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

STMicroelectronics TS4431ILT

Name: TS4431ILT
Brand: STMicroelectronics
SKU: TS4431ILT
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TS4431ILT

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

Package:: SC-74A, SOT-753

Datasheet:: TS4431ILT.pdf

Description:: IC VREF SHUNT 1% SOT23-5

Quantity:: RFQ Add To RFQ list

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Inventory:4,569

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Product details

Overview

TS4431ILT from STMicroelectronics is a 1% accuracy, 1.224V open-collector shunt voltage reference in SOT23-5L package, designed for feedback regulation in low-voltage SMPS. It features 75 mV max sink saturation voltage at 20 mA, 250 µA supply current, and operates across –40°C to +85°C with 100 ppm/°C temperature coefficient. Used in isolated DC/DC converters where precision secondary-side voltage sensing is required.

For engineers reviewing the TS4431ILT datasheet, TS4431ILT pinout, TS4431ILT application, or TS4431ILT equivalent, key selection criteria include reference accuracy (1%), ultra-low V_SAT (≤100 mV at 20 mA), thermal stability (100 ppm/°C), and compatibility with optocoupler-based feedback loops in sub-5V output SMPS designs.

Technical Context

The TS4431ILT integrates a precision 1.224V bandgap reference, error amplifier, and open-collector NPN output transistor in a single die. Its four-terminal architecture (REF, SINK, VCC, GND, NC) enables direct connection to optocoupler LED anodes for isolated feedback control without external biasing.

It functions as a programmable shunt regulator: when REF voltage exceeds 1.224V, the output transistor sinks current from VCC through the optocoupler LED, adjusting primary-side PWM duty cycle. The NC pin (Pin 3) is unconnected and must be left floating per ST's mechanical drawing and pinout diagram.

Key Specifications

Parameter	Value and Actual Design Meaning
V_REF	1.224 V ±1% (1.212–1.236 V at 25°C); sets precise feedback threshold for SMPS regulation loop
V_SAT (max)	100 mV at I_SINK = 20 mA; enables <5V output regulation with minimal headroom loss across optocoupler
I_CC	250–350 µA over temperature; ensures low quiescent power in always-on feedback path
T_C	100 ppm/°C; guarantees ≤±12.2 mV total drift over –40°C to +85°C operating range
I_SINK (max)	30 mA absolute maximum; supports robust optocoupler drive under transient load conditions
V_CC Range	1.5–10 V; allows operation directly from auxiliary winding or post-regulated rail without LDO

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	Supply input	Power source for internal reference and amplifier; accepts 1.5–10 V, no external decoupling required
2 - GND	Ground reference	Analog and power ground return for reference core and output transistor emitter
3 - NC	No connect	Unbonded die pad; must remain unconnected on PCB per ST mechanical data sheet
4 - REF	Reference input	High-impedance (≤1 µA I_REF) node sensing feedback divider voltage; regulates when ≥1.224 V
5 - SINK	Open-collector output	NPN collector terminal sinking current to GND; drives optocoupler LED cathode in standard SMPS topology

Key Features

Feature	Design Value
Ultra-low saturation voltage	V_SAT ≤100 mV @ 20 mA enables regulation of 3.3V/2.5V outputs with <150 mV overhead
Stable 1.224V reference	1% initial accuracy and 100 ppm/°C TC ensure ±1.5% total output voltage tolerance over full industrial temp range
Low quiescent current	250 µA typical I_CC minimizes standby power loss in energy-sensitive AC/DC adapters
Four-terminal isolation-ready interface	Dedicated REF and SINK pins simplify optocoupler integration without external resistors or level-shifting components

Applications

AC/DC Adapter Feedback

Isolated Telecom DC/DC

Use Scenario: Secondary-side voltage regulation in 5V/3.3V flyback adapters for consumer electronics.

IC Role / Device Role / Timing Role: Shunt reference providing closed-loop feedback signal to optocoupler, controlling primary-side PWM IC.

Use Value: 100 mV V_SAT allows stable 3.3V output regulation even with 3.4V minimum V_CC from auxiliary winding.

Use Scenario: Output voltage stabilization in 48V-to-12V isolated DC/DC modules for telecom base stations.

IC Role / Device Role / Timing Role: Precision voltage sense element in isolated feedback path, interfacing with high-CTR optocoupler.

Use Value: 1% accuracy and 100 ppm/°C TC maintain ±1.2% output tolerance across –40°C to +85°C ambient.

