FAQ: ADIS1648x SPI Extender

Document created by NevadaMark Employee on Sep 16, 2015Last modified by NevadaMark Employee on Sep 17, 2015
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Do you have any reference designs that can help me extend the reach of the SPI on the ADIS1648x?



We recently completed a project, where we helped someone establish communication between an ADIS16485 and the EVAL-ADIS evaluation system, which were over 2 meters apart from each other.  In addition to the distance, the ADIS16485 was on top of a rotating platform, inside of an temperature chamber, while the EVAL-ADIS was outside of the chamber.  Since the remote communication port (J1) on the EVAL-ADIS will only support 12 inches of ribbon cable to a remotely located ADIS1648x, we decided to see if using LVDS signals for the majority of the distance between the sensor (ADIS1648x) and the evaluation system (EVAL-ADIS) could reach the separation goal of at least 2 meters.  This approach was very successful, as our first set of PCBs supported nearly 9 meters of separation, without a single bad data point, while sweeping the temperature over a range of -40C to +85C. The following picture illustrates three different PCBs that supported this preliminary test.


This post relates to one of the PCBs in this group: the ADIS1648x SPI Extender board.   On this board, an ADN4665 provides the LVDS-to-SPI translation for the received signals (chip select, serial clock, data input) and an ADN4666 provides the SPI-to-LVDS translation for the transmitted signals (data output, data-ready).


Please find the file attachment, which contains a file bundle of the electrical schematic, PCB drawing, PCB gerbers, assembly view and bill of materials.  We (ADI) do not presently plan to sell this board, but hope that these documents help reproduce this PCB for those who are interested in doing so.