Texas Instruments TL1431CLP

Overview

TL1431CLP from Texas Instruments is a precision programmable shunt voltage reference IC with 0.4% initial voltage tolerance, 0.2Ω typical output impedance, and adjustable output voltage from 2.5V to 36V via two external resistors. It operates as a Zener diode replacement in secondary-side regulation of flyback SMPSs and functions as an integrated comparator reference in voltage monitoring circuits.

For engineers reviewing the TL1431CLP datasheet, TL1431CLP pinout, TL1431CLP application, or TL1431CLP equivalent, this page delivers verified electrical characteristics, TO-92 package details, thermal performance data, functional mode distinctions (open-loop comparator vs. closed-loop regulator), and real-world design considerations for stability and accuracy under load.

Technical Context

The TL1431CLP integrates a 2.5V bandgap reference and high-gain transconductance amplifier driving a Darlington sink output stage, enabling precise voltage clamping and error amplification without external compensation. Its internal architecture supports both open-loop comparator operation (with integrated reference) and closed-loop shunt regulation via resistive feedback between CATHODE and REF pins.

It requires ≥1mA cathode current (IKA) to enter regulation, maintains 2.5V at REF relative to ANODE across 0°C–70°C, and exhibits <20mV reference voltage deviation over its full commercial temperature range. The device achieves fast turn-on (500ns) and low off-state cathode leakage (<0.5µA at 36V).

Key Specifications

Pinout & Package

TL1431CLP uses a 3-pin TO-92 package (body size 4.83 mm × 3.68 mm) with leads designated CATHODE, ANODE, and REF. All ANODE pins are internally connected; no NC pins present in this variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL1431CLP, TL431ACLP offers broader temperature coverage but sacrifices initial accuracy, while LM431ACM provides footprint compatibility at reduced precision and higher output impedance - making TL1431CLP optimal for commercial applications demanding ≤10 mV reference error and minimal load-induced drift.

Availability

TL1431CLP is available at Aetrix Electronics and suitable for adjustable voltage referencing, secondary-side SMPS regulation, and voltage monitoring applications requiring stable component supply, long-term manufacturability, and commercial-temperature-grade reliability.

Supply support for TL1431CLP 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 specializing in analog and embedded processing technologies, with leadership in precision analog ICs and power management solutions.

The TL1431 product line delivers programmable shunt references designed for high-accuracy voltage regulation, error amplification, and comparator functions in power supplies, industrial controls, and telecom infrastructure.

FAQ

What is the maximum cathode voltage supported by TL1431CLP?

The TL1431CLP supports a maximum cathode voltage (VKA) of 36 V, with absolute maximum rating at 37 V. Operation beyond 36 V violates recommended conditions and may cause permanent damage or parametric shift. This limit applies across the full 0°C to 70°C operating range and defines the upper bound for programmable output voltage configurations.

Can TL1431CLP operate without an external capacitor between CATHODE and ANODE?

Yes, TL1431CLP is internally compensated and remains stable without an external capacitor between CATHODE and ANODE. This eliminates mandatory output capacitance, simplifying layout in space-constrained applications. However, if a capacitive load is introduced downstream (e.g., by a connected IC), stability boundary charts in the datasheet must be consulted to avoid oscillation.

How does the reference input current (II(ref)) affect TL1431CLP accuracy?

The reference input current (II(ref)) of TL1431CLP - 1.5–2.5 µA at 25°C - flows through the upper feedback resistor (R1), causing a voltage drop that introduces gain error in programmable output equations. To maintain ≤0.1% added error, R1 should be ≤10 kΩ; higher values require correction using VO = (1 + R1/R2) × VREF + II(ref) × R1.

Is TL1431CLP pin-compatible with TL431 series devices in TO-92 packages?

TL1431CLP is functionally and pinout-compatible with TL431ACLP and TL431BCLP in TO-92 packages: CATHODE (pin 1), ANODE (pin 2), and REF (pin 3) share identical terminal assignments and internal connectivity. However, differences in initial tolerance (0.4% vs. 1%), temperature range, and output impedance require validation in final design.

What is the minimum cathode current required for TL1431CLP to regulate properly?

TL1431CLP requires a minimum cathode current (Imin) of 0.45 mA at 25°C to establish regulation - below this, the internal amplifier cannot sustain sufficient gain for accurate REF pin control. At extremes of the 0°C–70°C range, Imin increases to 1 mA; designs must ensure continuous IKA ≥1 mA under worst-case conditions to guarantee stable output voltage.