Texas Instruments TL431LIBCDBZR

Overview

TL431LIBCDBZR from Texas Instruments is a precision programmable shunt regulator in SOT-23-3 package, functioning as an adjustable voltage reference or error amplifier with 0.5% initial reference voltage tolerance at 25°C, 2.495 V nominal Vref, and sink-current capability up to 15 mA. It operates across −40°C to +125°C (Q-temp grade) and replaces Zener diodes in secondary-side regulation of flyback SMPS.

For engineers reviewing the TL431LIBCDBZR datasheet, TL431LIBCDBZR pinout, TL431LIBCDBZR application, or TL431LIBCDBZR equivalent, key selection considerations include reference accuracy, cathode current range (1–15 mA), dynamic impedance (0.3 Ω typ), temperature drift (10 mV max over −40°C to +125°C), and IREF ≤ 0.4 µA for low-leakage biasing in precision feedback loops.

Technical Context

The TL431LIBCDBZR integrates a 2.495 V bandgap reference and high-gain op-amp driving a Darlington output stage, enabling sharp turn-on and stable shunt regulation without external compensation. Its three-terminal architecture (REF, CATHODE, ANODE) supports both open-loop comparator and closed-loop error-amplifier configurations.

It delivers 0.3 Ω typical dynamic impedance and maintains regulation with ≥1 mA cathode current (Imin), while reference input current remains ≤0.4 µA at 25°C and ≤0.3 µA over full temperature range - critical for high-impedance resistor-divider networks in isolated power supplies.

Key Specifications

Pinout & Package

SOT-23-3 (DBZ) package, 2.90 mm × 1.30 mm body size, surface-mount, tape-and-reel compatible.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431CDBZR, TL431LIBCDBZR offers higher accuracy and lower temperature drift at identical cost and footprint; compared with TL432LIBCDBZR, it provides direct pin compatibility with legacy TL431 designs - eliminating layout risk while retaining performance gains.

Availability

TL431LIBCDBZR is available at Aetrix Electronics and suitable for automotive power management, industrial SMPS design, and precision analog monitoring requiring stable component supply and long-term lifecycle support.

Supply support for TL431LIBCDBZR 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

Texas Instruments is a global semiconductor leader delivering analog and embedded processing solutions, with over 50 years of innovation in precision analog ICs and power management.

The TL43xLI family was designed specifically for high-accuracy, low-drift shunt regulation in safety-critical and thermally demanding applications - emphasizing optimized reference current, extended temperature range, and robustness in isolated feedback paths.

FAQ

What is the reference voltage tolerance of TL431LIBCDBZR at 25°C?

The TL431LIBCDBZR has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a nominal Vref of 2.495 V with a range of 2.483 V to 2.507 V. This B-grade accuracy is confirmed in the Electrical Characteristics table of the SLVSDQ6A datasheet and applies specifically to the TL431LIBCDBZR variant. The tighter tolerance directly improves system-level voltage regulation accuracy in feedback loops using this device.

Can TL431LIBCDBZR replace standard TL431 devices without layout changes?

Yes, TL431LIBCDBZR is pin-to-pin compatible with industry-standard TL431 devices in the SOT-23-3 (DBZ) package. Its pin configuration - CATHODE (Pin 1), REF (Pin 2), ANODE (Pin 3) - matches legacy TL431 footprints exactly. No PCB modifications are required, and it delivers improved IREF (≤0.4 µA) and II(dev) (≤0.3 µA) versus older versions, enhancing accuracy in high-impedance applications.

What is the minimum cathode current needed for TL431LIBCDBZR to regulate properly?

The TL431LIBCDBZR requires a minimum cathode current (Imin) of 1 mA to enter and maintain regulation, as specified in Section 7.4 of the SLVSDQ6A datasheet. Below this threshold, gain drops significantly, causing slow response or failure to regulate. Designers must ensure external biasing networks deliver ≥1 mA under all operating conditions - including worst-case temperature and input voltage - to guarantee stable TL431LIBCDBZR operation.

How does TL431LIBCDBZR perform over temperature?

TL431LIBCDBZR is characterized for operation from −40°C to +125°C (Q-temp grade) with a maximum reference voltage deviation (VI(dev)) of 10 mV across that range. This equates to approximately ±0.4 mV/°C average temperature coefficient - significantly better than standard TL431 variants. The low drift ensures consistent performance in automotive under-hood and industrial control environments where ambient temperature swings are extreme.

Is TL431LIBCDBZR suitable for use as a comparator?

Yes, TL431LIBCDBZR functions effectively as a comparator with integrated reference in open-loop configurations. When supplied with ≥1 mA cathode current, its high open-loop gain enables fast threshold detection. The REF pin serves as the input, comparing external voltage to the internal 2.495 V reference; CATHODE acts as the open-collector output. Applications include undervoltage lockout and overvoltage protection - confirmed in Section 9.4.1 and Figure 20 of the SLVSDQ6A datasheet.