Dual-power supplying system with circuit loop switching control circuit

摘要

An automatically switchable dual-power-circuit-loop circuit system selectively supplies a first power source through a first voltage output circuit loop to an output terminal, and a second power source is selectively supplied through a second voltage output circuit loop to the output terminal. A switching control circuit functions to detect the first output voltage of the first voltage output circuit loop. When the first output voltage regularly supplies electrical power, the first power source is supplied through the first voltage output circuit loop to the output terminal, while the switching control circuit generates a switching signal to switch a switching element to an open-circuit condition thereby cutting off the second voltage output circuit loop. When the first power source fails to supply power, the switching element is set in a closed-circuit condition to allow the second power source to be supplied through the second voltage output circuit loop to the output terminal.