We are using the MPC8313 in an application where it is the master controller to a few slave devices. Whenever the 8313 pulls either the SDA or SCL line low, we see excessive undershoot of up to -1V and causes communication problems with one of the slave devices. We currently have 2K pull-ups since one of the devices needs the faster 400Khz bus speed. Even if we increase the pull-up size (5-6K) we still get an unacceptable amount of undershoot. Putting in series resistors at the input of the MPC8313 is not an option since we do not want to re-spin the board. I'm not seeing any current control options for the I2C GPIO pins. Does anyone have any suggestions?