| 摘要 |
A core unit implements a predetermined function. An I/O unit controls input from and output to the outside. The core unit and the I/O unit are subject to independent control for supply of power. When power is turned off in the core unit, a signal output from the I/O unit to the core unit is fixed at a low level, while power is maintained in the I/O unit. A first level shifter and a second level shifter are provided between the core unit and the I/O unit and cancel a difference in power supply voltage level between the units. Power is turned off in the first level shifter and the second level shifter when power is turned off in the core unit.
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