Texas Instruments TLVH431QLPE3

Overview

TLVH431QLPE3 from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, ±0.5% initial tolerance (B-grade), and operation down to 100 µA cathode current. It delivers stable voltage reference and error amplification in isolated flyback SMPS feedback loops, secondary-side regulation, and low-leakage Zener replacement applications.

For engineers reviewing the TLVH431QLPE3 datasheet, TLVH431QLPE3 pinout, TLVH431QLPE3 application, or TLVH431QLPE3 equivalent, key selection criteria include its 1.24 V reference accuracy over –40°C to +125°C, 0.25 Ω dynamic impedance, ultra-low I_ref (0.1–0.5 µA), and TO-92 package compatibility with legacy through-hole designs requiring thermal robustness and board-level serviceability.

Technical Context

The TLVH431QLPE3 implements a precision bandgap reference and high-gain NPN-based error amplifier in a 3-terminal shunt topology. Its internal Darlington output stage enables sharp turn-on behavior and stable regulation with no external compensation required. The device operates in two functional modes: open-loop comparator (with integrated 1.24 V threshold) and closed-loop shunt regulator (using resistive feedback between cathode and reference pins).

Unlike the TL431, it supports cathode voltages as low as 1.24 V and minimum cathode currents of 100 µA - enabling use in 3.3 V and lower-output isolated power supplies. Its reference voltage exhibits <31 mV deviation across –40°C to +125°C (Q-grade), and its dynamic impedance remains ≤0.4 Ω up to 70 mA cathode current.

Key Specifications

Pinout & Package

TLVH431QLPE3 uses the 3-pin TO-92 package (4.30 mm × 4.30 mm body), optimized for manual assembly, thermal reliability in convection-cooled environments, and legacy PCB compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431QLPE3, TLVH431BQDBZR offers identical electrical performance in a smaller SMT package but sacrifices through-hole serviceability, while TLV431BIDBVR trades voltage range and current capability for lower cost in narrow-voltage applications - making TLVH431QLPE3 uniquely suited for rugged, wide-range, field-serviceable designs.

Availability

TLVH431QLPE3 is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, and test equipment requiring stable component supply with long lifecycle support and traceable sourcing.

Supply support for TLVH431QLPE3 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 delivering analog, embedded processing, and connectivity solutions with emphasis on reliability, longevity, and automotive-grade qualification.

The TLVH431 family was designed specifically for precision shunt regulation in isolated power supplies and voltage monitoring systems demanding low-voltage operation, wide temperature range, and high accuracy without external compensation.

FAQ

What is the reference voltage tolerance of TLVH431QLPE3 at 25°C?

The TLVH431QLPE3 has a reference voltage tolerance of ±0.5% at 25°C, corresponding to the 'B' grade designation in its part number. This means its V_REF falls between 1.234 V and 1.246 V under nominal conditions, enabling high-accuracy voltage setting in feedback networks without post-manufacturing trimming.

Can TLVH431QLPE3 operate in a 3.3 V isolated flyback supply?

Yes, TLVH431QLPE3 is explicitly designed for this application. With its 1.24 V reference and ability to regulate down to that voltage, it enables output regulation as low as ~2.7 V when paired with a typical optocoupler LED forward voltage (~1.4 V), making it ideal for modern 3.3 V SMPS secondary-side feedback circuits.

What is the minimum cathode current required for regulation in TLVH431QLPE3?

The TLVH431QLPE3 requires a minimum cathode current of 100 µA to maintain regulation, as specified in its Q-grade electrical characteristics. This ultra-low requirement allows stable operation in low-power standby modes and high-efficiency light-load conditions where traditional shunt regulators fail.

Does TLVH431QLPE3 require an external compensation capacitor?

No, TLVH431QLPE3 is internally compensated and does not require an external capacitor for stability in standard shunt regulator configurations. Its architecture maintains phase margin across capacitive loads up to 1 nF, simplifying design and eliminating capacitor-related aging or ESR concerns in TO-92-mounted applications.

How does the TO-92 package of TLVH431QLPE3 affect thermal performance?

The TO-92 package of TLVH431QLPE3 provides a junction-to-ambient thermal resistance (R_θJA) of 140 °C/W, supporting continuous power dissipation above 300 mW at 70°C ambient. This makes it suitable for through-hole applications where airflow is limited and heatsinking is impractical, unlike smaller SMT packages with higher thermal resistance.