Texas Instruments TLV431BCDBZT

Overview

TLV431BCDBZT from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, ±0.5% initial tolerance at 25°C, 0.25 Ω typical dynamic impedance, and operation down to 1.24 V cathode-anode voltage - used for secondary-side regulation in isolated 3.3 V flyback SMPSs and as a Zener diode replacement in space-constrained applications.

For engineers reviewing the TLV431BCDBZT datasheet, TLV431BCDBZT pinout, TLV431BCDBZT application, or TLV431BCDBZT equivalent, key selection criteria include reference accuracy over temperature (±4 mV from 0°C to 70°C), ultra-low 80 µA typical cathode current requirement, SC-70 package footprint (2.0 mm × 1.5 mm), and compatibility with optocoupler-based feedback loops in compact power supplies.

Technical Context

The TLV431BCDBZT implements a precision bandgap reference and high-gain NPN-based error amplifier in a 3-terminal shunt topology. It operates in two functional modes: open-loop comparator (with integrated 1.24 V reference) and closed-loop shunt regulator - requiring ≥55 µA minimum cathode current to maintain regulation across 0°C to 70°C.

Its internal Darlington output stage enables sharp turn-on behavior and stable operation without external compensation capacitors. The device achieves 0.25 Ω dynamic impedance by maintaining constant reference voltage under varying cathode current (0.1 mA to 15 mA) and exhibits <2.7 mV/V cathode voltage sensitivity - critical for accurate voltage sensing in feedback networks.

Key Specifications

Pinout & Package

TLV431BCDBZT is housed in an ultra-small SC-70 (DCK) package measuring 2.0 mm × 1.5 mm - offering 40% smaller footprint than SOT-23-3. This thermally efficient 6-pin surface-mount package supports high-density PCB layouts in space-constrained power modules and portable electronics.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431ACDBZT, TLV431BCDBZT delivers 2× tighter reference accuracy for precision feedback loops; compared with TLVH431ACDBVR, it offers smaller SC-70 footprint and lower minimum cathode current but sacrifices voltage headroom and current drive - making TLV431BCDBZT optimal for compact, low-power 3.3 V systems.

Availability

TLV431BCDBZT is available at Aetrix Electronics and suitable for isolated flyback SMPS regulation, Zener diode replacement, and voltage monitoring applications requiring stable component supply, consistent parametric performance, and long-term manufacturability in commercial-temperature designs.

Supply support for TLV431BCDBZT 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 and embedded processing technologies, with leadership in precision analog ICs, power management, and interface solutions.

The TLV431 family was designed specifically for low-voltage, high-accuracy shunt regulation - targeting space- and power-constrained applications in computing, telecom, and industrial power supplies where traditional TL431 devices cannot operate.

FAQ

What is the reference voltage tolerance of TLV431BCDBZT at 25°C?

The TLV431BCDBZT has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a 1.24 V nominal value with a range of 1.234 V to 1.246 V. This tight tolerance is confirmed in Section 5.7 of the TI datasheet and applies specifically to the 'B' grade variant. TLV431BCDBZT maintains this specification across its SC-70 package and commercial temperature range (0°C to 70°C).

Can TLV431BCDBZT replace a standard Zener diode in a 3.3 V regulation circuit?

Yes, TLV431BCDBZT is explicitly designed as a precision Zener diode replacement. With its 1.24 V reference, adjustable output up to 6 V, 0.25 Ω dynamic impedance, and sharp turn-on characteristic, TLV431BCDBZT delivers significantly better voltage accuracy and stability than discrete Zeners - especially under varying current and temperature conditions. Its SC-70 package also enables smaller PCB footprints than typical DO-35 or SOD-123 Zeners.

What is the minimum cathode current required for TLV431BCDBZT to regulate properly?

The TLV431BCDBZT requires a minimum cathode current of 55 µA to 100 µA depending on temperature - specified as I_K(min) in Section 5.7 of the datasheet. At 25°C, regulation is guaranteed above 55 µA; at full commercial range (0°C to 70°C), up to 100 µA may be needed. This ultra-low requirement enables TLV431BCDBZT to operate in energy-efficient designs where TL431 (1 mA min) would fail.

Does TLV431BCDBZT require an external compensation capacitor?

No, TLV431BCDBZT is internally compensated and stable without an external output capacitor between CATHODE and ANODE - a key advantage over many linear regulators. However, if a capacitive load is present (e.g., optocoupler CTR variation or PCB trace capacitance), Figure 5-19 in the TI datasheet provides phase-margin guidance to ensure stability. TLV431BCDBZT's design eliminates mandatory external compensation in standard shunt regulator configurations.

Which package does TLV431BCDBZT use, and what are its dimensions?

TLV431BCDBZT uses the SC-70 (DCK) package, a 6-pin surface-mount outline measuring 2.0 mm × 1.5 mm - confirmed in Package Information tables and Figure 4-5 of the TI datasheet. This package is 40% smaller than SOT-23-3 and features unused pins (2, 4, 5) that must remain unconnected. Thermal resistance is R_θJA = 87°C/W, supporting moderate power dissipation in compact layouts.