LMX2582: LMX2582 CE function

Shuang,
When you come out of a powerdown state, I have seen on similar devices the VCO is degraded unless you program with FCAL_EN=1. So I would answer this and say that the time is equal to the calibration time of the VCO, which is in the 100's of microseconds range.

Now if you want something that is fast, another approach is to just power down the output buffer. I think the power down time is less than 1 us, but to power this up, it is closer to 20 us.

Regards,
Dedan