Texas Instruments TLV431BCDCKT

Overview

TLV431BCDCKT 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, 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 compact 3.3 V isolated flyback SMPSs.

For engineers reviewing the TLV431BCDCKT datasheet, TLV431BCDCKT pinout, TLV431BCDCKT application, or TLV431BCDCKT equivalent, key selection considerations include its SC-70 package footprint (2.0 mm × 1.5 mm), thermal stability across –40°C to 85°C (TLV431BI grade), ultra-low reference current (≤0.5 µA), and compatibility with optocoupler-based feedback loops requiring sharp turn-on and minimal headroom.

Technical Context

The TLV431BCDCKT integrates an internal 1.24 V bandgap reference and high-gain transconductance amplifier driving a Darlington sink output stage. Its open-loop comparator mode enables precise voltage monitoring without external reference, while closed-loop configuration with resistive feedback achieves stable shunt regulation with <11 mV total VREF deviation over –40°C to 85°C.

Unlike the TL431, it operates with ≥1.24 V headroom and as low as 55 µA cathode current for regulation, enabling use in low-power systems where supply margins are constrained. Internal compensation ensures stability without mandatory output capacitance, though phase margin vs. capacitive load is characterized up to 1 nF for design validation.

Key Specifications

Pinout & Package

TLV431BCDCKT uses the SC-70 (DCK) 6-pin package with 2.0 mm × 1.5 mm body size and 0.65 mm lead pitch. Pin 1 is CATHODE, Pin 3 is ANODE, Pin 6 is REF; Pins 2, 4, and 5 are NC (no internal connection). Substrate (Pin 2) must be connected to ANODE or left floating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BCDCKT, TLV431ACDCKT trades initial accuracy for cost savings while retaining identical thermal and dynamic performance, whereas TLVH431IDBVR expands voltage/current capability at the expense of package compatibility and increased board area.

Availability

TLV431BCDCKT is available at Aetrix Electronics and suitable for industrial power supplies, isolated DC-DC converters, and embedded voltage monitoring systems requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for TLV431BCDCKT 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 leader delivering analog and embedded processing solutions, with over 90 years of innovation in precision analog ICs and power management.

The TLV431 family was designed specifically for low-voltage, high-accuracy shunt regulation in space- and power-constrained applications - targeting industrial, telecom, and computing systems needing reliable, small-footprint voltage references.

FAQ

What is the operating temperature range for TLV431BCDCKT?

The TLV431BCDCKT is specified for operation from –40°C to +85°C (industrial grade, denoted by 'I' suffix). Its reference voltage maintains ≤6 mV total deviation across this range, and all electrical characteristics - including minimum cathode current and dynamic impedance - are guaranteed within these limits per the TI SLVS139Z datasheet.

Can TLV431BCDCKT replace a standard Zener diode?

Yes, TLV431BCDCKT can directly replace low-voltage Zener diodes (e.g., 3.3 V or 5.1 V types) in shunt regulation applications. With its 1.24 V reference, adjustable output up to 6 V, 0.25 Ω dynamic impedance, and sharp turn-on, it offers superior accuracy, lower temperature drift, and better current-handling linearity compared to discrete Zeners - especially below 4 V.

What is the minimum cathode current needed for regulation in TLV431BCDCKT?

The TLV431BCDCKT requires a minimum cathode current of 55 µA to 80 µA (depending on temperature) to maintain regulation, as specified in Section 5.7 of the datasheet. This ultra-low requirement enables use in low-power systems such as battery-operated sensors or always-on monitoring circuits where standby current must be minimized.

Is TLV431BCDCKT compatible with optocoupler-based feedback in flyback converters?

Yes, TLV431BCDCKT is explicitly designed for optocoupler-coupled isolated feedback in flyback topologies. Its low 1.24 V reference and ability to regulate down to 2.7 V output (1.24 V + optocoupler LED drop) make it ideal for 3.3 V output supplies. TI's Application Note SLUA671 confirms its use in UCC28600-based designs with validated stability margins.

Does TLV431BCDCKT require an output capacitor for stability?

No, TLV431BCDCKT is internally compensated and stable without an output capacitor between cathode and anode - a key advantage over many linear regulators. However, if an output capacitor is used (e.g., for noise filtering), Figure 5-19 in the datasheet provides phase margin vs. capacitive load guidance to ensure stability up to 1 nF.