What is an SMPS?

Derek Schauland

SMPS is an acronym for Switched Mode Power Supply which is a power supply that produces a desired voltage by rapidly switching between full power on and full power off. The average between these two voltages produces the power needed for a device.

Woman doing a handstand with a computer
Woman doing a handstand with a computer

In many cases, these power supplies are used to convert from AC power supplied by the power company to DC regulated power used by devices. The switching taking place at an SMPS is happening at such a high frequency that the power to the device is not completely lost.

For example, an automated motor may be connected to a switched mode power supply and the motor will be started when the SMPS is turned on. Then the SMPS will cut off power and restore it almost immediately, allowing the motor to continue powering up. While there will be some decrease in the power supplied to the motor when the power is cut, this will merely slow the motor during the startup process. When the SMPS kicks back on, the motor will continue starting.

This process may seem rather useless to stop and start power to a motor or any device, but it allows the electric current to be better controlled and monitored than a power supply that constantly runs at the full desired voltage. Because power can fluctuate or spike, a power supply running constantly at the desired voltage may cause a blowout with a power spike, where as an SMPS will regulate the power passing through it and cut its supply to the motor, reducing the likelihood of a blowout.

There are four classifications of Switched-mode power supplies:

    AC to DC – referred to as an off line DC power supply
    DC to DC – referred to as a voltage converter
    DC to AC – referred to as a power inverter
    AC to AC – referred to as an AC power source or a frequency changer

Each of the different types of switched-mode power supplies can improve the performance of the applications they are used in by better regulating power input and output. There are many engineering firms in business today that work with SMPS and power electronics, which assist them in providing the correct devices for client usages and helping manufacturing and other facilities control the use of current.

There are many sites available on the Internet to provide assistance in creating Switched-mode Power Supplies for those that have custom applications or a desire to attempt creating an SMPS. They can also be purchased on-line or in retail locations throughout the world.

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