Texas Instruments TL431CDBZTG4

Overview

TL431CDBZTG4 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 adjustable output from 2.495 V to 36 V via two external resistors. It operates across 0°C to 70°C and serves as a Zener diode replacement in feedback loops of isolated DC/DC converters and AC/DC power supplies.

For engineers reviewing the TL431CDBZTG4 datasheet, TL431CDBZTG4 pinout, TL431CDBZTG4 application, or TL431CDBZTG4 equivalent, key selection criteria include reference accuracy over temperature, cathode current sink capability (1–100 mA), low output noise, thermal stability (6 mV drift over 0°C–70°C), and compatibility with standard SOT-23 PCB footprints.

Technical Context

The TL431CDBZTG4 implements an internal error amplifier with high-gain transconductance stage driving a Darlington-connected NPN output transistor, enabling sharp turn-on and stable regulation under varying load and line conditions. Its three-terminal shunt architecture requires only two external resistors to set output voltage, eliminating need for dedicated reference ICs or discrete op-amp/Zener combinations.

It features active output circuitry that maintains regulation down to 0.4 mA minimum cathode current and supports up to 100 mA continuous sink current. The device exhibits low temperature coefficient (6 mV max deviation over 0°C–70°C) and high PSRR, making it suitable for closed-loop feedback in switching regulators where reference stability directly impacts output voltage accuracy.

Key Specifications

Pinout & Package

SOT-23-3 package (2.90 mm × 1.30 mm body size), surface-mount, lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL431ACDBZRG4 and TLVH431IDBZR, the TL431CDBZTG4 provides the highest initial accuracy (±0.5%) in the SOT-23-3 form factor for commercial-temperature applications, making it optimal for high-precision 12 V, 15 V, or 24 V regulated outputs where reference stability directly determines system-level voltage tolerance.

Availability

TL431CDBZTG4 is available at Aetrix Electronics and suitable for rack server power, industrial AC/DC, and notebook PC adapter designs requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for TL431CDBZTG4 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 power management, signal chain, and precision analog ICs.

The TL431 product line delivers precision programmable shunt references for feedback control in power conversion systems, designed specifically to replace Zener diodes with superior accuracy, stability, and sink-current capability.

FAQ

What is the reference voltage tolerance of TL431CDBZTG4 at 25°C?

The TL431CDBZTG4 has a ±0.5% initial reference voltage tolerance at 25°C, corresponding to a 2.483 V–2.507 V range around the nominal 2.495 V. This B-grade accuracy is specified in TI's SLVS543S datasheet Section 6.11 and applies strictly to the TL431CDBZTG4 variant in SOT-23-3 packaging. The tolerance remains stable over temperature, with ≤6 mV total deviation from 0°C to 70°C.

Can TL431CDBZTG4 be used in place of a Zener diode?

Yes, TL431CDBZTG4 is explicitly designed as a precision replacement for Zener diodes in voltage regulation and reference applications. Its active error amplifier architecture provides sharper turn-on, lower dynamic impedance (0.2 Ω vs. typical Zener's 5–50 Ω), and adjustable output (2.495 V–36 V) using two resistors - unlike fixed-voltage Zeners. TI's datasheet Section 3 confirms its use in on-board regulation, adjustable power supplies, and switching power supplies as a direct functional upgrade.

What is the minimum cathode current required for regulation in TL431CDBZTG4?

The TL431CDBZTG4 requires a minimum cathode current of 0.4 mA to maintain regulation, as specified in Section 6.5 of the SLVS543S datasheet. This value is valid across the full 0°C–70°C operating range and ensures stable reference behavior even at light loads. Below this threshold, the device may exit regulation, causing output voltage to rise toward the cathode supply rail.

Does TL431CDBZTG4 support adjustable output voltage?

Yes, TL431CDBZTG4 supports fully adjustable output voltage from 2.495 V to 36 V using two external resistors configured as a voltage divider between cathode and anode. The REF pin senses the divided voltage, and regulation occurs when that voltage equals the internal 2.495 V reference. This configuration is detailed in TI's datasheet Figure 9-1 and enables flexible feedback design without requiring multiple fixed-reference parts.

What package type does TL431CDBZTG4 use?

TL431CDBZTG4 uses the SOT-23-3 package (body size 2.90 mm × 1.30 mm), as confirmed in TI's SLVS543S datasheet Section 12 and Device Information table. Pinout is REF–CATHODE–ANODE (top view), matching standard SOT-23 footprints. This package supports surface-mount assembly, offers thermal resistance of 206°C/W (R_θJA), and is RoHS-compliant and lead-free.