STMicroelectronics

TL431CDT - Adjustable Precision Shunt Regulator | STMicroelectronics

Name: TL431CDT
Brand: STMicroelectronics
Price: 0.12 USD
Availability: InStock

MPN: TL431CDT ✓ Active

In Stock (99,999) Ships in 1-3 business days

2.495 V ±1% Vdss 1 mA to 100 mA Id SOT-23-3 Package

$0.12 USD / Unit

MOQ: 1 |

Volume Pricing

Qty	Unit Price	Extended
1	$0.12	$0.12
10	$0.1	$1.00
100	$0.08	$8.00
500	$0.07	$35.00
1,000	$0.06	$60.00

ℹ️ All prices are in USD

View Datasheet (PDF) View Alternatives

Quantity

Drop-in alternatives for TL431CDT — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.

Quick Comparison Tool — Select alternative parts for side-by-side comparison:

TL431AIDBZR

✅ Drop-In

📦 SOT-23-3

Same SOT-23-3 package and pinout, reference voltage 2.495V ±1%, similar performance

📋 Reference alternative (not in catalog)

TL431QDBZR

✅ Drop-In

📦 SOT-23-3

Same SOT-23-3 package and pinout, automotive grade, reference voltage 2.495V ±1%

📋 Reference alternative (not in catalog)

TL431IDBZR

✅ Drop-In

📦 SOT-23-3

Same SOT-23-3 package and pinout, industrial temperature range, reference voltage 2.495V ±1%

📋 Reference alternative (not in catalog)

TL431CDT Maximum Ratings & Electrical Characteristics

Reference Voltage	2.495 V ±1%
Cathode Voltage Range	2.5 V to 36 V
Cathode Current Range	1 mA to 100 mA
Dynamic Output Impedance	0.2 Ω typical
Output Noise	90 nV/√Hz typical
Operating Temperature Range	-40°C to +105°C
Package	SOT-23-3
Mounting Type	Surface Mount
Reference Voltage Tolerance	±1%
Minimum Cathode Current	1 mA
Maximum Cathode Current	100 mA
RoHS Status	Compliant
Lead-Free	Yes
MSL Level	1
Output Type	Adjustable

TL431CDT Pin Configuration

Pin 1	Cathode (K) — Cathode of the shunt regulator, connected to the load and bias resistor
Pin 2	Reference (REF) — Reference input, connected to the external resistor divider
Pin 3	Anode (A) — Anode of the shunt regulator, typically connected to ground

Safe Operating Area (SOA) & Thermal Characteristics

No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.

Typical Applications

TL431CDT is suitable for 6 applications: Precision Voltage Reference, Error Amplifier in Switching Power Supplies, Voltage Monitoring and Detection, Adjustable Output Voltage Regulator, Battery Charger Control, LED Driver Current Regulation.

🔧

Precision Voltage Reference

The TL431CDT provides a stable 2.495V reference voltage with ±1% accuracy, making it ideal for precision voltage references in analog circuits. Its low dynamic impedance of 0.2Ω ensures excellent load regulation, maintaining a constant output voltage even with varying load currents. In a typical application, the TL431CDT is configured with two external resistors to set the desired output voltage, and a bypass capacitor is added to reduce noise. This configuration is widely used in ADC reference circuits, comparator thresholds, and sensor biasing, where accurate and stable voltages are critical for system performance. The device's low output noise of 90nV/√Hz further enhances its suitability for high-precision measurement and instrumentation systems.

Recommended

TL431AIDBZR (Drop-in alternative with same specifications) LM4040 (Fixed precision reference alternative)

⚡

Error Amplifier in Switching Power Supplies

In switching power supplies, the TL431CDT is used as an error amplifier to regulate the output voltage. It compares the divided output voltage to its internal 2.495V reference and generates a feedback signal that controls the PWM controller. The device's fast response and low output impedance ensure stable loop compensation, minimizing output voltage ripple and improving transient response. For example, in a flyback converter, the TL431CDT is placed on the secondary side, with an optocoupler providing isolation to the primary-side controller. The cathode current range of 1mA to 100mA allows flexible biasing, and the wide cathode voltage range of 2.5V to 36V accommodates various output voltage levels. This application is common in AC-DC adapters, battery chargers, and industrial power supplies.

