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

STMicroelectronics TL431ACZ-AP

Name: TL431ACZ-AP
Brand: STMicroelectronics
SKU: TL431ACZ-AP
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TL431ACZ-AP

Manufacturer:: STMicroelectronics

Category:: Voltage Reference

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

Datasheet:: TL431ACZ-AP.pdf

Description:: IC VREF SHUNT ADJ 1% TO92-3

Quantity:: RFQ Add To RFQ list

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Inventory:1,491

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Product details

Overview

TL431ACZ-AP from STMicroelectronics is an AEC-Q100 qualified adjustable shunt voltage reference with 1% initial voltage accuracy, operating across –40 °C to +125 °C for automotive power supply feedback and industrial regulation. It delivers 2.5–36 V programmable output via two external resistors, supports 1–100 mA sink current, and exhibits 0.22 Ω typical dynamic impedance.

For engineers reviewing the TL431ACZ-AP datasheet, TL431ACZ-AP pinout, TL431ACZ-AP application, or TL431ACZ-AP equivalent, key selection criteria include automotive temperature range compliance, shunt reference stability under varying load/line conditions, cathode current capability in feedback loops, and TO-92 package suitability for cost-sensitive board-level voltage setting.

Technical Context

The TL431ACZ-AP implements a precision bandgap-based reference amplifier driving an NPN transistor output stage in a three-terminal shunt configuration. Its internal 2.5 V reference is buffered and compared against external resistor-divided cathode voltage to regulate sink current.

It operates as a programmable zener replacement: cathode-anode voltage is set by R1/R2 ratio per V_OUT = V_REF(1 + R1/R2), with regulation maintained only when cathode current remains ≥0.5 mA and ≤100 mA across the full automotive temperature range.

Key Specifications

Parameter	Value and Actual Design Meaning
Reference Voltage	2.47–2.52 V at 25 °C (1% tolerance; sets minimum programmable output at 2.5 V)
Output Voltage Range	2.5–36 V (programmable via external R1/R2; enables wide-range feedback in SMPS and LDOs)
Sink Current Range	1–100 mA (supports direct drive of optocoupler LEDs or error amplifier inputs without buffering)
Dynamic Impedance	0.22 Ω typical (ensures <10 mV output deviation under 10 mA load transients)
Temp. Range	–40 °C to +125 °C (AEC-Q100 qualified; validated for engine control, body electronics, and ADAS power rails)
Voltage Drift	±15 mV over full temp. range (≤0.06% of 2.5 V ref; critical for stable closed-loop regulation)
Cathode-Anode Max. Voltage	37 V (defines absolute upper limit for input rail in shunt regulator configurations)

Pinout & Package

TL431ACZ-AP uses the TO-92 plastic package (3-pin, through-hole), with standardized pinout: Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Reference (Ref). This compact, low-cost package supports manual assembly and wave soldering in automotive and industrial PCBs.

Pin/Terminal	Circuit Role	Design Meaning
Anode (Pin 1)	Current return path	Connected to system ground or low-side return; completes shunt current loop
Cathode (Pin 2)	Regulated output node	Connected to feedback point (e.g., SMPS output); sinks current to maintain V_REF at Ref pin
Reference (Pin 3)	Precision voltage sense input	Internally biased at 2.47–2.52 V; externally connected to resistor divider midpoint for output programming

Key Features

Feature	Design Value
AEC-Q100 qualification	Validated for automotive applications including powertrain and chassis systems per stress test requirements
1% initial voltage accuracy	Reduces need for post-production trimming in factory calibration of power supplies
0.22 Ω dynamic impedance	Minimizes output voltage perturbation during fast load steps in DC-DC feedback paths
–40 °C to +125 °C operation	Enables use in under-hood ECUs and battery management modules without derating
TO-92 package compatibility	Supports legacy board designs and cost-sensitive volume production with standard through-hole assembly

Applications

Automotive Power Supply Feedback

Industrial SMPS Voltage Regulation

Use Scenario: Closed-loop feedback in 12 V/48 V automotive DC-DC converters supplying infotainment and ADAS ECUs.

IC Role / Device Role / Timing Role: Shunt reference providing precise voltage setpoint to optocoupler-driven primary-side controller.

Use Value: Maintains ±1% output accuracy across temperature and line variations, meeting ISO 16750-2 electrical load dump requirements.

Use Scenario: Output voltage programming in isolated flyback converters for PLC I/O modules and motor drives.

IC Role / Device Role / Timing Role: Adjustable reference generating error signal for secondary-side regulation via TL431-based optocoupler interface.

Use Value: Enables single-BOM support for multiple output voltages (5 V, 12 V, 24 V) using resistor changes only-no PCB redesign.

Programmable Precision Zener Replacement

Overvoltage Protection Threshold

Use Scenario: Replacing fixed-voltage zener diodes in high-reliability industrial power rails where 2.5–36 V flexibility is required.

IC Role / Device Role / Timing Role: Three-terminal shunt regulator acting as programmable breakdown element with superior stability vs. discrete zeners.

