We are using SPI communication at 5MHz at outside the PCB by converting single ended signals to differential signals by using ADN4695 ic’s. This SPI communication we are using for to sending the commands to motor. Now we are facing a problem, whenever motor was running SPI communication was failing and whatever the commands we are sending to motor when motor was running through SPI are corrupted and receiving spikes with irregularity. Same commands whatever we are sending to motor were receiving fine when the motor was not running. We thought that it was an EMI/EMC problem for that we use an all twisted pair wires for differential signals. Copper shielding was also made throughout the SPI path and it was shorted to chassis on both the ends. So please consider the mentioned observations and suggest some solutions for to solve these problems. Please respond as early as possible.
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The ADN4695 has an input compliance range of -1V to +3.4V which is likely exceeded in your setup.
It also is way faster than what you need at 100Mbps so any spikes will make it through to the processor.
You should either use RS485 type transceivers or better yet galvanic isolation transceivers.
Of course the first thing to make sure of is proper ground management between the power stages for the motor driver and the controller...