Texas Instruments TLV431BIDCKT

Overview

TLV431BIDCKT 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 down to 1.24 V cathode-anode voltage. It delivers 0.25 Ω typical dynamic impedance and supports output voltage adjustment from 1.24 V to 6 V using two external resistors. It serves as a Zener diode replacement in isolated flyback SMPS secondary-side regulation.

For engineers reviewing the TLV431BIDCKT datasheet, TLV431BIDCKT pinout, TLV431BIDCKT application, or TLV431BIDCKT equivalent, key selection criteria include reference accuracy over temperature (±6 mV from –40°C to 85°C), ultra-low 80 µA typical cathode current for regulation, SC-70 package footprint (2.0 mm × 1.5 mm), and compatibility with optocoupler-based feedback in 3.3 V switching-mode power supplies.

Technical Context

The TLV431BIDCKT implements an internal bandgap reference and high-gain NPN-based error amplifier driving a Darlington sink output stage. Its closed-loop operation enables precise shunt regulation by comparing the REF pin voltage to the 1.24 V internal reference and adjusting cathode current to maintain setpoint.

In open-loop mode, it functions as a comparator with integrated reference, exhibiting sharp turn-on and output saturation near 1 V (low) and rail-to-rail high-state capability. Stability is internally compensated-no external capacitor required-but phase margin vs. capacitive load is characterized up to 1 nF for design validation.

Key Specifications

Pinout & Package

TLV431BIDCKT uses the SC-70 (DCK) 6-pin package with 0.65 mm pitch. 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 regulator applications.

Compared with TLV431BIDBVR, TLV431BIDCKT offers 40% smaller footprint and better thermal resistance (R_θJA = 87°C/W vs 206°C/W), making it preferable for dense, thermally constrained layouts; TLVH431IDCKR extends voltage range but introduces pinout incompatibility and higher quiescent current.

Availability

TLV431BIDCKT is available at Aetrix Electronics and suitable for industrial power supplies, battery management systems, and embedded voltage monitoring requiring stable component supply and long-term manufacturability.

Supply support for TLV431BIDCKT 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 TLV431x family was designed specifically for low-voltage, high-accuracy shunt regulation in space- and power-constrained applications-including isolated SMPS feedback, voltage supervision, and compact reference circuits-replacing legacy TL431-based designs at lower operating voltages.

FAQ

What is the reference voltage tolerance of TLV431BIDCKT at 25°C?

The TLV431BIDCKT 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 tolerance is specified in Section 5.7 of the TI datasheet SLVS139Z and applies exclusively to the TLV431B grade. The 'B' suffix denotes this 0.5% initial accuracy, distinguishing it from TLV431A (±1%) and TLV431 (±1.5%). TLV431BIDCKT maintains this specification across its SC-70 packaging variant.

Can TLV431BIDCKT regulate output voltages below 3.3 V?

Yes, TLV431BIDCKT can regulate output voltages as low as 1.24 V-the value of its internal reference-and up to 6 V using an external resistor divider. It is commonly used to regulate 1.8 V, 2.5 V, and 3.3 V rails. In isolated flyback topologies with an optocoupler, the minimum achievable output is approximately 2.7 V (1.24 V + optocoupler LED forward voltage). TLV431BIDCKT's low 1.24 V reference and 80 µA cathode current requirement make it uniquely suited for sub-3.3 V regulation where legacy TL431 devices cannot operate.

What is the function of Pin 2, Pin 4, and Pin 5 on TLV431BIDCKT?

Pins 2, 4, and 5 of TLV431BIDCKT are labeled NC (No Connection) in the official TI datasheet and have no internal bond wire or circuit connection. They are unpopulated die pads in the SC-70 (DCK) package and must remain unconnected-no routing, no soldering, no grounding. These pins exist solely for mechanical package symmetry and do not affect electrical performance. TLV431BIDCKT functionality depends only on Pins 1 (CATHODE), 3 (ANODE), and 6 (REF).

How does TLV431BIDCKT differ from TLV431BIDBVR?

TLV431BIDCKT and TLV431BIDBVR share identical electrical specifications-including 0.5% V_REF tolerance, 0.25 Ω dynamic impedance, and 80 µA cathode current-but differ in package: TLV431BIDCKT uses SC-70 (6-pin, 2.0 mm × 1.5 mm), while TLV431BIDBVR uses SOT-23-3 (3-pin, 2.92 mm × 2.37 mm). The SC-70 version offers 40% smaller footprint and lower thermal resistance (87°C/W vs 206°C/W), but requires different PCB layout and stencil design. TLV431BIDCKT is not pin-compatible with TLV431BIDBVR.

Is TLV431BIDCKT internally compensated for stability?

Yes, TLV431BIDCKT is internally compensated and operates stably without an external output capacitor between CATHODE and ANODE-a key advantage over many discrete or op-amp-based references. Its compensation is optimized for resistive feedback networks. However, if a capacitive load is added (e.g., for noise filtering), Figure 5-19 in the TI datasheet shows phase margin vs. capacitive load up to 1 nF, guiding safe selection. TLV431BIDCKT's internal compensation eliminates external components while maintaining robustness across its full 1.24 V–6 V operating range.