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  • 40-Channel I2C Digital I/O Expander

40-Channel I2C Digital I/O Expander



The I2C-XIO is a 40-channel digital I/O expander with an I2C interface, based on the NXP PCA9698.  The board includes two 6P6C I2C Connectors, the PCA9698, a 5V @ 1.5A switching regulator, three address jumpers to select 1 of 8 possible addresses, and all I/Os pinned out to either terminal blocks or RJ11 jacks (in blocks of 4 I/O lines, including +5VDC and Ground on the other two pins).

Unlike many other I2C I/O solutions on the market, the PCA9698 doesn't impose significant restrictions on the total current it can source or sink.  Many parts rate +/- >20mA per I/O pin, but are severely limited by the total current the part can handle.  The PCA9698 is rated for sourcing 500mA and sinking a whopping 1100mA, allowing for significant current draw on each I/O line.  We've also included a 1.5A switching regulator on board so that you can achieve those current outputs without wasting significant power or hitting thermal limits.

The I2C-XIO is purely an I/O expander, and doesn't integrate either an MRBus interface or microcontroller.  For those interested in the same functionality, but with an onboard ATMega328 and MRBus interface, check out the MRB-XIO.

For Arduino users looking to expand the number of IO lines (up to 8 * 40 = 320!), be sure to check out the XIO Library Reference for details on the XIO library and example sketch.


5.25"(L) x 1.7"(W)


The complete gEDA design files are available on GitHub.


6P6C I2C Connector Standard

Arduino Library Reference

  • $55.00

Available Options

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Application Notes

Solar Car Teams

As alumni of the Iowa State University Solar Car Team, Team PrISUm, we recognized that many of Iowa Scaled Engineering’s products could be used by teams competing in solar racing competitions.  In fact, MRBus had its origins in the Sunrayce ’99 car, PrISUm Phoenix.



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