| 摘要 |
PROBLEM TO BE SOLVED: To reduce futile power consumption with a constitution where CMOS circuits to be operated by different power sources are connected to each other. SOLUTION: An AND gate 25 is provided in an RTC circuit 2, and the output is used as the inner signal 26 of the RTC circuit 2. When an RTC control circuit source 5 is turned off, a reset signal 8 is fixed to 'L' and the inner signal 26 to 'L'. Thus, conventional pull down resistance is unnecessitated. Even if the signal 6 of an output buffer 24 is 'H', unnecessary power consumption is not generated in the RTC control circuit power source 5. When only the RTC control circuit power source 5 is turned off, the voltage of the RTC control circuit power source 5 gradually drops and becomes 'L'. Even if the signal 6 of the output buffer 24 is 'H', the reset signal 8 becomes 'L' when the voltage of the RTC control circuit power source 5 becomes lower than a prescribed level. Thus, the inner signal 26 becomes 'L' and through current does not flow through the RTC circuit 2. |
