Are external PLL components mentioned in the iCE40 Hardware Checklist still required even if the PLL is not used?
VCCPLL must be tied to VCC even when PLL is not used. Also, the external components for the VCCPLL pin are still required regardless of whether the PLL is in use or not. This is to ensure that the device can meet ramp rate requirements. But, if the designer is confident enough that the power supply can meet the ramp rate requirement, capacitors may be removed but the 100-ohm resistor is still required.