Texas Instruments TL431CDBVT

Overview

TL431CDBVT from Texas Instruments is a precision programmable shunt voltage reference in SOT-23-3 package, delivering 2.495 V nominal reference voltage with ±0.5% initial tolerance at 25°C, 0.2 Ω typical dynamic impedance, and operation from 0°C to 70°C. It serves as a stable feedback element in isolated DC-DC converters, AC/DC power supplies, and voltage-monitoring circuits.

For engineers reviewing the TL431CDBVT datasheet, TL431CDBVT pinout, TL431CDBVT application, or TL431CDBVT equivalent, key selection criteria include reference accuracy over temperature, cathode current capability (1–100 mA), low output noise, thermal drift (≤6 mV over 0°C–70°C), and compatibility with standard resistor-divider feedback networks.

Technical Context

The TL431CDBVT implements an internal error amplifier and NPN transistor output stage configured as a 3-terminal adjustable shunt regulator. Its REF pin senses voltage relative to the ANODE terminal, triggering cathode current sink when the divider voltage exceeds V_ref. The device operates without external compensation in most feedback configurations but requires load capacitance <100 nF for stability per TI's recommended layout guidelines.

Unlike Zener diodes, it provides sharp turn-on characteristics and predictable temperature behavior-its 6 mV max reference deviation over 0°C–70°C stems from matched on-chip resistor and transistor thermal coefficients. The SOT-23-3 package enables high-density placement in compact power rails while maintaining thermal resistance of 206°C/W (R_θJA).

Key Specifications

Pinout & Package

SOT-23-3 package (2.90 mm × 1.30 mm), surface-mount, lead-free, RoHS-compliant. Thermal pad not present; junction-to-ambient R_θJA = 206°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431IDBVT, TL431CDBVT trades extended temperature support for lower cost and tighter qualification in commercial power supplies; versus LM4040CIM3-ADJ, it delivers full adjustability and 6.7× higher sink current-making it indispensable in optocoupler-driven isolated regulation.

Availability

TL431CDBVT is available at Aetrix Electronics and suitable for AC/DC power supplies, rack server VRMs, and notebook adapter designs requiring stable component supply, long-term manufacturability, and TI-qualified commercial-grade performance.

Supply support for TL431CDBVT 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 specializing in analog, embedded processing, and power management technologies, with decades of expertise in precision reference design.

The TL431 product line was engineered for high-accuracy, low-drift voltage regulation in isolated power conversion and system supervision-targeting cost-sensitive yet performance-critical commercial and industrial applications.

FAQ

What is the reference voltage tolerance of TL431CDBVT at 25°C?

The TL431CDBVT has a ±0.5% initial reference voltage tolerance at 25°C, corresponding to a 2.483 V to 2.507 V range around the nominal 2.495 V. This B-grade accuracy is confirmed in Section 6.11 of the TI SLVS543S datasheet and applies specifically to the C-temp (0°C–70°C) and DBVT (SOT-23-3) variant. It does not apply to A-grade or standard-grade versions.

Can TL431CDBVT replace a Zener diode in feedback circuits?

Yes, TL431CDBVT is explicitly designed as a superior replacement for Zener diodes in feedback applications. Its active error amplifier delivers sharper turn-on, lower dynamic impedance (0.2 Ω vs typical Zener's >10 Ω), and tighter temperature stability (≤6 mV drift over 0°C–70°C). TI's datasheet confirms its use in on-board regulation, adjustable power supplies, and switching power supplies-exactly where Zeners fall short.

What is the maximum cathode current supported by TL431CDBVT?

TL431CDBVT supports a continuous cathode current range of 1 mA to 100 mA, as specified in Section 6.4 (Recommended Operating Conditions) and validated in Figure 6-3 of the TI SLVS543S datasheet. This 100 mA rating enables direct driving of optocoupler LEDs in isolated flyback converters without external buffering, distinguishing it from lower-current references like the LM4040.

Does TL431CDBVT require external compensation capacitors?

TL431CDBVT typically does not require external compensation in standard resistor-divider feedback configurations. However, stability depends on load capacitance: TI's Figure 6-16 shows oscillation risk when CL exceeds ~100 nF at certain cathode currents. For robust operation, keep CL <10 nF or add a small series resistor (e.g., 10 Ω) between REF and divider node-per TI Application Report SLVA721.

How does the SOT-23-3 package affect thermal performance of TL431CDBVT?

The SOT-23-3 package of TL431CDBVT has a junction-to-ambient thermal resistance (R_θJA) of 206°C/W, as documented in Section 6.3 of the TI datasheet. This means at 100 mA cathode current and 5 V drop (500 mW dissipation), junction temperature rises ~103°C above ambient-requiring careful PCB copper area allocation. It lacks an exposed thermal pad, unlike larger packages such as SOIC or TO-92.