| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately detect a voltage drop of a battery before the battery becomes completely exhausted and urge a user to replace the battery, so as not to cause a battery backup operation for a programmable controller memory to be interrupted due to battery exhaustion. <P>SOLUTION: A backup circuit comprises: a backup continuation means for continuing backup using a battery for a predetermined period after a main power supply is turned on; and a battery voltage detection means for detecting a battery voltage during the continuation period, comparing it with a predetermined threshold value, and outputting the comparison result. <P>COPYRIGHT: (C)2012,JPO&INPIT |
