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Design Talk: January 2010

Mon, 12/21/2009 - 8:21am

Stop Compromising Your PCB Layout

David D-webBy David Donaldson, W. L. Gore & Associates, www.gore.com

As electronic devices are getting smaller and as consumers are demanding more features, designing printed circuit boards (PCBs) is becoming increasingly complex, not to mention that any finished design must face both performance testing and testing for compliance with Federal Communications Commission rules and other codes.

Many design engineers start by considering shielding requirements, doing such things as identifying the noisy components and placing them as far away from sensitive ones so as to reduce potential interference; however, they also realize that if the product fails in the testing lab, they will have to add cans to the board to provide shielding. To allow space for shielding cans, they may have to group the largest components together to make the best use of these cans. This reactive mindset translates to making the design conform to the shape of the shielding can and designing the board based on shielding requirements rather than seeking an optimal design that maximizes space usage and functionality.

Thermoformed, board-level shields permit design engineers to place components and circuits on a PCB based on function as opposed to the need to conform to the predefined geometry of the shield. Engineers can design the board based on circuit and component function without the constraints imposed by the shape of traditional shielding cans. Using a single thermoformed shield provides many specific advantages, all of which result in increased flexibility in board design, integration, and performance.

Board Design Flexibility
Today’s consumers want electronic devices in all shapes and sizes, which can dictate the enclosure design and the board shape. Stock components and cans are generally square or rectangular, and placing square cans on irregular boards has a significant impact on the engineer’s ability to place components on the board. Thermoformed shields can be shaped to fit any board, regardless of its geometry, without increasing the complexity of manufacturing the shield itself. Design engineers who opt for thermoformed shields at the outset of a design project can focus on effective board design without being limited by the shape and construction of their EMI shields

Additionally, thermoformed shields minimize the amount of space needed to shield individual areas. Rather than having multiple cans on a board, each of which needs its own trace to connect to the ground plane, a PCB only needs one thermoformed, multi-cavity shield with a single row of solder spheres to connect the individual cavities to the ground plane. For example, if an engineer plans to use individual cans to separate two cavities, each can needs its own ground trace with space between them. With a thermoformed, multi-cavity shield, only a single ground trace between the cavities is needed.

The design flexibility of thermoformed shields enables implementation of other necessary features such as mouse holes to avoid coupling, entry points for cables and connectors, and air perforations to facilitate cooling. This allows components and circuits to be placed in their optimum location without first considering shielding requirements.

Thermoformed shields are an innovative EMI shielding solution that maximize flexibility related to board design. Design engineers no longer need to compromise the layout of their printed circuit board. By selected this shielding type up front, they can create their ideal layout and have the EMI solution conform to this design.
 

COMs and Smart Batteries: Helping Deliver Advanced Imaging Devices

In an effort to enable life saving diagnostic imaging equipment to be taken anywhere it could be necessary, device manufacturers are seeking technologies to help them design devices that will facilitate fully functional, smaller, portable devices. Using computer-on-modules and smart battery technology, they are finding the tools they need to make these devices available.

By Christine A. Van De Graaf, Kontron, www.us.kontron.com 

Christine A. Van De Graaf is a product manager with the Embedded Modules Division at Kontron America. She is responsible for product management and product marketing for standard module and SBC products. Van De Graaf can be reached at 510-284-1150 or christine.vandegraaf@us.kontron.com.

Life threatening situations require the use of portable medical devices to deliver the right information to doctors in medical settings, emergency personnel on the go, and patients at home so they can make informed decisions. This “take everywhere” diagnostic imaging equipment has been a top challenge in embedded medical design. Characterized by a high demand for performance and low power, all within a small footprint, these devices require that designers pioneer new design thinking. They must pay particular attention to technologies that enable low power consumption, high efficiency driven by extended battery life, and high precision computing for the fastest response time.

