Texas Instruments TLVH431BCLP

Overview

TLVH431BCLP from Texas Instruments is a low-voltage adjustable precision shunt regulator in TO-92 package, providing 1.24 V reference voltage with ±0.5% initial tolerance at 25°C, 100 μA to 70 mA cathode current range, and operation from –40°C to +125°C. It serves as an ultra-low-voltage Zener replacement and integrated reference comparator in isolated flyback SMPS feedback loops.

For engineers reviewing the TLVH431BCLP datasheet, TLVH431BCLP pinout, TLVH431BCLP application, or TLVH431BCLP equivalent, key selection factors include its 1.24 V minimum operating voltage, 0.25 Ω typical dynamic impedance, 0.1–0.5 μA reference terminal current, and compatibility with optocoupler-based secondary-side regulation in 3.3 V systems.

Technical Context

The TLVH431BCLP implements a precision bandgap reference and high-gain transconductance amplifier in a 3-terminal shunt topology. Its internal Darlington output stage enables sharp turn-on behavior 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 distinct functional modes: open-loop comparator mode (with integrated 1.24 V reference) and closed-loop shunt regulator mode (using external resistor divider feedback from cathode to reference pin). Thermal stability is specified across –40°C to +125°C for automotive-grade (Q-temp) variants like TLVH431BCLP.

Key Specifications

Pinout & Package

TLVH431BCLP uses a 3-pin TO-92 through-hole package (4.30 mm × 4.30 mm body), optimized for cost-sensitive, space-constrained PCB layouts requiring manual assembly or wave soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431ACLPR and TLVH431BIDBZR, TLVH431BCLP delivers the tightest initial reference accuracy in a through-hole TO-92 package, offering superior manufacturability for prototyping and low-volume production while maintaining full automotive temperature compliance.

Availability

TLVH431BCLP is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, and test equipment requiring stable component supply with long-term lifecycle support.

Supply support for TLVH431BCLP 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 technologies, with decades of leadership in precision reference design.

The TLVH431 family was engineered to replace legacy TL431-based circuits in low-voltage, high-accuracy applications - particularly in isolated power conversion, data acquisition, and voltage supervision systems demanding <1.25 V reference capability.

FAQ

What is the minimum cathode current required for regulation in TLVH431BCLP?

The TLVH431BCLP requires a minimum cathode current of 100 μA to maintain regulation across its full temperature range. This value is specified in Section 5.5 of the datasheet under IK(min), and applies at –40°C to +125°C. Below this threshold, gain drops significantly, causing reference voltage inaccuracy and poor transient response. Designers must ensure external bias networks deliver ≥100 μA under worst-case conditions, including lowest input voltage and highest temperature.

Can TLVH431BCLP be used as a standalone comparator without external resistors?

Yes, TLVH431BCLP functions as a comparator in open-loop mode: connect the signal to the REF pin, tie ANODE to ground, and use CATHODE as the active output sink. When REF voltage exceeds 1.24 V, the device turns on and pulls CATHODE low. This configuration requires ≥100 μA cathode current for reliable switching and avoids floating REF - which would cause unpredictable behavior due to insufficient base drive for the internal NPN.

What is the dynamic impedance of TLVH431BCLP and how does it affect regulation accuracy?

TLVH431BCLP has a typical dynamic impedance of 0.25 Ω, measured at 1 kHz with cathode current between 0.1 mA and 70 mA. This low value directly determines output voltage variation under load changes: ΔV_OUT ≈ 0.25 Ω × ΔI_K. For example, a 10 mA load step causes only 2.5 mV droop - critical for maintaining tight regulation in precision SMPS feedback paths where optocoupler LED current varies dynamically.

Does TLVH431BCLP require an output capacitor for stability?

No, TLVH431BCLP is internally compensated and remains stable without an output capacitor between CATHODE and ANODE. This eliminates capacitor-related phase-margin risks and simplifies layout in isolated feedback circuits. However, if a capacitor is added for filtering, Figures 5-15 to 5-17 in the datasheet provide phase-margin guidance versus capacitive load - up to ~1 nF is generally safe at 1.25 V cathode voltage, but larger values may induce oscillation depending on operating point.

How does the TO-92 package of TLVH431BCLP compare thermally to SOT-23 variants?

TLVH431BCLP in TO-92 has a junction-to-ambient thermal resistance (R_θJA) of 140°C/W, lower than SOT-23 variants (206°C/W), enabling higher power dissipation in still-air environments. At 70 mA cathode current and 5 V drop, it dissipates 350 mW - resulting in ~49°C junction rise above ambient. This makes TLVH431BCLP more thermally robust than surface-mount equivalents for through-hole designs where heatsinking or airflow is limited.