SCAS131 - APRIL 1990 - REVISED APRIL 1993
m Process
The 74ACT11478 is an 8-bit dual-rank synchronizer circuit designedspecifically for data synchronization applications where the normalsetup and hold time specifications are frequently violated.
Synchronization of two digital signals operating at differentfrequencies is a common system problem. This problem is typicallysolved by synchronizing one of the signals to the local clock througha flip-flop. This solution, however, causes the setup and hold timespecifications associated with the flip-flop to be violated. When thesetup or hold time specification is violated, the output response isuncertain.
A flip-flop is metastable if its output hangs up in the regionbetween VIL and VIH. The metastable conditionlasts until the flip-flop recovers into one of its two stable states.With conventional flip-flops, this recovery time can be longer thanthe specified maximum propagation delay.
The problem of metastability is typically solved by adding anadditional layer of synchronization. This type of dual ranking isemployed in the 74ACT11478. The probability of the second stageentering the metastable state is exponentially reduced by thisdual-rank architecture. The 74ACT11478 provides a one-chip solutionfor system designers in asynchronous applications.
The 74ACT11478 is characterized for operation from - 40°C to85°C.
View more information about generic part numbers:74ACT11478
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