onsemi MC7806BD2TR4G 6V Linear Voltage Regulator: Datasheet, Pinout, and Application Circuits
The onsemi MC7806BD2TR4G is a classic positive-voltage linear regulator from the renowned 78xx series, specifically designed to provide a fixed +6V DC output. Housed in the industry-standard D2PAK surface-mount package, this device is built to deliver a robust 1A output current with essential internal protections, making it a fundamental component for a vast array of electronic power supplies.
Datasheet Overview and Key Specifications
The datasheet for the MC7806BD2TR4G details its absolute maximum ratings and electrical characteristics, which are critical for reliable circuit design.
Output Voltage: +6V ±4% (approx. 5.76V to 6.24V)
Output Current: Up to 1A (subject to adequate heat sinking)
Input Voltage Range: Up to 35V (typically 8V to 20V for optimal performance)
Line Regulation: 6mV (Typ.)
Load Regulation: 12mV (Typ.)
Dropout Voltage: 2V (Typ.) at 1A
Internal Protections: The IC includes internal thermal shutdown and short-circuit protection, safeguarding itself and the load from damage under fault conditions.
Operating Junction Temperature: -40°C to +125°C
Pinout Configuration (TO-263 / D2PAK)
The three-terminal pinout is straightforward:
1. INPUT: This pin receives the unregulated DC input voltage, which must be higher than the output voltage plus the dropout voltage.
2. GROUND (COMMON): This is the common reference point for both the input and output.
3. OUTPUT: This pin provides the stable, regulated +6V DC output.
Application Circuits
The primary application for the MC7806BD2TR4G is to create a simple and stable voltage rail from a higher unregulated source, such as a transformer-bridge-capacitor supply or a battery.
1. Basic Fixed Output Regulator Circuit
This is the most common configuration. The input capacitor (C1, typically 0.33µF) helps neutralize inductive effects from long input leads and improves stability. The output capacitor (C2, typically 0.1µF) is crucial for ensuring circuit stability and improving transient response. For higher loads, a larger electrolytic capacitor (e.g., 10µF) at the output is also recommended.
2. Regulator with Improved Ripple Rejection
For applications where the input has significant AC ripple, the circuit's ripple rejection performance can be enhanced. Adding a bypass capacitor (e.g., 10µF) between the input pin and ground and another between the output pin and ground significantly improves the regulator's ability to filter out noise from the input.
3. Current Source Circuit
By using a single external resistor, the MC7806 can be configured as a constant current source. The current delivered to the load is approximately (V_OUT / R) + I_Q, where V_OUT is 6V and I_Q is the regulator's quiescent current. This is useful for driving LEDs or charging batteries.
Design Considerations: Heat Sinking
A critical aspect of using this 1A regulator is thermal management. The D2PAK package is designed to be mounted on a PCB copper area or an external heat sink to dissipate power. The power dissipated (P_D) is calculated as (V_IN - V_OUT) I_LOAD. If this value exceeds a few watts, a proper heat sink is absolutely mandatory to prevent the internal thermal protection from shutting down the device.
The onsemi MC7806BD2TR4G remains a highly reliable and straightforward solution for generating a stable +6V power rail. Its built-in protections, high ripple rejection, and simple three-pin design make it an excellent choice for powering microcontrollers, digital logic circuits, sensors, and other low-voltage components in industrial, automotive, and consumer applications. While switching regulators offer higher efficiency, the 78xx series' simplicity and low noise output continue to secure its place in modern electronics.
Keywords: Linear Voltage Regulator, 6V Output, 1A Current, D2PAK Package, Thermal Protection
