Patent ID: 6650520
Filing Date: 2003-11-18
Classification: H02H

Abstract:
A polarity sensitive electrical circuit for protecting an electrical device coupled thereto from a reverse bias input voltage condition, the electrical circuit comprising:a positive supply terminal; a ground terminal; a first big pass transistor having a bulk, a gate, a source coupled to the positive supply terminal, and a drain resistively coupled to the ground terminal; and a second protection transistor including: a bulk coupled with the bulk of the first big pass transistor to form a coupled bulk, a source coupled with the positive supply terminal and with the source of the first big pass transistor to form a coupled source, a gate electrically coupled to the ground terminal, and a drain coupled to the coupled bulk and forming a first parasitic diode in a forward bias from the drain of the first big pass transistor to the coupled bulk and a second parasitic diode from the coupled bulk to the coupled source; wherein when said first big pass transistor is in a conductive state when a voltage is provided across the positive supply terminal and the ground terminal in a first predetermined polarity and wherein said first big pass transistor is in a non-conductive state when a voltage is provided across the positive supply terminal and the ground terminal in a second other predetermined polarity.