Recommended

PC817 (Optocoupler for feedback isolation) UC3842 (PWM controller for switching power supply)

🔧

Voltage Monitoring and Detection

The TL431CDT is widely used in voltage monitoring circuits to detect over-voltage or under-voltage conditions. By setting a threshold voltage with external resistors, the device can trigger an alarm or shutdown signal when the monitored voltage crosses the threshold. Its precise 2.495V reference and ±1% tolerance ensure accurate detection, which is critical in battery management systems, power supply supervision, and automotive electronics. The device's low quiescent current and small SOT-23-3 package make it suitable for portable and space-constrained applications. In a typical circuit, the TL431CDT is connected as a comparator, with the reference pin tied to the threshold voltage and the cathode driving a logic signal or LED indicator.

Recommended

TL431AIDBZR (Drop-in alternative) LM393 (Comparator for voltage detection)

⚡

Adjustable Output Voltage Regulator

The TL431CDT can be configured as an adjustable shunt regulator to provide a stable output voltage from 2.5V to 36V. By selecting appropriate external resistors, the output voltage can be set to any value within this range, making it a versatile building block for custom power supplies. The device's low dynamic impedance ensures good load regulation, and its wide cathode current range allows it to drive loads up to 100mA. In a typical application, the TL431CDT is used with a pass transistor to create a linear regulator with higher output current capability. This configuration is common in bench power supplies, battery chargers, and LED drivers, where adjustable and precise output voltages are required.

Recommended

2N2222 (Pass transistor for higher current) TL431AIDBZR (Drop-in alternative)

🔋

Battery Charger Control

The TL431CDT is used in battery charger circuits to regulate the charging voltage and current. Its precise 2.495V reference allows accurate voltage setpoints, ensuring that batteries are charged safely without overcharging. In a typical charger, the TL431CDT is used as an error amplifier to compare the battery voltage to a reference and adjust the charging current accordingly. The device's low output noise and stable operation over temperature make it suitable for various battery chemistries, including Li-ion, NiMH, and lead-acid. The SOT-23-3 package is ideal for compact charger designs, such as those found in portable electronics and power tools.

Recommended

TL431AIDBZR (Drop-in alternative) BQ2000 (Battery charge controller)

💡

LED Driver Current Regulation

The TL431CDT is used in LED driver circuits to regulate the current flowing through LEDs, ensuring consistent brightness and preventing damage from overcurrent. By using the TL431CDT as a shunt regulator, the current can be precisely controlled by setting a reference voltage across a sense resistor. The device's low dynamic impedance and fast response help maintain stable current even with variations in input voltage and LED forward voltage. This application is common in LED lighting, backlighting, and automotive lighting systems. The TL431CDT's small package and low cost make it an attractive choice for high-volume LED driver designs.

Recommended

TL431AIDBZR (Drop-in alternative) LM317 (Adjustable regulator for LED current)

Recommended Products Summary

TL431AIDBZR Drop-in alternative with same specifications Used in: Precision Voltage Reference, Voltage Monitoring and Detection, Adjustable Output Voltage Regulator, Battery Charger Control, LED Driver Current Regulation LM4040 Fixed precision reference alternative Used in: Precision Voltage Reference PC817 Optocoupler for feedback isolation Used in: Error Amplifier in Switching Power Supplies UC3842 PWM controller for switching power supply Used in: Error Amplifier in Switching Power Supplies LM393 Comparator for voltage detection Used in: Voltage Monitoring and Detection 2N2222 Pass transistor for higher current Used in: Adjustable Output Voltage Regulator BQ2000 Battery charge controller Used in: Battery Charger Control LM317 Adjustable regulator for LED current Used in: LED Driver Current Regulation

What is the reference voltage of TL431CDT?

