Omap 2420 != ARM 1136

What ARM site tells you about clock speed, power requirements and manufacturing process is interesting but not directly applicable to Omap 2420. I'm not sure if this is clear (sorry if it is) but TI does not buy ready made ARM 1136 chips from ARM and somehow stick them into their OMAPs. They get licence for the design and incorporate it into design of their own chip with their own limitations, features and then manufacture it themselves. ARM site is good for telling you about instruction set or other generic ARM 1136 core features (cache size, instruction timings), but for other stuff (like clock speed) it is better to search TI.