Why is excessive overshoot observed on signals when series on-chip termination (RS OCT) with calibration is enabled on some Cyclone IV GX devices? - Why is excessive overshoot observed on signals when series on-chip termination (RS OCT) with calibration is enabled on some Cyclone IV GX devices? Description Due to an issue in some Cyclone ® IV GX devices, excessive overshoot and ringing may be observed on signal rising edges when RS OCT with calibration is enabled for output pins. This is because the pull-up resistance in the I/O buffer is smaller than the intended 25 Ohms or 50 Ohms. This issue only affects the following Cyclone IV GX device variants : - EP4CGX15 - EP4CGX22 - EP4CGX30 Resolution If you observe excessive overshoot on signals driven from I/O pins which have RS OCT with calibration enabled in the affected devices, as a workaround, use RS OCT without calibration instead. Custom Fields values: ['novalue'] Troubleshooting novalue False ['novalue'] ['novalue'] novalue novalue ['Programmable Logic Devices'] ['novalue'] ['novalue'] ['novalue']