| 摘要 |
An oscillator generates a refresh request signal periodically. A storing circuit changes a stored value by a predetermined value in response to the refresh request signal and returns the stored value by one in response to a refresh operation. A store control circuit, when a state detecting circuit detects a change of an operational state of a semiconductor memory, increases or decreases the predetermined value which the storing circuit uses. A refresh decision circuit outputs refresh signals of a number corresponding to the stored value until the stored value returns to an initial value. This makes it possible to change the frequency of the refresh operations according to a change of the operational state without changing an oscillation cycle of the oscillator. Without unnecessary oscillation of the oscillator, it is possible to decrease a standby current of the semiconductor memory.
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