LatticeECP3: If I am not using one of the SERDES/PCS quads of my device, are there any special considerations as far as layout is concerned?If I don't want to use a quad of SERDES/PCS, what should I do with SERDES/PCS power and signal pins?
If you are not using SERDES/PCS, you need to do the following steps:
1. Connect power: VCCA and ground VSSA;
2. Let other power domains (VCCIB and VCCOB) floating;
3. Let the other signal pins such as ;HDINP/N, HDOUTP/N and REF-CLKP/N floating. all the unused channel outputs are tri-stated with approximately 10 KOhm internal resistor connecting between the differential output pair. You don't need to instantiate SERDES in the design at all. The whole SerDes is in power down mode without instantiation. User can also refer to TN1189 - Hardware Checklist, under section- LatticeECP3 SERDES/PCS Power Supplies.