A reset
signal generation circuit of the present invention includes a
phase locked loop (PLL) selector, a plurality of PLLs, a locking
detector, a
clock selector, a counter, and a reset
synchronizer. The PLL selector is activated when an external reset
signal is high and provides a
signal for selecting one of the plurality of PLLs according to a power down
control signal and a PLL selection signal. The plurality of PLLs have different input frequency signals and different output frequency signals. They are activated in response to an external
clock signal and inactivated in response to the power down
control signal. The locking
detector detects locking / unlocking of the PLLs based upon the output frequency signals of the PLLs and generates a locking signal. The
clock selector selectively provides one of the output signals of the PLLs and the external
clock signal. The counter is coupled to the clock selector and generates an overflow signal after completing count of a predetermined number. In response to the overflow signal of the counter, the reset
synchronizer generates an internal reset signal
synchronizing with the locking signal. The present invention controls the stable reset mode
release time regardless of the
settling time of the oscillation signal by controlling the reset signal using the locking signal of the PLL. A current state is maintained even though the locking state of the PLL is released, so the operation of the
chip is not influenced by the reset of the PLL.