DOSA Standard for High-Current Quarter Bricks

Nov 3, 2004 12:37 PM
Edited by PETech Staff

The Distributed-power Open Standards Alliance (DOSA) has announced a standard footprint and pin-out design for high-current quarter-brick dc-dc converters. This new standard establishes both the location and function of additional output pins required for a new generation of high-current quarter-bricks. The technically optimized solution was achieved through close collaboration with DOSA members and key OEM customers. In addition to DOSA founding members, Tyco Electronics Power Systems Inc. and SynQor Inc., new members Celestica, Lambda and Delta also participated in the standards development process.

The new DOSA standard establishes a common pin placement and designation for the two additional power output pins required for recently introduced high-current quarter-bricks, rated in the 50-A to 80-A range. Extra power pins are needed due to the increased complexity of the soldering and thermal relief requirements associated with mutilayer boards. The added pins reduce the total resistance, contributing to improved thermal performance and better reliability.

After studying the technical merits of several proposed solutions, DOSA based its standard footprint on the design of SynQor’s high current pin out proposal. In this design, the two additional power pins are located 0.15 in. (3.81 mm) outside of and in line with the existing quarter-brick power pin locations. More importantly, the extra output pins employ the opposite polarity of their adjacent power pin (see diagram). As a result, the DOSA solution maximizes the distance between like polarity pins, allowing significantly less spreading of resistance.

The DOSA standard offers a number of benefits over competing designs. With the specific location and function of the added pins, the overall loop inductance (from converter to board to converter) is reduced by a factor of 10. This improvement allows the module to exhibit better transient response performance, lower output ripple and improved load current balance between the pins. The additional pins reduce total power dissipation in the load board, which contributes to improved thermal performance, enhanced reliability and lower cost of ownership. In addition, because the two extra output pins are not positioned behind existing pins, the tasks of visual inspection and rework are greatly simplified. All other pins retain the same placement and function as the existing quarter-brick standard, which facilitates board layout to allow the use of both types of modules.

For more information, visit www.dosapower.com.

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