TechBites Says:

The CS1500 and CS1600 are digitally controlled, discontinuous conduction mode (DCM), active power factor correction ICs intended for use in power supplies rated up to 300 watts. The CS1500 is designed to address power supplies such as laptop adapters, digital TVs and PC power, while the CS1600 targets electronic lighting ballasts. The two devices announced here are variants of Cirrus’s EXL Core technology, a so-called “digital power factor correction” technique which has been tweaked to support these specific applications.

Cirrus’s metal-programmable digital architecture allowed them to quickly spin off these variants of the original product and, as we’ll see shortly, it will allow them to easily produce other optimized family members for new merchant applications or specialized versions for a specific customer. These unglamorous but important devices several important things to designers interested in selling computing, consumer electronics and energy-efficient lighting in Europe, Asia, and many other markets which have increasingly-stringent requirements for both efficiency and how much electrical crap your product can put back on the line.

Cirrus’s EXL Core architecture employs a variable-frequency switching technique where the PFC controller’s frequency is adjusted relative to the ac input voltage and phase angle on a near-continuous basis during a single cycle (28kHz -48kHz for the CS1500 and 42kHz-72 kHz for the CS16000. The controller reduces its switching frequency near the AC zero-crossing point for maximum efficiency. Conversely, the EXL Core increases its switching frequency as the input AC reaches its maximum amplitude which Cirrus claims dramatically reduces its conducted EMI output. The controller’s fine-grained PFC control also introduces less distortion on its output. While not essential for some power supplies, the reduced THD is a big plus in fluorescent ballast applications where waveform distortion can affect light quality.

This variable frequency technique also has the advantage of spreading the EMI energy the controller produces over a wider chunk of spectrum, reducing a typical design’s noise level by 14 dB (compared to fixed-frequency solutions). Designers can translate the reduced emissions into either lower operating noise levels or smaller (i.e. less expensive) filtering components. In addition to the actual cost savings, using smaller fewer passives enables easier, tighter layouts on the simple single-sided PCBs that are typically used in these cost-conscious applications. To make things even easier, Cirrus has introduced the chips with multiple reference designs– including a 75W Flyback regulator, as well as LLC controllers with 90W and 230W capacities.

According to Cirrus, their digitally-controlled EXL Core architecture help designers create supplies ranging between 65W and 300W that enjoy higher efficiency over wider load range than a conventional analog PFC solution. In most common applications they are able to deliver ~95% efficiency at low line voltage and full load conditions and still operate at over 90% efficiency under a 10% load. This is an important capability for products which have many activity levels between the “on” and “off” states - including laptop computers which adjust their clock rate and screen brightness according to demand. In laptop/desktop applications, the CSI-1600’s flat efficiency curve and sub-200 mW standby power will make it easier for manufacturers to meet tough new eco-labeling requirements like the 80 Plus standard while still working within the tight cost margins that dominate the consumer electronics market.

As I hinted at earlier, the EXL Core’s digital architecture allows it to be easily configured for a specific application with simple changes in its metal layer. While devices cannot be field-programmed, Cirrus can quickly produce a specialized variant with customized trip points, start-up characteristics, and other parameters that tailor its efficiency, protection, and BOM costs to a particular application. Cirrus says that the we can expect even better performance in follow-on family members. And while no specific plans have been announced, I’d also expect to see them adapting the technology to AC-DC converter applications. Watch this space for upcoming developments as they emerge.

The CS1500 and CS1600, which are available in an 8-pin SOIC package, are available today and priced at $.30 in quantities of 1,000,000. If you’re not quite up to buying at these unit levels yet, the controllers are also available through Mouser Electronics – Click here to visit Mouser’s product listing.

For more information and downloadable data sheets click here
For more information on global regulations and power consumption challenges within applications, see the Cirrus Logic White Paper: The Digital Imperative: The Rising Wave in Power Factor Correction (PFC) Techniques

Cirrus Logic Says:

 Cirrus Logic Introduces First Digital Power Factor Correction ICs That Surpass Analog PFCs on Performance, Price
Innovative Digital EXL Core Architecture Enables the CS1500, CS1600 to Increase Performance, Lower System Costs in Power Supplies, Lighting Ballasts

Kicking off a new line of products for growing energy-related markets, Cirrus Logic Inc. has unveiled the industry’s first digital power factor correction (PFC) controller ICs that surpass analog PFCs on performance and price. The CS1500 and CS1600 offer power supply and lighting ballast system designers improved performance and simplified designs compared to legacy analog PFC products. Both ICs are priced on par with analog PFCs, while also lowering the overall bill of materials by up to $0.25.

PFC is required in many electronic applications around the world, as global regulations are pushing to improve the overall efficiency of the utility grid. Analog PFC chips are nearing the end of their capabilities to meet increasingly strict global regulatory requirements and efficiency standards, and new digital solutions enable continued performance and feature improvements designed to meet future market demands.

“Global regulations for power efficiency will become increasingly more challenging long term, and we expect a transition in the PFC market away from analog and into digital PFC products, just as the digital transition has transformed many other markets,” said Linnea Brush, senior research analyst, Darnell Research.

Featuring the new EXL Core architecture, with its currently 53 patented and patent-pending digital algorithm technologies, the CS1500 and CS1600 have the advantage over analog products of being able to intelligently solve increasingly complex power management challenges. Through its patent-pending digital noise shaping technology, both the CS1500 and CS1600 enable reduced-sized EMI filters, which cut the need for additional high-priced components and circuitry. Additionally, these digital ICs improve energy efficiency across all load conditions, with a distinct performance advantage in light load conditions, and simplify system designs by reducing external component count by more than 30 percent.

 “We’re bringing disruptive digital technology to applications that are currently dominated by analog solutions,” said Jason Rhode, president and chief executive officer, Cirrus Logic. “Until today, no one has been able to develop a digital PFC controller that offers both performance improvements and cost savings compared to analog-based PFCs.”