| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device, in which undesirable operating modes are hardly activated by the undesirable fluctuation of an operating power supply voltage due to noise. SOLUTION: When power supply voltage is turned on, a voltage divided (VSENSE) by a voltage-dividing circuit (37) is increased with the rising of an operating power supply voltage (VPERI). A reference voltage generating circuit (35) maintains a certain reference voltage (VREF), in the middle of the rising of the operating power supply voltage. A differential amplifying circuit (36) detects the condition in which the divided voltage, that is rising at the speed slower than the rising speed of the reference voltage, becomes larger than the reference voltage, reverses an output (PUPB) and initializes internal circuits. When the operating power supply voltage is lowered by noise or the like, the divided voltage is gradually reduced by following the operating power supply voltage, and then the reference voltage is slowly reduced. When the operating power supply voltage again turns to rising, the reference voltage rises faster than the divided voltage and the detection signal starts to rise. At the point the divided voltage exceeds the reference voltage, the detection signal starts to fall and is changed.
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