If each device has 8 pF of input capacitance, then only 11 pF of trace capacitance is allowable . ( Routing traces on printed circuit boards usually have 1-2 pF per inch so the traces can be 5.5 inches long max . ) If this trace length condition can't be met, then the microcontroller must be run at a slower bus speed for reliable operation, or a buffer chip with higher current drive must be added.
22.
The stage effort is divided into two components : a "'logical effort "', " g ", which is the ratio of the input capacitance of a given gate to that of an inverter capable of delivering the same output current ( and hence is a constant for a particular class of gate and can be described as capturing the intrinsic properties of the gate ), and an "'electrical effort "', " h ", which is the ratio of the input capacitance of the load to that of the gate.
23.
The stage effort is divided into two components : a "'logical effort "', " g ", which is the ratio of the input capacitance of a given gate to that of an inverter capable of delivering the same output current ( and hence is a constant for a particular class of gate and can be described as capturing the intrinsic properties of the gate ), and an "'electrical effort "', " h ", which is the ratio of the input capacitance of the load to that of the gate.
