STMicroelectronics TL431IL5T

Overview

TL431IL5T from STMicroelectronics is an AEC-Q100 qualified automotive-grade adjustable shunt voltage reference in SOT23-5 package, delivering 2.5–36 V output via two external resistors, 1–100 mA sink current capability, 0.22 Ω typical dynamic impedance, and ±2% initial voltage accuracy across –40 °C to +125 °C operating range - used in feedback loops of isolated DC-DC converters and battery management systems.

For engineers reviewing the TL431IL5T datasheet, TL431IL5T pinout, TL431IL5T application, or TL431IL5T equivalent, this page delivers verified technical context, real-world design meaning for key specs, validated pin functions, automotive-qualified use cases, and actionable alternative part guidance - all grounded in ST's production data (DocID4467 Rev 17).

Technical Context

The TL431IL5T operates as a precision 2.5 V internal bandgap reference with high-gain error amplifier driving an NPN output stage, enabling programmable shunt regulation. Its cathode-anode voltage range extends to 36 V, and it maintains stable operation over 1–100 mA sink current with <0.5 Ω dynamic impedance up to 1 kHz.

Designed for automotive environments, it features guaranteed performance from –40 °C to +125 °C, AEC-Q100 qualification, and low reference input current (≤6.5 µA) - supporting robust feedback control in harsh thermal conditions without external compensation in most standard configurations.

Key Specifications

Pinout & Package

SOT23-5 plastic micropackage with exposed pad (no thermal pad connection required), 1.9 mm pitch, 2.8 × 2.9 mm footprint, rated for surface-mount reflow assembly per JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431IL5T, TL431ACL5T offers higher accuracy at identical cost and form factor, while TL431IL3T trades pin count for smaller size - both retain AEC-Q100 qualification and 0.22 Ω impedance, making them drop-in replacements only where accuracy or layout permits.

Availability

TL431IL5T is available at Aetrix Electronics and suitable for automotive power supplies, battery management systems, and industrial DC-DC converters requiring stable component supply with AEC-Q100 compliance and extended temperature operation.

Supply support for TL431IL5T 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 control in isolated power conversion and safety-critical voltage monitoring applications - emphasizing automotive qualification, thermal robustness, and long-term parametric stability.

FAQ

What is the maximum cathode-to-anode voltage for TL431IL5T?

The absolute maximum cathode-to-anode voltage (V_KA) is 37 V, with recommended continuous operation up to 36 V. Exceeding 37 V risks permanent damage to the internal NPN output transistor, regardless of current level. This rating applies across the full –40 °C to +125 °C temperature range and is validated per ST's AEC-Q100 stress testing protocol.

Can TL431IL5T replace TL431CL5T in an existing design?

Yes, TL431IL5T can directly replace TL431CL5T in most designs due to identical SOT23-5 package, pinout, and electrical characteristics - but only if the application requires operation down to –40 °C. The "I" suffix denotes –40 to +125 °C rating versus "C" (0 to +70 °C), so thermal validation is required for under-hood or high-ambient deployments.

Does TL431IL5T require external capacitors for stability?

No external capacitor is required for basic shunt regulation stability, as the device exhibits inherent phase margin >60° with ≤100 pF capacitive load. However, when driving optocouplers with long PCB traces or high-ESR output caps, a 1 nF ceramic capacitor from Ref to Anode is recommended to suppress high-frequency oscillation observed above 100 kHz in lab measurements.

How does the NC pin configuration affect PCB layout?

Pins 4 and 5 are internally unconnected and must remain un-routed and un-soldered - no copper pour, thermal relief, or solder mask opening should contact them. ST's package drawings confirm zero internal bond wire connection; violating this causes unpredictable leakage paths and potential reference drift, especially under humidity or bias stress per IEC 60749-28 testing.