Texas Instruments TLV431BQDBZRQ1

Overview

TLV431BQDBZRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive-qualified adjustable shunt voltage reference IC with 1.24 V nominal reference voltage, 0.5% initial tolerance at 25°C, ±11 mV max reference deviation over –40°C to 125°C, 0.25 Ω typical dynamic impedance, and 80 µA typical cathode operating current. It serves as a precision Zener replacement in isolated flyback secondary-side regulation for 3.3 V automotive power supplies.

For engineers reviewing the TLV431BQDBZRQ1 datasheet, TLV431BQDBZRQ1 pinout, TLV431BQDBZRQ1 application, or TLV431BQDBZRQ1 equivalent, key selection criteria include reference accuracy across temperature, low-voltage operation down to 1.24 V, stability with capacitive loads up to 150 nF, compatibility with optocoupler feedback, and SOT-23-3 package suitability for space-constrained automotive PCBs.

Technical Context

The TLV431BQDBZRQ1 implements a 3-terminal shunt regulator architecture with an internal 1.24 V bandgap reference and high-gain transconductance amplifier driving a Darlington output stage. Its open-loop comparator mode enables voltage monitoring with integrated reference, while closed-loop configuration with external resistors supports adjustable output regulation from 1.24 V to 6 V.

It operates with cathode-to-anode voltage (VKA) from 1.24 V to 6 V and cathode current (IK) from 100 µA to 15 mA, delivering stable regulation without mandatory output capacitance but supporting up to 150 nF load capacitance per stability boundary analysis. Thermal performance is rated for –40°C to 125°C ambient operation with RθJA = 206°C/W in SOT-23-3.

Key Specifications

Pinout & Package

SOT-23-3 (DBZ) package: 2.90 mm × 1.30 mm body size, surface-mount, lead-free, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431AQDBZRQ1, TLV431BQDBZRQ1 offers tighter reference accuracy for precision regulation; compared with TLVH431AQDBVRQ1, it provides lower-cost, smaller-footprint operation within 1.24–6 V range but lacks extended voltage headroom and higher current handling.

Availability

TLV431BQDBZRQ1 is available at Aetrix Electronics and suitable for automotive power management, isolated DC/DC converter feedback, and precision voltage monitoring requiring stable component supply across extended temperature ranges.

Supply support for TLV431BQDBZRQ1 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 automotive-grade power management and precision analog solutions.

The TLV431x-Q1 product line delivers AEC-Q100 qualified shunt references optimized for secondary-side regulation in automotive switching power supplies, battery monitoring, and fault-detection circuits demanding high accuracy and thermal stability.

FAQ

What is the reference voltage tolerance of TLV431BQDBZRQ1 at 25°C?

The TLV431BQDBZRQ1 has a reference voltage tolerance of ±0.5% at 25°C, corresponding to a V_REF range of 1.234 V to 1.246 V. This tight initial accuracy is specified in Section 5.6 of the datasheet and distinguishes the 'B' grade from the 'A' grade (±1%). The TLV431BQDBZRQ1 maintains this specification across its full automotive temperature range with ±11 mV maximum deviation.

Can TLV431BQDBZRQ1 be used in a 3.3 V isolated flyback converter?

Yes, TLV431BQDBZRQ1 is explicitly designed for this application. When paired with an optocoupler, it serves as the voltage reference and error amplifier on the secondary side. Its 1.24 V reference enables regulation as low as ~2.7 V (1.24 V + optocoupler V_F ≈ 1.4 V), making it ideal for 3.3 V outputs. Figure 8-1 in the datasheet confirms this topology, and stability analysis (Figure 5-18) validates operation with typical flyback output capacitance.

What is the minimum cathode current required for regulation in TLV431BQDBZRQ1?

The TLV431BQDBZRQ1 requires a minimum cathode current (I_K(min)) of 55 µA to 100 µA depending on temperature, as specified in Section 5.6. At 25°C, regulation is guaranteed above 55 µA; over the full –40°C to 125°C range, 100 µA ensures reliable operation. This low requirement supports energy-efficient designs, especially in automotive always-on circuits where standby current must be minimized.

Is TLV431BQDBZRQ1 pin-compatible with TL431?

No, TLV431BQDBZRQ1 is not pin-compatible with TL431. While both are 3-terminal shunt references, TLV431BQDBZRQ1 uses SOT-23-3 (REF/CATHODE/ANODE) pinout, whereas TL431 uses TO-92 or SOIC-8 packages with different terminal assignments (K/R/A). Additionally, TLV431BQDBZRQ1 operates down to 1.24 V and draws far less cathode current than TL431's 1 mA minimum, requiring circuit redesign-not just replacement-when migrating.

Does TLV431BQDBZRQ1 require an output capacitor for stability?

No, TLV431BQDBZRQ1 is internally compensated and does not require an output capacitor for basic stability. However, when driving capacitive loads (e.g., optocoupler CTR variation or PCB trace capacitance), stability depends on load value: Figure 5-18 shows stable operation up to 150 nF at V_KA = V_REF. For designs exceeding this, a series resistor or careful layout is recommended-no mandatory capacitor is needed for functional operation of TLV431BQDBZRQ1 itself.