Power supply

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Linear-Power-Supply-AB

Regatron - Model 238 AMB - Rowan Controller Co - Electronic Measurements - front panel

Bench power supply

Wall wart opened

Switched mode power adapter

Power supply is a device or system that supplies electrical energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are integral to the operation of virtually all electronic devices. The most common form of power supply today is the switched-mode power supply (SMPS), which, due to its efficiency and cost-effectiveness, has replaced the older linear power supply technology in many applications.

Types of Power Supplies

Power supplies can be broadly categorized into two types: AC power supplies and DC power supplies.

AC Power Supplies

An AC (Alternating Current) power supply typically takes the form of a power adapter or AC adapter, converting mains AC voltage to a lower-voltage AC output, suitable for powering an appliance or charging batteries. Examples include the power bricks used with laptop computers, smartphones, and other portable devices.

DC Power Supplies

A DC (Direct Current) power supply provides a constant DC voltage to its load. Examples of DC power supplies include battery chargers, computer power supplies, and power supplies used in industrial and telecommunications equipment.

Components

A typical power supply might include components such as a transformer, rectifier, filter, and regulator. The transformer adjusts the input voltage to a more suitable level; the rectifier converts AC to DC; the filter smooths out the DC signal, removing any residual AC components; and the regulator maintains a constant output voltage or current despite variations in the input voltage or load conditions.

Switched-Mode Power Supply (SMPS)

The switched-mode power supply (SMPS) uses a high-frequency switching regulator to convert electrical power efficiently. Unlike a linear power supply, the pass transistor of a switching-mode supply continually switches between low-dissipation, full-on and full-off states, and spends very little time in the high dissipation transitions, which minimizes wasted energy. SMPS is more efficient and smaller than a linear power supply but can produce more noise and interference.

Applications

Power supplies are used in a wide range of applications including, but not limited to, personal computers, telecommunications equipment, medical equipment, and industrial machinery. The specific requirements of the application, such as voltage, current, and stability, dictate the design and components of the power supply.

Safety and Regulation

Power supplies must comply with safety standards to prevent electrical shock and fire hazards. In addition, electromagnetic compatibility (EMC) regulations limit the amount of electromagnetic interference (EMI) that a power supply can emit. Compliance with these standards ensures that power supplies do not interfere with other electronic equipment and operate safely under all conditions.