This document introduces the compatibility between Analog Devices' 28x28 MQFP and LQFP packages. It provides a land pattern design that accommodates both packages.
Analog Devices offers its ADSP-21369 and ADSP-21371 SHARC processors in either a standard 28x28 mm metric quad flat pack (MQFP) or an enhanced thermal low-profile quad flat pack (LQFP_EP). While the lead width and pitch dimensions are identical between these packages, their footprints differ significantly: the MQFP has a footprint of 2.6 mm with a foot length of 0.6 mm, whereas the LQFP_EP has a footprint of 2.0 mm with the same foot length.
To address this difference, the document provides guidelines for designing a PCB land pattern that accommodates both packages. It illustrates how to extend the MQFP land pattern in the negative x-direction by 0.25 mm relative to the LQFP_EP pattern when following IPC-7351 standards. The note concludes that while it offers an example design, the final dimensions should be determined by the end user based on specific application requirements.
This document describes a land pattern design that accommodates both MQFP and LQFP_EP packages.
The land pattern of the MQFP package must be extended 0.25 mm in the negative x-direction.
No, it is not a recommendation; it is up to the end user to determine the correct dimensions.