onsemi MC78LC40NTRG Low Dropout Voltage Regulator: Datasheet, Pinout, and Application Circuits
The onsemi MC78LC40NTRG is a member of the popular 78xx series of linear voltage regulators, specifically engineered for applications requiring a low dropout voltage and very low quiescent current. This positive voltage regulator is capable of providing a fixed 5.0V output at up to 100mA of current, making it an ideal solution for powering low-power microcontrollers, sensors, and other circuitry in battery-operated portable devices.
Key Features and Datasheet Overview
According to its datasheet, the MC78LC40NTRG distinguishes itself with several critical characteristics:
Low Dropout Voltage: Typically 60 mV at 40 mA load, allowing it to continue regulating effectively even when the input voltage dips very close to the output voltage. This is crucial for maximizing battery life.
Very Low Quiescent Current: Typically 30 µA, which minimizes the drain on the battery when the system is in a standby or idle state.
Fixed 5V Output: Provides a stable and reliable voltage rail.
High Accuracy: ±2.5% output voltage tolerance.
Internal Protection: Built-in short circuit and thermal overload protection safeguard the regulator and the load from damage.
Package: Supplied in a space-saving SOT-23-5 package, perfect for compact PCB designs.
Pinout Configuration
Understanding the pinout is essential for proper circuit design. The 5-pin SOT-23 package has the following configuration:
1. IN (Input Pin): This pin receives the unregulated input voltage. A input capacitor is recommended for stability.
2. GND (Ground Pin): The common ground reference for the regulator.
3. NC (No Connect): This pin is not internally connected and can be left floating.
4. BYPASS: Connecting a small-value capacitor (typically 47 pF to 1000 pF) to ground from this pin significantly reduces output noise.
5. OUT (Output Pin): The regulated 5.0V output is supplied from this pin. An output capacitor is required for stability.
Application Circuits
The MC78LC40NTRG is simple to use, requiring only a few external components for most applications.
1. Standard 5V Regulator Circuit:
The most straightforward application is a basic voltage regulator. The input capacitor (C1, 0.1µF to 1µF) helps suppress high-frequency noise and improves stability, especially if the regulator is located far from the primary power source. The output capacitor (C2, 0.1µF to 1µF) is crucial for ensuring stability and providing a good transient response. For optimal noise reduction, a small ceramic capacitor (C3, e.g., 47 pF) should be connected between the BYPASS pin and ground.
2. Battery-Powered Device Circuit:
This regulator excels in battery-powered applications like remote controls, IoT sensors, or portable medical devices. Its low dropout voltage allows the system to continue functioning until the battery is nearly depleted. Its ultra-low quiescent current ensures the battery isn't drained quickly during periods of inactivity, dramatically extending operational life.
The onsemi MC78LC40NTRG is a highly efficient and reliable LDO regulator that stands out for its exceptional power-saving capabilities. Its combination of low dropout voltage and ultra-low quiescent current makes it a superior choice for designers of portable, battery-dependent electronics where every millivolt and microampere counts. Its simple implementation and robust protection features further solidify its position as a go-to component for creating stable and efficient 5V power rails.
Keywords: Low Dropout Voltage Regulator, Low Quiescent Current, 5V Output, SOT-23-5 Package, Battery-Powered Applications
