Texas Instruments TLVH431QLPRE3

Overview

TLVH431QLPRE3 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 0.25 Ω typical dynamic impedance and supports output voltage adjustment from 1.24 V to 18 V using two external resistors. It serves as a high-accuracy, low-leakage replacement for Zener diodes in isolated flyback SMPS feedback loops.

For engineers reviewing the TLVH431QLPRE3 datasheet, TLVH431QLPRE3 pinout, TLVH431QLPRE3 application, or TLVH431QLPRE3 equivalent, key selection criteria include its 1.24 V reference threshold, –40°C to +125°C Q-grade temperature range, ultra-low I_ref (0.1–0.5 µA), and compatibility with optocoupler-based secondary-side regulation in 3.3 V switching-mode power supplies.

Technical Context

The TLVH431QLPRE3 implements a precision bandgap reference and high-gain transconductance amplifier in a 3-terminal shunt topology. Its internal architecture forces the REF pin to 1.24 V when sufficient cathode current (≥100 µA) is supplied, enabling closed-loop regulation or open-loop comparator operation without external compensation.

Unlike the TL431, it operates at lower headroom (down to 1.24 V cathode-to-anode) and draws significantly less reference current-critical for low-power monitoring and battery-backed systems. Its B-grade tolerance (±0.5% at 25°C) and guaranteed performance over –40°C to +125°C make it suitable for automotive and industrial feedback control where thermal stability is essential.

Key Specifications

Pinout & Package

SOT-23-3 (DBZ) package: 2.92 mm × 1.30 mm body, 3-pin surface-mount with gull-wing leads. Pin 1 = CATHODE, Pin 2 = REF, Pin 3 = ANODE.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431CLPRE3 and TLVH431AILPR, TLVH431QLPRE3 offers the highest initial accuracy (±0.5%) and widest temperature qualification (–40°C to +125°C), making it the only option among the three qualified for automotive powertrain and ADAS subsystems where long-term stability under thermal stress is mandatory.

Availability

TLVH431QLPRE3 is available at Aetrix Electronics and suitable for automotive powertrain control, industrial PLC analog I/O modules, and isolated DC/DC converter design requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TLVH431QLPRE3 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 developed to extend shunt-regulator functionality into low-voltage, low-power domains-specifically targeting secondary-side regulation in compact, efficient isolated power supplies and high-accuracy sensing systems.

FAQ

What is the reference voltage tolerance of TLVH431QLPRE3 at 25°C?

The TLVH431QLPRE3 has a reference voltage tolerance of ±0.5% at 25°C, corresponding to the 'B' grade designation in the part number. This means its V_REF falls between 1.234 V and 1.246 V under nominal conditions, as confirmed in Section 5.7 of the TI SLVS555N datasheet. This tight tolerance directly supports high-accuracy voltage monitoring and precision feedback loop design in the TLVH431QLPRE3 application space.

Can TLVH431QLPRE3 operate with cathode-to-anode voltage below 2.5 V?

Yes, TLVH431QLPRE3 is specifically designed for low-voltage operation and regulates stably with cathode-to-anode voltage as low as 1.24 V - its internal reference voltage. This capability distinguishes it from the TL431 (2.5 V minimum) and enables use in 1.8 V, 2.5 V, and 3.3 V systems. The TLVH431QLPRE3 datasheet confirms this in Section 1 (Features) and Section 7.1 (Overview).

What is the minimum cathode current required for regulation in TLVH431QLPRE3?

The TLVH431QLPRE3 requires a minimum cathode current of 100 µA to maintain regulation, as specified in Section 5.5 (IK(min)) of the TI SLVS555N datasheet. This value is guaranteed over the full –40°C to +125°C temperature range. Operating below this threshold may result in degraded gain and unstable regulation behavior in the TLVH431QLPRE3 circuit implementation.

Does TLVH431QLPRE3 require an output capacitor for stability?

No, TLVH431QLPRE3 is internally compensated and remains stable without an output capacitor between cathode and anode - a key advantage over many linear regulators. However, if an output capacitor is used for noise filtering or transient response shaping, Figures 5-15 through 5-17 in the TLVH431QLPRE3 datasheet provide phase-margin guidance for selecting appropriate capacitance values based on load conditions.

How does TLVH431QLPRE3 differ from TLVH432 variants?

TLVH431QLPRE3 and TLVH432 share identical electrical specifications, but TLVH432 uses reversed pinout in SOT-23-3 and SOT-89 packages (REF and ANODE swapped). TLVH431QLPRE3 uses the standard DBZ pinout: Pin 1 = CATHODE, Pin 2 = REF, Pin 3 = ANODE. Using TLVH432 in place of TLVH431QLPRE3 without PCB revision would cause functional failure due to incorrect signal routing.