This user’s guide describes the operation and use of the OPA928 evaluation module (EVM). The user's guide provides information on how to set up the EVM and describes different circuit configurations that can be used to evaluate the performance of the OPA928 femtoampere, input-bias-current op amp. Throughout this document, the terms evaluation board, evaluation module, and EVM are synonymous with the OPA928EVM. This document also includes an electrical schematic, simplified schematics of OPA928 applications circuits, a printed circuit board (PCB) layout drawing, and a parts list for the EVM.
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Applications requiring femtoampere-level performance are extremely sensitive to contamination. Contaminants in the form of solder flux, salts, oils, organic acids, and more can form conductive paths over PCB traces that allow small currents to leak into input traces or other sensitive nodes, thus degrading performance. For best possible performance, make sure to keep the OPA928EVM as clean as possible.
The following list of best practices helps prevent the EVM from becoming contaminated:
The OPA928EVM undergoes a rigorous cleaning protocol before shipping to customers, providing femtoampere-level performance directly out of the box. Follow the cleaning procedures detailed in Section 5 to maintain best performance. The EVM must be cleaned per these instructions anytime the board is soldered or modified near sensitive nodes, or if these nodes become contaminated by other means.