Many of these size and performance demandsparticularly key in medical imagingcan be fully realized with Intel multicore processor architectures integrated into computer-on-modules (COMs). Multicore processing has definitely changed the course of computing, providing new levels of energy-efficient performance enabled by advanced parallel processing and next-generation hafnium-based 45-nm technology. Applications that previously faced barriers due to size, performance issues, or power consumption limitations can now be developed using a standard COM implementation.

COMs Are Key in Medical Design
The COM solution is a highly integrated component SBC that supports system expansion and application-specific customization. With COMs, the CPU module provides the core functionality, with all the application-specific features designed directly onto the baseboard for a semi-custom embedded solution. The inherent ability to swap the COM module without touching the existing customized carrier board makes upgrading simple, which is important as technologies change rapidly.

The development of smaller and smaller devices has propelled the need for smaller and smaller COMs as well. To address this need, several variants are now available: the basic form factor COM Express Pin-out Type 2 module defined by PICMG; the compact form factor COM Express Type 2 compatible module; and the ultra small form factor COM Express Pin-out Type 1 module. With heat-sinks or heat-spreaders mounted directly on the module or coupled to the system enclosure, cooling is effectively managedparticularly important in sealed medical devices that have completely restricted airflow to minimize bacteria.

Power Efficiency with Smart Battery Technology
Integrated smart battery technology goes beyond low power to provide the power efficiency required by today’s ultraportable medical devices. This may call for software-enabled customization, an easy fit for any COMs solution that can be designed into the custom carrier board, and includes set parameters for recharging certain portions of the device while keeping others in standby mode, resuming full power and function when needed. Customized solutions based on ETX, COM Express (basic FF pin-out type 2), and microETXexpress (compatible to COM Express pin-out type 2) are an ideal fit for smart battery implementation. MARS (mobile application platform for rechargeable systems) is one such modular reference design developed by Kontron in which two smart batteries are added to the customized carrier board to work in conjunction with the COM. This is ideal for the variety of COM solutions available, providing an easy method to put smart battery capabilities onto a customized carrier board. 

Silicon-platform and operating system independent, the MARS approach is modular, meaning it allows designers to select only those blocks of functionality necessary for a specific design. Medical electronics engineers can employ a variety of options to optimize mobile applications, integrating uninterruptible power supplies (UPS), in-operation battery recharging and a wide range of input voltage (from 5 to 20 VDC). MARS permits ATX functionality with a single voltage input and ATX voltage output and support for suspend modes S0 through S5. In addition, surge and short circuit protection and monitoring extend the overall use of the device and its applicability for ultra-portable applications.

With a reference design that both simplifies and accelerates the design process, designers have a quick evaluation platform that is open for unlimited design use and provides a guideline for spot-on engineering. It’s key that these reference designs be silicon-platform and operating system independent to make development and integration into the overall solution as easy as possible.

For example, today’s ultrasound units must provide advanced performance and be simple to use. In emergency situations, an ultrasound system that is small, portable, and highly reliable is also essential to the well-being of the patient. A compact ultrasound unit about the size of a brick incorporates a COM Express design, including smart battery, and the graphics capabilities required for immediate medical diagnosis. Conveying information directly to emergency room personnel, an EMT is able to scan patient images that can be interpreted remotely by doctors to ascertain the appropriate care en route to the hospital and upon arrival. With this system, decisions can be made more accurately and quickly as the patient begins treatment.

Medical Design Moving Forward
Medical applications that have faced obstacles due to size, performance, or power limitations have found a viable solution in the standard COM implementation. For instance, a portable medical device can be acquiring data while another portion of the device can either be “asleep” or transmitting that datadrawing on complex power management capabilities to greatly improve the speed and quality of patient care. Seamless, constant usability and data collection gives medical care professionals the ability to focus on caring for the patient with little or no manual management of the devices they use.

Small form factors with low power consumption and energy efficiency are likely to keep driving the industry, enabling medical device designers to build products that deliver the vital information doctors need at the point of care.

Online
For additional information on the technologies and products discussed in this article, see MDT online at www.mdtmag.com or Kontron at www.kontron.com.

 

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