The CTI implements a synchronous channel interface. It is synchronous to ATCLK.
It is possible to convert between synchronous and asynchronous versions of the channel interface using the circuit shown in Figure 15.3, which also includes a BYPASS signal to enable the converter to be bypassed if not required.
If you implement a synchronous to asynchronous converter, you increase the likelihood of merger of events. This is likely to happen if the events to be counted occur close together. For more information, see the section on Channel interface limitations in the CoreSight Architecture Specification.