Day · TL431 — SOT-23 adjustable shunt regulator

Part of the Day · 2026-10-23

A precision shunt regulator that sets a voltage between 2.5 ~ 36V with two resistors. Its reference voltage is 2.495V, and it is widely used in place of a Zener diode or as the voltage reference in switching power supplies.

Actual size

↓ Actual size, left edge aligned to 0 on the ruler

One ruler tick = 1mm. On PC this is actual size on a 24-inch FHD monitor at 100% zoom; on iPhone it adjusts automatically. For other screens, use “Calibrate ruler” below.

Enlarged (SOT-23 · top view · approx. 20×)

Pins 1 Cathode (K) · 2 REF · 3 Anode (A)

Package SOT-23

Key specifications

Values are from the Texas Instruments datasheet.

Marking and pins

Typical uses

• Output voltage reference / feedback in switching power supplies
• Precision reference and voltage regulation circuits used in place of a Zener diode

Companion & similar parts

• TL432 — Same function and electrical characteristics, only the pinout differs — in SOT-23 (DBZ), pin 1 is REF and pin 2 is the cathode
• TL431A — 1% reference accuracy grade
• TL431B — 0.5% reference accuracy grade

Even within TI, the TL432 has SOT-23 pins 1 and 2 swapped relative to the TL431. SOT-23 versions from other makers may also have a different pin order, so check the pin table in that maker's datasheet.