Texas Instruments TLV431ACLPR

Overview

TLV431ACLPR from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, ±1% initial tolerance at 25°C, 0.25 Ω typical dynamic impedance, and operation down to 1.24 V cathode-anode voltage - used as an integrated reference in isolated flyback secondary-side regulation, Zener replacement, and voltage monitoring circuits.

For engineers reviewing the TLV431ACLPR datasheet, TLV431ACLPR pinout, TLV431ACLPR application, or TLV431ACLPR equivalent, this page delivers verified electrical specs, SC-70 package details, functional mode distinctions (open-loop comparator vs closed-loop shunt regulator), thermal performance data, and real-world design constraints for 3.3 V SMPS feedback and low-voltage sensing.

Technical Context

The TLV431ACLPR implements a bandgap-referenced NPN-based error amplifier with Darlington output stage, enabling precise shunt regulation from 1.24 V to 6 V using two external resistors. Its internal reference is trimmed to 1.24 V ±1% at 25°C and exhibits 6 mV max deviation over –40°C to 85°C industrial range.

It operates in two distinct functional modes: open-loop comparator mode (with integrated 1.24 V threshold) and closed-loop shunt regulator mode (requiring ≥55 µA minimum cathode current and external feedback). Unlike linear regulators, it is internally compensated and stable without output capacitance, though phase margin vs capacitive load is characterized up to 1 nF.

Key Specifications

Pinout & Package

TLV431ACLPR is packaged in ultra-small SC-70 (DCK) format (2.0 mm × 1.5 mm), offering 40% smaller footprint than SOT-23-3. The 6-pin package includes two no-connect (NC) pins and substrate connection (pin 2) that must be tied to anode or left floating per TI specification.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431BCLPR, TLV431ACLPR trades 0.5% reference accuracy for lower unit cost while retaining identical thermal, dynamic impedance, and functional mode behavior. Compared with TLVH431ILP, TLV431ACLPR offers superior size efficiency and lower quiescent current but lacks high-voltage and high-current capability.

Availability

TLV431ACLPR is available at Aetrix Electronics and suitable for isolated flyback SMPS design, voltage monitoring systems, and low-voltage Zener replacement applications requiring stable component supply across industrial temperature ranges (–40°C to 85°C).

Supply support for TLV431ACLPR 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, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The TLV431 family was designed specifically to extend precision shunt regulation into low-voltage domains (1.24 V–6 V), addressing limitations of legacy TL431 in 3.3 V and sub-3 V power architectures.

FAQ

What is the minimum cathode current required for regulation in TLV431ACLPR?

The TLV431ACLPR requires a minimum cathode current of 55 µA to 80 µA depending on temperature - 55 µA at 25°C and up to 80 µA across the full –40°C to 85°C industrial range. Below this threshold, the internal amplifier exits linear region and regulation fails. This value is confirmed in Section 5.6 of the TI SLVS139Z datasheet for TLV431A devices. TLV431ACLPR must be biased above this level in all closed-loop applications.

Can TLV431ACLPR replace a standard Zener diode in a 3.3 V power rail?

Yes, TLV431ACLPR can directly replace Zener diodes in 3.3 V rails with significant advantages: ±1% reference tolerance (vs ±5% typical for Zeners), 0.25 Ω dynamic impedance (vs 10–100 Ω), and stable performance over temperature. It requires only two external resistors to set the clamping voltage and draws less than 1 µA reference current. TLV431ACLPR is explicitly cited in TI documentation as a "Zener replacement" for on-board regulation.

What is the function of Pin 2 (substrate) on TLV431ACLPR in the SC-70 package?

Pin 2 on TLV431ACLPR is the substrate connection - a die attach pad with no internal circuit connection. Per TI's Pin Configuration and Functions table (Figure 4-5), it must be either connected to the ANODE terminal or left electrically floating. It is not a ground pin or thermal pad for soldering; improper connection may affect thermal resistance (R_θJC(top) = 259°C/W) but does not impact electrical functionality.

Does TLV431ACLPR require an output capacitor for stability?

No, TLV431ACLPR is internally compensated and stable without an output capacitor between cathode and anode - a key distinction from many linear regulators. TI confirms this in Section 7.3: "Unlike many linear regulators, TLV431 is internally compensated to be stable without an output capacitor." However, if an output capacitor is added for noise filtering, Figure 5-19 in the datasheet provides phase margin vs capacitive load guidance up to 1 nF.

How does TLV431ACLPR differ from TLV431CLPR?

TLV431ACLPR has ±1% reference voltage tolerance at 25°C, while TLV431CLPR has ±1.5%. Both share identical SC-70 packaging, pinout, dynamic impedance (0.25 Ω), temperature drift (6 mV over –40°C to 85°C), and functional specifications. The 'A' suffix denotes the tighter initial tolerance grade - making TLV431ACLPR suitable for applications demanding higher accuracy without upgrading to the 0.5% TLV431BCLPR variant.