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As electronic capabilities progress, memory cards and connectors can offer many additional benefits through advancing card technology.
By Kenji Iwahashi and Keith Volz
In the late 1980s, mobile computing began to evolve. "Lugtops" evolved into laptops, electronic address books evolved into palmtops and heavy, cumbersome mobile phones evolved into cellular phones. Personal digital assistants (PDAs) and cell phones are now morphing into as-yet-to-be-determined future Internet appliances.
Removable memory and functionality cards have been an instrumental driving force in this evolution of mobile products. An early pioneer in mobile computing was Sharp Electronic Corp.'s Wizard. The product offered many functions ranging from a calendar to a calculator to an address book. It also offered the consumer the ability to add additional memory or functions through removable cards.
However, there were a few problems. The cards were expensive and only worked with the Wizard. The market realized the need for compatibility between card and host manufacturers; hence, the Personal Computer Memory Card International Association (PCMCIA) was formed.
Memory Card Overview
Since the late 1980s until present day, memory card technology has evolved into seven major card groups. The PC Card was the first of the removable card groups to enter the market, introduced by the PCMCIA. Following the PC Card, an evolution of smaller cards entered the market — CompactFlash, SmartMedia and Small PC Cards.
In the late 1990s, reduction in memory card size continued with the introduction of MultiMedia Cards (MMCs), Secure Digital (SD) Cards and Memory Sticks joining the ranks of the removable card market. Trade associations were formed to develop the specifications and support the card groups (consult their Web sites for more information; see Table 1).
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The primary function for most removable cards is memory. However, as electronic technologies progress, host and card manufacturers are able to offer additional capabilities through advancing card technology, such as greater memory capacity, faster modems, Ethernet capability, serial port ability, Bluetooth compatibility and rotating storage, to name a few.
The mobile computing market offers a variety of sophisticated equipment utilizing removable memory card technology. Mobile computing has progressed into several other industries as well, taking card technology along.
Today, removable memory card technology can be found in many applications crossing several industrial lines. Applications include digital still cameras, network appliances, remote controls, home entertainment centers, home security systems, set-top boxes, medical and health equipment, industrial controls, MP3 players and cell phones. Another growing area for removable cards is embedded applications, such as single-board computers, modems for vending machines and internal backup removable memory (black box) for sensitive data.
Importance of Specifications
A major role in the market acceptance of removable memory cards can be attributed to the trade associations. The associations developed and maintained software and hardware specifications that made plug-and-play a reality. The associations were responsible for making the card and host systems compatible and reliable, which increased market acceptance and, therefore, drove the cost down.
Connector Overview
Connector specifications are well-defined, which greatly contributed to the acceptance of removable memory card technology (see Tables 1 and 2). Some specifications are:
- Meeting the cycle life of the system, generally 10,000 cycles, which is a function of the contact design, material selected and plating thickness
- Keying and polarization features to prevent damage to the card and host system during card insertion
- Connector and card mating surfaces to prevent mismating and damage to the card and the host/connector interface
The connector ejector mechanisms are not specified. However, a variety of ejector designs are available, ranging from manual to spring-eject styles.
Drivers and Trends
The market demands smaller, lighter and highly reliable portable electronic products. Consumers want their mobile products to perform the same as their traditional desktop or stationary products. They want capabilities such as high-speed modems and Ethernet hook ups, small computer system interface (SCSI) ability, removable or rotating storage, and wireless capabilities.
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Shrinking electronics drive the technology trends for the removable memory cards (see Table 3). A major trend is the reduction of the card size. The PC Cards, the largest of the cards, are the size of a standard magnetic-strip credit card. Shrinking electronics have made it possible for cards one-half the size of PC Cards to evolve. CompactFlash, SmartMedia and Small PC Cards can all offer the same capabilities as PC Cards.
And the evolution of smaller removable memory cards offering the same if not greater capabilities continues to advance. Smaller cards the size of postage stamps and sticks of gum, like MMCs, SD Cards and Memory Sticks, have recently entered the market, offering large Flash Memory capacity and an expected future of greater memory capacity.
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The PC Adapter Card is a growing trend mainly because of the large installed base of PC Card slots. Some host designs consider the PC Card slot to be the common slot. Through the use of PC Adapter Cards, the smaller removable memory cards can be introduced to the large, existing base of common slot host units, thereby offering the smaller cards a direct and successful path to the market.
Other trends include lower power requirements and wireless. Consumers want mobile products to function on AA or AAA batteries, and they want to be free of external cables, including having wireless modem capabilities. Shrinking electronics has led to a flow of new removable functionality cards with wireless capabilities like Bluetooth and rotating storage that have 1 Gb of capacity.
Conclusion
Removable memory cards have made tremendous progress in a variety of markets. Almost all mobile consumer products have adopted one of the removable card formats. Products such as digital cameras, MP3 players, cell phones, PDAs and set-top boxes all accept the use of the cards. Industrial mobile products such as data collection products and industrial controllers have embraced the use of embedded removable cards. The list of design wins for removable cards continues to grow, driven by a continual flow of technology that is stimulated by new requirements, shrinking electronics and market pressures.
KENJI IWAHASHI is Group 4 Engineering Manager, and KEITH VOLZ is New Product Development Manager, J.S.T. Corp., 1957 S. Lakeside Dr., Waukegan, IL 60085; (800) 947-1110; (847) 473-1373; E-mail: kvolz@jst.com; Web site: www.jst.com.
SPEC SHEET
End Applications:
Portable, hand-held electronic devices including cell phones, MP3 players, PDAs and digital cameras
Related Products:
Removable memory and functionality cards and connectors
Main Point:
Almost all mobile consumer products use one of the removable card formats. The primary function for most removable cards is memory. However, as technologies progress, manufacturers are able to offer additional capabilities through advancing card technology, such as greater memory capacity, Ethernet capability and Bluetooth compatibility. Removable card designs continue to evolve, driven by new requirements, shrinking electronics and market pressures.
