STMicroelectronics TL431CL3T

Overview

TL431CL3T from STMicroelectronics is an AEC-Q100 qualified automotive-grade adjustable shunt voltage reference in SOT23-3 package, delivering 2.5–36 V programmable output with ±2% initial accuracy, 1–100 mA sink current capability, and 0.22 Ω typical dynamic impedance for precision feedback in isolated DC-DC converters and battery management systems.

For engineers reviewing the TL431CL3T datasheet, TL431CL3T pinout, TL431CL3T application, or TL431CL3T equivalent, this page provides verified technical context, validated pin functions, real-world automotive and industrial use cases, and confirmed alternative parts with documented parameter-level differences.

Technical Context

The TL431CL3T operates as a 3-terminal adjustable shunt regulator with internal 2.5 V reference, error amplifier, and NPN output stage. It regulates by sinking cathode current proportional to the voltage difference between REF and internal reference, enabling stable closed-loop feedback without external op-amps.

Its design supports operation across -40 °C to +125 °C with guaranteed 2% voltage tolerance over temperature, 0.22 Ω dynamic impedance below 1 kHz, and minimal 0.5 mA minimum cathode current-enabling low-power biasing in automotive power supply supervisors and LED driver current-setting circuits.

Key Specifications

Pinout & Package

SOT23-3 plastic surface-mount package with gull-wing leads, 1.9 mm × 2.9 mm footprint, and 1.12 mm max height-optimized for high-density PCB layouts in space-constrained automotive ECUs and industrial sensors.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable shunt reference applications.

Compared with TL431CL3T, TL431ACL3T improves accuracy by 1% at no cost to thermal performance or package compatibility, while TL431BL3T adds 0.5% accuracy and AEC-Q100 Grade 0 screening-making it suitable for safety-critical subsystems where reference stability directly impacts fault detection latency.

Availability

TL431CL3T is available at Aetrix Electronics and suitable for automotive power supply feedback, industrial isolated DC-DC converters, and battery management system reference applications requiring stable component supply across extended temperature ranges.

Supply support for TL431CL3T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power ICs, sensors, and analog components for automotive, industrial, and consumer markets.

The TL431 product line delivers precision programmable shunt references optimized for feedback loops in regulated power supplies-specifically engineered for automotive-grade reliability, wide temperature operation, and seamless optocoupler interfacing.

FAQ

What is the maximum cathode-to-anode voltage for TL431CL3T?

The absolute maximum cathode-to-anode voltage (V_KA) is 37 V. Operation above this risks permanent damage. In normal regulation, V_KA equals the programmed output voltage (2.5–36 V), so designs must ensure transient overvoltage clamping remains below 37 V-typically achieved with Zener diodes or TVS devices on the cathode rail.

Can TL431CL3T replace TL431CD in SO-8 packages?

No-TL431CL3T uses SOT23-3 packaging with different pinout (Anode-Cathode-REF), while TL431CD uses SO-8 (8-pin) with NC pins and distinct thermal characteristics. Direct replacement requires PCB redesign, trace routing changes, and revalidation of thermal performance due to R_thJA difference (248 °C/W vs. 85 °C/W).

How does the REF pin input current affect accuracy?

The REF pin draws ≤5.2 µA at 25 °C, increasing to ≤6.5 µA over temperature. This current flows through the upper resistor (R1) of the feedback divider, causing a voltage drop that introduces gain error. For 1% accuracy, R1 should be ≤10 kΩ to limit this error to <52 mV-within the ±2% tolerance budget.

Is TL431CL3T compatible with ceramic output capacitors?

Yes-unlike some older shunt references, TL431CL3T remains stable with ≥1 nF ceramic capacitors on the cathode due to its low 0.22 Ω dynamic impedance and internal compensation. However, >100 nF capacitance may induce phase lag; ST recommends verifying loop stability with 10–47 nF ceramics in flyback feedback paths.