Texas Instruments TLVH431QDBVT

Overview

TLVH431QDBVT from Texas Instruments is a low-voltage adjustable precision shunt regulator in SOT-23-5 package, featuring 1.24 V reference voltage (±0.5% at 25°C), 100 μA to 70 mA cathode current range, and operation from –40°C to +125°C. It serves as an error amplifier or voltage reference in isolated flyback SMPS feedback loops, replacing Zener diodes with lower leakage and sharper turn-on.

For engineers reviewing the TLVH431QDBVT datasheet, TLVH431QDBVT pinout, TLVH431QDBVT application, or TLVH431QDBVT equivalent, key selection factors include its Q-grade temperature rating, 5-pin SOT-23 package configuration, 0.25 Ω dynamic impedance, and compatibility with optocoupler-based secondary-side regulation in 3.3 V systems.

Technical Context

The TLVH431QDBVT implements a precision bandgap reference and high-gain NPN-based error amplifier in a single 3-terminal shunt topology. Its internal Darlington output stage enables sharp turn-on and stable regulation down to 1.24 V with only 100 μA minimum cathode current - significantly lower than TL431's 1 mA requirement.

It operates in two functional modes: open-loop comparator mode (using integrated 1.24 V reference for voltage monitoring) and closed-loop shunt regulator mode (with resistive feedback from cathode to reference pin). The device is internally compensated and stable without external output capacitance, though phase margin vs. capacitive load is characterized up to 100 nF.

Key Specifications

Pinout & Package

SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm body, 0.95 mm max height, gull-wing leads, RoHS-compliant matte tin lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431QDBVT, TLVH431QDBZ offers identical performance in a smaller 3-pin package but demands layout revision, while TLVH432QDBZ provides the same electrical behavior with a cathode-leading pinout - both require schematic and footprint updates, making TLVH431QDBVT the preferred choice for new 5-pin SOT-23 designs requiring maximum flexibility and thermal margin.

Availability

TLVH431QDBVT is available at Aetrix Electronics and suitable for automotive power management, industrial isolated SMPS, and precision analog monitoring requiring stable component supply across extended temperature ranges.

Supply support for TLVH431QDBVT 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 expertise in precision reference and power IC design.

The TLVH431 family was designed specifically for low-voltage, high-accuracy shunt regulation in isolated power supplies and precision analog systems - addressing limitations of legacy TL431 in sub-2.5 V applications.

FAQ

What is the reference voltage tolerance of TLVH431QDBVT at 25°C?

The TLVH431QDBVT has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 1.24 V nominal value ranging from 1.234 V to 1.246 V. This B-grade tolerance is specified in the TLVH431B electrical characteristics table and applies across the full Q-grade temperature range (–40°C to +125°C) with a maximum deviation of 31 mV.

Can TLVH431QDBVT replace TL431 in existing designs?

TLVH431QDBVT can replace TL431 in many applications but requires circuit adaptation: its 1.24 V reference enables lower-voltage operation, yet its 5-pin SOT-23 package and NC pins differ from TL431's TO-92 or SOIC-8 footprints. Direct substitution is not possible without layout and bias network changes, especially to accommodate the substrate pin (Pin 2) and reduced minimum cathode current (100 μA vs. 1 mA).

What is the minimum cathode current required for regulation in TLVH431QDBVT?

The TLVH431QDBVT requires a minimum cathode current of 100 μA to maintain regulation, as specified in the IK(min) parameter under Recommended Operating Conditions. This value is valid across the full –40°C to +125°C temperature range and is significantly lower than TL431's 1 mA requirement, enabling ultra-low-power feedback implementations.

Does TLVH431QDBVT require an output capacitor for stability?

No, TLVH431QDBVT is internally compensated and stable without an output capacitor between cathode and anode. However, if an output capacitor is used for noise filtering or transient response shaping, Figures 5-15 through 5-17 in the datasheet provide phase margin vs. capacitive load data for values up to 100 nF at various cathode voltages - critical for maintaining stability in sensitive feedback loops.

How does the substrate pin (Pin 2) on TLVH431QDBVT affect PCB layout?

Pin 2 on TLVH431QDBVT is an internal substrate connection that must either be tied to the ANODE (Pin 5) or left electrically floating - it must never be connected to ground or any other potential. This requirement avoids parasitic substrate currents and ensures proper biasing of the internal NPN transistor; incorrect handling causes regulation failure or thermal instability.