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

STMicroelectronics TL1431CZ-AP

Name: TL1431CZ-AP
Brand: STMicroelectronics
SKU: TL1431CZ-AP
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL1431CZ-AP

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

Package:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Datasheet:: TL1431CZ-AP.pdf

Description:: IC VREF SHUNT ADJ 0.4% TO92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

TL1431CZ-AP from STMicroelectronics is an adjustable shunt voltage reference IC with 0.4% initial voltage precision, 2.5 V to 36 V programmable output via two external resistors, and guaranteed operation from −20 °C to +70 °C. It delivers 1–100 mA sink current capability with typical dynamic impedance of 0.22 Ω and supports precision feedback in isolated DC-DC converters and linear regulator circuits.

For engineers reviewing the TL1431CZ-AP datasheet, TL1431CZ-AP pinout, TL1431CZ-AP application, or TL1431CZ-AP equivalent, key selection considerations include its TO-92 package mechanical compatibility, temperature-stable reference input voltage (2.490–2.510 V at 25 °C), low off-state cathode current (≤500 nA), and automotive-grade thermal performance validation per AEC-Q100 for extended-range variants.

Technical Context

The TL1431CZ-AP implements a bandgap-based reference core with internal error amplifier and NPN pass transistor, configured as a 3-terminal shunt regulator. Its reference input (REF) senses voltage across an external resistor divider, while cathode (K) sinks current to maintain regulation - enabling direct replacement of Zener diodes in high-precision feedback paths.

It operates over a wide cathode-to-anode voltage range (V_KA = V_REF to 36 V) with minimal load regulation error (±1.1 mV/V) and maintains stable output impedance (0.2–0.5 Ω) across 1–100 mA cathode current and −20 °C to +70 °C ambient temperature.

Key Specifications

Parameter	Value and Actual Design Meaning
Reference voltage (V_REF)	2.490–2.510 V at 25 °C - sets minimum programmable output (2.5 V) and defines accuracy baseline for external resistor ratio design
Voltage precision	±0.4% over temperature - ensures ≤14.4 mV total deviation across −20 °C to +70 °C for closed-loop stability in power supplies
Sink current range	1–100 mA - supports direct drive of optocoupler LEDs or error amplifier bias networks without external buffering
Dynamic impedance	0.2–0.5 Ω - provides low AC impedance path for high-frequency noise rejection in feedback loops up to 1 kHz
Reference input current (I_REF)	1.5–3 µA - enables high-impedance voltage divider design (e.g., 10 kΩ/10 kΩ) with <0.03% loading error
Temperature coefficient	±13 ppm/°C - contributes ≤0.33 mV drift over full operating range, critical for industrial-grade voltage monitoring
Off-state cathode current	≤500 nA - minimizes standby power loss in battery-backed or energy-harvesting systems

Pinout & Package

TL1431CZ-AP uses the TO-92 plastic package (bulk or ammopack format), with 3 leads in standard through-hole configuration. Pin 1 is Anode (A), Pin 2 is Cathode (K), and Pin 3 is Reference (REF), as confirmed by Figure 1 (top view) in ST DocID5286 Rev 9.

Pin/Terminal	Circuit Role	Design Meaning
Anode (Pin 1)	Current return path to ground or supply rail	Connected to system ground or low-side return; must handle full cathode current plus reference current
Cathode (Pin 2)	Regulated current sink output	Drives optocoupler LED or feedback network; voltage at this node equals programmed output minus drop across series resistor
Reference (Pin 3)	High-impedance voltage sense input	Connects to resistor divider midpoint; draws only 1.5–3 µA, enabling >1 MΩ divider designs without accuracy penalty

Key Features

Feature	Design Value
Adjustable output range	2.5 V to 36 V - achieved with two external resistors; eliminates need for multiple fixed-voltage references
Low dynamic impedance	0.22 Ω typical - improves transient response and reduces output ripple in switching regulator feedback paths
Guaranteed temp. stability	Specified over −20 °C to +70 °C - ensures consistent regulation in commercial-grade power modules and embedded supplies
High ESD robustness	2000 V HBM - protects against handling damage during PCB assembly and field service
Low quiescent current	≤3 µA reference input - enables use in ultra-low-power applications such as sensor signal conditioning and battery monitors

Applications

Isolated Flyback Converter Feedback

Programmable Linear Regulator

Use Scenario: Provides precise voltage feedback across transformer isolation barrier using optocoupler coupling.

IC Role / Device Role / Timing Role: Shunt reference generating stable 2.5 V reference at secondary side; cathode drives optocoupler LED current proportional to output error.

Use Value: Enables ±1% output regulation over line/load/temperature with no secondary-side LDO required.

Use Scenario: Sets output voltage of adjustable linear regulator (e.g., LM317-based) with improved accuracy vs. internal reference.

IC Role / Device Role / Timing Role: External precision reference replacing LM317's 1.25 V bandgap; REF pin connected to ADJ node, cathode to output.

Use Value: Achieves 0.4% output tolerance vs. ±2% typical with internal reference, reducing calibration overhead.

