Texas Instruments TL431QDBZRG4

Overview

TL431QDBZRG4 from Texas Instruments is a precision programmable shunt voltage reference in SOT-23-3 package, delivering 2.495 V nominal reference voltage with ±0.5% initial tolerance (B-grade), −40°C to +125°C operating range, 0.2 Ω typical dynamic impedance, and 1–100 mA sink-current capability. It serves as an adjustable feedback element in isolated DC/DC converters, AC/DC power supplies, and servo drive voltage regulation circuits.

For engineers reviewing the TL431QDBZRG4 datasheet, TL431QDBZRG4 pinout, TL431QDBZRG4 application, or TL431QDBZRG4 equivalent, key selection criteria include automotive-grade temperature stability (Q-temp), low output noise, sharp turn-on characteristic for Zener replacement, and compatibility with standard resistor-divider feedback networks across 2.5 V to 36 V output ranges.

Technical Context

The TL431QDBZRG4 implements a high-gain transconductance amplifier with internal 2.495 V bandgap reference, comparing REF pin voltage against V_REF and driving the CATHODE to maintain regulation via external resistor network. Its Q-temp qualification ensures stable operation over −40°C to +125°C, with ≤34 mV total reference voltage deviation across that range.

Unlike fixed-voltage references, it operates as a three-terminal adjustable shunt regulator-requiring no external compensation in most configurations-and achieves low 0.2 Ω dynamic impedance below 1 kHz, enabling fast transient response in closed-loop feedback paths of switching regulators and linear post-regulators.

Key Specifications

Pinout & Package

SOT-23-3 package (2.90 mm × 1.30 mm), surface-mount, RoHS-compliant, with gull-wing leads and thermal pad not connected internally.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431CDBZR and TLVH431QDBZR, TL431QDBZRG4 uniquely combines automotive-grade temperature range, ±0.5% accuracy, and ultra-low 2–4 µA reference current-making it optimal for high-reliability, wide-temperature, precision feedback applications where stability and low power loss are prioritized.

Availability

TL431QDBZRG4 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 long production lifecycles.

Supply support for TL431QDBZRG4 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 leadership in precision reference and power control technologies.

The TL431 product line delivers highly stable, adjustable shunt references for feedback, regulation, and voltage supervision in power conversion systems-designed specifically for reliability in automotive, industrial, and computing infrastructure applications.

FAQ

What is the reference voltage tolerance of TL431QDBZRG4 at 25°C?

The TL431QDBZRG4 has a ±0.5% initial reference voltage tolerance at 25°C, corresponding to the B-grade specification. This means its nominal 2.495 V reference falls within 2.482 V to 2.507 V at room temperature, verified per TI's SLVS543S datasheet Section 6.13. This tight tolerance reduces or eliminates need for system-level calibration in precision power supplies.

Does TL431QDBZRG4 support operation beyond 125°C junction temperature?

No. The TL431QDBZRG4 is rated for a maximum junction temperature of 150°C, with recommended operating free-air temperature limited to −40°C to +125°C (Q-grade). Exceeding TJ = 150°C risks permanent parametric shift or failure. Thermal design must ensure θJA and ambient conditions keep TJ within spec-e.g., at 100 mA sink current, power dissipation must stay below (150°C − TA)/206°C/W (SOT-23-3 RθJA).

Can TL431QDBZRG4 replace a Zener diode directly in existing circuits?

Yes-TL431QDBZRG4 functions as a superior Zener diode replacement due to its sharp turn-on characteristic, low 0.2 Ω dynamic impedance, and adjustable 2.5 V–36 V output. However, direct substitution requires verifying that the existing circuit provides ≥1 mA cathode current and uses a compatible three-pin layout (REF/CATHODE/ANODE). Unlike Zeners, TL431QDBZRG4 cannot operate with REF floating or shorted.

What is the minimum cathode current required for regulation in TL431QDBZRG4?

The TL431QDBZRG4 requires a minimum cathode current (I_min) of 0.4 mA to maintain regulation, per Section 6.13 of the datasheet. Below this threshold, the device exits regulation and CATHODE voltage rises uncontrollably. Designers must ensure feedback network and optocoupler LED current collectively sustain ≥0.4 mA under all operating conditions-including light-load and startup.

Is TL431QDBZRG4 pin-compatible with TL432QDBZRG4?

No. TL431QDBZRG4 and TL432QDBZRG4 share identical electrical specifications and Q-temp rating but feature reversed pinouts in the SOT-23-3 package: TL431QDBZRG4 uses REF–CATHODE–ANODE (Pin 1–2–3), while TL432QDBZRG4 uses CATHODE–REF–ANODE. PCB layout and schematic symbols must be updated to avoid functional failure or damage.