The ADSP-BF606/ADSP-BF607/ADSP-BF608/ADSP-BF609 Blackfin Dual Core Embedded Processors data sheet (rev PrF of later) contains preliminary AC specifications for BF60x peripheral, system, and core clocks using preliminary data that is subject to change:
http://www.analog.com/en/processors-dsp/blackfin/products/data-sheets/resources/index.html