| 摘要 |
<p>PURPOSE:To prevent the reverse flowing of the power supply voltage and the like, by supplying the system power supply voltage via the DC boosting circuit to the CMOS memory circuit having the battery backup circuit and thus obtaining the working voltage of the CMOS circuit at the low power supply voltage of the system side. CONSTITUTION:The system power supply voltage VCC to be supplied to CMOS memory circuit 3 is supplied via DC boosting circuit 1, and this boosting output is supplied in the form of power supply voltage VDD to circuit 3 through diode D1 which constitutes the power supply switching circuit. At the same time, battery voltage VB is also supplied in the form of voltage VDD to circuit 3 via diode D2 constituting the power supply circuit. Then circuit 1 is actuated by voltage VCC, and the level of input signal Vin which is supplied to circuit 3 from memory control circuit 2 is regulated by voltage VCC to prevent the latch-up phenomenon of CMOS. At the same time, a margin is secured for the power supply switching and setting voltage.</p> |
