Texas Instruments TLV431BIDBZT

Overview

TLV431BIDBZT from Texas Instruments is a low-voltage adjustable precision shunt regulator with 0.5% initial reference voltage tolerance at 25°C, 1.24 V nominal reference voltage, and operation down to 1.24 V cathode-anode voltage. It delivers 0.25 Ω typical dynamic impedance, 80 µA typical minimum cathode current for regulation, and supports output voltage adjustment from 1.24 V to 6 V using two external resistors - ideal for secondary-side regulation in isolated 3.3 V flyback SMPS designs.

For engineers reviewing the TLV431BIDBZT datasheet, TLV431BIDBZT pinout, TLV431BIDBZT application, or TLV431BIDBZT equivalent, key selection criteria include reference accuracy over temperature (±4 mV from 0°C to 70°C), ultra-low cathode current requirements, SC-70 package footprint compatibility, and open-loop comparator functionality with integrated reference.

Technical Context

The TLV431BIDBZT implements a precision bandgap reference and high-gain NPN-based error amplifier in a single silicon die, enabling both closed-loop shunt regulation and open-loop comparator operation. Its internal Darlington sink output provides sharp turn-on behavior and stable regulation without requiring an output capacitor.

It operates in two distinct functional modes: closed-loop (feedback from cathode to REF pin) for voltage/current regulation, and open-loop (no feedback) for threshold detection. The device requires ≥55 µA cathode current to maintain linear operation across its full industrial temperature range (–40°C to 85°C).

Key Specifications

Pinout & Package

TLV431BIDBZT is housed in a 6-pin SC-70 (DCK) package with exposed substrate connection. Pin 2 is substrate-connected and must be tied to ANODE or left floating per TI design guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BIDBZT, TLV431BIDBVR offers identical regulation performance in a larger SOT-23-5 package with dedicated substrate control, while TLVH431IDBZR extends voltage and current capability but requires circuit redesign for voltage range and thermal management.

Availability

TLV431BIDBZT is available at Aetrix Electronics and suitable for isolated flyback SMPS regulation, precision voltage monitoring, and low-voltage Zener replacement applications requiring stable component supply and guaranteed long-term sourcing.

Supply support for TLV431BIDBZT 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 and power management solutions.

The TLV431 family was designed specifically for low-voltage, high-accuracy shunt regulation and integrated reference applications in space-constrained, energy-efficient power systems - targeting industrial, telecom, and computing end equipment.

FAQ

What is the reference voltage tolerance of TLV431BIDBZT at 25°C?

The TLV431BIDBZT 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 specified in Section 5.7 of the TI datasheet and applies exclusively to the TLV431B grade - the 'B' suffix denotes the 0.5% initial accuracy bin. TLV431BIDBZT maintains this specification across its SC-70 package variant.

Can TLV431BIDBZT operate as a comparator without external components?

Yes, TLV431BIDBZT can function as a comparator in open-loop mode with only a cathode current source (≥55 µA) and a resistor from REF to the signal being monitored. Its integrated 1.24 V reference eliminates the need for an external reference IC. When the REF pin voltage exceeds V_REF, the cathode sinks current - producing a logic-compatible output transition. This mode is explicitly supported in TI's Application Note SLVA671 and validated in Figure 8-2 of the TLV431BIDBZT datasheet.

What is the minimum cathode current required for regulation in TLV431BIDBZT?

The TLV431BIDBZT requires a minimum cathode current of 55 µA to maintain regulation at 25°C, rising to 100 µA over its full operating temperature range (–40°C to 85°C). This value is specified in Section 5.7 (IK(min)) of the datasheet and reflects the current needed to bias the internal Darlington output stage into linear operation. Operating below this threshold may result in degraded gain, slow response, or loss of regulation.

Does TLV431BIDBZT require an output capacitor for stability?

No, TLV431BIDBZT is internally compensated and does not require an output capacitor between cathode and anode for basic shunt regulation stability. TI confirms this in Section 7.3 of the datasheet: "Unlike many linear regulators, TLV431 is internally compensated to be stable without an output capacitor." However, if a capacitive load is added (e.g., for noise filtering), Figure 5-19 provides phase margin guidance to select a stable value - typically ≤1 nF for most configurations.

What is the thermal resistance (R_θJA) of TLV431BIDBZT in its SC-70 package?

The junction-to-ambient thermal resistance (R_θJA) of TLV431BIDBZT in the SC-70 (DCK) package is 87°C/W, as specified in Table 5.4 of the TI datasheet. This value assumes standard JEDEC high-K board conditions (2S2P) and enables power dissipation up to ~140 mW at 70°C ambient before reaching the 150°C maximum junction temperature. Layout practices such as thermal vias under the exposed pad further improve real-world thermal performance.