2pcs L7808 voltage regulator

🔹 2PCS L7808 / LM7808 – +8V Fixed Positive Voltage Regulator (TO-220)

A classic, linear positive voltage regulator IC that provides a stable, fixed +8V DC output from a higher unregulated DC input (up to 35V). Renowned for its simplicity, robustness, and built-in protection features, it’s an ideal choice for creating local 8V power rails in various electronic circuits, devices, and DIY projects.

✅ Specifications:

• Part Number: L7808CV / LM7808 (Common TO-220 variant)

• Type: Linear Positive Voltage Regulator

• Output Voltage: Fixed +8V DC (±4% typical)

• Output Current: Up to 1.5A (with adequate heatsinking)

• Input Voltage Range: 10.5V to 35V DC (Recommended: ≥ 10.5V for proper regulation; Absolute Max: 35V)

• Dropout Voltage: ~2V (Minimum required difference between Input and Output)

• Line Regulation: 60 mV (Typ.)

• Load Regulation: 60 mV (Typ.)

• Package: TO-220 (Through-Hole, with metal tab for heatsinking)

• Pinout (TO-220, front view, tabs facing you):

  1. Input (Vin) – Unregulated DC Input

  2. Ground (GND)

  3. Output (Vout) – Regulated +8V DC

• Operating Junction Temperature: 0°C to +125°C

• Quantity: 2 pieces

⚙️ Key Features:

• Fixed Output: No external components needed to set the voltage (just input/output capacitors).

• Built-in Protections:

  • Overcurrent Protection

  • Thermal Shutdown

  • Short-Circuit Protection

• Easy to Use: The classic “3-terminal” design makes circuit implementation straightforward.

• Widely Available & Inexpensive: An industry-standard component with decades of proven reliability.

📦 Typical Applications:

• Local 8V Power Rails: Powering op-amp circuits, analog sensors, or specific ICs requiring 8V.

• Step-Down Regulation: Converting common 12V, 15V, or 24V DC supplies (e.g., from wall adapters or batteries) to a clean 8V supply.

• Microcontroller Projects: Providing a stable 8V rail for peripherals or as a pre-regulator before a 5V LDO.

• Battery-Powered Devices: Stabilizing voltage from a 9V battery as it discharges.

• DIY & Hobbyist Bench Power Supplies: As a building block for multi-voltage power sources.

🔧 Basic Connection Circuit:

1. Input Capacitor (Cin): Place a 0.33µF ceramic capacitor close to the IC’s input pin to ground. Add a larger 10µF – 100µF electrolytic capacitor for bulk filtering if the input is far from the source.

2. Output Capacitor (Cout): Place a 0.1µF ceramic capacitor close to the IC’s output pin to ground. A 10µF – 100µF electrolytic capacitor improves transient response.

3. Heatsinking: Required if power dissipation exceeds ~1W. Power Dissipation Pd=(Vin−Vout)×IloadPd​=(Vin​−Vout​)×Iload​. For example, with 15V input, 8V output, and 1A load: $(15-8)\ast 1=7W$ → a large heatsink is mandatory.

⚠️ Critical Design Notes & Limitations:

• Linear Regulator = Heat Generator: It dissipates excess voltage as heat. Inefficient for high input-output differentials or high currents. For such cases, consider a switching regulator (buck converter).

• Minimum Input Voltage: Must be at least ~10.5V to maintain 8V output. For an 8V output, plan for ≥ 10.5V input.

• Heatsink Calculation: Use the formula above. The TO-220 tab is connected to Ground (Pin 2). Use a thermal pad/heatsink compound. For high power, an electrically isolated heatsink mount is recommended.

• Reverse Polarity Protection: This IC does not protect against reversed input polarity. Add a series diode (1N4007) on the input if needed.