| 摘要 |
<p>PURPOSE:To save data under the status that a stable logic power source is supplied by providing the titled power supply circuit with a circuit sending a detecting signal at the detection of the reduction of power supply voltage and outputting a data saving signal on the basis of the detecting signal. CONSTITUTION:The power supply circuit is provided with a circuit sending a detecting signal at the detection of the reduction of power supply voltage and outputting a data saving signal on the basis of the detecting signal. If an ignition switch of a car is turned on for instance, the input level of an ignition terminal IGN is turned to ''H'' and the 1st power supply switch 4 is turned on to supply logic power source VDD through a power supply part 8. If the ignition switch is turned off, the logic power source VDD is reduced, and when the voltage reaches a set-up power supply reduction detecting level L, the output level of a comparator 51 in a detecting part 5 is turned to ''H''. The Q output and Q' output of a d-type flip flop in a storing part 6 are latched at ''H'' and ''L'' respectively and the 2nd power supply switch 7 is turned on to supply the logic power source VDD again.</p> |
