PURPOSE: To shorten the setting time for a power-on reset circuit and to start a system in a short time by starting up the microcomputer into an active state instantaneously irrelevantly to the charging of a backup capacitor when the power source is turned on.
CONSTITUTION: A 2nd diode 7 is connected forward between the connection point of a power line Vcc for the backup capacitor 2 and the microcomputer 4 and the microcomputer 4 is connected to the anode side of a 1st diode 1 on the power line Vcc through a 3rd diode 6. When the power source is turned on, a supply power source is connected to the microcomputer 4 through the 3rd diode 6 simultaneously with the charging start of the backup capacitor 2 and the microcomputer 4 is placed in the active state instantaneously. Consequently, the adverse influence of the backup capacitor 2 is ignored to shorten the setting time for the power-on reset circuit 3, thereby shortening the time required to start up the system.
IKEUCHI YASUHIDE
MATSUO TAKAHIRO
MATSUBARA TADASHI
| JPS5519269B2 | 1980-05-24 |