Texas Instruments TLVH431QPK

Overview

TLVH431QPK from Texas Instruments is a low-voltage adjustable precision shunt regulator in SOT-89-3 package, delivering 1.24 V reference voltage with ±0.5% initial tolerance (Q-grade), 100 μA minimum cathode current for regulation, and operation from –40°C to +125°C. It functions as a programmable Zener replacement or error amplifier in isolated flyback SMPS feedback loops.

For engineers reviewing the TLVH431QPK datasheet, TLVH431QPK pinout, TLVH431QPK application, or TLVH431QPK equivalent, key selection criteria include its 1.24 V low-voltage reference capability, ultra-low 0.25 Ω dynamic impedance, wide 1.24–18 V output adjustability, and automotive-grade temperature range - critical for secondary-side regulation in compact 3.3 V power supplies.

Technical Context

The TLVH431QPK 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 and stable sink-current regulation down to 100 μA cathode current, supporting both open-loop comparator and closed-loop shunt-regulator modes.

Unlike the TL431, it operates at lower headroom (≥1.24 V) and features integrated thermal stability across –40°C to +125°C. The Q-grade variant guarantees ≤31 mV VREF deviation over full temperature range and ≤0.5 μA reference input current drift, making it suitable for automotive and industrial feedback circuits requiring long-term DC accuracy.

Key Specifications

Pinout & Package

SOT-89-3 package (4.50 mm × 2.50 mm body), thermally enhanced for power dissipation up to 52°C/W junction-to-ambient (R_θJA).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431QDBZ and TLVH432QPK, the TLVH431QPK offers optimal thermal performance (52°C/W) in SOT-89 while maintaining standard pinout compatibility - making it preferred for production designs requiring reliability, serviceability, and thermal headroom in automotive and industrial power supplies.

Availability

TLVH431QPK is available at Aetrix Electronics and suitable for automotive power management, industrial SMPS feedback, and precision analog reference applications requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for TLVH431QPK 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 ICs, with decades of expertise in precision reference and power control solutions.

The TLVH431 family was designed specifically to replace TL431 in low-voltage, high-accuracy shunt regulation - targeting automotive, industrial, and computing applications demanding extended temperature operation and ultra-low quiescent current.

FAQ

What is the reference voltage tolerance of TLVH431QPK at 25°C?

The TLVH431QPK has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 1.24 V nominal VREF with a range of 1.234 V to 1.246 V. This grade is designated by the "B" suffix in the full part number (e.g., TLVH431BQPK), and the Q-grade indicates –40°C to +125°C qualification. The TLVH431QPK meets this specification per TI's SLVS555N datasheet Section 5.7.

Can TLVH431QPK operate with a cathode voltage below 2.5 V?

Yes - the TLVH431QPK is explicitly designed for low-voltage operation starting at 1.24 V, unlike the TL431 which requires ≥2.5 V. It regulates stably with cathode voltages from 1.24 V to 18 V, enabling use in 1.8 V, 2.5 V, and 3.3 V systems. The TLVH431QPK achieves this via a lower-bandgap reference and optimized Darlington output stage, as confirmed in Section 7.1 of the TI datasheet.

What is the minimum cathode current required for regulation in TLVH431QPK?

The TLVH431QPK requires a minimum cathode current (IK(min)) of 100 μA to maintain regulation, as specified in Sections 5.5–5.7 of the TI datasheet. This value is guaranteed across the full –40°C to +125°C temperature range for the Q-grade variant. Operating below this level risks insufficient gain and unstable regulation - a key differentiator from TL431 (1 mA IK(min)).

Is TLVH431QPK pin-compatible with TLVH432QPK?

No - TLVH431QPK and TLVH432QPK have opposite pinouts in the same SOT-89-3 package. TLVH431QPK uses Pin 1 = CATHODE, Pin 2 = REF, Pin 3 = ANODE; TLVH432QPK uses Pin 1 = REF, Pin 2 = ANODE, Pin 3 = CATHODE. Swapping them without PCB revision will cause functional failure. This is documented in Figures 4-6 and 4-7 of the SLVS555N datasheet.

Does TLVH431QPK require an external output capacitor for stability?

No - the TLVH431QPK is internally compensated and remains stable without an output capacitor between CATHODE and ANODE, per Section 7.3 of the TI datasheet. However, if a capacitor is added for noise filtering or transient response, Figures 5-15 to 5-17 provide phase-margin guidance versus capacitive load. The TLVH431QPK's stability is inherent and does not depend on external components.