| 摘要 |
<p>PURPOSE:To provide the microcomputer capable of switching a sense amplifier circuit having plural circuit constants so as to secure the optimal operation range according to the power supply voltage or switching the frequency of a system clock by detecting that the power supply voltage drops or the frequency of the system clock becomes high to reach the operation limit. CONSTITUTION:A monitor ROM 100 is provided which has a monitor sense amplifier 113 where the normal operation range for a power supply voltage Vcc is set narrower than that of a sense amplifier 13 of a ROM 20. The sense amplifier 13 of the ROM 20 is provided with plural sense amplifier circuit parts and their switching circuit parts so as to secure the optimal operation range for the plural power supply voltages by changing the circuit characteristic according to the signal given from the monitor ROM 100.</p> |
