Deciphering the New SUMIT™ Specification

The new SUMIT specification is managed by the Small Form Factor Special Interest Group (SFF-SIG). SFF-SIG is a newly formed, non-profit industry group that develops, promotes, and supports small form factor circuit board specifications and related technologies. The group embraces the latest technologies, but also has a philosophy of maintaining legacy compatibility and enabling smooth transitions to next-generation interfaces.

A SIG Is Born

The Small Form Factor Special Interest Group (www.sff-sig.org) is an international organization devoted to identifying, creating, and promoting standards that help electronics system and device manufacturers and integrators move to small form factor technologies as building blocks in their products. Benefits of small form factor products include smaller size, reduced power consumption (eco-friendly, “green” products), and greater reliability compared to larger legacy products. Additionally, the SFF-SIG seeks to enable practical, mainstream, real-world applications rather than extremely high-performance and high-power dissipation systems. The SFF-SIG is concerned about all components of the system-level solution, not just the processor section. The rationale is that it doesn’t help much to shrink the board if the packaging, cabling and thermal issues are not addressed at the same time.

The SFF-SIG has formed three working groups to address different product categories. The SBC Working Group is discussing new small form factor single board computers. The Modules Working Group is developing a specification for a new small computer-onmodule (COM) form factor. The Stackables Working Group is examining approaches to adapt new highspeed serial technologies into legacy systems in a smooth manner that preserves investments in I/O, cabling, and enclosure designs.

From the Stackables Working Group came the SUMIT™ Specification. The word ‘SUMIT’ is an acronym that stands for Stackable Unified Module Interconnect Technology. It is pronounced “sum it”. The specification takes a unique approach to separating the connector technology from a particular board size. The purpose of this specification was to define a unified expansion interface that could be supported by many standard and custom SBC form factors in a flexible and compact manner to meet a very broad range of application requirements. Form factor details are distinct from the SUMIT connector, and pinout details, therefore, are left to those respective specifications.