Power supply reverse bias protection circuit for protecting both analog and digital devices coupled thereto
AssigneeKoninklijke Philips Electronics N.V.
InventorQing He
Life of this patent
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Abstract
All integrated circuits (ICs) require a power supply having a potential difference for use in powering internal integrated circuit components to ensure their operation. In some cases it is possible to inadvertently reverse the bias of the applied potential difference, resulting in damage to the IC. For propagating large currents big pass transistors are used within the circuit. Reverse bias protection for these ICs is achieved by utilizing either a protection transistor in parallel with the big pass transistor, or a diode within the big pass transistor for protecting both analog and digital ICs.
Claims12
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.
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 with the positive supply terminal and a drain resistively coupled with the ground terminal and forming a first parasitic diode in a forward bias from the drain to the bulk;
- and
- a protection diode having an anode coupled to the source and a cathode coupled to the bulk of the first big pass transistor;
- wherein said 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 current follow through the first big pass transistor is inhibited due to reverse biased current flow through the protection diode.
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;
- and
- a second protection transistor including:
- a bulk coupled with the bulk of the first big pass transistor and to the drain of the first big pass transistor to form a coupled bulk,
- a source coupled with the coupled bulk,
- a gate resistively coupled to the positive supply terminal, and
- a drain coupled to the ground terminal;
- 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.
Dependencies are inferred from the claim text.