VOLTAGE DROP CONTROLLER FOR ELECTRONIC EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To provide the voltage drop controller for electronic equipment which lowers the access frequency of a CPU by a specific quantity when the source voltage drops to a drop voltage and resets the CPU when the source voltage drops to a reset voltage lower than the drop voltage. SOLUTION: A voltage drop detecting circuit 3 once detecting the system source voltage Vcc outputted by a power circuit 2 dropping to the drop voltage VL outputs a switching signal SE to a switch 9, which is normally connected to a high-speed clock generating circuit 7 to outputs a high-speed clock CH to the CPU 10 as a system clock CS, but once inputting the switching signal SH, is switched from the high-speed clock generating circuit 7 to a low-speed clock generating circuit 8 to output a low-speed clock CL to the CPU 10. The CPU 10 accesses a memory 12, etc., with the access frequency of this low-speed clock CL. A reset voltage detecting circuit 4 once detecting the system source voltage Vcc dropping to the reset voltage VR lower than the drop voltage VL, outputs a reset signal SR to the CPU 10 to reset the CPU.