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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Reference

STMicroelectronics TS4431AILT

Name: TS4431AILT
Brand: STMicroelectronics
SKU: TS4431AILT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TS4431AILT

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

Package:: SC-74A, SOT-753

Datasheet:: TS4431AILT.pdf

Description:: IC VREF SHUNT 0.5% SOT23-5

Quantity:: RFQ Add To RFQ list

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Inventory:2,785

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Product details

Overview

TS4431AILT from STMicroelectronics is a four-terminal, open-collector shunt voltage reference IC designed for feedback regulation in low-voltage switch-mode power supplies (SMPS). It integrates a 1.224 V ±0.5% precision reference, error amplifier, and ultra-low-saturation-output transistor (VSAT ≤ 60 mV at 20 mA), operating from 1.5 V to 10 V supply with 250 µA typical supply current across –40°C to +85°C.

For engineers reviewing the TS4431AILT datasheet, TS4431AILT pinout, TS4431AILT application, or TS4431AILT equivalent, key selection criteria include its 100 ppm/°C temperature coefficient, 20 mA max sink current capability, SOT23-5L package compatibility with optocoupler-based isolated feedback loops, and industrial-grade thermal stability in secondary-side SMPS designs.

Technical Context

The TS4431AILT implements a closed-loop shunt regulation architecture where the REF pin senses feedback voltage and controls sink current through the open-collector output (SINK) to maintain 1.224 V at REF. Its internal amplifier drives an NPN transistor with ultra-low saturation voltage, enabling direct series connection with optocoupler LEDs in isolated DC/DC converters.

Unlike three-terminal references, its four-terminal configuration separates VCC, GND, REF, and SINK-allowing independent biasing and eliminating ground-path errors. The device operates down to 1.5 V VCC and maintains <2 mV VREF drift over full supply range (1.5–10 V) and <10 mV drift over 0.5–20 mA sink current variation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_REF	1.224 V ±0.5% (1.218–1.230 V at 25°C); enables precise 3.3 V or 5 V output regulation via resistor divider scaling
Tempco	100 ppm/°C; ensures ≤±8.2 mV VREF shift over –40°C to +85°C, critical for stable output under thermal cycling
V_SAT	≤60 mV at 20 mA sink; minimizes voltage drop in optocoupler LED path, preserving loop gain and transient response
I_CC	250 µA typical at 2 mA sink; reduces standby power loss in energy-sensitive SMPS designs
ΔV_REF/ΔV_CC	≤2 mV over 1.5–10 V VCC range; decouples reference accuracy from input rail fluctuations
I_REF	≤1 µA at 25°C; allows high-impedance feedback dividers without loading error
T_OP	–40°C to +85°C; qualified for industrial ambient environments without derating

Pinout & Package

SOT23-5L plastic micropackage (3.0 × 2.8 × 1.3 mm), lead-free ECOPACK® compliant, with exposed pad not connected internally.

Pin/Terminal	Circuit Role	Design Meaning
1 - V_CC	Positive supply input	Biases internal amplifier and reference; operates from 1.5 V to 10 V; must be ≥ V_REF + V_SAT for regulation
2 - GND	Analog ground reference	Return path for internal circuitry; separate from power ground to avoid noise coupling into REF node
3 - NC	No connect	Internally unconnected; must remain floating or tied to GND per layout best practice to minimize parasitic coupling
4 - REF	Reference input sensing node	High-impedance (≤1 µA) feedback point; voltage at this pin is regulated to 1.224 V; connects to resistor divider midpoint
5 - SINK	Open-collector NPN output	Sinks current to GND when REF > 1.224 V; drives optocoupler LED anode directly; requires external pull-up to V_CC or auxiliary rail

Key Features

Feature	Design Value
Four-terminal architecture	Separates REF sense, SINK output, VCC, and GND-eliminates common-impedance errors in high-accuracy feedback paths
Ultra-low saturation voltage	V_SAT ≤ 60 mV at 20 mA enables use with low-V_F optocouplers (e.g., PC817, SFH615A) without headroom compromise
Low quiescent current	250 µA typical ICC supports >90% efficiency in sub-1 W standby modes of AC/DC adapters
Industrial temperature grade	Specified performance over –40°C to +85°C ensures reliability in enclosed power enclosures without forced cooling
ECOPACK® packaging	Lead-free SOT23-5L meets RoHS and JEDEC JESD97 marking requirements for green manufacturing compliance

Applications

Isolated DC/DC Converter

Low-Voltage SMPS

Use Scenario: Secondary-side voltage regulation in flyback or forward converters with optocoupler-based feedback isolation.

IC Role / Device Role / Timing Role: Shunt reference and error amplifier that sinks current proportional to REF node error to modulate optocoupler LED brightness.

Use Value: Enables ±1% output regulation at 3.3 V/5 V with minimal component count and no primary-side controller dependency.

Use Scenario: Compact off-line adapter (<10 W) powering microcontrollers or sensors from universal AC input.

IC Role / Device Role / Timing Role: Precision feedback element in TL431-compatible topology, replacing legacy parts with lower V_SAT and tighter initial tolerance.

Use Value: Reduces output voltage drift by up to 40% vs. TL431 under load transients due to lower ΔV_REF/ΔI_SINK.

