Switching regulators have been around for many decades, yet new products continue to be released regularly. Some of the new designs offer capabilities that were previously not offered in existing products, but the vast majority can be used as replacements for existing designs with resultant benefits.
When an engineer selects a switcher for an application usually the selection is done using parameter matching with voltage in, voltage out, and current out being the primary parameters. Once an engineer selects a product for a certain design, a bias towards using the same product on the next design is established, assuming the product meets the new design parameters that is. The experience and trust gained when building the first designs make it easy to use same design over and over. That's why 10 and 15 year old switching regulators still remain very popular.
But, technology marches on, and in the switching regulator world technology advancements are sometimes hard to see. Let's go beyond the parametrics to understand why modern switching regulators are far superior to older products so that, if you are using an old product, you'll understand why it is time for you to switch!
Can you guess which 2A power supply utilizes the most modern switcher technology?
The process technology used to fabricate a switching regulator has a huge impact on the parameters that a product can achieve. Modern processes enable faster switching frequencies. The impact of a faster switching frequency on your design, in general, is smaller design footprint. A higher switching frequency results in a much smaller inductors and much smaller output filtering capacitors. When combined with the decreased footprint of a modern switching regulator IC, this means your power supply footprint can be decreased drastically, sometimes by 50%, without impacting output quality.
The switching elements within a switching regulator (ie, a product with internal switches) are essentially field effect transistors (FETs). Advances in the power handling capability of these switches have led to much higher switching capacity, in terms of output current, and also much lower heat dissipation. From a power switching standpoint, the key parameter of a switching FET is Rds(on) – resistance from the drain to source. New modern processes offer Rds(on) in the milliohms – a factor of 10 to 100 better than an older design. Low Rds(on) also makes it possible to implement synchronous rectification where an efficient FET replaces the traditional high loss rectification diode. The impact of this on your design is a regulator that offers higher output capacity while running cooler, offering a much more robust solution.
Process technology also impacts a switching regulator's quiescent power requirements. Modern switchers have much lower quiescent power requirements than those designed even a few years ago. The impact of this on your design is power savings and reduced heat – mostly important in handheld designs, but important overall in all designs.
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As discussed above, process technology improvements inherently provide better specifications in terms of both power dissipation and power handling capacity. Because the modern processes are usually based on finer line widths, they offer more capacity for bringing external circuitry onto the silicon itself. Many new products offer self contained compensation circuitry, eliminating the need for many external passive components. The impact on your design is a small design footprint and an easier design.
In the past, switching regulators with internal switches could only handle low current levels – under an Amp, and even these would need an external switching diode. Much improved process technology has allowed the integration of advanced FET switches onto a single chip resulting in smaller designs even at higher output power levels (from 1A to 10A).
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A switching regulator's architecture has to do with the logic algorithms used to drive the switches and the switching architecture itself. Because modern processes provide more room within an IC it is now possible to incorporate more control logic and offer different modes of operation. By providing different operating modes it is possible to provide increased conversion efficiency in different operating environments. Modern switching regulators will offer multiple modes of operation for increased efficiency over a broad range of operating conditions.
The switching architecture used within a switching regulator also impacts its efficiency. Switching regulators with synchronous switching control provide the highest efficiency in moderate to high load conditions. In the past, products that incorporated synchronous switch control were expensive and the technology was offered mainly on switching controller products (that is products that controlled external switches). Many modern switching regulators now incorporate synchronous switching logic along with internal MOSFET switches thereby providing the highest efficiency available, all in a single low cost product.
Due to the synchronous switching action and the associated switching losses, basic synchronous switching regulators can suffer from lower efficiency at light load conditions. Advanced Multi-mode control architecture eliminates this problem, delivering the best efficiency across the entire load range. The most advanced and modern switching regulators offer synchronous switching along with multi-mode control for highest operating efficiency over a wide range of output loads.
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We've explained how modern switching regulators are far superior to those which were designed in the past. The benefits offered by newer products are extraordinary: smaller design footprints; easier design; cooler running; higher efficiency; and higher capacity circuits resulting in much more robust and reliable end products.
Now that you understand the technology, it's time to do your part: it's time for you to switch from using your tried and t(rusty) decade-old switching regulator to a new more modern product so you can add these benefits into your new and existing designs.
You should begin your evaluation today. While you are looking at alternatives to replace your existing standbys, please make sure to evaluate Maxim's ultra modern Himalaya step down switching regulator products. Our Himalaya product family incorporates all of the elements discussed above.
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