Texas Instruments TLV431BQDBZR

Overview

TLV431BQDBZR 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. It functions as a programmable Zener replacement or error amplifier in isolated flyback secondary-side regulation for 3.3 V SMPS designs.

For engineers reviewing the TLV431BQDBZR datasheet, TLV431BQDBZR pinout, TLV431BQDBZR application, or TLV431BQDBZR equivalent, key selection considerations include reference accuracy over temperature (±11 mV from –40°C to 125°C), minimum cathode current (55–100 µA), ultra-small SC-70 package footprint, and open-loop comparator capability with integrated reference.

Technical Context

The TLV431BQDBZR implements a bandgap-referenced transconductance amplifier driving a Darlington sink output stage. Its internal reference is trimmed to 1.24 V with 0.5% tolerance at 25°C and exhibits 11 mV total deviation across –40°C to 125°C. The device operates in two functional modes: open-loop comparator (high-gain, reference threshold detection) and closed-loop shunt regulator (feedback-controlled voltage or current regulation).

It requires ≥1.24 V cathode-to-anode voltage and ≥55 µA cathode current to enter regulation. Unlike many references, it is internally compensated and stable without an output capacitor, though capacitive load stability depends on phase margin versus CL (as characterized in Figures 5-19–5-21).

Key Specifications

Pinout & Package

TLV431BQDBZR is housed in a 6-pin SC-70 (DCK) package with exposed substrate pad. Pin 2 is the substrate connection and must be tied to the anode or left floating; it is not electrically isolated.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BIDBZR and TLVH431IDBVR, TLV431BQDBZR uniquely combines automotive-grade temperature range (–40°C to 125°C), 0.5% reference accuracy, and ultra-compact SC-70 packaging-making it optimal for space-constrained, high-reliability power management in modern automotive ECUs and industrial controllers.

Availability

TLV431BQDBZR is available at Aetrix Electronics and suitable for automotive power management, industrial SMPS feedback, and precision voltage monitoring requiring stable component supply across extended temperature ranges.

Supply support for TLV431BQDBZR 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 delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The TLV431 family was designed as a low-voltage, precision alternative to the TL431, targeting space- and power-constrained applications needing accurate 1.24 V referencing and shunt regulation down to 1.24 V cathode-anode voltage.

FAQ

What is the maximum cathode-to-anode voltage (V_KA) rating for TLV431BQDBZR?

The absolute maximum cathode-to-anode voltage for TLV431BQDBZR is 7 V, as specified in Section 5.1 of the datasheet. Operation beyond this voltage risks permanent damage. For reliable regulation, the recommended operating range is 1.24 V to 6 V, ensuring the device remains within its linear region while supporting common low-voltage SMPS outputs. TLV431BQDBZR must never be subjected to reverse polarity or transient spikes exceeding 7 V.

Does TLV431BQDBZR require an external capacitor for stability in shunt regulator applications?

No, TLV431BQDBZR is internally compensated and stable without an external output capacitor between cathode and anode. This simplifies layout and reduces BOM count in most feedback configurations. However, if a capacitive load is added (e.g., for noise filtering), stability must be verified using the phase margin vs. capacitive load curves in Figures 5-19 through 5-21 of the datasheet. TLV431BQDBZR's stability boundary depends on both load capacitance and cathode voltage.

How does the substrate pin (Pin 2) on TLV431BQDBZR affect circuit operation?

Pin 2 on TLV431BQDBZR is the substrate connection and is not electrically active in normal operation. Per the datasheet, it must be connected to the ANODE terminal or left unconnected-it must never be tied to a different potential. Improper connection can degrade thermal performance or cause latch-up. The substrate pin serves mechanical die attachment and thermal conduction; it does not carry signal current or influence regulation accuracy or reference behavior in TLV431BQDBZR.

Can TLV431BQDBZR be used as a standalone comparator without external feedback?

Yes, TLV431BQDBZR operates reliably in open-loop comparator mode with integrated 1.24 V reference. When supplied with ≥55 µA cathode current and proper voltage headroom, it compares the REF pin voltage to its internal reference and drives CATHODE low when the threshold is exceeded. This eliminates the need for separate reference and comparator ICs. TLV431BQDBZR's high open-loop gain ensures sharp transitions, making it suitable for brown-out detection and level-triggered logic interfacing.

What is the minimum cathode current required for TLV431BQDBZR to maintain regulation at 125°C?

At 125°C, TLV431BQDBZR requires a minimum cathode current (I_K(min)) of 100 µA to maintain regulation, as specified in Section 5.7 for the TLV431BQ grade. This is higher than the 55 µA minimum at 25°C due to increased base current requirements in the internal Darlington output stage at elevated temperature. Designers must ensure the external bias network delivers ≥100 µA continuously across the full –40°C to 125°C range to guarantee stable reference behavior in automotive or industrial applications.