Off-Board Power Supplies Definition

Power supplies are gadgets that convert one form of electrical energy into another. Most computers have power supplies built inside them, but a lot of other electronics use external ones. For instance, some monitors and external hard drives come with power supplies that are separate from the main device. These power supplies are attached to the cable that plugs into the wall.

Power Supply

A power supply is an electrical device that provides power to a load. Its main job is to convert electric current from a source to the right voltage, current, and frequency needed to power a load. Because of this, power supplies are sometimes called electric power converters. Some power supplies are standalone devices, while others are built into the appliances they support. The power supplies found in desktop computers and consumer electronics are examples of the latter.

Types of Power Supplies

There are two types of power supplies: AC power supplies and DC power supplies. Which one to use depends on the electrical characteristics of the device. There are also various kinds of power supplies available in the market, like Variable AC Power Supply, Unregulated Linear Power Supply (which includes things like an Input Transformer, bleeder resistor, rectifier, step-down transformer, filter capacitor), Programmable Power Supply, Computer Power Supply, Regulated Linear Power Supply (which contains a Voltage Regulator, Series regulator, Shunt regulator), Switch Mode Power Supply (SMPS) (made up of a regulator, series transistor, filter capacitor, transformer, rectifier), UPS (Uninterruptible Power Supply) (which includes conditioning circuitry, power sensing, and a bank of rechargeable batteries), and DC Power Supply.

AC-DC Converter

An AC-DC converter is a type of power supply that changes an alternating current input voltage (from 10 V to 766 VAC) into a direct current output voltage (from -54.5 V to 400 VDC). AC-DC converters can be either on-board or off-board. Off-board power sources typically have 1 to 10 outputs, while on-board power sources usually have 1 to 3 outputs.

DC-DC Converter

DC-DC converters are high-frequency power conversion circuits that turn switching noise into smooth, regulated DC voltages using high-frequency switching along with inductors, transformers, and capacitors. Even if the input voltages and output currents change, closed feedback loops keep the voltage output steady.

Different electronic devices, like ICs, need different voltages, so a specific voltage must be provided for each device. Depending on how they convert power, DC-DC converters are also known as linear regulators or switching regulators.

A Buck Converter, or Step-Down Converter, provides a lower voltage than the source, while a Boost Converter (Step-Up Converter) gives a higher voltage. A Boost-Buck Converter can convert to either a higher or lower voltage, and a Negative Voltage/Inverting Converter supplies a negative voltage.

Frequently Asked Question

What are the three types of standby power supplies?

• Emergency Systems (Level 1 or Critical Life Safety Systems)
• Optional Standby Systems
• Legally Required Standby Systems (Level 2 or Less Critical Systems)
• Critical Operations Power Systems

What is an offline power supply?

An offline power supply is one where the AC line voltage is rectified and filtered without a line frequency isolation transformer. It switches into service when there’s a line loss to keep power to the load with minimal interruption. It’s also called Off Line Switchers (OLS).

What causes power board failure?

Failures can be caused by things like heat, over or under voltage, or normal component aging. Some problems might be visible, like exploded components, but often they look fine and require testing each component with a meter.

Can a power supply board be repaired?

Yes, a power supply board can be repaired depending on the issue. However, it’s often more cost-effective and safer to replace the unit with a new one, especially since repairing power supplies can be tricky if you’re not familiar with it.

What electronics use standby power?

Standby power is used to keep things like displays and clocks running without turning the equipment to full power. For battery-powered devices connected to mains electricity, it helps keep the battery fully charged even when the device is off. For example, a mobile phone can stay ready to receive calls without draining its battery.