ELECTRONIC EQUIPMENT WITH SYSTEM CLOCK SWITCHING FUNCTION

摘要

PURPOSE:To improve the working efficiency of an electronic equipment by switching automatically the frequency of a system clock in accordance with the ambient tempera ture. CONSTITUTION:When the temperature exceeds a set level, an alarm module 17 informs a CPU 10 of the comparison result showing a high temperature. Thus, the CPU 10 sets a selection signal 16 at logic '1'. A selection circuit 15 outputs selectively the clock signal given from an oscillation circuit 14 to the CPU 10 as a system clock 11. Thus, the CPU 10 works synchronously with the clock 11. The processing ability of the CPU 10 is deteriorated owing to a low working speed. However the working of the CPU 10 is stabilized owing to a margin secured in terms of timing. The signal 16 is set at logic '0' with a low temperature, and the circuit 15 outputs selectively the clock signal given from an oscillation circuit 13 to the CPU 10 as the clock 11. Thus, the processing ability of the CPU 10 is improved synchronously with the clock 11 having a rather high frequency. As a result, the processing ability of the CPU 10 can improve its processing ability and work effectively in a satisfactory temperature environment. When the environment is deteriorated, the processing ability is rather deteriorated. Thus, the stable working is secured with no occurrence of errors.