LD1117S33TR: Low drop positive voltage regulator, 3.3V, 800mA, SOT-223

The LD1117S33TR is part of the LD1117 series of low drop voltage regulators capable of delivering up to 800 mA of output current. This particular model offers a fixed output voltage of 3.3V, which is common for powering digital circuits. The regulator is designed to maintain high efficiency and thermal performance in a compact SOT-223 package, making it suitable for space-constrained applications.

The LD1117S33TR features a low dropout voltage of approximately 1V, ensuring efficient operation even when the input voltage is close to the output voltage. It includes internal current and thermal limit protections, safeguarding the device and the load from excessive current and overheating. The device's output voltage tolerance is tightly controlled, within ±1% at 25°C, due to on-chip trimming.

This voltage regulator is designed for use in applications requiring stable and reliable power supply, such as in digital systems, microcontrollers, and peripheral devices. Its low dropout characteristic and compact form factor make it an ideal choice for battery-operated devices and portable electronics.

Key Specifications and Features

  • Output Voltage: 3.3V
  • Output Current: Up to 800mA
  • Dropout Voltage: 1V (typical)
  • Output Voltage Tolerance: ±1% at 25°C
  • Package: SOT-223
  • Internal Protections: Current and thermal limit
  • Supply Voltage Rejection: 75 dB (typical)

LD1117S33TR Datasheet

LD1117S33TR datasheet (PDF)

LD1117S33TR Substitutes
Equivalent alternate parts that may serve as a substitute for LD1117S33TR, most popular parts first


  • Digital circuits
  • Microcontroller power supply
  • Peripheral devices
  • Battery-operated devices
  • Portable electronics


Voltage Regulator

General information

Voltage regulators are electronic components designed to maintain a constant voltage level. They play a crucial role in protecting sensitive electronic circuits by stabilizing the power supply and preventing voltage fluctuations that can cause damage or erratic behavior. Voltage regulators are widely used in various applications, from consumer electronics to industrial systems, to ensure reliable operation of electronic devices.

When selecting a voltage regulator, several factors must be considered, including the output voltage and current requirements, dropout voltage, thermal performance, and package size. The output voltage and current define the power delivery capabilities of the regulator, while the dropout voltage indicates the minimum difference between the input and output voltages for the regulator to maintain the specified output voltage. Thermal performance is important for determining how well the regulator can dissipate heat during operation, and the package size is a key consideration for space-constrained applications.

Low dropout (LDO) regulators, like the LD1117 series, offer the advantage of operating efficiently with a small input-output voltage differential, making them suitable for applications where battery life is a priority. They typically include features such as overcurrent protection, thermal shutdown, and low quiescent current, enhancing the safety and efficiency of the device.

In summary, voltage regulators are fundamental components in electronic systems, ensuring stable power supply and enhancing the reliability and performance of electronic devices. The choice of a voltage regulator should be based on the specific requirements of the application, including power needs, space constraints, and environmental conditions.

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