SLKORMICRO TL431: 36V Adjustable Three‑Terminal Shunt Voltage Reference, SOT‑23 / TO‑92 Package

TL431 is a three-terminal adjustable shunt voltage reference device released by SLKORMICRO. It delivers excellent temperature stability with typical dynamic output impedance of 0.2Ω. Its output voltage can be adjusted up to 36V, and it supports shunt operating current from 1mA to 100mA. Featuring low output noise and fast on-state response, it is available in SOT-23 and TO-92 packages. It can replace zener diodes in most circuits, and is widely used in voltage regulation and current-limiting circuit designs. Its operating junction temperature ranges from -40℃ to +125℃, suitable for building reference voltage circuits in industrial and consumer electronics.

1. Core Product Parameters

1. Voltage parameters: Maximum cathode voltage 36V; typical reference input voltage 2.5V, minimum 2.475V, maximum 2.525V.
2. Current parameters: Continuous cathode current range -100mA ~ +150mA; reference input current range 0.05mA-10mA; minimum cathode current for regulation typical 0.45mA, maximum 1.0mA; off-state cathode current typical 0.05A, maximum 1.0A.
3. Impedance parameter: Typical dynamic output impedance 0.2Ω, maximum 0.5Ω.
4. Power dissipation and thermal parameters: Power dissipation 300mW for SOT-23 package, junction-to-ambient thermal resistance 417℃/W; power dissipation 500mW for TO-92 package, junction-to-ambient thermal resistance 250℃/W.
5. Temperature parameters: Operating junction temperature -40℃ ~ +125℃; storage temperature -65℃ ~ +150℃; typical equivalent temperature coefficient 50ppm/℃ across full temperature range.
6. Package information: SOT-23 package with marking 431, reel packing, 3000pcs per reel; TO-92 part TL431L, bulk bag packing, 1000pcs per bag.
7. Pin assignment: For SOT-23, pin1 is reference, pin2 is cathode, pin3 is anode. For TO-92, pin1 is reference, pin2 is anode, pin3 is cathode.

2. Key Product Features

1. Adjustable output voltage up to 36V, meeting various reference voltage requirements.
2. Low dynamic output impedance with typical value of 0.2Ω, so reference voltage is slightly disturbed by load current.
3. Wide shunt operating current range from 1mA to 100mA.
4. Low output noise voltage for high-purity reference output.
5. Fast on-state response for sensitive dynamic circuit regulation.
6. Effective temperature compensation across full operating temperature range with stable temperature drift performance.
7. Direct replacement for conventional zener diodes with good component compatibility.
8. Two package options including SOT-23 surface-mount and TO-92 through-hole for different PCB layout requirements.

3. Main Application Fields

1. Shunt regulator circuits for basic reference voltage stabilization loops.
2. High-current shunt regulator circuits for voltage stabilization under high-current working conditions.
3. Precision current limiter for accurate current-limit protection of circuits.

4. Engineering Design Recommendations

1. A capacitor with value higher than 0.1μF is recommended to connect at the device output pin to smooth output voltage and suppress voltage fluctuation.
2. The filter capacitor shall be placed as close as possible to the device output pin, with the shortest wiring path to ground to reduce interference caused by parasitic parameters of traces.
3. The cathode operating current shall exceed the minimum cathode current for regulation to guarantee normal regulating operation of the device.
4. Actual power dissipation of the device shall be controlled below the maximum rated power dissipation of corresponding package to prevent overheating damage.
5. Pay attention to pin arrangement difference between two packages. The anode and cathode pin sequence of SOT-23 differs from TO-92. Verify pin definition during PCB layout and soldering to avoid wrong wiring.
6. The reference terminal draws input current. Its influence on output voltage shall be considered when selecting voltage divider resistors.

5. Product Summary

TL431 is a mature three-terminal adjustable shunt voltage reference chip. It features wide voltage adjustment range, favorable temperature stability and low dynamic impedance, together with broad operating current range. It supports both surface-mount and through-hole packages, and can easily replace zener diodes for voltage regulation and current-limiting circuits. In practical engineering design, attention shall be paid to filter capacitor placement, minimum operating current, power dissipation limit and pin differences of different packages. When operating conditions are satisfied, the chip delivers stable and reliable reference voltage, and fits various circuit systems such as consumer electronics and industrial control.

About Slkor：

Slkor has research and development offices in Busan, South Korea, Beijing, China, and Suzhou, China. Most of the wafer manufacturing and packaging and testing are carried out within China. The company employs and collaborates with individuals and organizations worldwide, with a laboratory for product performance and reliability testing and a central warehouse located at its headquarters in Shenzhen. Slkor has filed for over a hundred invention patents, offers more than 2,000 product models, and serves over ten thousand customers globally. Its products are exported to countries and regions including Europe, the Americas, Southeast Asia, and the Middle East, making it one of the rapidly growing semiconductor companies in recent years. With well-established management systems and streamlined workflows, Slkor has rapidly enhanced the brand awareness and reputation of its "SLKOR" brand through its outstanding quality and standardized services. Its product range includes three major series: diodes, transistors, and power devices, with recent introductions of new products such as Hall elements and analog devices, expanding its presence in sensors, Risc-v microcontrollers, and other product categories.

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