Voltage Regulator IC Selection for 12V, 1 Amp Power Supply

A voltage regulator is a device that maintains a constant output voltage, regardless of changes in the input voltage or load current. In power supply circuits, a voltage regulator is used to ensure a stable and reliable output voltage, which is essential for many electronic devices to function correctly.

Without a voltage regulator, the output voltage of a power supply would vary with changes in the input voltage or load current, which could cause electronic devices to malfunction or fail. A voltage regulator provides a stable output voltage that is independent of these fluctuations, ensuring that the electronic device receives a consistent and reliable power supply.

There are two main types of voltage regulator ICs: linear regulators and switching regulators.

  • Linear regulators: Linear regulators use a series pass transistor to regulate the output voltage. They operate by dropping the excess voltage across the transistor as heat, which can make them inefficient for high voltage differences or high current applications. However, they are simple to use, have low output noise, and are well-suited for low current applications.
  • The 78xx series provides a fixed positive voltage output, while the 79xx series provides a fixed negative voltage output.
  • These ICs are linear regulators, which means that they regulate the output voltage by dissipating excess voltage as heat.
  • The input voltage must be at least 2V higher than the output voltage for the IC to regulate properly.
  • The maximum input voltage that can be applied to the IC is typically around 35V, depending on the specific model.
  • These ICs have built-in overcurrent and over-temperature protection circuitry, which protects the IC from damage in case of a fault.
  • They also have a built-in bypass capacitor that helps to reduce output noise.
  • The 78xx and 79xx series of ICs are widely used in many electronic devices that require a stable and regulated power supply.
  • Popular models include the 7805 and 7812 (78xx series) and the 7905 and 7912 (79xx series).
  • They are easy to use, low cost, and widely available.

Common linear regulators include the LM7805, which regulates the output voltage to 5V, and the LM317, which can be adjusted to provide a wide range of output voltages.

  • Switching regulators: Switching regulators use a high-frequency oscillator to convert the input voltage to a higher or lower voltage, depending on the requirements of the circuit. They use an inductor to store and release energy to maintain a constant output voltage, making them more efficient than linear regulators for high voltage differences and high current applications. However, they can be more complex to use and can generate more output noise.

Common switching regulators include the LM2575 and LM2596, which are step-down regulators that convert a higher input voltage to a lower output voltage, and the LM2576 and LM340, which are step-up regulators that convert a lower input voltage to a higher output voltage.

The choice of voltage regulator IC will depend on the specific requirements of the circuit, including input and output voltage range, current requirements, efficiency, and noise tolerance. Careful consideration should be given to these factors when selecting a voltage regulator for a power supply circuit.