Texas Instruments TLV431ILPR

Overview

TLV431ILPR from Texas Instruments is a low-voltage adjustable precision shunt regulator with 1.24 V reference voltage, ±1.5% initial tolerance at 25°C, 0.25 Ω typical dynamic impedance, 80 µA typical minimum cathode current, and operation from 1.24 V to 6 V output range. It serves as a Zener diode replacement and error amplifier in isolated flyback power supplies.

For engineers reviewing the TLV431ILPR datasheet, TLV431ILPR pinout, TLV431ILPR application, or TLV431ILPR equivalent, key selection considerations include its SC-70 (DCK) package footprint, temperature-stable 1.24 V reference, low cathode current requirement, open-collector comparator capability, and compatibility with optocoupler-based feedback in 3.3 V SMPS designs.

Technical Context

The TLV431ILPR implements a bandgap-referenced NPN-based shunt regulator architecture with internal Darlington sink output. Its functional modes include closed-loop regulation (as adjustable shunt reference) and open-loop operation (as comparator with integrated 1.24 V reference), both requiring ≥55 µA cathode current for stable linear behavior.

It features internal compensation enabling stability without external output capacitance, while phase margin vs. capacitive load curves (Figures 5-19–5-21) define safe CL ranges per VKA. The reference pin draws 0.1–0.5 µA and must not be left floating due to base-current dependency of the input NPN stage.

Key Specifications

Pinout & Package

TLV431ILPR is packaged in ultra-small SC-70 (DCK) format (2.0 mm × 1.5 mm), offering 40% smaller footprint than SOT-23-3. This 6-pin package includes one no-connect (NC) pin and substrate connection tied to ANODE.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV431ILPR, TLV431ACLPR improves reference accuracy without changing layout or thermal design, while TLVH431ILP expands voltage and current capability at the cost of larger footprint and non-interchangeable pinout.

Availability

TLV431ILPR is available at Aetrix Electronics and suitable for isolated SMPS regulation, precision voltage monitoring, and low-power Zener replacement applications requiring stable component supply across industrial, medical, and consumer electronics programs.

Supply support for TLV431ILPR 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 delivering analog and embedded processing solutions, with leadership in precision analog, power management, and signal chain technologies.

The TLV431 family was designed specifically for low-voltage, low-power shunt regulation and integrated-comparator applications in space-constrained and energy-sensitive systems such as IoT endpoints and portable electronics.

FAQ

What is the reference voltage tolerance of TLV431ILPR at 25°C?

The TLV431ILPR has a reference voltage tolerance of ±1.5% at 25°C, corresponding to a VREF range of 1.222 V to 1.258 V. This is specified in Section 5.5 of the TI SLVS139Z datasheet. The "L" suffix denotes the industrial temperature grade (–40°C to 85°C), and the "PR" indicates tape-and-reel packaging. TLV431ILPR maintains this tolerance across its full operating range.

Can TLV431ILPR replace a standard Zener diode in a 3.3 V regulator circuit?

Yes, TLV431ILPR can directly replace a Zener diode in 3.3 V regulation circuits. With its 1.24 V reference and external resistor divider, it achieves precise 3.3 V output (VO = 1.24 V × (1 + R1/R2)). Its 0.25 Ω dynamic impedance and 80 µA minimum cathode current provide superior regulation accuracy and lower quiescent power versus typical 5% Zeners. TLV431ILPR also offers better temperature stability - ±6 mV drift over –40°C to 85°C.

What is the correct pin configuration for TLV431ILPR in SC-70 (DCK) package?

TLV431ILPR in SC-70 (DCK) uses Pin 1 = CATHODE, Pin 3 = REF, Pin 6 = ANODE, Pins 4 and 5 = NC, and Pin 2 = Substrate (must connect to ANODE or leave unconnected). This mapping is confirmed in Figure 4-5 and Table 4-1 of the SLVS139Z datasheet. Misconnecting Pin 2 risks latch-up or parametric shift; NC pins must remain unstubbed on PCB.

Does TLV431ILPR require an output capacitor for stability?

No, TLV431ILPR is internally compensated and operates stably without an output capacitor between CATHODE and ANODE. However, if an output capacitor is added for noise filtering, Figures 5-19–5-21 in the datasheet specify maximum allowable values based on VKA (e.g., ≤1 nF at VKA = 5 V). Exceeding these limits risks oscillation due to phase margin degradation - TLV431ILPR's stability boundary is defined by capacitive loading, not ESR.

How does TLV431ILPR function as a comparator?

In open-loop mode, TLV431ILPR acts as a comparator with integrated 1.24 V reference: when voltage at the REF pin exceeds VREF, the CATHODE sinks current; below VREF, CATHODE goes high-impedance. It requires ≥55 µA cathode current to maintain sufficient open-loop gain. Output swing is rail-to-rail (ANODE to VKA), making TLV431ILPR ideal for threshold detection in battery monitors - no external reference or pull-up resistor is needed beyond the bias network.