The TL431CDT has a reference voltage of 2.495 V with a tolerance of ±1% over the full operating temperature range. According to the STMicroelectronics TL431 datasheet, this precision reference is stable and accurate, making it suitable for voltage regulation and error amplification.

What is the cathode voltage range of TL431CDT?

The TL431CDT operates with a cathode voltage range of 2.5 V to 36 V. This wide range allows the device to be used in various applications, from low-voltage battery-powered circuits to higher-voltage industrial power supplies.

What is the cathode current range of TL431CDT?

The TL431CDT supports a cathode current range of 1 mA to 100 mA. The minimum cathode current of 1 mA is required for proper regulation, while the maximum of 100 mA defines the current handling capability of the shunt regulator.

What is the dynamic output impedance of TL431CDT?

The TL431CDT has a typical dynamic output impedance of 0.2 Ω. This low impedance ensures excellent load regulation, meaning the output voltage remains stable even when the load current varies.

What is the output noise of TL431CDT?

The TL431CDT has a typical output noise of 90 nV/√Hz. This low noise characteristic makes it suitable for precision analog applications where a clean reference voltage is critical.

What is the operating temperature range of TL431CDT?

The TL431CDT operates over a temperature range of -40°C to +105°C. This wide range ensures reliable performance in both industrial and automotive environments.

What is the package type of TL431CDT?

The TL431CDT is offered in the SOT-23-3 package, which is a small surface-mount package with three leads. This package is ideal for space-constrained PCB designs and is widely used in consumer and industrial electronics.

Is TL431CDT RoHS compliant?

Yes, the TL431CDT is RoHS compliant and lead-free. According to the STMicroelectronics product page, the device meets the requirements of the RoHS directive, making it suitable for use in products sold in the European Union and other regions with similar regulations.

What is the difference between TL431CDT and TL431CLP?

The TL431CDT is in the SOT-23-3 package, while the TL431CLP is in the TO-92 package. Both have the same electrical specifications, but the package difference affects the PCB footprint and thermal performance. The SOT-23-3 is surface-mount, while the TO-92 is through-hole.

Can TL431CDT be used as a voltage reference?

Yes, the TL431CDT is commonly used as a precision voltage reference. Its 2.495 V reference voltage with ±1% tolerance provides a stable and accurate reference for analog-to-digital converters, comparators, and other precision circuits.

Can TL431CDT be used in switching power supplies?

Yes, the TL431CDT is widely used as an error amplifier in switching power supplies. It compares the output voltage to the internal reference and provides feedback to the PWM controller, ensuring stable and accurate output regulation.

What is the minimum cathode current required for TL431CDT?

The TL431CDT requires a minimum cathode current of 1 mA to operate correctly. If the cathode current falls below this value, the device may not regulate properly, so an external resistor must be used to ensure adequate bias current.

What is the maximum cathode current of TL431CDT?

The TL431CDT can handle a maximum cathode current of 100 mA. Exceeding this limit can damage the device, so the external resistor should be chosen to keep the current within the specified range.

Where can I buy TL431CDT online?

The TL431CDT is available from major distributors such as DigiKey and Mouser. As of 2026-08-05, the price for a single unit is approximately $0.12, with volume discounts available for larger quantities. Check current stock and pricing on their websites.

What is the price of TL431CDT?

As of 2026-08-05, the TL431CDT is priced at approximately $0.12 per unit for single quantities, $0.10 for 10 units, $0.08 for 100 units, $0.07 for 500 units, and $0.06 for 1000 units. Prices may vary by distributor and order quantity.

What is the lead time for TL431CDT?

The lead time for TL431CDT is typically 2-4 weeks from major distributors like DigiKey and Mouser, depending on stock availability. For large orders, it is advisable to check with the distributor for current lead times.

Is TL431CDT in stock?

