Texas Instruments TL431ACP

Overview

TL431ACP from Texas Instruments is a precision programmable shunt voltage reference IC in SOIC-8 package, delivering 2.495 V nominal reference voltage with ±0.5% initial tolerance (B grade), 0.2 Ω typical dynamic impedance, and sink-current capability from 1 mA to 100 mA. It operates across −40°C to 85°C (I-grade) and serves as a Zener diode replacement in feedback loops of isolated DC/DC converters, AC/DC power supplies, and voltage-monitoring circuits.

For engineers reviewing the TL431ACP datasheet, TL431ACP pinout, TL431ACP application, or TL431ACP equivalent, key selection criteria include its adjustable output range (2.5 V to 36 V), low temperature drift (14 mV over −40°C to 85°C), sharp turn-on characteristic, and compatibility with standard resistor-divider programming for stable regulation in industrial and computing power systems.

Technical Context

The TL431ACP implements an internal error amplifier with high-gain transconductance stage driving an NPN output transistor, enabling precise comparison of the REF pin voltage against an internal 2.495 V bandgap reference. Its active output circuitry provides fast response and low output impedance, supporting stable closed-loop control without external compensation in many configurations.

It functions exclusively as a three-terminal shunt regulator: cathode sinks current when REF-to-anode voltage exceeds Vref; anode serves as common return; and REF senses the divider node. No digital interface, clock input, or enable logic is present - operation is purely analog and continuous.

Key Specifications

Pinout & Package

TL431ACP is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package measuring 4.90 mm × 3.90 mm, with gull-wing leads and standard JEDEC MS-012AC footprint. The package supports automated assembly and offers thermal resistance R_θJA = 97°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431CDBVR and TL431AIDR, the TL431ACP delivers the highest initial accuracy (±0.5%) in the same SOIC-8 footprint, making it optimal for industrial power supplies requiring tight regulation without post-production calibration.

Availability

TL431ACP is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC supplies, and servo drive control modules requiring stable component supply with guaranteed long-term manufacturability.

Supply support for TL431ACP 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 experience in precision reference design.

The TL431 product line was engineered specifically for high-stability, programmable shunt regulation in power supply feedback networks - targeting industrial, computing, and motor control applications where Zener diodes lack accuracy and thermal stability.

FAQ

What is the reference voltage tolerance of TL431ACP at 25°C?

The TL431ACP has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a nominal 2.495 V output ranging from 2.483 V to 2.507 V. This B-grade accuracy is confirmed in Section 6.11 of the TI SLVS543S datasheet and applies specifically to the I-temperature-grade SOIC-8 variant TL431ACP. The tolerance remains stable across load and line variations within specified operating conditions.

Can TL431ACP replace a Zener diode in feedback circuits?

Yes, TL431ACP is explicitly designed as a superior Zener diode replacement in feedback circuits. Its active error amplifier delivers sharper turn-on, lower dynamic impedance (0.2 Ω vs. >10 Ω for typical Zeners), and tighter initial tolerance (±0.5% vs. ±5%–±10%). Unlike passive Zeners, TL431ACP maintains regulation down to 1 mA cathode current and supports programmable output voltages from 2.5 V to 36 V using two external resistors.

What is the maximum cathode voltage rating for TL431ACP?

The absolute maximum cathode voltage (V_KA) for TL431ACP is 37 V, with recommended operating range from V_ref (≈2.5 V) to 36 V. Exceeding 37 V risks permanent damage. This rating is defined in Section 6.1 of the TI SLVS543S datasheet and applies across all temperature grades and packages, including the SOIC-8 TL431ACP variant.

Does TL431ACP require external capacitors for stability?

TL431ACP does not require external capacitors for basic shunt regulation, but stability depends on load capacitance and cathode current. Figure 6-16 and 6-18 in the datasheet define oscillation boundaries: for example, at 10 mA cathode current and 10 V cathode voltage, instability may occur with >0.1 µF capacitive load. Layout best practices recommend minimizing trace inductance and avoiding large bypass caps directly at the cathode unless compensated per TI's stability guidelines.

How does TL431ACP differ from TL432 series devices?

TL431ACP and TL432 devices share identical electrical specifications and functionality, but TL432 uses different pinouts in SOT-23-3, SOT-23-5, and SOT-89 packages. TL431ACP (SOIC-8) has no TL432 pin-compatible variant - its pin configuration (CATHODE–ANODE–REF on Pins 1–2–3) is unique to TL431-family SOIC and PDIP packages. Substituting TL432 parts requires PCB redesign due to reversed REF/CATHODE placement.