Texas Instruments TLVH431QDBZT

Overview

TLVH431QDBZT 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 from –40°C to +125°C. It delivers 0.25 Ω typical dynamic impedance, supports cathode current from 100 μA to 70 mA, and functions as an integrated voltage reference, error amplifier, or comparator in isolated feedback loops for 3.3 V SMPS.

For engineers reviewing the TLVH431QDBZT datasheet, TLVH431QDBZT pinout, TLVH431QDBZT application, or TLVH431QDBZT equivalent, key selection criteria include its Q-grade temperature range, SOT-23-3 package pin compatibility with TLVH432 variants, low-voltage regulation down to 1.24 V, and use in secondary-side flyback regulation where Zener replacement with sub-μA reference current is required.

Technical Context

The TLVH431QDBZT implements a bandgap-referenced transconductance amplifier driving a Darlington sink output stage. Its internal 1.24 V reference is trimmed at wafer test for B-grade (±0.5% at 25°C) and characterized across –40°C to +125°C (Q-grade). The device operates in open-loop comparator mode or closed-loop shunt regulation depending on external feedback configuration between CATHODE and REF pins.

Unlike the TL431, it achieves regulation with only 100 μA minimum cathode current and supports output voltages from V_REF to 18 V using two external resistors. Its 0.25 Ω dynamic impedance and absence of mandatory output capacitance simplify stability design in optocoupler-coupled feedback paths for isolated DC/DC converters.

Key Specifications

Pinout & Package

SOT-23-3 package (2.92 mm × 1.30 mm body size), surface-mount, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431BDBZT, TLVH431QDBZT provides extended high-temperature operation critical for automotive power modules; compared with TLVH432QDBZT, it offers standard pinout compatibility with legacy TL431 layouts and simplified cathode-ground referencing in flyback feedback networks.

Availability

TLVH431QDBZT is available at Aetrix Electronics and suitable for automotive power management, industrial sensor signal conditioning, and isolated DC/DC converter design requiring stable component supply across extended temperature ranges.

Supply support for TLVH431QDBZT 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, embedded processing, and power management ICs, with leadership in precision reference and power conversion technologies.

The TLVH431 product line delivers low-voltage, high-precision shunt references optimized for isolated feedback, data converter references, and Zener replacement in space-constrained, thermally demanding applications.

FAQ

What is the reference voltage tolerance of TLVH431QDBZT at 25°C?

The TLVH431QDBZT has a reference voltage tolerance of ±0.5% at 25°C, corresponding to its B-grade specification. This yields a V_REF range of 1.222 V to 1.258 V under nominal conditions, confirmed in Section 5.5 of the TI SLVS555N datasheet. The Q-grade temperature rating does not affect the 25°C tolerance value - it only extends the operating range to –40°C to +125°C while maintaining the same initial accuracy binning.

Can TLVH431QDBZT operate with a 1.8 V supply?

Yes, TLVH431QDBZT can operate with a 1.8 V supply when configured as a shunt regulator. Its minimum cathode-to-anode voltage is 1.24 V, leaving 0.56 V headroom - sufficient to sustain >100 μA cathode current through a series resistor (e.g., 5.6 kΩ). The device remains in regulation as long as V_KA ≥ V_REF and I_K ≥ 100 μA, per Section 5.3 Recommended Operating Conditions in the TLVH431QDBZT datasheet.

What is the maximum cathode voltage rating for TLVH431QDBZT?

The absolute maximum cathode-to-anode voltage (V_KA) for TLVH431QDBZT is 20 V, as specified in Section 5.1 Absolute Maximum Ratings. However, the recommended operating maximum is 18 V per Section 5.3 - exceeding this may accelerate parametric shift or reduce long-term reliability. Operation at 18 V is validated across the full –40°C to +125°C range and supported by dynamic impedance and thermal data in the datasheet.

How does TLVH431QDBZT differ from TL431 in practical design?

TLVH431QDBZT differs from TL431 by offering a lower 1.24 V reference (vs. 2.5 V), 10× lower minimum cathode current (100 μA vs. 1 mA), and operation down to 1.24 V supply headroom. These differences enable direct regulation from 1.8 V rails, reduce power loss in resistor dividers, and improve efficiency in battery-powered and isolated flyback topologies - all while maintaining pin-compatible SOT-23-3 packaging and identical functional block architecture.

Is an output capacitor required for stability with TLVH431QDBZT?

No, TLVH431QDBZT is internally compensated and stable without an output capacitor between CATHODE and ANODE. This is explicitly stated in Section 7.3 Feature Description. However, if an output capacitor is added (e.g., for noise filtering), Figures 5-15 to 5-17 in the datasheet provide phase margin vs. capacitive load curves for 1.25 V, 2.5 V, and 5 V cathode voltages - guiding selection of ≤1 nF for robust stability across the Q-grade temperature range.