L7805 Voltage Regulator DC-DC

Overview

The L7805 Voltage Regulator is a fixed 5V linear regulator IC from the 78xx family that provides a stable +5V DC output from an unregulated DC input. With its simple 3-pin configuration and TO-220 package, the L7805 is a widely used solution for powering microcontrollers, logic circuits, sensors, and small embedded systems.

Key Specifications

• Output voltage: +5V DC (fixed)
• Input voltage range: 7-35V DC
• Maximum output current: Up to 1A (with adequate heat sinking)
• Package: TO-220

Main Features

• Stable, low-noise 5V regulation for digital circuits
• On-chip protection: thermal shutdown, current limiting, and short-circuit protection
• Simple 3-pin input, ground, and output configuration
• Low cost and easy to integrate into custom power supplies and modules

Protection and Thermal Management

The L7805 includes built-in safety features to protect the device and the load under fault conditions:

• Thermal shutdown: Automatically turns the regulator off if junction temperature is too high.
• Current limiting: Restricts output current to protect against overloads.
• Short-circuit protection: Helps prevent damage during accidental short circuits.

Typical Applications

• Powering Arduino boards, ESP32 peripherals, Raspberry Pi add-ons, and sensors
• Regulation for logic ICs, digital circuits, and small embedded systems
• DIY power supply modules and battery-powered hobby circuits
• Educational electronics and prototype development

Usage and Design Tips

• Minimum input voltage: allow for the regulator’s dropout voltage (typical dropout ~2V). For reliable regulation, use at least 7V input for a 5V output.
• Heat sinking: if drawing near 1A, attach a suitable heat sink to the TO-220 tab to manage power dissipation.
• Power dissipation calculation: P = (Vin – 5V) x Iout. Verify that the regulator and heat sink can dissipate this heat safely.
• Recommended bypass capacitors: place a 0.33µF on the input and 0.1µF on the output close to the regulator pins to ensure stability and reduce transient response.
• For battery-powered or high-efficiency designs, consider a switching regulator alternative to reduce heat and improve efficiency.
• Keep wiring short and use proper decoupling for noisy loads or long traces.

Package and Pinout

• Package type: TO-220
• Pinout (facing the front/label side): left = Input, middle = Ground, right = Output

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