Texas Instruments TLVH431BCPK

Overview

TLVH431BCPK from Texas Instruments is a precision 3-terminal adjustable shunt voltage reference with 0.5% initial tolerance at 25°C, 1.24 V nominal reference voltage, and operation down to 1.24 V cathode-anode voltage. It delivers stable regulation across –40°C to +125°C, supports cathode currents from 100 μA to 70 mA, and features 0.25 Ω typical dynamic impedance-enabling accurate secondary-side feedback in isolated 3.3 V flyback SMPS designs.

For engineers reviewing the TLVH431BCPK datasheet, TLVH431BCPK pinout, TLVH431BCPK application, or TLVH431BCPK equivalent, key selection criteria include its B-grade reference accuracy, SOT-89 thermal performance (R_θJA = 52°C/W), low-temperature coefficient, and compatibility with optocoupler-based isolated feedback loops requiring sub-2.5 V reference capability.

Technical Context

The TLVH431BCPK implements an internal bandgap reference and high-gain NPN-based error amplifier driving a Darlington sink output stage. Its open-loop comparator mode enables precise voltage monitoring without external references, while closed-loop operation with resistive feedback (REF–CATHODE–ANODE) achieves adjustable output regulation from 1.24 V to 18 V.

Unlike the TL431, it operates with ≥100 μA minimum cathode current and requires no external compensation capacitor for stability. The SOT-89 package provides enhanced thermal dissipation versus SOT-23 variants, supporting higher continuous power in compact industrial power supplies.

Key Specifications

Pinout & Package

SOT-89 package (4.50 mm × 2.50 mm body), 3-pin surface-mount, thermally enhanced with exposed tab connected to ANODE for PCB heat sinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431ACPK, TLVH431BCPK delivers tighter reference accuracy critical for metrology-grade feedback, while TLVH432BCPK offers identical performance in mechanically constrained layouts where REF-to-ANODE routing conflicts occur-neither is pin-compatible without board revision.

Availability

TLVH431BCPK is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, and precision instrumentation requiring stable component supply with full temperature-range qualification and long-term traceability.

Supply support for TLVH431BCPK 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 over 50 years of innovation in precision analog ICs.

The TLVH431 family was designed specifically for low-voltage, high-accuracy shunt regulation in isolated power supplies and precision monitoring systems-addressing limitations of legacy TL431 devices in modern 3.3 V and lower architectures.

FAQ

What is the minimum cathode current required for regulation in TLVH431BCPK?

The TLVH431BCPK requires a minimum cathode current of 100 μA to maintain regulation across its full operating temperature range (–40°C to +125°C). At 25°C, regulation begins at 60 μA, but design must ensure ≥100 μA under worst-case conditions including temperature extremes and part-to-part variation. This value is specified in Section 5.5 of the TLVH431BCPK datasheet and directly impacts stability in low-power feedback loops.

Can TLVH431BCPK replace a standard Zener diode in voltage-clamp applications?

Yes, TLVH431BCPK can replace Zener diodes in clamp and reference applications due to its 0.5% initial tolerance, 0.25 Ω dynamic impedance, and leakage current <0.1 μA at 18 V. Unlike Zeners, it provides sharp turn-on characteristics and stable voltage over temperature-making it ideal for precision clamping in ADC front-ends and power-rail supervisors where TLVH431BCPK's 1.24 V reference enables lower-voltage operation than 2.4 V or 3.3 V Zeners.

What is the thermal resistance (R_θJA) of TLVH431BCPK in its SOT-89 package?

The TLVH431BCPK in SOT-89 package has a junction-to-ambient thermal resistance (R_θJA) of 52°C/W, as specified in Section 5.4 of the datasheet. This value assumes standard JEDEC 2S2P board layout with 1 in² copper pour under the exposed tab. Actual thermal performance depends on PCB copper area, layer stack-up, and airflow-designers should verify junction temperature using P_D = (T_J(max) – T_A) / R_θJA with TLVH431BCPK's 150°C max junction rating.

Does TLVH431BCPK require an external capacitor for stability in shunt regulator mode?

No, TLVH431BCPK is internally compensated and remains stable without an external capacitor between CATHODE and ANODE. However, if a capacitor is added for noise filtering or transient response shaping, Figures 5-15 through 5-17 in the TLVH431BCPK datasheet provide phase-margin guidance for 0–10 nF loads at various cathode voltages. Stability margins degrade above 10 nF, so capacitor selection must follow those curves-not generic "add 100 nF" recommendations.

How does the TLVH431BCPK pinout differ from TLVH432BCPK?

TLVH431BCPK uses Pin 1 = CATHODE, Pin 2 = REF, Pin 3 = ANODE. TLVH432BCPK reverses Pins 1 and 2: Pin 1 = REF, Pin 2 = ANODE, Pin 3 = CATHODE. Both share identical SOT-89 mechanical dimensions and electrical specifications, but TLVH432BCPK is not a drop-in replacement-PCB layout and schematic must be modified to accommodate the swapped REF and CATHODE connections. This difference is explicitly documented in Figures 4-6 and 4-7 of the TLVH431BCPK datasheet.