Laptop Charger Regulation

Industrial PLC Power Supply

Use Scenario: Multi-output flyback charger delivering 20V, 5V, and 3.3V rails with independent secondary-side regulation.

IC Role / Device Role / Timing Role: Dedicated reference for 3.3V rail feedback, decoupled from higher-voltage rails via separate optocoupler.

Use Value: Low 250 µA I_CC prevents loading of sensitive 3.3V divider network, preserving regulation accuracy.

Use Scenario: Redundant 24V isolated power supply in programmable logic controller backplane.

IC Role / Device Role / Timing Role: Fault-tolerant shunt reference monitoring main 24V output, triggering shutdown if deviation exceeds ±2%.

Use Value: 30 mA absolute max I_SINK supports fail-safe optocoupler drive during overvoltage events.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TL431ACDBVR	2.495V nominal V_REF, 0.5% accuracy, higher V_SAT (≈300 mV)	Requires resistor divider to scale down to 1.224V target; less efficient in low-V_OUT designs	Select only if existing design uses TL431 footprint and higher reference voltage is acceptable
AS431ASTZTR-G1	1.24V nominal V_REF, 1% accuracy, V_SAT = 120 mV @ 20 mA	16 mV higher reference voltage shifts output setpoint; 20 mV higher V_SAT reduces margin for 3.3V outputs	Acceptable for 5V+ outputs but requires recalculating feedback resistors and verifying V_CC headroom

Compared with TL431ACDBVR and AS431ASTZTR-G1, TS4431ILT delivers lower V_REF and lower V_SAT, enabling tighter regulation and higher efficiency in sub-5V isolated SMPS-critical where auxiliary winding voltage is constrained.

Availability

TS4431ILT is available at Aetrix Electronics and suitable for low-voltage switch mode power supplies, isolated DC/DC converters, and industrial PLC power supplies requiring stable component supply with guaranteed long-term availability.

Supply support for TS4431ILT 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The TS4431 series belongs to ST's precision analog reference product line, engineered specifically for high-efficiency, low-headroom isolated power conversion in space-constrained applications.

FAQ

What is the function of the NC pin (Pin 3) on TS4431ILT?

Pin 3 is a no-connect terminal with no internal bond wire or die connection. ST's mechanical data sheet explicitly states it must remain unconnected on the PCB. Routing traces to or placing vias near this pin may cause parasitic coupling or mechanical stress, degrading long-term reliability.

Can TS4431ILT replace TL431 in existing designs?

Direct replacement is not possible due to different reference voltage (1.224V vs. 2.495V) and pinout (TS4431ILT has VCC, GND, NC, REF, SINK; TL431 has ANODE, CATHODE, REF). A redesign of the feedback divider and optocoupler interface is required to accommodate the lower VREF and dedicated supply pin.

What is the minimum VCC required for stable operation?

The datasheet specifies 1.5 V minimum VCC for operation. At 1.5 V, the device maintains regulation with ≤100 mV V_SAT at 20 mA sink current, enabling use with auxiliary windings delivering as low as 1.6 V after diode drop-critical for ultra-low-output SMPS.

How does temperature affect output voltage accuracy?

Over –40°C to +85°C, VREF shifts by ±1.224 V × 100 ppm/°C × 125°C = ±15.3 mV (±1.25%). Combined with initial 1% tolerance (±12.24 mV), total worst-case deviation is ±27.5 mV (±2.25%)-within typical 3.3V ±5% system spec.

TS4431ILT 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:: ±1%

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

TS4431ILT FAQ

1.How can I place an order for TS4431ILT through Aetrix?

Please submit a Request for Quotation (RFQ) for TS4431ILT 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 TS4431ILT reliable?

The price and inventory of TS4431ILT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TS4431ILT is usually 5 days.

3.What payment methods are accepted for TS4431ILT?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TS4431ILT transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TS4431ILT?

TS4431ILT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TS4431ILT 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 TS4431ILT?

For technical support, including TS4431ILT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TS4431ILT requirements.

6.How does Aetrix verify that TS4431ILT is sourced from the original manufacturer or authorized distributors?

All TS4431ILT 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 TS4431ILT meets industry standards.

7.What is the process for return or replacement of TS4431ILT?

All TS4431ILT units undergo pre-shipment inspection (PSI). If there is an issue with TS4431ILT, 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 TS4431ILT part is unused and in its original packaging.

Return procedure for TS4431ILT:

1.Submit a request within 90 days.

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

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