| 摘要 |
PROBLEM TO BE SOLVED: To provide a power supply sequence control circuit in which the order of the closing and the cutting-off of a power source of a CPU and a peripheral unit can be specified with simple circuit formation. SOLUTION: The cathode of a Zener diode ZD continues for a power supply 14 for driving a CPU 12 and is connected to a power supply line 16 with a power switch 18 on the way, the anode thereof is connected to the base of a first transistor 20, one end of a delay circuit 30 comprising a resistor R2 and a capacitor C is connected to the power supply line 16, and the other end thereof is connected to the base of a second transistor 22. The anode of the light emitting diode 24 of a photo MOS relay 28 is connected to the power supply line 16, the cathode thereof is connected to the collector of the second transistor 22, and the emitter of the second transistor 22 is connected to the collector of the first transistor 20. The emitter of the first transistor 20 is grounded, one end of a MOS transistor 26 is connected to a power supply A for driving an LCD 32, and the other end thereof is connected to the LCD 32. |
