Texas Instruments TL431AQDCKT

Overview

TL431AQDCKT from Texas Instruments is a precision programmable shunt voltage reference in SOT-23-3 (DCK) package, rated for automotive-grade operation from −40°C to 125°C, with 1% initial reference voltage tolerance at 25°C (2.47 V–2.52 V), 0.2 Ω typical dynamic impedance, and 1 mA to 100 mA sink-current capability. It serves as a stable feedback element in isolated DC/DC converters and adjustable linear regulators for industrial power supplies.

For engineers reviewing the TL431AQDCKT datasheet, TL431AQDCKT pinout, TL431AQDCKT application, or TL431AQDCKT equivalent, key selection criteria include its Q-temp automotive qualification, SOT-23-3 footprint compatibility, 14 mV max reference voltage drift over temperature, and direct replacement capability for Zener diodes in closed-loop regulation circuits requiring <1% accuracy.

Technical Context

The TL431AQDCKT implements an internal error amplifier with a precise 2.495 V bandgap reference, comparing the REF pin voltage to Vref and driving the cathode to maintain regulation via external resistor divider. Its three-terminal shunt topology requires no external compensation in most applications but exhibits conditional stability dependent on load capacitance and cathode current.

It operates as a two-quadrant device: sinking current when VKA > Vref (regulation mode), and presenting high-impedance off-state behavior (Ioff ≤ 0.5 µA at VKA = 36 V) when VKA < Vref. The SOT-23-3 (DCK) package supports thermal dissipation up to 206°C/W junction-to-ambient, limiting continuous power to ~300 mW at TA = 125°C.

Key Specifications

Pinout & Package

SOT-23-3 (DCK) package: 2.90 mm × 1.30 mm body, gull-wing leads, 0.95 mm pitch, JEDEC MO-178AC compliant. Thermal pad not present; mounted on standard PCB copper pour for heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431AQDCKT, TL431ACDBVR trades automotive qualification for lower temperature drift in benign environments, while TL431BQDBVR delivers tighter initial tolerance at identical thermal rating-both retain the same SOT-23-3 footprint and functional interface but differ in grade-specific accuracy and temperature limits.

Availability

TL431AQDCKT is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and servo drive control module applications requiring stable component supply with automotive-grade reliability and long-term lifecycle support.

Supply support for TL431AQDCKT 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 design and automotive-qualified components.

The TL431 product line was developed to replace Zener diodes in feedback networks of isolated power supplies, delivering higher accuracy, lower drift, and better noise performance across industrial and automotive operating conditions.

FAQ

What is the maximum cathode voltage rating for TL431AQDCKT?

The absolute maximum cathode-to-anode voltage (VKA) for TL431AQDCKT is 37 V. Operating continuously above 36 V violates recommended conditions and risks permanent damage. In practice, designs must limit VKA to ≤36 V with appropriate margin, especially under transient conditions like load dump or inductive kickback, to ensure long-term reliability and avoid exceeding the 150°C junction temperature limit.

Does TL431AQDCKT require external compensation capacitors?

TL431AQDCKT does not require external compensation in basic shunt regulator configurations, but stability depends on load capacitance and cathode current. Per Figure 6-18, oscillation risk increases with CL > 1 µF at IKA < 10 mA. For robust operation across all loads, a 1 nF ceramic capacitor from cathode to anode is recommended, particularly when driving optocouplers or capacitive feedback networks in isolated converters using TL431AQDCKT.

How does the REF pin input current affect voltage divider design in TL431AQDCKT circuits?

The REF pin input current of TL431AQDCKT is 2–4 µA at 25°C and rises to ≤2.5 µA over full temperature range. This current flows through the upper resistor (R1) of the feedback divider, causing a voltage drop that offsets the setpoint. To maintain ≤0.1% error, R1 should be ≤10 kΩ (yielding ≤40 mV drop), and both R1 and R2 must be ≤0.1% tolerance if targeting <0.5% total output error. TL431AQDCKT's low II(dev) ensures predictable bias current across temperature.

Can TL431AQDCKT be used in series (non-shunt) regulator configurations?

No-TL431AQDCKT is strictly a shunt regulator and cannot operate as a series pass element. Its internal architecture sinks current from cathode to anode to regulate voltage at the REF node; it lacks a series pass transistor or source-follower output stage. Attempting series use results in uncontrolled conduction or latch-up. For series regulation, discrete NPN/PNP transistors or dedicated LDOs must be used alongside TL431AQDCKT as the error-sensing element only.

What is the thermal resistance (RθJA) of TL431AQDCKT in its SOT-23-3 package?

The junction-to-ambient thermal resistance (RθJA) of TL431AQDCKT in the SOT-23-3 (DCK) package is 206°C/W, as specified in Section 6.3 of the datasheet. This value assumes standard JEDEC 2S2P board conditions (two-layer board, 1 in² copper per side). With a maximum junction temperature of 150°C and ambient of 125°C, the maximum allowable power dissipation is (150 − 125)/206 ≈ 121 mW-dictating a practical cathode current limit of ~30 mA at 4 V VKA in high-ambient applications.