onsemi NCP1117DT50 3V LDO Voltage Regulator: Datasheet, Application Circuit, and Pinout Explanation

The onsemi NCP1117DT50 is a popular low-dropout (LDO) positive voltage regulator from a renowned semiconductor manufacturer. Designed to deliver a fixed 3.0V output at currents up to 1A, this component is a cornerstone in power management for countless electronic devices. Its primary function is to provide a stable, clean, and precisely regulated voltage source from a higher, often noisy, input supply, making it indispensable for powering sensitive digital logic, microcontrollers, and sensors.

This device is part of the versatile NCP1117 series, with the "DT50" suffix indicating the fixed 3V output version in the DPAK surface-mount package. A key advantage of this LDO regulator is its remarkably low dropout voltage—typically 1.2V at 1A of load current. This means it can continue to regulate the 3V output even when the input voltage drops as low as approximately 4.2V, enhancing efficiency and extending battery life in portable applications. Furthermore, it offers internal current limiting and thermal shutdown protection, safeguarding both the regulator and the load circuitry under fault conditions.

Pinout Explanation (DPAK Package)

The NCP1117DT50 in the DPAK (TO-252) package has three pins/pads:

1. Input (IN): This pin connects to the unregulated input DC supply voltage. A minimum input capacitor (typically 10µF) is required near this pin to ensure stability and improve transient response.

2. Ground (GND)/Adjust (ADJ): For fixed-voltage variants like the DT50, this pin is the ground reference for the internal voltage reference and error amplifier. It must be connected to the system ground.

3. Output (OUT): This pin provides the regulated 3.0V output. A larger output capacitor (typically 22µF) is necessary for circuit stability and to optimize the regulator's transient response.

Application Circuit

The standard application circuit for a fixed-output NCP1117 is straightforward. The input voltage `VIN` (which must be greater than `VOUT + VDROP`) is fed to the IN pin. The GND pin is connected directly to the common ground plane. The regulated 3V is available at the OUT pin.

The selection of capacitors is critical for performance. While the internal circuit requires a capacitor on the output for stability, using a low-ESR (Equivalent Series Resistance) aluminum electrolytic or tantalum capacitor of 22µF or greater on the output is highly recommended. A 10µF capacitor on the input is also advised to filter incoming noise.

Datasheet Highlights

The official datasheet is the ultimate source of truth for designing. Key parameters to review include:

Output Voltage Tolerance: Typically ±2% (0.06V) over line, load, and temperature conditions.

Dropout Voltage (`VDROP`): The maximum dropout voltage at 1A is 1.3V (ensuring regulation down to `VIN = 4.3V`).

Line Regulation: Typically 0.2% (6mV) for an input voltage change from 4.75V to 12V.

Load Regulation: Typically 0.4% (12mV) for a load change from 5mA to 1A.

Maximum Operating Junction Temperature (`TJ`): +150°C. The integrated thermal shutdown activates at approximately 165°C.

ICGOODFIND Summary

The onsemi NCP1117DT50 is a highly reliable and robust 1A LDO voltage regulator ideal for applications demanding a stable 3V power rail. Its low dropout voltage, built-in protections, and simple application requirements make it a superior choice for both novice and experienced designers across consumer, industrial, and automotive electronics.

Keywords:

1. LDO Regulator

2. 3V Output

3. 1A Current

4. Low Dropout Voltage

5. Thermal Protection