onsemi NCP1117DTARKG 1A Low-Dropout Positive Voltage Regulator: Datasheet, Pinout, and Application Circuits

The onsemi NCP1117DTARKG is a popular 1A low-dropout (LDO) positive voltage regulator designed to provide a stable and fixed output voltage from an unregulated input source. Renowned for its reliability and efficiency, it is a common choice for a vast array of applications, from consumer electronics to industrial systems. This article delves into its key specifications, pinout configuration, and typical application circuits.

Datasheet Overview and Key Specifications

The NCP1117DTARKG belongs to a family of LDO regulators that offer excellent line and load regulation performance. The "DTARKG" suffix specifically denotes a fixed 3.3V output voltage in a SOT-223 package. Key parameters from its datasheet include:

Output Current: Up to 1A

Dropout Voltage: Typically 1.2V at 1A load current. This low dropout feature allows it to continue regulating effectively even when the input voltage is only slightly higher than the output voltage, improving efficiency.

Output Voltage Tolerance: ±2% under specified conditions of line, load, and temperature.

Line Regulation: 0.2% (Typ.)

Load Regulation: 0.4% (Typ.)

Package: SOT-223, which offers a compact footprint while providing superior thermal performance over older packages like TO-252, thanks to its dedicated heatsink tab.

Protection Features: The IC includes built-in over-current protection and thermal shutdown, safeguarding both the regulator and the downstream circuitry from damage.

Pinout Configuration

Understanding the pinout is crucial for proper PCB layout. The SOT-223 package has four pins, but two are internally connected.

1. Pin 1 (Adjust/Ground): For fixed voltage versions (like the 3.3V model), this pin is connected to Ground (GND). In adjustable versions, this is the 'Adjust' pin for setting the output voltage with external resistors.

2. Pin 2 (Output - Vout): This pin provides the regulated output voltage (e.g., 3.3V).

3. Pin 3 (Input - Vin): The unregulated input voltage is applied to this pin.

4. Pin 4 (Tab): The metal tab is internally connected to the Output (Vout) pin. It must be soldered to a copper pour on the PCB to act as a heatsink, which is critical for dissipating heat, especially when operating at high currents or with a high input-to-output voltage differential.

Application Circuits

The NCP1117DTARKG is straightforward to implement in circuit designs.

1. Basic Fixed Voltage Regulator Circuit:

This is the most common application. The input capacitor (C1, typically 10µF) helps neutralize the effects of source inductance, while the output capacitor (C2, typically 22µF) is essential for maintaining stability and improving the transient response. The value and Equivalent Series Resistance (ESR) of the output capacitor are critical; a tantalum or aluminum electrolytic capacitor with the correct ESR range is recommended.

2. Adjustable Voltage Regulator Circuit:

While the NCP1117DTARKG is a fixed voltage part, the NCP1117 family also includes an adjustable version (Vref = 1.25V). Its output voltage is set by two external resistors (R1 and R2) using the formula: Vout = Vref (1 + R2/R1). A small output capacitor (e.g., 22µF) remains necessary for stability.

ICGOODFIND: The onsemi NCP1117DTARKG stands out as a robust and highly reliable 1A LDO voltage regulator. Its low dropout voltage, strong protection features, and thermally efficient SOT-223 package make it an ideal solution for power management tasks requiring a stable 3.3V supply. Proper attention to heatsinking and capacitor selection is the key to unlocking its full performance in any application.

Keywords: Low-Dropout (LDO) Regulator, Voltage Regulation, SOT-223 Package, Thermal Shutdown, 1A Output Current