2pcs L7805 Voltage Regulator

🔹 2PCS L7805CV – Fixed +5V Positive Voltage Regulator (TO-220)

A classic, monolithic integrated circuit that provides a stable, fixed +5V DC output from a higher unregulated DC input (up to 35V). The L7805 (or 7805) is one of the most ubiquitous linear voltage regulators, essential for powering digital logic, microcontrollers, sensors, and countless other 5V circuits with built-in protection and simplicity.

✅ Specifications:

• Part Number: L7805CV (Common TO-220 commercial grade variant)

• Type: Linear Positive Voltage Regulator

• Output Voltage: Fixed +5V DC (±2% typical)

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

• Input Voltage Range: 7V to 35V DC (Recommended: 7.5V – 20V)

• Dropout Voltage: ~2V (Minimum required difference between Vin and Vout)

• Line Regulation: 50 mV (Typ.)

• Load Regulation: 50 mV (Typ.)

• Ripple Rejection: 62 dB (Typ.)

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

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

  1. Input (Vin) – Unregulated DC Input (+7V to +35V)

  2. Ground (GND)

  3. Output (Vout) – Regulated +5V DC Output
     The metal tab is connected to Pin 2 (Ground).

• Protections: Internal overcurrent, thermal shutdown, and safe-area compensation.

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

• Quantity: 2 pieces

⚙️ Key Features:

• Fixed 5V Output: No external components needed to set the voltage (just input/output capacitors).

• Robust & Protected: Built-in current limiting and thermal shutdown prevent damage from overloads.

• Easy to Use: The quintessential “3-pin regulator” with a straightforward pinout.

• Wide Input Range: Can regulate from common voltages like 9V, 12V, or 24V down to a clean 5V.

• Industry Standard: Found in virtually every electronics lab and workshop worldwide.

📦 Typical Applications:

• Microcontroller Power: Providing a stable 5V rail for Arduino boards (when not using USB), PICs, AVRs, and other 5V logic.

• Digital Logic Circuits: Powering TTL (74LSxx) and CMOS (74HCxx) logic families.

• Sensor & Module Power: For 5V sensors, motor drivers (e.g., L298N logic supply), and displays.

• Step-Down Regulation: Converting common 9V or 12V wall adapter output to 5V for projects.

• Bench Power Supplies: As a building block for a fixed 5V output module.

🔧 Basic Connection Circuit:

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

2. Output Capacitor (Cout): Place a 0.1µF ceramic capacitor close to the output pin (Pin 3) to ground. A 10-100µF electrolytic capacitor improves transient response.

3. Heatsinking: Required if power dissipation exceeds ~1-2W. Power Dissipation: Pd=(Vin−Vout)×IloadPd​=(Vin​−Vout​)×Iload​. Example: 12V in, 5V out, 1A load: $(12-5)\times 1=7W$ → a large heatsink is mandatory. The TO-220 tab is connected to Ground, simplifying heatsink mounting.

⚠️ Critical Design Notes & Warnings:

• Minimum Input Voltage: Requires input to be at least ~7V to maintain 5V regulation. For a 5V output, plan for ≥ 7.5V input.

• Linear Regulator = Heat Generator: It dissipates excess voltage as heat. Inefficient for high input-output differentials or high currents. For example, converting 12V to 5V at 1A is only ~42% efficient; 6W is wasted as heat.

• Heatsinking is Crucial: Always calculate power dissipation. Without a heatsink, the internal thermal shutdown will activate at low currents.

• Input Voltage Limit: Do not exceed 35V input. For higher voltages, use a pre-regulator or a switching buck converter.

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

• Improving Ripple Rejection: For noisier inputs, increase the value of the input capacitor.