Texas Instruments TL431QDCKTG4

Overview

TL431QDCKTG4 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, 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 voltage regulation circuits.

For engineers reviewing the TL431QDCKTG4 datasheet, TL431QDCKTG4 pinout, TL431QDCKTG4 application, or TL431QDCKTG4 equivalent, key selection criteria include automotive-grade temperature stability (Q-temp), low output noise (<10 µV_RMS over 10 s), sink-current capability up to 100 mA, and compatibility with standard resistor-divider feedback networks for output voltages from 2.5 V to 36 V.

Technical Context

The TL431QDCKTG4 implements a high-gain transconductance amplifier with internal 2.495 V bandgap reference, comparing REF pin voltage to V_REF and controlling cathode current to maintain regulation. Its sharp turn-on characteristic and low output impedance enable stable operation in switching power supply feedback loops without external compensation in many cases.

Designed for Q-temp (−40°C to +125°C) automotive and industrial applications, it exhibits ≤34 mV total reference voltage deviation across temperature and maintains <2.5 µA reference input current drift. The SOT-23-3 package supports high-density PCB layouts while enabling thermal dissipation up to 350 mW at 25°C ambient.

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 = Anode, Pin 3 = Reference (REF).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431CDCKR and TL431BQDBVR, TL431QDCKTG4 uniquely combines automotive-grade temperature range, B-grade accuracy, and compact SOT-23-3 footprint-enabling drop-in replacement in space-constrained, high-reliability power systems without thermal derating or layout change.

Availability

TL431QDCKTG4 is available at Aetrix Electronics and suitable for AC/DC power supplies, servo drive control modules, and rack server power management requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TL431QDCKTG4 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 and embedded processing technologies, with decades of expertise in precision reference and power management ICs.

The TL431 product line was designed for high-accuracy, low-drift voltage regulation in isolated power supplies, battery chargers, and industrial control systems-emphasizing robustness, wide temperature operation, and ease of implementation.

FAQ

What is the reference voltage tolerance of TL431QDCKTG4 at 25°C?

The TL431QDCKTG4 has a reference voltage tolerance of ±0.5% at 25°C (B grade), corresponding to a 2.495 V nominal value with ±12.5 mV absolute deviation. This tight tolerance is specified per TI's SLVS543S datasheet Section 6.13 and enables high-accuracy output regulation without calibration in automotive and industrial power designs where TL431QDCKTG4 is deployed.

Does TL431QDCKTG4 support operation beyond 125°C junction temperature?

No. TL431QDCKTG4 has a maximum junction temperature (T_J) of 150°C per Absolute Maximum Ratings (Section 6.1), but its guaranteed operating range is −40°C to +125°C ambient (Q grade). Operation above 125°C ambient requires thermal design verification to ensure T_J remains ≤150°C; sustained operation near 150°C may impact long-term reliability of TL431QDCKTG4.

Can TL431QDCKTG4 replace a Zener diode in a linear regulator feedback path?

Yes. TL431QDCKTG4 replaces Zener diodes with superior performance: 0.2 Ω dynamic impedance vs. typical Zener impedance >10 Ω, ±0.5% initial tolerance vs. ±5% for standard Zeners, and stable 2.495 V reference vs. voltage drift with current/temperature. In TL431QDCKTG4 implementations, feedback accuracy improves by >10× and load regulation becomes significantly tighter.

What is the minimum cathode current required for TL431QDCKTG4 to regulate?

The TL431QDCKTG4 requires a minimum cathode current (I_KA(min)) of 0.4 mA to maintain regulation, as specified in Sections 6.5–6.13 of the datasheet. Below this threshold, the device exits regulation and cathode voltage rises toward the supply rail. Designers must ensure feedback network and optocoupler LED current keep TL431QDCKTG4 above 0.4 mA under all operating conditions.

How does TL431QDCKTG4 handle capacitive loads on its cathode node?

TL431QDCKTG4 exhibits conditional stability with capacitive loads: Figure 6-18 shows oscillation risk for CL >1 µF at I_KA <10 mA and V_KA >5 V. For stable operation, keep cathode capacitance ≤100 nF unless compensated with series resistance (e.g., 10–100 Ω) - a constraint explicitly documented for TL431QDCKTG4 in the Stability Boundary Conditions section.