Texas Instruments TLV431BQDCKR

Overview

TLV431BQDCKR from Texas Instruments is a low-voltage adjustable precision shunt regulator with 0.5% 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, 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 SMPSs.

For engineers reviewing the TLV431BQDCKR datasheet, TLV431BQDCKR pinout, TLV431BQDCKR application, or TLV431BQDCKR equivalent, key selection considerations include its SC-70-6 package footprint (2.0 mm × 1.5 mm), ±11 mV reference drift over –40°C to 125°C, ultra-low I_REF (0.1–0.5 µA), and compatibility with optocoupler-based feedback loops requiring stable, low-headroom voltage references.

Technical Context

The TLV431BQDCKR operates as a 3-terminal adjustable shunt reference with an internal bandgap reference and high-gain NPN-based error amplifier. Its functional modes include open-loop comparator operation (with integrated 1.24 V reference) and closed-loop shunt regulation-enabling precise voltage or current referencing without external compensation.

It achieves regulation by sinking cathode current when the reference pin voltage exceeds the internal 1.24 V threshold, with active output circuitry delivering sharp turn-on characteristics. The device is internally compensated and stable without an output capacitor, though capacitive load stability depends on VKA and is characterized up to 10 nF per Figure 5-19–5-21.

Key Specifications

Pinout & Package

TLV431BQDCKR uses the SC-70-6 (DCK) package: 2.0 mm × 1.5 mm body, 0.65 mm pitch, 6-pin single-row layout with exposed pad (non-electrical). Pin 1 is CATHODE; Pin 3 is ANODE; Pin 6 is REF; 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 reference applications.

Compared with TLV431BIDCKR, TLV431BQDCKR adds extended temperature qualification critical for automotive engine control and industrial motor drives; compared with TLVH431ACDBVR, it trades voltage range and current capability for tighter 0.5% tolerance and lower quiescent current-making it optimal for precision, low-power 3.3 V/5 V regulation.

Availability

TLV431BQDCKR is available at Aetrix Electronics and suitable for isolated flyback power supplies, voltage monitoring circuits, and precision current-sink references requiring stable component supply across automotive, industrial, and telecom applications.

Supply support for TLV431BQDCKR 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 headquartered in Dallas, Texas, designing and manufacturing analog and embedded processing chips for industrial, automotive, and communications markets.

The TLV431BQDCKR belongs to TI's precision shunt reference product line, engineered specifically for low-voltage, high-accuracy regulation in space- and power-constrained systems-including isolated DC/DC converters and battery management subsystems.

FAQ

What is the maximum cathode voltage rating for TLV431BQDCKR?

The absolute maximum cathode-to-anode voltage (V_KA) for TLV431BQDCKR is 7 V, as specified in Section 5.1 of the datasheet. Exceeding this voltage risks permanent damage. For reliable operation, the recommended V_KA range is 1.24 V to 6 V under normal conditions, aligning with its design as a low-voltage shunt reference. This limit ensures safe operation in 3.3 V and 5 V systems while preventing overstress in transient events.

Does TLV431BQDCKR require an external capacitor for stability?

No, TLV431BQDCKR is internally compensated and remains stable without an external output capacitor between CATHODE and ANODE-unlike many linear regulators. However, when driving capacitive loads (e.g., optocoupler CTR variation or PCB trace capacitance), stability must be verified using Figures 5-19 to 5-21 in the datasheet. For loads >1 nF, series resistance or careful layout is recommended to avoid phase margin degradation.

How does the REF pin current affect accuracy in TLV431BQDCKR feedback networks?

The REF pin draws 0.1–0.5 µA (typical 0.1 µA at 25°C), which flows through the upper resistor (R1) in standard two-resistor feedback configurations. This introduces a small but measurable error in the setpoint voltage: V_OUT = V_REF(1 + R1/R2) + I_REF×R1. To minimize error, use R1 ≤ 10 kΩ and R2 ≥ 10 kΩ-keeping I_REF×R1 < 5 mV. TLV431BQDCKR's ultra-low I_REF makes it significantly more accurate than TL431 (I_REF ≈ 4 µA) in high-impedance dividers.

Can TLV431BQDCKR replace TL431 in existing designs?

TLV431BQDCKR can replace TL431 only with circuit modifications: its 1.24 V V_REF is half that of TL431 (2.5 V), requiring resistor-divider recalculations to maintain the same output voltage. Also, minimum cathode current is 55–100 µA vs. TL431's 1 mA-so bias networks must be redesigned. Pinout differs (SC-70-6 vs. TO-92/SOT-23-3), so PCB layout change is mandatory. It is not a drop-in replacement.

What is the thermal resistance (R_θJA) of TLV431BQDCKR in its SC-70-6 package?

The junction-to-ambient thermal resistance (R_θJA) for TLV431BQDCKR in the SC-70-6 (DCK) package is 87°C/W, as listed in Table 5.4 of the datasheet. This value assumes standard JEDEC 2S2P board conditions. With typical power dissipation below 100 mW in shunt regulator use, temperature rise remains under 9°C above ambient-enabling reliable operation in sealed enclosures and high-density power modules without forced airflow.