Four-bit binary synchronous up-counter
(1) Low order 4-bits = 1111
(3) High order 4-bits are incremented
Standard component with many applications
- synchronous load and clear inputs
- positive edge-triggered FFs
- parallel load data from D, C, B, A
- enable inputs: must be asserted to enable counting
- RCO: ripple-carry out
- high when counter is in its highest state 1111
- implemented using an AND gate
- used for cascading counters