An external access timing signal becomes active according to changes of the external
address. An address latch signal becomes active according to the timing when the
external access timing signal becomes active. In a case where the changes of the
external address occurs while the address latch signal is active and consequently
the external access timing signal becomes active, a refresh arbiter signal does
not become active. When the refresh arbiter signal becomes active after the generation
of the refresh timing signal, a refresh execution timing signal becomes active
according to the change of the refresh arbiter signal. The time period when the
address latch signal is active is set to be substantially the same as the preferable
activation time period. The time period when the external access timing signal
is active is set to be substantially the same as the preferable pre-charge time period.