Use Value: Eliminates inventory of multiple zener values; achieves <0.1% drift vs. >5% typical for 5% zeners over temperature.

Use Scenario: Threshold detection in battery management systems monitoring 12 V lead-acid or 48 V LiFePO₄ packs for overvoltage shutdown.

IC Role / Device Role / Timing Role: Reference input to comparator circuit triggering MOSFET gate cutoff when cell voltage exceeds safe limit.

Use Value: Provides repeatable 14.4 V or 57.6 V trip points with <±15 mV tolerance-critical for cell longevity and safety compliance.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TL431CZ-AP	2% initial accuracy (2.44–2.55 V), 0 °C to +70 °C rating	Not qualified for automotive or extended industrial environments	Select only for cost-sensitive commercial-grade power supplies with ambient temperature <70 °C
TL431AIZ-AP	1% accuracy, –40 °C to +105 °C rating, same TO-92 package	Lacks AEC-Q100 qualification; not validated for automotive stress testing	Acceptable for non-automotive industrial applications requiring wider temp. range than TL431CZ but no AEC-Q100 mandate

Compared with TL431CZ-AP and TL431AIZ-AP, TL431ACZ-AP uniquely combines AEC-Q100 qualification, 1% accuracy, and full –40 °C to +125 °C operation-making it the only choice for production automotive systems requiring both reliability certification and tight voltage tolerance.

Availability

TL431ACZ-AP is available at Aetrix Electronics and suitable for automotive power supply feedback, industrial SMPS regulation, and programmable overvoltage protection requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for TL431ACZ-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 microcontrollers, power ICs, sensors, and analog components for automotive, industrial, and consumer markets.

TL431ACZ-AP belongs to ST's precision analog voltage reference product line, engineered specifically for robust, high-accuracy feedback in safety-critical automotive power systems and industrial control equipment.

FAQ

What is the minimum cathode current required for regulation in TL431ACZ-AP?

The TL431ACZ-AP requires a minimum cathode current of 0.5 mA to maintain regulation across its full –40 °C to +125 °C operating range. Below this threshold, the device exits regulation and output voltage becomes undefined. This value is confirmed in Table 3 of ST's DocID4467 Rev 17, under "Imin Minimum cathode current for regulation" for TL431AC grade.

Can TL431ACZ-AP be used in place of TL431CZ-AP in existing designs?

TL431ACZ-AP is pin-compatible and functionally identical to TL431CZ-AP except for tighter 1% voltage accuracy and extended –40 °C to +125 °C operation with AEC-Q100 qualification. Electrical parameters including dynamic impedance, reference current, and thermal resistance match within spec limits. No layout or schematic change is needed for drop-in replacement where enhanced accuracy and temperature range are beneficial.

What is the maximum power dissipation for TL431ACZ-AP in TO-92 package?

In TO-92 package, TL431ACZ-AP has a junction-to-ambient thermal resistance (R_thJA) of 200 °C/W. With a maximum junction temperature of 150 °C and ambient up to +125 °C, maximum continuous power dissipation is calculated as (150 °C − 125 °C)/200 °C/W = 125 mW. Derating is required above +70 °C ambient per Figure 22 in the datasheet.

Does TL431ACZ-AP require external compensation for stability?

No external compensation is required for basic shunt regulator operation. The device is internally compensated and stable with capacitive loads up to 1 nF, as verified in Figure 21 of the datasheet. For applications with >1 nF output capacitance or high-frequency feedback loops, a series resistor (typically 1–10 Ω) between cathode and capacitor improves phase margin without affecting DC accuracy.

TL431ACZ-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):: 2.495V

Voltage - Output (Max):: 36 V

Current - Output:: 100 mA

Tolerance:: ±1%

Temperature Coefficient:: -

Noise - 0.1Hz to 10Hz:: -

Noise - 10Hz to 10kHz:: -

Voltage - Input:: -

Current - Supply:: -

Current - Cathode:: 600 µA

Operating Temperature:: 0°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

TL431ACZ-AP FAQ

1.How can I place an order for TL431ACZ-AP through Aetrix?

Please submit a Request for Quotation (RFQ) for TL431ACZ-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 TL431ACZ-AP reliable?

The price and inventory of TL431ACZ-AP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TL431ACZ-AP is usually 5 days.

3.What payment methods are accepted for TL431ACZ-AP?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TL431ACZ-AP transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TL431ACZ-AP?

TL431ACZ-AP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TL431ACZ-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 TL431ACZ-AP?

For technical support, including TL431ACZ-AP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TL431ACZ-AP requirements.

6.How does Aetrix verify that TL431ACZ-AP is sourced from the original manufacturer or authorized distributors?

All TL431ACZ-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 TL431ACZ-AP meets industry standards.

7.What is the process for return or replacement of TL431ACZ-AP?

All TL431ACZ-AP units undergo pre-shipment inspection (PSI). If there is an issue with TL431ACZ-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 TL431ACZ-AP part is unused and in its original packaging.

Return procedure for TL431ACZ-AP:

1.Submit a request within 90 days.

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

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