How Vicor meets the demands of modern LED applications
Vicor's new PI3523 is a 48VIN, 3.3VOUT nominal Buck Regulator capable of supplying up to 22A. One of the key applications is for LED lighting, so Vicor asked Travis Williams, the product manager for this new regulator, to explain how Vicor meets the needs of modern LED applications.
Thanks for taking the time to explain the new product. So, is this a part designed specifically for the lighting market?
Not at all! The PI3523 is the third component in a family of general purpose ZVS Buck regulators that are used in applications ranging from telecoms, automotive and industrial test equipment to data centre to communications. But the feature set just happens to be the perfect combination for many LED lighting applications.
What are the challenges faced by designers of large LED displays?
LED display makers are quickly closing the cost/performance gap relative to large-format TVs. So, engineers are being asked to design systems with better resolution, true colour and higher brightness in a more robust system. Basically, users want better visual impact with high reliability.
It won’t be long until people start replacing LED backlit LCD TVs with LEDs in the future, although the economics aren’t quite there yet. The introduction of the PI3523 is one step to enabling a brighter future for LED displays.
Can you explain why the PI3523 meets the needs of the LED display market?
This regulator has a set of features that both simplify and improve the density of LED displays. Firstly, the output range is 2.2-4V is suited to supply drivers for both 1.8Vf and 3.3Vf LEDs. LEDs, typically those of different colours, require different voltages and different drivers; the PI3523 is versatile enough to be used for the most common voltage ranges further simplifying system power design.
Secondly, power system designers working on LED applications are looking to increase density. This is one factor contributing to the move away from AC to 48VDC power distribution. Our regulators offer direct-to-point-of-load conversion with high density, even when using large step-down ratios. The industry wants to move to 48V, but the lack of suitable power products has been holding back progress.
Today only a few LED display manufacturers have moved to 48V power distribution, although almost every company I talk to has an R&D project looking at this architecture. While it makes sense to avoid the cost of retooling for as long as possible, most of the engineers I talk to say that they will have no choice other than moving to 48VDC in the next couple of years if they are going to remain competitive.
How does the 22A capability enable higher density in LED applications?
Higher power is one of the biggest trends in LED applications. Designers are being asked to create higher pixel density panels, making LED displays like high-resolution TVs. The higher densities, however, mean more LEDs and therefore regulators that can supply higher currents are needed. The ability to supply up to 22A from such as small package is unique to this new ZVS Buck Regulator.
It’s important to realise that power density increases by the square of pixel density, so higher resolutions demand much more power. We’ve doubled the power output in a package that’s only 40% larger than the 10A family. This increase in power density is something that will help enable higher pixel densities and resolutions.
Are there any other trends in the display market that are enabled by the PI3523?
Yes! Panel manufacturers are being asked to create thinner, lighter panels. Thinner panels obviously look better, but it’s the cost of installation that means that weight is critical for modern LED panels. It’s important to remember that many LED panels are rented for events, rather than being permanent, so the cost of installation is very important. Heavy panels are expensive to install, and the market wants LED displays to be like modern TVs: small light and HD.
LED panels have traditionally used AC/DC Bricks, which are thick and heavy, so it’s impossible to make a thin and light display with these products. Using 48VDC distribution and Vicor ZVS Buck regulators, however, enable very thin panels with greatly reduced weight.
What else is driving LED display power systems?
We’ve already talked about the need for high power density and small size. The other electrical requirement is efficiency. With modern displays, you’re burning lots of power. Removing heat can be challenging, so engineers want to make thermal design easier by cutting wasted heat, as well as making the displays greener.
Reliability is also a problem. Large displays use tens or even hundreds of small panels, and the failure of even one panel is not acceptable. Today the AC/DC bricks might have a failure rate of 500 PPM. When they move to 48V power distribution, designers are replacing these components with Buck Regulators that have a failure rate of only 5 PPM, which dramatically reduces the chance of a panel failing.
Why is there such a demand for LED displays?
Advertising is the traditional market, and we are seeing greater use of displays, particularly the smaller ones that are placed inside shops or shopping malls. The number of applications is growing as the resolution goes up and the cost comes down, with LCD monitors being replaced by LED displays in command and control rooms ranging from local governments to national disaster monitoring centres, to weather stations, and airport security: anyone using a video wall should be considering switching to the better more reliable displays provided by LEDs.