PURPOSE: To prevent large delay of access even if the greater part of power consumption is cut off to save the power, by constituting two power supply systems and providing a control circuit with a means to control the on/off the power supply sequentially or simultaneously in each power supply system in accordance with the access from the external.
CONSTITUTION: The 1st system of power supply is a group consisting of a HR driving circuit 21 supplying electric power through a cut-off circuit 25 controlled by a control circuit 20a, a function driving circuit 22, a detecting circuit 23 and a timing circuit 20b and the 2nd system is a group consisting of a control circuit 20a to which electric power is directly supplied from a power supply switch 24 and an on/off circuit 25. Power supplying method to a memory device is the same as the ordinary method. In the waiting state, the control circuit 20a actuates the circuit 25 to cut off power supply. Every access from the external, the control circuit 20a supplies power to each circuit in suspending by the circuit 25 and supplies power to all circuits in the same manner as the ordinary method.
HOSHI TOSHIHIRO
TAKAI SHIGERU