As of 2026-08-05, the TL431CDT is generally in stock at major distributors such as DigiKey and Mouser. However, stock levels can change rapidly, so it is recommended to check the distributor's website for real-time availability.

What is the best drop-in replacement for TL431CDT?

The best drop-in replacement for TL431CDT is the TL431AIDBZR from Texas Instruments, which is also in the SOT-23-3 package and has the same pinout and electrical specifications. Other drop-in alternatives include the TL431QDBZR and the TL431IDBZR, both in SOT-23-3.

Can TL431AIDBZR replace TL431CDT?

Yes, the TL431AIDBZR from Texas Instruments is a drop-in replacement for the TL431CDT. Both are in the SOT-23-3 package, have the same pinout, and offer similar electrical specifications, including a 2.495 V reference voltage and ±1% tolerance.

Where can I download the TL431CDT datasheet PDF?

The TL431CDT datasheet PDF can be downloaded from the STMicroelectronics website at https://www.st.com/resource/en/datasheet/tl431.pdf. The datasheet contains detailed specifications, application circuits, and package information.

Where can I find the TL431CDT pinout?

The TL431CDT pinout is available in the STMicroelectronics datasheet. In the SOT-23-3 package, pin 1 is the cathode (K), pin 2 is the reference (REF), and pin 3 is the anode (A). The pinout is also shown on the product page and in the datasheet.

Engineering reference data for TL431CDT — comparison, design guidance, and compliance information.

Selection Guide

Choose the TL431CDT when you need a precision shunt regulator in a compact SOT-23-3 package for general-purpose applications. It offers a wide operating temperature range of -40°C to +105°C, making it suitable for industrial environments. If you require automotive qualification, select the TL431QDBZR instead. For applications with a lower maximum temperature of +85°C, the TL431IDBZR is a cost-effective alternative. All three parts are drop-in compatible, so you can switch between them without PCB changes. The TL431CDT is ideal for voltage references, error amplifiers, and voltage monitoring in power supplies, battery chargers, and LED drivers.

Comparison with Alternatives

Parameter	This Product	TL431AIDBZR	TL431QDBZR	TL431IDBZR
Package	SOT-23-3	SOT-23-3	SOT-23-3	SOT-23-3
Reference Voltage	2.495 V ±1%	2.495 V ±1%	2.495 V ±1%	2.495 V ±1%
Cathode Voltage Range	2.5 V to 36 V	2.5 V to 36 V	2.5 V to 36 V	2.5 V to 36 V
Cathode Current Range	1 mA to 100 mA	1 mA to 100 mA	1 mA to 100 mA	1 mA to 100 mA
Dynamic Output Impedance	0.2 Ω typical	0.2 Ω typical	0.2 Ω typical	0.2 Ω typical
Output Noise	90 nV/√Hz	90 nV/√Hz	90 nV/√Hz	90 nV/√Hz
Operating Temperature Range	-40°C to +105°C	-40°C to +105°C	-40°C to +125°C	-40°C to +85°C
Automotive Grade	No	No	Yes (AEC-Q100)	No

Key Differentiators

Wide operating temperature range of -40°C to +105°C (vs TL431IDBZR)
Automotive grade option available (vs TL431QDBZR)
Low output noise of 90 nV/√Hz (vs TL431AIDBZR)

Design Notes

Ensure the cathode current is at least 1 mA for proper regulation. If the current is too low, the TL431CDT may not regulate correctly, leading to output voltage drift. Use an appropriate bias resistor to set the current within the 1 mA to 100 mA range.

Place a bypass capacitor (typically 0.1 µF) close to the cathode pin to ground to reduce noise and improve stability. For high-frequency applications, a small resistor in series with the capacitor may be needed to prevent oscillation.

The SOT-23-3 package has limited thermal dissipation capability. If the TL431CDT is used at high cathode currents (e.g., 100 mA) with a large voltage drop, power dissipation can be significant. Ensure adequate PCB copper area for heat sinking to keep the junction temperature within limits.