How to Use 7808: Examples, Pinouts, and Specs

The 7808 is a fixed positive-voltage regulator integrated circuit, designed to provide a stable 8V output from a wider range of input voltages. It is part of the 78xx series of voltage regulators, which are popular in various electronic applications due to their ease of use and robust performance. Common applications include power supplies for electronic devices, microcontrollers, and other digital systems where a consistent 8V power source is required.

• Output Voltage (Vout): +8V
• Input Voltage (Vin): 10.5V to 35V
• Output Current (Iout): Up to 1A (with adequate heat sinking)
• Output Voltage Tolerance: ±5%
• Line Regulation: Typically 0.01% / V
• Load Regulation: Typically 0.1%
• Operating Temperature Range: 0°C to 125°C

1. Input Capacitor: Place a capacitor (typically 0.33µF) between the input pin and ground to filter input noise.
2. Output Capacitor: Place a capacitor (typically 0.1µF) between the output pin and ground to improve transient response.
3. Heat Sinking: For currents above 100mA, a heat sink is recommended to dissipate the heat generated by the regulator.
4. Bypass Diodes: In cases where the input voltage may fall rapidly, a diode from output to input and another from input to ground can protect the regulator.

• Ensure the input voltage is always at least 2.5V higher than the desired output to maintain regulation.
• Avoid exceeding the maximum input voltage to prevent damage to the IC.
• Keep the input and output capacitors close to the regulator pins to minimize noise and oscillations.
• Use thermal paste and an appropriately sized heat sink if the regulator is expected to dissipate significant power.

• Output Voltage Fluctuations: This can be caused by insufficient input voltage, inadequate filtering, or thermal shutdown due to overheating.
• IC Overheating: Ensure proper heat sinking and verify that the input voltage is not too high, as excess voltage will be dissipated as heat.
• No Output Voltage: Check for correct pin connections, input voltage presence, and that the input and output capacitors are in good condition.

Q: Can I use the 7808 without capacitors? A: While the 7808 may work without capacitors, it's strongly recommended to use them for stability and noise reduction.

Q: How much current can the 7808 supply? A: The 7808 can supply up to 1A, but this is dependent on adequate heat sinking to manage thermal dissipation.

Q: What happens if I exceed the input voltage rating? A: Exceeding the maximum input voltage can permanently damage the regulator.

Q: Is the 7808 protected against short circuits? A: Yes, the 7808 includes internal short-circuit protection and thermal overload protection.

// No specific code is required for the 7808 as it is a hardware component.
// However, below is an example of how to connect the 7808 to an Arduino UNO
// to provide a stable 8V to the board.

// Arduino UNO pin -- 7808 pin
// Vin (raw voltage) -- Input (Vin)
// GND -- Ground (GND)
// 5V pin (if used as a power source) -- Output (Vout)

// Note: When using the 7808 to power the Arduino, ensure that the Arduino's
// onboard voltage regulator can handle the 8V input safely.

Remember to consult the Arduino UNO specifications to ensure that it can accept an 8V input on the voltage input pin if you are using the 7808 to power the board directly.