GPIO and CLD interface considerations

AN2674

16/22

Doc ID 14204 Rev 2

4

GPIO and CLD interface considerations

There are no stringent requirements for GPIO or CLD interfaces, but some precautions

should be considered for some applications that employ very wide buses switching

simultaneously, or have electrically long interconnects, such as signal traces 1 ns or longer.

These conditions apply heavy loading to the power distribution network supplying these

I/Os, and it is imperative that good decoupling practices are used for the 3.3 V supply. See

Appendix A for decoupling capacitor layout guidelines. When wide buses or long interfaces

are necessary, 22 Ohm series resistors placed close to SPEAr provide additional benefit by

reducing the loading seen by the I/Os.