Texas Instruments TL431AQDBZT

Overview

TL431AQDBZT from Texas Instruments is a precision programmable shunt voltage reference in SOT-23-3 package, delivering 2.47–2.52 V reference voltage at 25°C with ±1% initial accuracy (A grade), −40°C to +125°C operating range (Q grade), and 0.2 Ω typical dynamic impedance. It serves as an adjustable feedback element in isolated DC/DC converters, AC/DC power supplies, and servo drive control modules.

For engineers reviewing the TL431AQDBZT datasheet, TL431AQDBZT pinout, TL431AQDBZT application, or TL431AQDBZT equivalent, key selection criteria include its automotive-grade temperature stability (VI(dev) ≤ 34 mV over full range), low reference input current (2–4 µA), sink-current capability (1–100 mA), and compatibility with standard two-resistor output programming.

Technical Context

The TL431AQDBZT implements a precision bandgap-based error amplifier with internal reference and output transistor, configured as a three-terminal shunt regulator. Its REF pin senses voltage relative to ANODE, triggering cathode current sink when threshold is exceeded - enabling precise closed-loop regulation without external op-amps.

It operates exclusively in shunt mode: cathode sinks current to maintain regulated voltage across external resistor divider; ANODE serves as common return (typically grounded); no high-side or series-pass functionality is present. The SOT-23-3 pinout (REF–CATHODE–ANODE) differs from TL432 variants and excludes NC pins.

Key Specifications

Pinout & Package

SOT-23-3 package (2.90 mm × 1.30 mm body size), surface-mount, lead-free, RoHS-compliant. Thermal resistance R_θJA = 206°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBZT, TL431AQDBZT adds automotive-grade reliability without increasing footprint; compared with TL431BQDBZT, it trades 0.5% accuracy for lower unit cost while retaining full Q-temp qualification - making it optimal for mid-tier industrial power supplies.

Availability

TL431AQDBZT is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and servo drive control module applications requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for TL431AQDBZT 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 technologies, with decades of leadership in precision reference design.

The TL431 product line was engineered for high-accuracy, low-drift voltage regulation in isolated power conversion topologies - targeting cost-sensitive yet thermally demanding applications in computing, industrial automation, and motor control.

FAQ

What is the maximum cathode voltage rating for TL431AQDBZT?

The absolute maximum cathode-to-anode voltage (V_{K A}) for TL431AQDBZT is 37 V. Operation beyond this risks permanent damage. For reliable long-term use, the recommended maximum is 36 V, aligning with its specified adjustable output voltage range from V_ref up to 36 V. This limit applies regardless of current level or ambient temperature.

Can TL431AQDBZT replace a Zener diode directly in existing circuits?

Yes, TL431AQDBZT can directly replace Zener diodes in most shunt-regulator configurations, provided the circuit uses a two-resistor divider to set output voltage and respects its 1–100 mA cathode current range. Unlike Zeners, TL431AQDBZT requires connection of the ANODE pin (Pin 3) - typically to ground - and exhibits sharper turn-on and lower dynamic impedance (0.2 Ω vs. 5–50 Ω for Zeners).

Does TL431AQDBZT require external compensation for stability?

No external compensation is required for basic operation, but stability depends on load capacitance and cathode current. Per Figure 6-18 in the datasheet, TL431AQDBZT remains stable with 0.001–1 µF capacitive loads at I_KA = 1–100 mA. Avoid >1 µF directly at cathode without series resistance; use RC snubbers if interfacing with optocouplers exhibiting high CTR variation.

How does the reference input current (I_ref) of TL431AQDBZT affect resistor divider design?

TL431AQDBZT draws 2–4 µA into its REF pin, which flows through the upper resistor (R1) of the feedback divider. To minimize voltage error and thermal drift, R1 should be ≤100 kΩ (yielding ≤0.4 mV drop), and both R1 and R2 should be metal-film with ≤100 ppm/°C TCR. Higher values increase sensitivity to I_ref variation and noise coupling.

Is TL431AQDBZT pin-compatible with TL432AQDBZT?

No, TL431AQDBZT is not pin-compatible with TL432AQDBZT. While both are Q-grade, A-accuracy devices in SOT-23-3, TL432AQDBZT uses CATHODE–REF–ANODE pinout (Pin 1=CATHODE, Pin 2=REF, Pin 3=ANODE), whereas TL431AQDBZT uses REF–CATHODE–ANODE (Pin 1=REF, Pin 2=CATHODE, Pin 3=ANODE). Swapping them causes immediate functional failure.