Texas Instruments TLV431IDBZR

Overview

TLV431IDBZR from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, ±1% initial tolerance at 25°C, and operation from 1.24 V to 6 V output range. It delivers 0.25 Ω typical dynamic impedance, 80 µA typical minimum cathode current, and supports secondary-side regulation in isolated flyback SMPSs.

For engineers reviewing the TLV431IDBZR datasheet, TLV431IDBZR pinout, TLV431IDBZR application, or TLV431IDBZR equivalent, this page provides verified electrical parameters, SC-70 package details, functional mode distinctions (open-loop comparator vs. closed-loop shunt regulator), and real-world design implications for voltage monitoring and Zener replacement.

Technical Context

The TLV431IDBZR operates as a 3-terminal adjustable shunt reference with an internal NPN-based amplifier and 1.24 V bandgap reference. Its open-loop configuration functions as a comparator with integrated reference; closed-loop operation-using external resistive feedback between cathode and reference pins-enables precise voltage or current regulation.

It achieves stable regulation without output capacitance due to internal compensation, but capacitive load stability depends on cathode voltage and requires phase margin verification per Figure 5-19–5-21. The device's substrate-connected pin (Pin 2 in SC-70) must be tied to anode or left floating-no internal connection exists.

Key Specifications

Pinout & Package

TLV431IDBZR uses the SC-70 (DCK) package: 2.0 mm × 1.5 mm footprint, 6-pin configuration, 0.65 mm pitch. Pin 2 is substrate-connected and must be tied to anode or left unconnected; it is not electrically active.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431ACDBZR, TLV431IDBZR trades 0.5% reference accuracy for lower unit cost while retaining identical thermal drift, dynamic impedance, and package compatibility. Against TLVH431IDBVR, TLV431IDBZR offers smaller SC-70 footprint and lower quiescent current-but lacks extended voltage/current capability.

Availability

TLV431IDBZR is available at Aetrix Electronics and suitable for industrial power supplies, isolated DC-DC converters, and embedded voltage monitoring systems requiring stable component supply, consistent parametric performance, and long-term manufacturability.

Supply support for TLV431IDBZR 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 solutions, with leadership in precision analog ICs and power management.

The TLV431IDBZR belongs to TI's precision shunt reference product line, designed specifically for low-voltage, high-accuracy regulation in space-constrained and energy-efficient power systems-including isolated flyback converters and battery-powered monitoring circuits.

FAQ

What is the reference voltage tolerance of TLV431IDBZR at 25°C?

The TLV431IDBZR has a reference voltage tolerance of ±1% at 25°C, meaning its V_REF falls between 1.228 V and 1.252 V under nominal conditions. This tolerance directly impacts the accuracy of any output voltage set using external resistors. The TLV431IDBZR is part of the TLV431A grade, confirmed in TI's SLVS139Z datasheet Section 5.6. TLV431IDBZR remains within this specification across its full operating temperature range (–40°C to 85°C).

Can TLV431IDBZR replace a standard Zener diode in a 3.3 V regulator circuit?

Yes, TLV431IDBZR can directly replace a Zener diode in 3.3 V regulator circuits, offering superior performance: adjustable output (1.24–6 V), ±1% initial tolerance (vs. typical 5% Zener), 0.25 Ω dynamic impedance (vs. 10–100 Ω Zener), and sharper knee characteristics. In TLV431IDBZR configurations, the REF pin connects to a resistor divider from cathode to anode, enabling precise voltage setting. Unlike Zeners, TLV431IDBZR requires ≥80 µA cathode current to regulate-verify bias network compliance.

What package type does TLV431IDBZR use, and how does it differ from SOT-23-3?

TLV431IDBZR uses the SC-70 (DCK) package: 6-pin, 2.0 mm × 1.5 mm body, 0.65 mm lead pitch. It differs from SOT-23-3 by having more pins (6 vs. 3), smaller footprint (40% reduction), and dedicated NC and substrate pins. Pin 2 is substrate-connected and must tie to anode or float; Pins 4 and 5 are no-connect. This contrasts with SOT-23-3 variants (e.g., TLV431IDBZT), which integrate anode, cathode, and ref into three terminals without NC or substrate pins.

How does TLV431IDBZR behave in open-loop versus closed-loop configurations?

In open-loop mode (no feedback to REF), TLV431IDBZR acts as a comparator with integrated 1.24 V reference-output swings rail-to-rail based on REF voltage vs. internal threshold. In closed-loop mode (REF connected via resistor divider to cathode), it functions as a shunt regulator, sinking cathode current to hold REF at 1.24 V and thereby regulating cathode voltage. TLV431IDBZR's internal compensation ensures stability in both modes without added capacitance, though phase margin must be checked for capacitive loads per TI's Figure 5-19–5-21.

What is the minimum cathode current required for TLV431IDBZR to maintain regulation?

The TLV431IDBZR requires a minimum cathode current (I_K(min)) of 80 µA typical to maintain regulation, as specified in Section 5.5 of the TI SLVS139Z datasheet. Below this threshold, the device exits regulation and behaves non-linearly. This value increases slightly over temperature-up to 100 µA at –40°C to 125°C extremes. Designers must ensure the bias network (e.g., optocoupler LED series resistor) delivers ≥80 µA under worst-case input voltage and temperature conditions for reliable TLV431IDBZR operation.