Texas Instruments TLV431BQDBZT

Overview

TLV431BQDBZT from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, 0.5% 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 is qualified for automotive temperature range (–40°C to 125°C) in the SC-70 (DCK) package. It serves as a Zener replacement and error amplifier in isolated flyback power supplies.

For engineers reviewing the TLV431BQDBZT datasheet, TLV431BQDBZT pinout, TLV431BQDBZT application, or TLV431BQDBZT equivalent, key selection criteria include reference accuracy over temperature, cathode current requirements for regulation, dynamic impedance under load, stability with capacitive loads, and compatibility with optocoupler-based feedback in 3.3 V SMPS designs.

Technical Context

The TLV431BQDBZT integrates an internal 1.24 V bandgap reference and high-gain transconductance amplifier driving a Darlington sink output stage. Its open-loop mode enables comparator functionality with integrated reference, while closed-loop configuration-using external resistors between cathode and reference pins-enables precise shunt regulation across 1.24 V–6 V.

It operates with ≥100 µA cathode current for full gain and regulation, exhibits <11 mV VREF deviation over –40°C to 125°C, and maintains stability without output capacitance-though phase margin vs. capacitive load is characterized up to 1 nF for design guidance.

Key Specifications

Pinout & Package

TLV431BQDBZT is housed in the SC-70 (DCK) 6-pin package, measuring 2.0 mm × 1.5 mm. Pin 1 is CATHODE, Pin 3 is REFERENCE, and Pin 6 is ANODE; Pins 2, 4, and 5 are NC (no internal connection).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BIDCKR, TLV431BQDBZT adds automotive qualification and extended temperature margin; compared with TLVH431QDBVR, it trades wider voltage/current range for tighter 0.5% tolerance and smaller SC-70 footprint-making it optimal for compact, high-accuracy 3.3 V flyback and low-voltage monitoring.

Availability

TLV431BQDBZT is available at Aetrix Electronics and suitable for automotive power management, isolated DC/DC converters, and precision voltage monitoring requiring stable component supply across extended temperature ranges.

Supply support for TLV431BQDBZT 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, power management, and automotive electronics.

The TLV431 family was designed specifically for low-voltage, high-accuracy shunt regulation and integrated reference applications in space-constrained, thermally demanding environments-including automotive, industrial, and telecom power systems.

FAQ

What is the maximum cathode voltage rating for TLV431BQDBZT?

The absolute maximum cathode voltage (V_KA) for TLV431BQDBZT is 7 V, defined as voltage at the cathode pin relative to the anode pin. Operation above this level risks permanent damage. The recommended operating range is 1.24 V to 6 V, aligning with its adjustable shunt regulator function. This 7 V rating allows safe transient margin during startup or fault conditions in 5 V and 6 V systems.

Does TLV431BQDBZT require an external output capacitor for stability?

No, TLV431BQDBZT is internally compensated and remains stable without an external capacitor between cathode and anode in standard shunt regulator configurations. However, when driving capacitive loads (e.g., optocoupler CTR variation or long traces), phase margin degrades-Figure 5-19 in the datasheet shows stability boundaries up to 1 nF. For robust designs, TI recommends verifying stability with actual layout parasitics rather than adding capacitance unnecessarily.

How does the 0.5% reference tolerance of TLV431BQDBZT impact feedback resistor selection?

The 0.5% V_REF tolerance at 25°C means the total output voltage error in a resistor-divider configuration is dominated by resistor tolerance and temperature coefficient-not the IC itself. For example, using 1% resistors with 100 ppm/°C TCR yields higher overall error than the 0.5% IC spec. TLV431BQDBZT's tight reference allows designers to use lower-cost resistors while still meeting ±2% output accuracy targets in automotive power supplies.

Can TLV431BQDBZT be used in open-loop comparator mode with a 1.8 V supply?

Yes, TLV431BQDBZT functions as a comparator with integrated 1.24 V reference using a 1.8 V supply, provided ≥100 µA cathode current is delivered. Its output pulls low to ~1 V (sinking) and floats high to the supply rail (open-collector). For 1.8 V logic interfaces, the ~1 V low-level may not meet V_IL-so a pull-up to 1.8 V and optional resistive divider is recommended to ensure clean logic transitions without violating receiver thresholds.

What is the significance of the 'Q' suffix in TLV431BQDBZT?

The 'Q' in TLV431BQDBZT denotes automotive qualification per AEC-Q100 Grade 1, specifying guaranteed operation from –40°C to 125°C ambient temperature. It also indicates enhanced process controls, rigorous testing (including HTOL and ESD), and traceable manufacturing-distinct from commercial ('C') or industrial ('I') variants. This makes TLV431BQDBZT suitable for engine control units, ADAS cameras, and other safety-relevant automotive subsystems.