Keywords : 6.1i, 6.2i, CPLD, CoolRunner-II, power, current, quiescent
When using setting the Unused IO Termination option to Ground, the CPLD shows higher than expected current draw (mAs to tens of mA) on Vccio. Changing this option from Ground to Pullup causes the excess current draw to disappear.
Use care when using this option. If this option is set to Ground, then an unused pin will act as a ground pin on the device. Therefore, a pullup connected to an unused pin will sink current unnecessarily. Conversely, if the Pullup option is selected, connecting that pin to Ground on the board would also sink current. Ensure that you consider this option when dealing with unused IO pins on the board.
There is a bug where unbonded IO pads are not properly configured by the Ground option. These internal nodes are left floating, resulting in high leakage current (the amount depends on the device, as a XC2C256VQ100 has more unbonded IO pads than a XC2C256PQ208).
This problem has been fixed in the latest 6.2i Service Pack, available at:
The first service pack containing the fix is 6.2i Service Pack 1.