Computer Power Supply

Low-Voltage Discrete Regulator

Use Scenario: Standby (5 VSB) rail regulation in ATX PSUs requiring tight tolerance and low no-load consumption.

IC Role / Device Role / Timing Role: Reference for secondary-side PWM controller feedback, maintaining regulation during deep sleep states.

Use Value: 250 µA I_CC cuts standby power by ~150 µW vs. TL431 (500 µA), improving Energy Star compliance.

Use Scenario: Local 1.2 V or 1.8 V point-of-load regulation using discrete pass transistor and resistive divider.

IC Role / Device Role / Timing Role: High-stability reference driving base/gate of external BJT or MOSFET pass element.

Use Value: 100 ppm/°C tempco ensures <±10 mV output drift over full industrial range, outperforming Zener-based solutions.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TL431ACDT	2.495 V nominal VREF, ±1% initial accuracy, VSAT ≈ 1 V at 100 mA, higher ICC (1–2 mA)	Requires different resistor divider ratio; unsuitable for sub-2 V output regulation without level-shifting	Select when 2.5 V reference and higher sink current (>100 mA) are required; avoid for low-headroom or low-power designs
MAX8502ESA+	1.235 V VREF, ±0.5% accuracy, but only 10 mA max sink current, higher tempco (50 ppm/°C)	Limited to <5 W isolated converters; less robust under high-current optocoupler drive	Prefer for space-constrained designs needing SO-8 footprint; verify loop stability with reduced sink margin

Compared with TL431ACDT and MAX8502ESA+, TS4431AILT delivers superior low-voltage regulation (1.224 V), lowest saturation voltage for optocoupler drive, and tighter thermal stability-making it optimal for compact, high-efficiency 3.3 V/5 V SMPS where headroom and standby power are critical.

Availability

TS4431AILT is available at Aetrix Electronics and suitable for isolated DC/DC converters, low-voltage switch-mode power supplies, and computer standby power rails requiring stable component supply, consistent parametric performance, and long-term industrial lifecycle support.

Supply support for TS4431AILT 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The TS4431 belongs to ST's precision analog reference product line, engineered specifically for high-accuracy, low-headroom feedback in isolated power conversion architectures-emphasizing thermal stability, low saturation, and compatibility with optocoupler-coupled control loops.

FAQ

What is the minimum VCC required for TS4431AILT to regulate properly?

The TS4431AILT requires VCC ≥ VREF + VSAT, or at least 1.224 V + 0.06 V = 1.284 V under worst-case conditions. However, the datasheet specifies 1.5 V as the absolute minimum operating VCC to ensure reliable amplifier biasing and full parameter guarantee across temperature. Below 1.5 V, regulation may become unstable or cease entirely.

Can TS4431AILT replace TL431 in existing designs without modification?

No-direct replacement is not possible due to differing pinouts (TL431 is 3-pin; TS4431AILT is 5-pin with dedicated VCC, GND, NC, REF, SINK), voltage reference value (1.224 V vs. 2.495 V), and sink transistor characteristics. Resistor divider values, PCB layout, and optocoupler drive strength must all be re-evaluated and adjusted.

Does TS4431AILT require an external capacitor on the REF pin?

No external capacitor is required on the REF pin for basic operation. However, a small ceramic capacitor (10–100 pF) is recommended between REF and GND in noisy environments to suppress high-frequency interference that could cause regulation instability or oscillation in the feedback loop.

What is the maximum continuous sink current rating for TS4431AILT?

The absolute maximum sink current is 30 mA, but the recommended continuous operating limit is 20 mA per electrical characteristics table. Exceeding 20 mA risks exceeding the 500 mW package power dissipation limit (P = VSAT × ISINK), especially at elevated temperatures, potentially triggering thermal shutdown or long-term reliability degradation.

TS4431AILT Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Package/Case:: SC-74A, SOT-753

Series:: -

Packaging:: Tape & Reel (TR)

Product Status:: Active

Reference Type:: Shunt

Output Type:: Fixed

Voltage - Output (Min/Fixed):: 1.224V

Voltage - Output (Max):: -

Current - Output:: 20 mA

Tolerance:: ±0.5%

Temperature Coefficient:: 100ppm/°C

Noise - 0.1Hz to 10Hz:: -

Noise - 10Hz to 10kHz:: -

Voltage - Input:: -

Current - Supply:: -

Current - Cathode:: 350 µA

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-5

TS4431AILT FAQ

1.How can I place an order for TS4431AILT through Aetrix?

Please submit a Request for Quotation (RFQ) for TS4431AILT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for TS4431AILT reliable?

The price and inventory of TS4431AILT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TS4431AILT is usually 5 days.

3.What payment methods are accepted for TS4431AILT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TS4431AILT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TS4431AILT?

TS4431AILT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TS4431AILT order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for TS4431AILT?

For technical support, including TS4431AILT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TS4431AILT requirements.

6.How does Aetrix verify that TS4431AILT is sourced from the original manufacturer or authorized distributors?

All TS4431AILT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that TS4431AILT meets industry standards.

7.What is the process for return or replacement of TS4431AILT?

All TS4431AILT units undergo pre-shipment inspection (PSI). If there is an issue with TS4431AILT, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The TS4431AILT part is unused and in its original packaging.

Return procedure for TS4431AILT:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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