Since your device only sinks 2µA there will be no problem when the VDD voltage levels of your PSoC and the AD7603 are the same.
There are AC considerations, eg. trace L causing under/overshoot. This
can in some circumstances require series R on the order of tens of ohms
to clean up transients due to fast edges. You can also overcome this by
setting pins to slow slew rate. But that only fixes PSOC outputs, not inputs
driven by fast logic from A/D interface.