| 摘要 |
PURPOSE:To eliminate the need of a special external circuit, and also, to reduce the capacity of a backup power source by holding a service interruption time by an IC itself. CONSTITUTION:When a main power source is disconnected, a backup signal 10 is outputted from a backup detecting part 3 for detecting a fact that an IC has become a backup state, while monitoring a power source signal 9. When the backup signal 10 is received, a service interruption time holding part 2 for receiving the backup signal 10 holds the contents of time information 12 generated from a time generating part 1. Thereafter, the main power source is reset, and at the time of reading a time data held by the service interruption time holding part from the outside, a write/read-out control part 4 inputs a time selecting signal 8 and a read-out signal 7 from the outside. The write/ read-out control part 4 can read the time of a service interruption time by outputting a command through an internal control bus 11 to the service interruption time holding part 2. In such a way, a special external circuit is not required, and also, the capacity of a backup power source can be maintained small. |
