Texas Instruments TL431ILPR

Overview

TL431ILPR from Texas Instruments is a precision programmable shunt voltage reference IC with 1% initial tolerance at 25°C, adjustable output from 2.495 V to 36 V, −40°C to 85°C operating temperature range (I-grade), 0.2 Ω typical dynamic impedance, and 1–100 mA sink-current capability-used in feedback loops of isolated DC-DC converters and AC/DC power supplies.

For engineers reviewing the TL431ILPR datasheet, TL431ILPR pinout, TL431ILPR application, or TL431ILPR equivalent, this page delivers verified electrical specs, SOT-23-3 package details, thermal performance data, and real-world implementation guidance for industrial and server power designs.

Technical Context

The TL431ILPR implements a three-terminal adjustable shunt regulator architecture with an internal 2.495 V reference and high-gain error amplifier. Its active output stage provides sharp turn-on characteristics and low output impedance, enabling stable regulation without external compensation in many configurations.

It operates as a voltage-controlled current sink: when the REF pin voltage exceeds 2.495 V, the cathode-anode path conducts to clamp VKA; regulation accuracy depends on external resistor divider ratio and device's VI(dev) of ≤34 mV over −40°C to 85°C.

Key Specifications

Pinout & Package

TL431ILPR is supplied in the SOT-23-3 (DBZ) package: 2.90 mm × 1.30 mm body, surface-mount, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACLPR, TL431ILPR offers extended temperature operation critical for factory automation; versus TL431BILPR, it trades 0.5% accuracy for lower unit cost while retaining identical thermal and package compatibility.

Availability

TL431ILPR is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC converters, and servo drive control modules requiring stable component supply across long production lifecycles.

Supply support for TL431ILPR 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The TL431 product line was designed specifically for precision voltage regulation in isolated power supplies, offering programmability, low drift, and robust sink-current capability across extended temperature grades.

FAQ

What is the reference voltage tolerance of TL431ILPR at 25°C?

The TL431ILPR has a reference voltage tolerance of ±1% at 25°C, corresponding to a nominal 2.495 V output with a guaranteed range of 2.470 V to 2.520 V. This A-grade specification is confirmed in Section 6.8 of the TI SLVS543S datasheet. The tolerance remains stable across its −40°C to +85°C operating range, with total deviation capped at ≤34 mV. TL431ILPR achieves this via laser-trimmed internal resistors and matched transistor pairs.

Does TL431ILPR require external capacitors for stability?

TL431ILPR does not require external compensation capacitors in most standard configurations, but stability depends on load capacitance and cathode current. Per Figure 6-18 in the datasheet, oscillation risk increases above 100 nF load capacitance at low cathode currents (<10 mA). For robust operation in switching power supplies, a 1 nF ceramic capacitor from CATHODE to ANODE is recommended. TL431ILPR's SOT-23-3 layout inherently limits parasitic inductance, aiding high-frequency stability.

Can TL431ILPR replace a Zener diode in my design?

Yes, TL431ILPR is explicitly designed as a superior replacement for Zener diodes in voltage regulation and reference applications. Unlike Zeners, TL431ILPR offers adjustable output (2.495–36 V), tighter tolerance (±1%), lower dynamic impedance (0.2 Ω vs. 5–50 Ω for Zeners), and predictable temperature coefficient. Its three-terminal architecture allows precise feedback control in isolated DC-DC converters-where Zeners lack gain and regulation fidelity. TL431ILPR also draws only 2–4 µA at REF, reducing divider losses.

What is the maximum cathode voltage rating for TL431ILPR?

The absolute maximum cathode-to-anode voltage (VKA) for TL431ILPR is 37 V, with recommended operating range from Vref (≈2.495 V) to 36 V. Exceeding 37 V risks permanent damage per Section 6.1 of the datasheet. This rating applies regardless of current level. For 48 V bus applications, TL431ILPR must be used with a series resistor or clamping circuit to limit VKA. Derating is advised above 30 V to maintain long-term reliability under thermal stress.

Is TL431ILPR pin-compatible with other TL431 variants in SOT-23-3?

Yes, TL431ILPR is pin-compatible with all TL431x variants offered in the SOT-23-3 (DBZ) package-including TL431ACLPR, TL431BILPR, and TL431CLPR-as confirmed by Table 5-1 and Pin Configuration diagrams in the TI datasheet. All share identical REF–CATHODE–ANODE pinout (Pin 1–2–3), allowing drop-in substitution where grade or temperature requirements align. No PCB changes are needed when upgrading from C- to I-grade or adjusting initial tolerance.