Overvoltage Protection Circuit

Battery Voltage Monitor

Use Scenario: Triggers shutdown when input voltage exceeds safe threshold in DC input stages.

IC Role / Device Role / Timing Role: Configured as comparator with hysteresis; REF pin biased to trip point, cathode drives MOSFET gate via pull-up.

Use Value: Delivers fast, repeatable 2.5–36 V trip thresholds with <10 µs response time and no external op-amp needed.

Use Scenario: Monitors Li-ion or lead-acid battery pack voltage for charge termination or low-battery warning.

IC Role / Device Role / Timing Role: Reference input tied to scaled-down battery voltage; cathode current indicates threshold crossing via microcontroller ADC or GPIO.

Use Value: Consumes <3 µA total, enabling months of operation on coin cell; supports 3.0–4.2 V range with 1% accuracy.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TL431ACZ-AP	0.25% initial precision, same TO-92 package and pinout	Higher accuracy required in metrology or precision DAC references	Select when tighter V_REF tolerance (±0.25%) is mandatory and cost premium is acceptable
TL1431IZ-AP	−40 °C to +105 °C operating range, identical electrical specs	Industrial or extended-temperature environments (e.g., motor drives, outdoor equipment)	Choose for wider ambient operation where TL1431CZ-AP's −20 °C lower limit is insufficient

Compared with TL1431CZ-AP, TL431ACZ-AP offers higher initial accuracy but no temperature range extension, while TL1431IZ-AP maintains identical precision but guarantees functionality down to −40 °C - making them non-interchangeable without verifying thermal and tolerance requirements.

Availability

TL1431CZ-AP is available at Aetrix Electronics and suitable for isolated DC-DC converter feedback, programmable linear regulator setpoints, and overvoltage protection circuits requiring stable component supply and long-term manufacturability.

Supply support for TL1431CZ-AP 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 sensing solutions for industrial, automotive, and consumer markets.

The TL1431 product line delivers precision shunt references optimized for power supply feedback, voltage monitoring, and programmable regulation - targeting cost-sensitive, high-reliability applications where Zener replacement and accuracy upgrades are needed.

FAQ

What is the maximum cathode-to-anode voltage for TL1431CZ-AP?

The absolute maximum cathode-to-anode voltage (V_KA) is 37 V, per Table 1 in ST DocID5286 Rev 9. Continuous operation above 36 V violates the recommended operating condition and risks permanent device failure due to junction breakdown or thermal runaway.

Can TL1431CZ-AP be used in place of a Zener diode?

Yes - TL1431CZ-AP replaces Zener diodes in shunt regulator configurations with superior performance: 0.4% initial accuracy vs. ±5% typical for Zeners, 0.22 Ω dynamic impedance vs. 10–100 Ω, and stable operation across 1–100 mA without knee voltage variation.

Does TL1431CZ-AP require external capacitors for stability?

No external capacitor is required for basic DC regulation. However, Figure 20 shows stability degradation with >100 nF capacitive loads; a 1 nF ceramic capacitor across REF–ANODE is recommended for high-frequency noise suppression in switching applications.

What is the minimum cathode current needed for regulation?

The minimum cathode current (I_min) is 0.5–1.0 mA depending on temperature, per Table 4. Below this threshold, the device exits regulation mode and V_KA rises toward the unregulated input voltage - critical for optocoupler LED bias design.

TL1431CZ-AP Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Package/Case:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Series:: -

Packaging:: Cut Tape (CT)

Product Status:: Active

Reference Type:: Shunt

Output Type:: Adjustable

Voltage - Output (Min/Fixed):: 2.5V

Voltage - Output (Max):: 36 V

Current - Output:: 100 mA

Tolerance:: ±0.4%

Temperature Coefficient:: 90ppm/°C

Noise - 0.1Hz to 10Hz:: -

Noise - 10Hz to 10kHz:: -

Voltage - Input:: -

Current - Supply:: -

Current - Cathode:: 1 mA

Operating Temperature:: -20°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

TL1431CZ-AP FAQ

1.How can I place an order for TL1431CZ-AP through Aetrix?

Please submit a Request for Quotation (RFQ) for TL1431CZ-AP 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 TL1431CZ-AP reliable?

The price and inventory of TL1431CZ-AP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL1431CZ-AP is usually 5 days.

3.What payment methods are accepted for TL1431CZ-AP?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL1431CZ-AP transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL1431CZ-AP?

TL1431CZ-AP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL1431CZ-AP 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 TL1431CZ-AP?

For technical support, including TL1431CZ-AP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL1431CZ-AP requirements.

6.How does Aetrix verify that TL1431CZ-AP is sourced from the original manufacturer or authorized distributors?

All TL1431CZ-AP 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 TL1431CZ-AP meets industry standards.

7.What is the process for return or replacement of TL1431CZ-AP?

All TL1431CZ-AP units undergo pre-shipment inspection (PSI). If there is an issue with TL1431CZ-AP, 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 TL1431CZ-AP part is unused and in its original packaging.

Return procedure for TL1431CZ-AP:

1.Submit a request within 90 days.

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

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