LD1117AS33TR: Low drop fixed and adjustable positive voltage regulator, up to 1A output, 3.3V
STMicroelectronics

The LD1117A series from STMicroelectronics encompasses a range of low dropout (LDO) voltage regulators capable of providing up to 1A of output current. These regulators are available in both fixed and adjustable versions, with the fixed versions offering output voltages of 1.2V, 1.8V, and 3.3V. The adjustable versions allow for output voltages starting from 1.25V, providing flexibility for various application needs.

The LD1117A regulators are designed for high efficiency, which is achieved through an NPN pass transistor. A minimal external component requirement (only a 10µF capacitor for stability) makes these regulators suitable for compact designs. Additionally, the regulators feature internal current and thermal limit protections, ensuring safe operation under different conditions. The device's low dropout voltage and very low quiescent current make it an ideal choice for battery-powered applications where power efficiency is critical.

Key Specifications and Features

  • Output Voltage: Fixed at 1.2V, 1.8V, 3.3V; adjustable from 1.25V
  • Output Current: Up to 1A
  • Dropout Voltage: 1.15V typ. at 1A load, 25°C
  • Quiescent Current: 5mA typ. at 25°C
  • Temperature Range: 0°C to 125°C
  • Package Options: SOT-223, DPAK, TO-220
  • Stability: Requires only a 10µF capacitor

LD1117AS33TR Datasheet

LD1117AS33TR datasheet (PDF)

LD1117AS33TR Substitutes
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Applications

  • Battery-powered devices: Due to its low dropout voltage and low quiescent current.
  • Microcontroller power supply: Provides stable voltage supply for MCUs.
  • Portable electronics: Ideal for compact designs due to minimal external component requirement.

Category

Voltage Regulators

General information

Low dropout (LDO) voltage regulators are designed to provide a stable output voltage with a very small voltage difference between the input and output, making them highly efficient in battery-powered applications. They are crucial in systems where the supply voltage is only slightly higher than the required output voltage. LDOs are widely used in portable devices, microcontroller power supplies, and other applications where power efficiency and space are important considerations.

When selecting an LDO regulator, engineers should consider the dropout voltage, output current capability, quiescent current, and the thermal performance of the device. The dropout voltage determines how low the input voltage can go below the output voltage while still maintaining regulation. The output current capability is important to ensure the regulator can supply sufficient current to the load. Quiescent current is critical for battery-powered applications since it affects the power efficiency and battery life. Thermal performance is also important to prevent the device from overheating during operation.

STMicroelectronics' LD1117A series offers a range of LDO regulators with low dropout voltage and high efficiency, suitable for a variety of applications. The availability of both fixed and adjustable output voltages provides flexibility for different design requirements. The internal current and thermal limit protections enhance the safety and reliability of these regulators in various operating conditions.

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