DC Regulated Power Supply | Fundamentals of Electronic Circuits Lesson

A DC regulated power supply is an electronic device that converts an input AC voltage into a stable and regulated DC output voltage. The primary function of a regulated power supply is to provide a constant output voltage, regardless of variations in input voltage or load current. This is crucial in electronic circuits and systems where a stable voltage is required for the proper functioning of the components.

A typical DC regulated power supply consists of the following stages:

  1. Transformer: The transformer is used to step up or step down the input AC voltage according to the requirements of the output voltage. It also provides electrical isolation between the input and output, enhancing safety.
  2. Rectifier: The rectifier circuit, consisting of diodes, is responsible for converting the AC voltage from the transformer into a pulsating DC voltage. Depending on the configuration, this can be either a half-wave or a full-wave rectifier.
  3. Filter: The filter stage is used to smooth out the pulsating DC voltage from the rectifier. This is commonly achieved using capacitors, inductors, or a combination of both, known as an LC or π (pi) filter. The output of this stage is a smoother, yet still varying, DC voltage.
  4. Voltage Regulator: The voltage regulator is the critical component responsible for maintaining a stable and constant output voltage. There are two main types of voltage regulators:

a. Linear Voltage Regulator: Linear regulators use a series-pass transistor to control the voltage drop between the input and output, based on the desired output voltage. They are simple, provide low output noise, and have a fast transient response. However, they suffer from low efficiency, especially when the input-output voltage difference is significant.

b. Switching Voltage Regulator: Switching regulators use a combination of inductors, capacitors, and switches to provide a stable output voltage. They operate by rapidly switching the input voltage on and off, and controlling the duty cycle of the switching waveform to maintain the desired output voltage. Switching regulators are more efficient than linear regulators, particularly for large voltage differences, but they produce more output noise and have a slower transient response.

  1. Load Regulation and Protection: The regulated power supply must be able to maintain a constant output voltage under varying load conditions. Additionally, protection features such as short-circuit protection, over-voltage protection, and over-temperature protection may be included to prevent damage to the power supply and the connected load.

In summary, a DC regulated power supply is an essential component in electronic systems, providing a stable and constant output voltage despite variations in input voltage or load current. Its main stages include a transformer, rectifier, filter, voltage regulator, and load regulation and protection circuits.

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