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NI 8451 driving 3.3V circuitry

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I'm wondering if it's at all possible to read/write to 3.3V (ideally 1.8V) circuitry on the I2C lines of the USB 8451.  As best as I understand, it's a 5V only bus.  Unfortunately, the part doesn't come in higher voltage and I have haven't found a NI device that reads/writes to I2C on any other voltage than 5V.  Any help is appreciated.  Thanks.



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Take a look at the 8451 specifications. This says that the I2C interface can read an input as high in a range from 2.0 to 5.8 V. The high output is specced to be above 2.0 V.


Depending on your external hardware requirements, you can use these signals or use some sort of external circuitry for a more disciplined value or to limit the output to a lower value (1.8 V).


Peter Flores
Applications Engineer
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