An apparatus, a method, and a computer program are provided to gate a Phased Locked Loop (PLL). In microprocessors, the clock distribution system can account for a substantial amount of power consumption. Gating the PLLs, however, has been difficult because of the usual requirement for a separate clock for control logic and because the PLL requires timed to reacquire phase/frequency lock. Therefore, lock detection logic can be employed to allow the PLL to reacquire phase/frequency lock. Additionally, signals from external devices and the processor can be employed to gate the PLL and allow the processor to be awakened without a need for a separate clock.