Onsemi MC78L05ACD: Technical Datasheet, Application Circuit, and Pinout Configuration
The Onsemi MC78L05ACD is a classic, fixed-output, positive voltage regulator from the 78L series, delivering a stable +5V DC output at currents up to 100 mA. This device is renowned for its internal current limiting and thermal shutdown protection, making it a robust and reliable solution for a vast array of low-power electronic applications. Its compact SOT-89 package offers a superior power dissipation capability compared to smaller SOT-23 alternatives.
Technical Datasheet Overview
Key specifications define the operational boundaries and performance of the MC78L05ACD:
Output Voltage: +5V (4.75V to 5.25V)
Output Current: Up to 100 mA
Input Voltage Range: 7V to 30V (Recommended: 7V to 20V for optimal performance)
Line Regulation: 6 mV (Typ.)
Load Regulation: 15 mV (Typ.)
Dropout Voltage: 1.7V (Typ.) at IOUT = 40 mA
Operating Junction Temperature: -40°C to +125°C
Package: 3-Lead SOT-89
A critical parameter is the dropout voltage, which is the minimum required difference between the input and output voltage to maintain regulation. For the MC78L05ACD, this means the input must always be at least ~7V to guarantee a regulated 5V output under all load conditions.
Pinout Configuration
The device is housed in a 3-lead SOT-89 package. When viewing the component with the flat face and the single lead on top:
Pin 1 (Input): This pin receives the unregulated input DC voltage.
Pin 2 (Ground): The common ground reference for both the input and output.
Pin 3 (Output): Provides the regulated +5V output.
Application Circuit
The standard application circuit for the MC78L05ACD is straightforward, requiring only two external capacitors for stability. The circuit is designed to suppress oscillations and improve the regulator's transient response.
1. An unregulated DC input voltage (VIN), typically between 7V and 20V, is applied to Pin 1 (Input).
2. A 0.33 µF input capacitor (CIN) is connected between the input pin and ground. This ceramic capacitor helps neutralize the effects of inductive long input leads and ensures stable operation.
3. A 0.1 µF output capacitor (COUT) is connected between the output pin and ground. This capacitor is crucial for improving the stability of the regulator and its transient response.
The load is then connected between the output (Pin 3) and ground.
ICGOODFIND: The Onsemi MC78L05ACD remains an indispensable component for designers seeking a simple, cost-effective, and highly reliable solution for generating low-current 5V power rails. Its built-in protection features and minimal external component count make it an excellent choice for powering microcontrollers, sensors, op-amps, and other logic circuits in consumer, industrial, and automotive applications.
Keywords: Voltage Regulator, 5V Output, SOT-89 Package, Low Dropout Voltage, Onsemi
