High Voltage AC Adapter Detection Circuit
Original Publication Date: 2003-Mar-25
Included in the Prior Art Database: 2003-Mar-25
Generally, an electric appliance like notebook PC uses AC adapter for power supply. A user should use an appropriate one, but, if AC adapter output plug and electric appliance connector are all-purpose type, there is some possibility that a user can attach another AC adapter which isn't appropriate for use. In that case, if non-appropriate AC adapter is higher voltage output type than appropriate one, electrical parts of appliance may be damaged by de-rating voltage over. Especially, a capacitor may burn. To solve this concern, a zener diode is used on power line which is connected to AC adapter. It can regulate power line voltage, and supply regulated voltage to electrical circuit even if a user attach non-appropriate AC adapter to appliance. But, this method causes power loss, because a zener diode always consumes power. In worst case, a zener diode is broken by over stress.