Xilinx® CPLDs have been a great solution for control logic, state machines, and simple system integration for years, but were not used in consumer portable equipment because of the stigma of high power consumption. In the late 1990s, CPLDs ventured into the low-power domain with the first CoolRunner™ product family.

But prices remained out of reach for many high-volume applications. Today, through a steady progression of Moore’s law, pricing is low enough to be competitive with discrete logic devices. Now you can easily implement a wide variety of logic functions in a single package. Plus, you can save board space and get the benefits of reprogrammable logic to maximize time to market.

Some designers may still believe that CPLDs are just logic and flip-flops. But with today’s new breed of CPLDs, you get a lot more from a single device. For instance, new discrete logic devices are introduced every year, driven by demands from system integration that arise from product legacy mismatch. CPLDs fill this niche nicely by offering multiple I/O banks at low cost points.

CPLDs are also offering more integration of common features, such as voltage translation, I/O standards translation, HSTL and SSTL memory interfaces, clocking features, and higher performance flip-flops. But integration isn’t the only addition to current CPLD product offerings; CoolRunner-II CPLDs include an elaborate scheme to prevent read back and copycat designs. Potential thieves would have to go to extreme measures for the encapsulated design file, such that the money and effort required becomes truly cost prohibitive.

CoolRunner-II CPLDs also offer low-power features to assist you in lowering overall dynamic power consumption. These features include gating inputs, clock frequency scaling (division and doubling), and input hysteresis. With these features, you can differentiate your product and still consume low power, maintain low cost, and get your product to market quickly.

Success Story
HTC Corporation specializes in designing and manufacturing mobile computing and communication solutions for OEM and ODM customers. Today, with design expertise in consumer products, HTC has expanded into the wireless handset market. Figure 1 shows the HTC GSM/GPRS Magician handset platform with camera, touch screen, SD/MMC memory expansion, microphone, audio jack, and mini USB connector for synchronization.

The company’s products include smart phones, smart music phones, PDA phones, and compact PDAs. With this strong focus, Microsoft chose HTC as a platform development partner for Windows CE designs.

According to THT Business Research, HTC is the world’s largest producer of pocket PC-based PDAs, accounting for 48% of total OEM supply. They began manufacturing processes in the second quarter of 2001, foreseeing a huge market in G3 handsets. Now HTC produces more than 90% of the PDA phones based on Windows CE and continues to ship more than 3.5 million units per year.

By being cost competitive and continually adding features that other handset manufacturers wait to see a demand for, HTC has grabbed market share from some of the most well-known manufacturers. Studies show that low-end handsets are decreasing in volume, while feature-rich handsets are continuing to grow (see Table 1). By 2006, approximately 40% of new handset sales will be in the entry-level category, a figure forecasted to decline 10% each year thereafter. With this dramatic shift, handset manufacturers will have to change their products rapidly to meet consumer trends.

In addition, Windows CE operating system handsets have seemed to catch on with users. According to a Gartner Research report from April 2005, Windows CE-based PDAs have taken the lead in shipments (Table 2).

Three years ago, HTC began to study alternative logic devices that would give their products a competitive advantage in the market. They looked at price, features, ease of use, and power consumption. The study also included integration challenges and how to keep re-inventing new products with market dynamics.

To keep pace with changing technology in displays, touch screens, memory, and wireless communications, HTC needed a flexible and feature- rich solution. With changes to these technology products occurring every six to eight months, redesigns would occur often to incorporate the latest and lowest cost components. HTC examined multiple vendors from both a support perspective and best features/lowest cost competitiveness. The company also looked at partnerships, paying particular attention to those who stand behind promises of pricing, roadmaps, and technical assistance.

A Clear Choice
With a list of both supplier and component criteria, HTC chose Xilinx as a preferred vendor for low-power CPLD products. Weighing competitors not only by price, but by reputation of product, delivery, quality, and attention to special needs, Xilinx came out on top. According to HTC, the device features were what tipped the scale. Not only did the base power consumption meet or exceed power budgets, but key low-power enhancements played a large role in part selection. “HTC has received a substantial amount of performance capabilities in Xilinx products,” said Peter Chou, HTC’s president. “Their combination of leading-edge technologies, complete programmable system design, and full technical service support are essential to the success of HTC.”

When compared to other suppliers, power consumption was basically equal; the deciding factor was integrating differences from other competing products. Integrated low-power features gave HTC designers a creative method to both increase battery life and phone features. By using clock features, the designers eliminated external oscillators and reduced costs. These clocking features also helped reduce overall power consumption and increase battery life. With this one feature, they reduced board space without using additional power.

Another low-power feature that helped overall battery life was input gating. This technique has been used on other products, but Xilinx was one of the first companies to incorporate it in a CPLD. This feature helped reduce overall dynamic power consumption by powering down circuits to their standby or quiescent state. By turning off circuits that are only used part of the time, battery life can be extended well beyond a competitor’s product with the same features.

Device integration also added a key advantage to HTC’s designs. By using a single device to shift voltage levels for certain circuits, discrete devices were eliminated. Plus, the availability of small chip-scale packages saved board space when compared to discrete devices. By consolidating various functions into a single reprogrammable device, HTC saved layout problems when faced with high integration goals. Also, by condensing signal paths on a PCB layer, layout became much easier.

Faster Designs with WebPACK
To make use of special features as HTC has, you need to be able to implement them without extra effort. Low-power features such as clock frequency scaling, signal gating, and hysteresis are easy to use and have example code listed in ISE™ WebPACK™ software. This enabled HTC to turn designs around faster with the confidence that all critical timing and power consumption goals would be met.

The best part of Xilinx WebPACK software is that the features are free. Not only can you design with high-level languages like VHDL and Verilog, but functional and timing verification tools work flawlessly. Plus, the XPower power analysis tool gives you a reliable estimation of how much power will be consumed at each point of the operation. This easy-to-use software tool gave the HTC designers confidence that the results they saw through simulation were the results they measured in actual designs. For HTC, precisely knowing what to expect let them pack the most into their designs.

Conclusion
HTC has embraced low-power CPLDs with a passion, taking advantage of the features offered by CoolRunner-II products and obtaining a larger share of mid- to high-end handset sales than their competitors. With more users embracing more features, HTC is well positioned to continue their leadership and maintain growth in emerging markets. Through the use of Xilinx silicon products and software tools, HTC will continue to design innovative solutions and deliver these products on time.

To further explore the Xilinx family of CPLDs, visit www.xilinx.com/cpld/index.htm. To see HTC’s line of handsets, visit www.htc.com.tw.

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