When it comes to power supplies, there are various options and switch mode power supplies are among those choices. Here’s our industry guide to switch mode power supplies (SMPS) to help you work out if this is what you need for your power supply.
What is a SMPS?
A SMPS is an electronic power supply that incorporates a switching regulator to convert electrical power, efficiently. Just like other power supplies, an SMPS transfers the power from a source, such as mains power, to a product, such as a personal computer, while converting the voltage and current characteristics.
The supply continually switches – hence the name – between low-dissipation full-on and full-off states and spends very little time in high dissipation transitions. This ensures that energy wastage is minimised.
What is the difference between linear power supplies and switched mode power supplies?
Linear power supplies work by getting the voltage from the power grid and changing this voltage using a transformer – although this voltage is still AC. Rectification is then done by a set of diodes, which transform the AC voltage into a pulsating voltage. Then filtering is done by electrolytic capacitors, transforming the pulsating voltage into almost DC. The DC obtained after, oscillates a little bit (this is called ripple), so it is necessary to regulate the voltage and this is done by a zener diode or by a voltage regulator integrated circuit.
A SMPS regulates either the output voltage or current by switching ideal storage elements, such as the inductors and capacitors, into and out of different electrical configurations. Ideal switching elements (for example, the transistors operated outside of their active mode) have no resistance when “closed” and they carry no current when “open”. The converters can theoretically operate with 100 percent efficiency. All the input power is delivered to the load and no power is wasted as dissipated heat.
Where would you use SMPS?
Is a switched mode power supply right for your product and requirements? A SMPS is chosen when various factors are considered – its weight, its efficiency, its size and/or its wide input range tolerance – make it a better choice than linear power supplies. The costs of SMPS has reduced significantly in recent years, making them an option for many applications. Personal computers, battery chargers, consumer electronics such as TVs are all examples of SMPS applications. The powering of LED circuits also uses SMPS set up as its constant energy source, as LED circuits need energy efficiency.
What are the benefits of SMPS?
Energy efficiency, basically. The linear regulator was widely used by industry for many years – SMPS became prevalent in the 1960s. Linear power supplies are simple to use and can have some minor performance advantages.
But the high efficiency, low power dissipation and high power density (i.e. the small size of the product) form the main reasons for designers to choose SMPS – especially for high current applications where a SMPS can achieve efficiency of more than 90 percent, compared to less than 30 percent from a linear regulator.
Power for Your Product Ltd offers optimal, cost-effective and reliable solutions for all of your power supply requirements – from the off-the-shelf standards products to custom-design. Email us to find out more.
To view our range of switch mode power supplies, click here.