Hi,

I have Gecko G540 Rev.5. Now I'm rebuilding my machine and I'd like to put resistors on motor side of the cable. However, Rev.5 is not noise-tolerant, and I'd like to mod it. As far as I can see, the current set resistor is connected in series with the diode to the CC source (pnp+opamp) and then a npn emitter follower is used to provide reference voltage to the rest of the circuit.

Assuming that the noise is mostly caused by the inter-wire capacitance inside the cable, which I expect to be in order of magnitude of 100 pF/meter and definitely less than 1000 pF/meter, I suspect that adding a 0.1uF...1uF capacitor in parallel to the Gecko input would suppress the noise. There is some unpopulated place for SMD resistor or capacitor on the breakout board at the current set resistor input, and I plan to place 1 uF filter capacitor on them.

Am I right? Will it solve the problem?

Regards,
Alex