| 摘要 |
<p>PURPOSE:To prevent the unnecessary consumption of an auxiliary power supply, by switching a load to a holding state from an active state with a switching circuit which works when the voltage of a primary power supply drops less than a certain level and at the same time, applying the voltage of the auxiliary power supply. CONSTITUTION:When the constant voltage supplied from a primary power supply battery 10, a resistance 11 and a Zener diode 12 drops less than a certain level, both TR15 and TR17 are turned off from on. When the TR17 is turned off, an active/holding switching terminal Run/Halt of a load 19 is set at a low level. Then the load L is set in a holding state regardless of the ON/OFF of a switch 21. Thus the power consumption is reduced. When the TR15 is turned off, a TR24 is turned on. Then the voltage of an auxiliary power supply battery 23 is applied to a terminal Vdd of the load 19. As a result, the waste of the battery 23 is prevented. Such as power supply circuit is suited to a power supply of a computer.</p> |
