Texas Instruments TLVH431IDBZT

Overview

TLVH431IDBZT from Texas Instruments is a low-voltage adjustable precision shunt regulator in SOT-23-3 package, providing 1.24 V reference voltage with ±1% initial tolerance at 25°C, 100 μA to 70 mA cathode current range, and operation from –40°C to +85°C. It serves as an error amplifier or voltage reference in isolated flyback SMPS feedback loops and replaces Zener diodes in low-leakage on-board regulation.

For engineers reviewing the TLVH431IDBZT datasheet, TLVH431IDBZT pinout, TLVH431IDBZT application, or TLVH431IDBZT equivalent, key selection factors include its 1.24 V minimum operating voltage, 0.25 Ω typical dynamic impedance, ultra-low 0.1–0.5 μA reference terminal current, thermal stability across industrial temperature range, and compatibility with optocoupler-based secondary-side regulation circuits.

Technical Context

The TLVH431IDBZT implements a precision bandgap reference (1.24 V) paired with a high-gain NPN-based error amplifier and Darlington output stage. Its internal architecture enables sharp turn-on behavior and stable closed-loop regulation when configured with external resistive dividers between cathode and reference pins.

It operates in two distinct functional modes: open-loop comparator mode (using integrated reference for voltage monitoring) and closed-loop shunt regulator mode (with feedback establishing adjustable output voltage from 1.24 V to 18 V). No external compensation capacitor is required for stability due to internal frequency compensation.

Key Specifications

Pinout & Package

SOT-23-3 package (2.92 mm × 1.30 mm), surface-mount, lead-free, RoHS-compliant. Pin 1 = CATHODE, Pin 2 = ANODE, Pin 3 = REF.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLVH431ACDBZT and TLV431BIDBZR, TLVH431IDBZT balances industrial temperature range (–40°C to +85°C), 1% reference accuracy, and 100 μA minimum cathode current - making it optimal for cost-sensitive yet robust secondary-side regulation and voltage supervision tasks.

Availability

TLVH431IDBZT is available at Aetrix Electronics and suitable for isolated flyback SMPS feedback, voltage rail monitoring, adjustable data converter references, and low-power shunt regulation requiring stable component supply across industrial temperature ranges.

Supply support for TLVH431IDBZT 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 and power control ICs.

The TLVH431IDBZT belongs to TI's precision shunt regulator product line, designed specifically for low-voltage, high-accuracy regulation and error amplification in isolated power supplies, voltage supervisors, and data acquisition systems.

FAQ

What is the minimum cathode current required for regulation in TLVH431IDBZT?

The TLVH431IDBZT requires a minimum cathode current of 100 μA to maintain regulation across its full operating temperature range (–40°C to +85°C). Below this threshold, gain drops significantly, causing poor reference tracking and unstable output. This value is specified in Section 5.5 of the datasheet under IK(min) and is critical for sizing the current-limiting resistor in optocoupler feedback circuits. Always verify IK ≥ 100 μA under worst-case conditions including low temperature and minimum input voltage.

Can TLVH431IDBZT replace a standard Zener diode in a shunt regulator design?

Yes, TLVH431IDBZT is explicitly designed as a Zener diode replacement with superior performance: it provides 1.24 V reference voltage (vs fixed Zener voltages), ±1% initial tolerance (vs ±5% typical for Zeners), 0.25 Ω dynamic impedance (vs 10–100 Ω for Zeners), and <0.1 μA off-state current (vs μA-level leakage in Zeners). Its active regulation architecture also enables adjustable output voltage from 1.24 V to 18 V using two resistors - a capability discrete Zeners lack.

What is the role of the ANODE pin in TLVH431IDBZT operation?

The ANODE pin of TLVH431IDBZT serves as the common reference node and must be connected to system ground or the lowest potential point in the circuit. All internal circuitry-including the 1.24 V bandgap reference and error amplifier-is referenced to ANODE. Unlike floating references, TLVH431IDBZT cannot operate with ANODE disconnected or biased above ground; doing so violates absolute maximum ratings and disables regulation. In SOT-23-3 DBZ package, ANODE is Pin 2.

Does TLVH431IDBZT require an external compensation capacitor?

No, TLVH431IDBZT is internally compensated and remains stable without an external output capacitor between CATHODE and ANODE. This simplifies layout and eliminates capacitor-related instability risks. However, if a capacitive load is intentionally added (e.g., for filtering), Figures 5-15 through 5-17 in the datasheet provide phase-margin guidance versus capacitive load and cathode voltage. For most feedback and shunt applications, no capacitor is needed.

How does TLVH431IDBZT differ from TLVH432IDBZT?

TLVH431IDBZT and TLVH432IDBZT share identical electrical specifications and functionality, but TLVH432IDBZT uses a different pinout in the same SOT-23-3 package: Pin 1 = REF, Pin 2 = CATHODE, Pin 3 = ANODE. TLVH431IDBZT uses Pin 1 = CATHODE, Pin 2 = ANODE, Pin 3 = REF. This difference affects PCB layout and schematic symbol assignment - they are not pin-compatible replacements. Always match the pinout to the selected variant during design.