METHOD AND CIRCUIT FOR PROTECTING CLASS-II INTEGRATED CIRCUIT FROM NEGATIVE TRANSIENT

PROBLEM TO BE SOLVED: To provide a method and circuit for protecting a class-II integrated circuit from a negative transient. SOLUTION: A clamp circuit which is biased from a battery but refers to a ground, is used to protect a class-II integrated circuit bus from the negative transient. Namely, a current path reaches a bus pin from the battery through a blocking diode, a transistor, a resistor and a plurality of diodes but the bus refers to the ground. In one embodiment, the transient protection circuit is provided with a reference diode whose cathode is connected to the ground, the transistor which is biased as a current source and whose output terminal is operably connected to an anode of the reference diode, and at least a second diode operably connected between the anode of the reference diode and the bus pin, and the transistor supplies a current when module grounding is not damaged. COPYRIGHT: (C)2004,JPO&NCIPI