| 摘要 |
<p>PURPOSE:To enlarge an area operating at low voltage so as to prevent malfunction by making the frequency of a system clock low when power voltage drops and it becomes low voltage less than standard voltage. CONSTITUTION:Power voltage 11 is compared with reference voltage generation circuits 12(1)-12(n) by comparators 13(1)-13(n), and it is converted into comparator output signals 14(1)-14(n). A multiplexer 7 selects frequency-dividing clocks 16(1)-16(n) in accordance with the comparator outputs 14(1)-14(n). Thus, the clock of the frequency, which corresponds to power voltage 11, is selected. Thus, the area (margin) operating at low voltage is enlarged and malfunction is eliminated.</p> |
