COM Express
The Concept
Customer demand for small, high performance computer modules is strongly increasing. For this reason, congatec AG, some large customers and two additional embedded computer manufacturers decided to create the miniaturized “COMPACT” computer module based on the COM Express connector and signal definition.
Size
The newly defined Compact module features all the functions of the Basic module/type 2 connector layout but reduces the size to 95x95 mm². The PICMG has already defined two module sizes: the Basic module (125x95 mm²) and the Extended module (155x110 mm²). The primary difference between the Basic module and the Extended module is the overall physical size and the performance envelope supported by each. The Extended module is bigger and can support more power consuming processors and chips with larger footprints. The Compact module, the Basic module and the Extended module use the same connectors and pin-outs and utilize several common mounting hole positions.
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Interfaces
COM Express Compact will offer a maximum of 22 PCI Express Lanes, 4 Serial ATA, 8x USB 2.0 and Gigabit Ethernet. The parallel PCI Bus and the parallel IDE interface will still be maintained thereby allowing a smooth upgrade to todays fastest serial buses.
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Compatibility
A high level of compatibility allows that a carrier board designed to accommodate a Basic module can also support a Compact module. The Type 2 connector layout is available for all board sizes. It defines 440 interconnect pins between the COM Express module and the carrier board. Legacy buses such as PCI, parallel ATA and LPC are supported along with new serial high speed interfaces such as PCI Express, Serial ATA and Gigabit Ethernet.
Thermal Design
Like XTX™ and ETX®, the COM Express definition includes a heatspreader that acts as a thermal interface between the COM Express module and the system‘s cooling solution. The height of a COM Express module, including the heatspreader, has been defined as 18 mm and covers the complete area of the Embedded Computer module. All heat generating components are thermally conducted to the heatspreader in order to avoid hot spots.
Advantage
This new concept will permit easy integration while providing the latest I/O interface technologies and will also enable large headroom for future applications.