Texas Instruments TL431BIDBZT

Overview

TL431BIDBZT from Texas Instruments is a precision programmable shunt voltage reference in SOT-23-3 package, featuring 0.5% initial reference voltage tolerance at 25°C, adjustable output from 2.495 V to 36 V, and operation across −40°C to 125°C. It delivers 0.2 Ω typical dynamic impedance and supports 1–100 mA sink current, widely used in isolated feedback loops of AC/DC adapters and industrial power supplies.

For engineers reviewing the TL431BIDBZT datasheet, TL431BIDBZT pinout, TL431BIDBZT application, or TL431BIDBZT equivalent, key selection criteria include temperature drift (≤34 mV over full range), low noise performance, cathode current stability under varying load, and compatibility with standard resistor-divider feedback networks in flyback and forward converters.

Technical Context

The TL431BIDBZT implements a three-terminal adjustable shunt regulator architecture with an internal error amplifier, reference, and output transistor. Its REF pin senses voltage relative to ANODE, enabling precise regulation via external resistive divider, while CATHODE sinks current to maintain setpoint.

As a Q-grade (−40°C to 125°C) B-tolerance (0.5%) variant in DBZ package, it exhibits 14–34 mV total reference voltage deviation over temperature and maintains ≤0.5 Ω dynamic impedance up to 1 kHz - critical for stable loop response in high-frequency switching supplies.

Key Specifications

Pinout & Package

SOT-23-3 package (2.90 mm × 1.30 mm), surface-mount, lead-free, RoHS-compliant. Pin 1 = CATHODE, Pin 2 = REF, Pin 3 = ANODE.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431CDBZR, TL431BIDBZT adds 125°C operation and tighter thermal drift control - essential for reliability in sealed industrial drives. Versus TL431BQDBZR, the DBZ-3 version saves board space and eliminates unused pins, reducing routing complexity in dense power sections.

Availability

TL431BIDBZT is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and servo drive control modules requiring stable component supply with guaranteed long-term manufacturability.

Supply support for TL431BIDBZT 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 specializing in analog, embedded processing, and power management ICs, with decades of expertise in precision reference and power control solutions.

The TL431 family was designed specifically for high-accuracy, low-drift voltage regulation in isolated power supply feedback paths - targeting industrial, automotive, and computing applications demanding long-term stability and wide-temperature operation.

FAQ

What is the reference voltage tolerance of TL431BIDBZT at 25°C?

The TL431BIDBZT has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 2.495 V nominal output with ±12 mV deviation. This B-grade accuracy is confirmed in Section 6.11 of the TI SLVS543S datasheet and applies specifically to the TL431BQ variant in DBZ packaging. The TL431BIDBZT maintains this tolerance across its full operating temperature range.

Can TL431BIDBZT replace a Zener diode in a linear regulator circuit?

Yes, TL431BIDBZT can directly replace Zener diodes in shunt regulator configurations due to its sharp turn-on characteristic, low dynamic impedance (0.2 Ω), and adjustable 2.495–36 V output. Unlike Zeners, TL431BIDBZT offers superior temperature stability (≤34 mV drift) and lower noise - making it ideal for precision references where Zener voltage variation with current or temperature would degrade performance.

What is the maximum cathode voltage rating for TL431BIDBZT?

The absolute maximum cathode voltage (VKA) for TL431BIDBZT is 37 V, referenced to the ANODE pin. Per Section 6.1 of the TI SLVS543S datasheet, continuous operation is specified up to 36 V. Exceeding 37 V risks permanent damage. Designers must ensure the cathode-to-anode differential remains within this limit, especially during transient overvoltage events in power supply feedback networks.

Does TL431BIDBZT require external compensation for stability?

TL431BIDBZT does not require external compensation in standard resistor-divider feedback configurations. Figure 6-18 confirms stability with ≥0.01 µF load capacitance across its operating current range. However, when driving capacitive loads >1 µF or interfacing with optocouplers exhibiting significant CTR variation, a small series resistor (10–100 Ω) at the CATHODE improves phase margin - a practice validated in TI Application Report SLVA614.

How does the REF pin input current affect feedback resistor selection in TL431BIDBZT designs?

The REF pin input current of TL431BIDBZT is 2–4 µA (typical), enabling use of high-value feedback resistors (e.g., 100 kΩ–1 MΩ) without introducing significant voltage division error. This low bias current minimizes standby power loss and improves accuracy versus higher-current references - particularly valuable in energy-sensitive applications like notebook adapters where TL431BIDBZT is commonly deployed.