| 摘要 |
A semiconductor integrated circuit has an applied external voltage detector (3) which determines if a level of an applied external voltage (Vex) exceeds a threshold level. When the applied external voltage does not exceed the threshold voltage, an internal voltage selector (4) selects and outputs to a voltage drop circuit (10) a constant reference voltage which is generated and dropped from the applied external voltage by a reference voltage generator (1), based on an output of the applied external voltage detector. The voltage drop circuit generates and applies an internal voltage equal to the constant reference voltage, i.e. a dropped applied external voltage to internal circuit. On the other hand, when the applied external voltage exceed the threshold voltage, the internal voltage selector selects an aging voltage output from an aging voltage generator (2), based on an output of the applied external voltage detector. The aging voltage is higher than the constant reference voltage, and is dependent upon the applied external voltage. An internal voltage equivalent to the aging voltage is generated and applied to the internal circuit by the voltage drop circuit.
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