Assembling a list of valid replacements is an essential step in securing the supply chain for an electronics bill of materials. Without it, a drop in supply for one component could delay the entire manufacturing process weeks or even months. The process of creating this list of alternative parts, however, is far from trivial. Someone with an expertise in each component category is required to search for and verify cross-references, which is an expensive and time consuming process. The component manufacturers themselves can be used as a resource, but their tools will only recommend their own products and they typically don’t support the latest products or products from more obscure suppliers. In this article, the requirements for cross-referencing two through hole (THT) aluminum electrolytic capacitors will be described and an automated tool to speed up this process will be introduced.
Requirements for THT Aluminum Electrolytic Capacitor Cross-References
When creating a cross-reference, an engineer needs to verify the electrical and mechanical compatibility of the two parts. For a THT aluminum electrolytic capacitor, the mechanical properties include diameter, length, and pin spacing. This ensures that the two parts can use the same PCB footprint and fit in the same enclosure. The electrical properties include capacitance, voltage rating, equivalent series resistance (ESR), lifetime at rated temperature, rated ripple current, and operating temperature.
One capacitor from Würth’s WCAP-ATLI and one capacitor from Panasonic’s SXE series will be compared to demonstrate how much analysis is required in a traditional cross-referencing process. Both the Würth 860080775010 and the Panasonic 63SXE68M are 68uF, 63V THT aluminum electrolytic capacitors with a tolerance of 20%. The first step for an engineer in the cross-referencing process is to compare the datasheet values, found either at the manufacturer’s websites or on a distributor page. Mechanically, the two parts are quite similar. Both have a diameter of 10mm and a lead spacing of 5mm, meaning that they should be footprint compatible. The height of the Würth part is 12.5mm and the height of the Panasonic part is 13mm, so they are also size compatible in most designs. The Würth part is rated up to 105 Celsius while the Panasonic part is rated up to 125 Celsius. The datasheet values show that the two capacitors may be compatible, but that is not the end of the analysis.
In order to truly verify the compatibility of the two parts, an engineer needs to know their performance at the operating point of the device. This can be one of the most expensive parts of the cross-referencing process. If the engineer is lucky, the two parts have impedance and ESR curves on the manufacturer datasheet and the two parts can be compared if the lab conditions and units are consistent. If not, the only way to verify this behavior is to purchase the two parts and test them in their own lab. Repeating this process for all items on the device bill of materials takes a lot of time and a lot of money.
Using the SourcingBot Cross-Reference Tool to Automate the THT Aluminum Electrolytic Capacitor Cross-Referencing Process
The task of comparing datasheet values may seem too simple for an engineer to perform, but only they have the expertise in knowing which values should be compared and the importance of each value. The engineers at SourcingBot have automated this process, calculating the most similar parts in terms of datasheet values for every THT aluminum electrolytic capacitor. And unlike manufacturer cross-reference tools and lists, their database will return the best match, regardless of manufacturer, and contains the latest parts from a diverse range of manufacturers.
In addition to automating the datasheet comparison step of cross-referencing, SourcingBot also offers quick comparison of lab-measured data to help increase confidence in the compatibility of two parts. This means no more converting units and scales between two datasheets from different manufacturers.
Here the ESR behavior against frequency can be seen for the two parts. At operating frequencies below 1kHz, the difference in ESR is quite small. However, at higher frequencies, the ESR of the Würth part is significantly higher. This could be a critical difference in some applications, and an unimportant difference in others. SourcingBot allows engineers to investigate the behavior of parts at their desired operating point, speeding up the THT aluminum electrolytic capacitor cross-referencing process significantly.
The SourcingBot cross-referencing tool is available for single parts, entire bills of material, and even as an API. Not only have their engineers found the best capacitor cross-references, similar parts in MOSFETs, TVS diodes, connectors, inductors, resistors, and other categories can be found. Research a single part at sourcingbot.com, or secure your entire bill of materials at sourcingbot.com/xref-tool.