onsemi MC78M06CDTRKG 3-Terminal Positive Voltage Regulator: Datasheet, Pinout, and Application Circuits
The onsemi MC78M06CDTRKG is a member of the classic 78Mxx series of fixed-output, positive linear voltage regulators. This component is engineered to deliver a stable +6V DC output voltage at currents up to 500mA, making it a fundamental building block for power management in a vast array of electronic devices. Housed in a space-saving DPAK (TO-252) surface-mount package, it is well-suited for automated PCB assembly and offers good thermal performance.
This article provides a detailed overview of this regulator, covering its key specifications, pinout configuration, and practical application circuits.
Datasheet Overview and Key Specifications
The datasheet for the MC78M06CDTRKG provides all necessary information for design-in. Key absolute maximum ratings and electrical characteristics include:
Input Voltage (VI): Up to 35V. This provides a wide margin for input ripple and variations.
Output Voltage (VO): 6V ±4% (typically).
Output Current (IO): 500mA maximum.
Dropout Voltage: Typically 2V at IO = 500mA (TJ = 25°C). This is the minimum required difference between input and output voltage for regulation to be maintained.
Line Regulation: Typically 6mV (ΔVI = 8V to 20V).
Load Regulation: Typically 12mV (IO = 5mA to 500mA).
Ripple Rejection: 62dB typical (f = 120Hz). This highlights its excellent ability to suppress AC ripple on the input DC line.
Internal Protection: The device is internally protected against overcurrent (short-circuit) and overtemperature conditions, enhancing system reliability.
Pinout Configuration
The MC78M06CDTRKG in the DPAK package has three pins:
1. Pin 1 (INPUT): This is the unregulated input voltage pin. The input voltage must always be higher than the output voltage by at least the dropout voltage (typically 2V).
2. Pin 2 (GROUND): This is the common ground reference for both the input and output circuits.
3. Pin 3 (OUTPUT): This pin provides the regulated +6V output.
Standard Application Circuits
The basic application circuit for a 78Mxx regulator is straightforward, requiring only a minimal number of external components.
1. Basic Fixed Output Regulator:
The most common circuit is shown below. Capacitors are used for stability and to improve transient response.
CIN (Input Capacitor): A 0.33μF ceramic or tantalum capacitor placed close to the input pin. It helps to neutralize inductive effects from long input leads and provides local bypassing.
COUT (Output Capacitor): A 0.1μF ceramic capacitor placed close to the output pin. This capacitor is crucial for ensuring stability and improving the regulator's transient response.
2. Enhanced Regulator with Ripple Rejection:
For applications with significant input ripple or noise, the circuit's performance can be enhanced.
Adding a larger electrolytic capacitor (e.g., 10μF to 100μF) at the input is recommended, especially if the input source is located far from the regulator.
Adding a larger electrolytic capacitor (e.g., 10μF) at the output will further improve transient response and filtering.
For even better noise performance, diodes can be added for protection against reverse voltage scenarios.
Important Design Considerations
Heat Sinking: Although the DPAK package has good thermal properties, power dissipation is a critical factor. The power dissipated by the regulator is calculated as PD = (VIN - VOUT) IOUT. At full load (500mA) with a large voltage difference (e.g., VIN=12V, VOUT=6V), PD would be 3W, which requires attention to PCB layout. Using a sufficient copper area under the tab of the DPAK package is essential to act as a heat sink and prevent the internal overtemperature protection from shutting down the device.
Minimum Input Voltage: Ensure that the minimum input voltage remains above VOUT + Dropout Voltage (VDO) under all operating conditions, including low line voltage and full load.
ICGOOODFIND
The onsemi MC78M06CDTRKG stands as a highly reliable and cost-effective solution for deriving a stable 6V supply from a higher unregulated input. Its simplicity, built-in protections, and robust performance have cemented its role in countless applications, from industrial control systems and automotive electronics to consumer gadgets. While switching regulators offer higher efficiency, the 78M06's low noise output and design simplicity ensure it remains a popular choice for powering analog circuits, sensors, and low-power microcontrollers.
Keywords: Linear Voltage Regulator, 6V Output, 500mA, DPAK Package, Ripple Rejection
