AMS1117-LDO 3.3V Linear Voltage Regulators SOT-89

AMS1117-LDO 3.3V Linear Voltage Regulators SOT-89 provides a reliable and efficient solution for stepping down higher DC voltages to a stable 3.3V output required by modern microelectronics. This low dropout (LDO) regulator maintains precise voltage regulation even when the input voltage sits just above the target output. Consequently, it serves as a staple component for powering ESP8266 modules, STM32 microcontrollers, and various sensors that demand a clean power rail. The SOT-89 package offers a balance between a compact footprint and improved thermal dissipation compared to smaller surface-mount alternatives. Furthermore, the integrated protection circuitry ensures the longevity of both the regulator and the connected load by preventing damage from overcurrent or overheating. Therefore, you should utilize the AMS1117-3.3V to achieve stable power delivery in space-constrained printed circuit board designs.

Key Features:

• Low Dropout Voltage: The device operates with a small voltage differential, typically requiring only 1.1V to 1.3V above the output to maintain regulation.
• Fixed 3.3V Output: Provides a factory-trimmed, high-accuracy 3.3V supply, eliminating the need for external adjustment resistors.
• Thermal Overload Protection: Includes internal circuitry that shuts down the device if the junction temperature exceeds safe limits.
• Current Limiting: Features built-in short-circuit protection to prevent catastrophic failure during fault conditions.
• SOT-89 Package: Offers a surface-mount design with a large thermal tab for effective heat transfer to the PCB copper.

Technical Specifications:

• Output Voltage: 3.3 V (±1.5% accuracy)
• Maximum Input Voltage: 15 V (Absolute Maximum)
• Maximum Output Current: 1 A (Peak), 800 mA (Continuous under ideal thermal conditions)
• Dropout Voltage: ≈ 1.1 V at 800 mA load
• Quiescent Current: ≈ 5 mA (Typical)
• Line Regulation: 0.2% maximum
• Load Regulation: 0.4% maximum
• Operating Junction Temperature: −40°C to +125°C

Mechanical Specifications:

• Package Type: SOT-89 (Surface Mount Device)
• Lead Finish: Matte Tin / Lead-Free
• Encapsulation: Molded Plastic Case
• Thermal Resistance: High thermal conductivity via the central collector/output tab.

Dimensions:

• Body Length: ≈ 4.5 mm
• Body Width: ≈ 2.5 mm (excluding leads)
• Total Height: ≈ 1.5 mm
• Tab Width: ≈ 1.7 mm
• Pin Pitch: 1.5 mm

Pinout and Wiring:

• Pin 1 (GND/ADJ): Connect this pin directly to the common circuit ground.
• Pin 2 / Tab (Vout): This is the regulated 3.3V output; however, ensure you use a 10µF to 22µF tantalum or electrolytic capacitor for stability.
• Pin 3 (Vin): Connect the unregulated input voltage (typically 5V to 12V) to this pin.
• Wiring Note: Always place input and output capacitors as close to the pins as possible to minimize oscillation and noise.

Datasheet Reference:

• Download AMS1117 Series LDO Datasheet

Commonly Used in:

• Arduino and Raspberry Pi Projects: Providing 3.3V power to peripheral sensors and shields from a 5V rail.
• Battery Management Systems: Regulating Li-ion battery voltages for low-power microcontrollers.
• Network Hardware: Supplying steady power to Ethernet controllers and Wi-Fi chips.

Applications:

• Post-Regulator for Switching Supplies: Filtering high-frequency noise from DC-DC converters to provide a clean analog rail.
• Active SCSI Terminators: Providing precise termination voltages for legacy data interfaces.
• Variable Power Supplies: Serving as a fixed reference within larger adjustable voltage circuits.
• IoT Edge Devices: Powering wireless modules where efficiency and small size are paramount.

Equivalent Models:

• LM1117-3.3: The industry-standard equivalent from various manufacturers like Texas Instruments.
• LD1117V33: STMicroelectronics’ version of the 1117 series, sharing similar electrical characteristics.
• NCP1117ST33T3G: ON Semiconductor alternative offering comparable dropout and current ratings.

Package Includes:

• 1 x AMS1117-LDO 3.3V Linear Voltage Regulator SOT-89