Hi.
I have some noise present on the CS and CSG pins of an LM5119 due to adjacent circuitry (another LM5119) switching at inconvenient moments. They are synchronised, so it happens rather predictably.
Adding a 1nF / 100R / 100R differential filter improved the situation dramatically, but there is some residual noise affecting the current measurement. I know this because the input current draw changes (reduces) if the source of noise is removed.
My questions are:
1. What are the maximum permitted values for the differential current sense filter components? I presume that the consequence of lowering the current sense filter bandwidth too far will be reduced accuracy / sensitivity to overcurrent conditions. My switching frequency is 250kHz.
2. Are there any other strategies for reducing the sensitivity to noise of the CS and CSG pins?
Thank you in advance!
Kind regards,
Andrew