Texas Instruments TL431ACPS

Overview

TL431ACPS from Texas Instruments is a three-terminal adjustable precision shunt regulator optimized for 0°C to 70°C commercial operation. It delivers a tightly specified reference voltage of 2.47–2.52 V, supports sink current from 1 mA to 100 mA, exhibits 0.2 Ω typical dynamic impedance, and enables output voltage adjustment from 2.5 V to 36 V using two external resistors-commonly deployed in feedback loops of isolated DC-DC converters and programmable voltage monitors.

For engineers reviewing the TL431ACPS datasheet, TL431ACPS pinout, TL431ACPS application, or TL431ACPS equivalent, key selection considerations include its ±1% initial reference tolerance, 30 ppm/°C full-range temperature coefficient, low-noise performance, and compatibility with high-density through-hole PS (8-pin plastic DIP) packaging for legacy board designs requiring robust thermal derating and manual assembly support.

Technical Context

The TL431ACPS integrates an internal 2.495 V bandgap reference, error amplifier, and NPN output stage in a single monolithic IC. Its sharp turn-on characteristic and active output circuitry enable precise regulation without external compensation in most shunt configurations.

It operates as a programmable Zener replacement: the REF pin senses voltage via resistor divider, the ANODE serves as ground reference, and the CATHODE sinks current to maintain regulation-supporting both shunt and series-derived topologies including crowbar protection, voltage monitoring, and adjustable linear regulators.

Key Specifications

Pinout & Package

TL431ACPS uses the PS package: 8-pin plastic dual in-line package (DIP), through-hole mount, 0.3-inch width, with standard pin spacing (0.1 inch). Pin 1 is bottom-left corner when notch faces up.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431CPS and TL431ACLP, TL431ACPS offers superior thermal performance (lower θ_JA than LP), tighter initial tolerance than TL431CPS, and standardized 8-pin DIP layout ideal for serviceability and hand-soldered prototypes-making it optimal for mid-volume industrial power supplies where accuracy, reliability, and repairability are balanced.

Availability

TL431ACPS is available at Aetrix Electronics and suitable for isolated DC-DC converters, programmable voltage monitors, crowbar protection circuits, and adjustable linear regulators requiring stable component supply across extended production cycles.

Supply support for TL431ACPS 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 heritage in precision reference design.

The TL431 product line was engineered for high-accuracy voltage regulation in cost-sensitive power systems-from consumer adapters to industrial controls-emphasizing thermal stability, wide output adjustability, and Zener diode replacement capability.

FAQ

What is the reference voltage range of TL431ACPS at 25°C?

The TL431ACPS has a reference voltage (V_ref) range of 2.47 V to 2.52 V at 25°C, reflecting its ±1% initial tolerance specification. This tight range ensures predictable output programming across production lots and enables high-accuracy feedback networks without post-manufacture trimming. The TL431ACPS maintains this specification over its full 0°C to 70°C operating temperature range.

Can TL431ACPS replace a standard Zener diode in existing designs?

Yes, TL431ACPS can directly replace many Zener diodes in shunt regulation applications, especially where adjustable output or tighter tolerance is needed. Unlike passive Zeners, TL431ACPS requires only two external resistors to set output voltage from 2.5 V to 36 V and delivers far better thermal stability (30 ppm/°C) and lower dynamic impedance (0.2 Ω). Its PS package also matches common DIP footprints used for axial-leaded Zeners in legacy layouts.

What is the minimum cathode current required for TL431ACPS to regulate properly?

The TL431ACPS requires a minimum cathode current (I_min) of 0.4 mA to 0.6 mA to maintain regulation, per its datasheet specifications. This value ensures the internal amplifier remains biased and the output stage operates in active mode. Designers must size the feedback resistor network to guarantee ≥0.6 mA flows through the TL431ACPS CATHODE even under worst-case low-input-voltage and high-output-voltage conditions.

How does the PS package of TL431ACPS compare thermally to other TL431 variants?

The PS (8-pin plastic DIP) package of TL431ACPS has a junction-to-ambient thermal resistance (θ_JA) of approximately 85°C/W, significantly lower than the LP (TO-226AA) package's 156°C/W. This makes TL431ACPS more suitable for higher-power shunt applications (e.g., >30 mA continuous sink) without external heatsinking. Its dual CATHODE and dual ANODE pins further enhance current handling and thermal spreading compared to 3-pin variants.

Does TL431ACPS support operation in crowbar protection circuits?

Yes, TL431ACPS is widely used in crowbar overvoltage protection due to its sharp turn-on characteristic and fast response. When configured with a resistor divider on the REF pin, it triggers an SCR or TRIAC when output exceeds a precise threshold-e.g., 3.6 V for a 3.3 V rail. The TL431ACPS' low 100 mV transition width and sub-microsecond propagation delay ensure reliable, repeatable fault activation without nuisance tripping.