onsemi NCP551SN50T1 50V Low-Dropout Voltage Regulator: Datasheet, Pinout, and Application Circuits
The onsemi NCP551SN50T1 is a high-performance, 50V rated low-dropout (LDO) linear voltage regulator designed for a wide range of industrial and automotive applications. Its ability to function with a high input voltage while providing a stable, clean output makes it an ideal choice for powering sensitive circuitry in electrically noisy environments.
This LDO regulator delivers a fixed 5.0V output with a maximum output current of 150mA. A key feature of this device is its remarkably low dropout voltage, typically 240mV at 100mA load, which enhances efficiency and allows it to continue regulating even when the input voltage dips close to the output level. The NCP551SN50T1 is also equipped with essential protection features, including internal current limiting and thermal shutdown, safeguarding both the regulator and the load under fault conditions. Its low ground current makes it suitable for battery-powered applications.
Datasheet Overview
The datasheet for the NCP551SN50T1 provides critical specifications for design engineers. Key parameters include:
Input Voltage Range (VIN): 6.0V to 50V (60V max)
Output Voltage (VOUT): 5.0V ±2%
Output Current (IOUT): Up to 150mA
Dropout Voltage (VDO): 240mV (typ) at IOUT = 100mA
Standby Current: 20µA (typ)
Line Regulation: 0.2mV (typ)
Load Regulation: 5.0mV (typ)
Operating Junction Temperature: -40°C to +150°C
Pinout and Package
The NCP551SN50T1 is offered in a space-saving SOT-223 surface-mount package with three pins and an integrated tab for enhanced thermal performance. The pinout is as follows:
1. Pin 1 (INPUT): The input supply voltage pin. A input capacitor (e.g., 1µF) is recommended to be placed close to this pin for stability.
2. Pin 2 (GROUND): The ground reference pin for the regulator.
3. Pin 3 (OUTPUT): The regulated 5.0V output pin. An output capacitor (e.g., 1µF) is required between this pin and ground to ensure stability and improve transient response.
4. Tab (OUTPUT): The metal tab is internally connected to the OUTPUT pin (Pin 3). Proper soldering of this tab to the PCB is crucial for effective heat dissipation.
Application Circuits
The primary application circuit for the NCP551SN50T1 is straightforward, making it easy to implement.
1. Basic 5V Regulator Circuit:
This is the standard configuration for generating a stable 5V supply from a higher input voltage (e.g., 12V, 24V, or 48V rails).
Connect the input voltage (VIN) to Pin 1 (INPUT) through a fuse if necessary.
Place a 1µF ceramic capacitor between the INPUT pin and ground, positioned as close as possible to the regulator.
Connect Pin 3 (OUTPUT) to the load.
Place a 1µF (min) ceramic capacitor between the OUTPUT pin and ground. A larger capacitor value (e.g., 10µF) may be used to improve transient performance.
Ensure the PCB has a sufficient copper pour connected to the tab (OUTPUT) to act as a heat sink.
2. Reverse Voltage Protection Circuit:
While the NCP551SN50T1 can handle high input voltages, it is not inherently protected against reverse voltage. A simple series diode between the input supply and the regulator's INPUT pin can provide this protection, preventing damage if the input leads are accidentally reversed.
The onsemi NCP551SN50T1 stands out as an exceptionally robust and reliable LDO solution for high-voltage applications. Its combination of a wide 50V input range, low dropout, integrated protections, and a simple design-in process makes it a superior choice for powering microcontrollers, sensors, and CAN transceivers in demanding automotive and industrial systems where voltage spikes and noise are common challenges.
Keywords:
High-Voltage LDO, 50V Input, Low Dropout Voltage, 5V Regulator, Automotive Grade
