When manufacturing a product containing electronic components, a well-assembled cross-reference list is vital for protecting the supply chain against product obsolescence and out of stock products. Creating this cross reference list for a bill of materials is easier said than done, however. An engineer must search for and verify all replacements before they can be used, which is a large sink of time and money. This is especially true in semiconductor products, where packaging information is often proprietary and hard to compare. In MOSFETs for example, ON Semiconductor labels a package as ‘IPAK’ while Vishay and others label the same package ‘TO-251AA.’ Of course, it is possible for an engineer to compare the footprints of these two packages and see that they are the same, but optimally these rote comparisons would be automated and only the final verification would be done by the engineer. In this article, the cross-reference method used for MOSFETs today is presented as well as an automated tool for generating MOSFET cross-references.
Technical Requirements of MOSFET Cross-References
The first step in finding MOSFET cross-references is finding parts with the same datasheet information. For a drop-in replacement, both the electrical and mechanical specifications of the parts must be similar and meet the product requirements. In mechanical specifications, it is important that the devices fit on the same PCB footprint. Because of the naming issues outlined in the introduction, this step often requires comparing the measurements in the datasheet manually. If the two products are mechanically compatible, then the electrical parameters are compared. For MOSFETs, the specifications which are typically compared are maximum drain to source voltage (Vds), drain to source resistance, power rating, rated current, maximum gate to source voltage (Vgs), channel type, and the values of various parasitic capacitances present in a MOSFET. After all of these values are compared between the two products and against the project requirements, the cross-reference can be added to the list of possible replacements. Additionally, the two components can be bought and tested for thermal and electrical performance in the final product.
Using the SourcingBot Cross-Reference Tool to Automate the MOSFET Cross-Referencing Process
The engineers at SourcingBot have automated much of the above process to help other engineers quickly find and validate cross-references for their bill of materials. All proprietary package names have been made comparable, as well as electrical properties of each component. To start finding suggested cross-references, input a part number in their search and visit the part page. There, the specifications of the searched part are shown as well as a list of recommended alternatives. The match table shows the most important specifications of each component so that they can be quickly compared, and the matches are ranked by a transparent similarity score, given out of 100 percentage points. All of the latest products from top MOSFET manufacturers are compared, making it easy for engineers to assemble their cross-reference lists quickly and reliably.
The SourcingBot website can also cross-reference an entire bill of materials automatically. Just visit their tool at sourcingbot.com/xref-tool and upload a bill of material to get started. It can return replacements from all manufacturers or from a given list of manufacturers. In addition to MOSFETs and other discrete semiconductor products, SourcingBot can calculate cross references in many passive component categories, including resistors, capacitors, and inductors, as well as many connector categories, including circular connectors, terminal blocks, FFC and FPC connectors, and more.
