Texas Instruments TL431ACDCKT

Overview

TL431ACDCKT from Texas Instruments is a precision programmable shunt voltage reference IC in SC-70 (DCK) package, featuring 1% initial reference voltage tolerance at 25°C (A-grade), adjustable output from 2.47 V to 36 V via two external resistors, 0.2 Ω typical dynamic impedance, and operation across −40°C to 85°C (I-temp grade). It serves as a high-stability Zener replacement in secondary-side regulation of flyback SMPSs.

For engineers reviewing the TL431ACDCKT datasheet, TL431ACDCKT pinout, TL431ACDCKT application, or TL431ACDCKT equivalent, this page delivers verified specifications, validated pin functions, confirmed thermal and electrical behavior per TI SLVS543P, and real-world implementation context for power supply feedback loops, voltage monitoring, and adjustable referencing.

Technical Context

The TL431ACDCKT implements an internal 2.495 V bandgap reference with precision error amplifier and NPN output stage, enabling sharp turn-on and stable shunt regulation. Its three-terminal architecture (REF, CATHODE, ANODE) operates as a programmable sink, where cathode current (1–100 mA) is controlled by the voltage divider on the REF pin relative to ANODE.

It exhibits low temperature drift (VI(dev) = 14 mV over −40°C to 85°C), minimal cathode-to-anode voltage sensitivity (ΔVref/ΔVKA = −1.4 to −2.7 mV/V), and sub-microampere reference input current (Iref = 2–4 µA), making it suitable for high-accuracy, low-power feedback networks without loading external dividers.

Key Specifications

Pinout & Package

TL431ACDCKT uses the SC-70 (DCK) 3-pin surface-mount package (2.20 mm × 1.35 mm × 0.95 mm), optimized for space-constrained power management layouts. Pin 1 is CATHODE, Pin 2 is REF, Pin 3 is ANODE - matching the standard TL431 DBZ/SOT-23-3 pinout orientation (REF–CATHODE–ANODE top view).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDCKT, TL431ACDBVR offers identical performance in a slightly larger SOT-23-3 package, while TLVH431ACDBVR shifts the reference baseline to 1.24 V-enabling lower-output regulation but sacrificing maximum voltage range and requiring recalculated resistor values.

Availability

TL431ACDCKT is available at Aetrix Electronics and suitable for industrial power supplies, isolated DC-DC converters, and embedded voltage monitoring systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for TL431ACDCKT 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 expertise in precision reference and power control ICs.

The TL431 family was designed specifically for high-accuracy, low-drift shunt regulation in cost-sensitive and space-constrained power systems-including SMPS feedback, voltage supervision, and programmable references.

FAQ

What is the reference voltage tolerance of TL431ACDCKT at 25°C?

The TL431ACDCKT has a 1% initial reference voltage tolerance at 25°C, corresponding to a Vref range of 2470 mV to 2520 mV under standard test conditions (VKA = Vref, IKA = 10 mA). This A-grade specification is explicitly defined in TI's SLVS543P datasheet Section 7.8 and distinguishes it from standard (2%) and B-grade (0.5%) variants. The TL431ACDCKT maintains this tolerance across its rated operating temperature range.

What is the operating temperature range for TL431ACDCKT?

The TL431ACDCKT is rated for operation from −40°C to +85°C (I-temp grade), as confirmed in TI's SLVS543P datasheet Section 7.4 and Table 5 (Device Comparison Table). This extended industrial temperature range is validated across all electrical characteristics including Vref deviation (VI(dev) = 14–34 mV), reference input current (II(dev)), and dynamic impedance.

Does TL431ACDCKT require an external capacitor for stability?

No, the TL431ACDCKT does not require an external compensation capacitor for basic shunt regulation. Its internal amplifier is unity-gain stable with capacitive loads up to 1 nF, as documented in TI's SLVS543P Section 9.4 and Figure 25. However, when driving optocouplers in isolated SMPS feedback loops, a small capacitor (e.g., 100 pF–1 nF) across the REF–ANODE pins may be used to suppress high-frequency noise without affecting regulation stability.

Can TL431ACDCKT replace a standard Zener diode directly?

Yes, TL431ACDCKT can directly replace Zener diodes in most shunt regulation applications. With its 2.47–36 V programmability, 0.2 Ω dynamic impedance, and 1% tolerance, it outperforms typical Zeners (e.g., 5% tolerance, >10 Ω impedance). Physical replacement requires only three connections (REF, CATHODE, ANODE) instead of two, and the REF pin must be biased via a resistor divider-no additional active components are needed.

What is the minimum cathode current required for regulation in TL431ACDCKT?

The TL431ACDCKT requires a minimum cathode current (Imin) of 0.4–0.7 mA to maintain regulation, as specified in Section 7.8 (TL431AC) and Section 7.9 (TL431AI) of TI's SLVS543P datasheet. Below this threshold, the device exits regulation and cathode voltage rises above the programmed setpoint. This value is critical for sizing optocoupler LED current in flyback feedback designs.