Patent ID: 7106567

Claim:
An overvoltage protection circuit, comprising: one or more hard disk drive integrated circuit chips residing on a board; a first voltage supply potential for supplying power to at least one of the one or more hard disk drive integrated circuit chips; a second voltage supply potential having an intended value which is less than the first voltage supply potential, the second voltage supply potential for supplying power to at least one of the one or more hard disk drive integrated circuit chips; a voltage detection circuit operable to detect a value of the second voltage supply potential; and a voltage reduction circuit operably coupled to the voltage detection circuit, wherein the voltage detection circuit is operable to activate the voltage reduction circuit when the second voltage supply potential exceeds a predetermined threshold, and wherein the voltage reduction circuit is operable to reduce the value of the second supply potential when activated by the voltage detection circuit, further comprising a reset circuit coupled to the voltage detection circuit, wherein the reset circuit is operable to activate a reset signal to a controller circuit associated with the board to reset the first and second voltage supply potentials when the voltage detection circuit detects a first voltage supply potential which exceeds an another predetermined threshold, and wherein the voltage detection circuit further comprises a resistor coupled in series with a zener diode, wherein when the zener diode has a reverse bias voltage thereacross which exceeds the predetermined threshold, the zener diode breaks down and conducts current therethrough, thereby generating a voltage across the resistor, and wherein when the voltage across the resistor exceeds a predetermined level, the voltage activates the voltage reduction circuit.