Texas Instruments TL431ACPSR

Overview

TL431ACPSR from Texas Instruments is a precision programmable shunt voltage reference in SOIC-8 package, delivering 2.495 V nominal reference voltage with ±0.5% initial tolerance at 25°C, 0.2 Ω typical dynamic impedance, and sink-current capability from 1 mA to 100 mA. It operates across −40°C to 85°C and serves as a stable feedback element in isolated DC-DC converters and AC/DC power supplies.

For engineers reviewing the TL431ACPSR datasheet, TL431ACPSR pinout, TL431ACPSR application, or TL431ACPSR equivalent, this page delivers verified electrical specs, thermal behavior, stability boundaries, and real-world implementation guidance for power supply feedback loop design, voltage monitoring, and adjustable regulation circuits.

Technical Context

The TL431ACPSR implements a three-terminal adjustable shunt regulator architecture with an internal error amplifier, reference, and output transistor. Its sharp turn-on characteristic and low 0.2 Ω dynamic impedance enable precise voltage regulation without external compensation in most configurations.

It functions as a programmable Zener replacement: the REF pin senses a fraction of cathode-to-anode voltage via external resistors, and the device sinks current through the CATHODE pin to maintain V_REF = 2.495 V ±12.5 mV (A-grade) across temperature. Stability depends on load capacitance and cathode current, with oscillation boundaries documented per I_KA and C_L.

Key Specifications

Pinout & Package

TL431ACPSR uses the SOIC-8 (D) package (4.90 mm × 3.90 mm), with pins arranged in standard dual-inline configuration. Pin 1 is CATHODE, Pin 2 is REFERENCE, Pin 3 is ANODE; Pins 4–8 are NC (no internal connection).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431AIDR, TL431ACPSR offers identical performance but differs in packaging format (tube vs. tape-and-reel) and MSL rating; compared with TLVH431AQDBVR, it provides higher reference voltage, tighter tolerance, and lower input current-making it the preferred choice for legacy 2.5 V–36 V feedback architectures.

Availability

TL431ACPSR is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and servo drive control module applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for TL431ACPSR 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 over 90 years of innovation in precision analog components.

The TL431 product line was designed for high-accuracy, low-drift voltage reference applications in power conversion, industrial control, and automotive systems-emphasizing robustness, wide temperature operation, and Zener-diode replacement capability.

FAQ

What is the reference voltage tolerance of TL431ACPSR at 25°C?

The TL431ACPSR has a reference voltage tolerance of ±1% at 25°C, corresponding to a nominal 2.495 V output ranging from 2.470 V to 2.520 V. This A-grade specification is confirmed in Section 6.8 of the TI SLVS543S datasheet and applies across the full operating temperature range of −40°C to +85°C. The TL431ACPSR maintains this tolerance without requiring external calibration.

Can TL431ACPSR replace a Zener diode in feedback circuits?

Yes, TL431ACPSR is explicitly designed as a precision Zener diode replacement. Its sharp turn-on characteristic, 0.2 Ω dynamic impedance, and programmable 2.495 V to 36 V output make it superior to standard Zeners in feedback loops. Unlike Zeners, TL431ACPSR provides stable regulation with minimal voltage drift over temperature and current, eliminating the need for trimming in applications like isolated DC-DC converters.

What are the absolute maximum ratings for TL431ACPSR cathode voltage and current?

The absolute maximum cathode voltage (V_{K A}) for TL431ACPSR is 37 V, and the continuous cathode current (I_{K A}) ranges from −100 mA to +150 mA. These ratings are specified in Section 6.1 of the TI datasheet. Operation beyond these limits risks permanent damage. For reliable operation, TI recommends staying within 1 mA to 100 mA cathode current and ≤36 V cathode voltage under normal conditions.

How does temperature affect the reference voltage of TL431ACPSR?

Over its −40°C to +85°C operating range, TL431ACPSR exhibits a maximum reference voltage deviation (V_I(dev)) of 50 mV for SOIC-8 devices, translating to approximately ±20 ppm/°C average drift. This is documented in Section 6.9 (TL431AI characteristics) of the datasheet. The deviation is non-linear and peaks near temperature extremes, but remains fully specified and tested - ensuring predictable behavior in industrial power supply feedback networks.

Is TL431ACPSR pin-compatible with other TL431 variants in SOIC-8 packages?

Yes, TL431ACPSR is pin-compatible with all TL431x variants in the SOIC-8 (D) package, including TL431C, TL431I, TL431Q, TL431B, and TL431A versions. Pin 1 is CATHODE, Pin 2 is REF, and Pin 3 is ANODE across all variants; Pins 4–8 are NC. Electrical differences (tolerance, temp grade, drift) do not affect pinout or basic functionality, enabling direct substitution in existing PCB layouts when performance requirements align.