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US 5,517,379 AGranted
Reverse battery protection device containing power MOSFET
AssigneeSiliconix Incorporated
InventorsRichard K. Williams, Thomas Toombs, King Owyang, Hamza Yilmaz
Life of this patent
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Abstract
A device for protecting battery-powered semiconductor devices and the like against a reverse battery condition. During normal operation a charge pump charges the gate of a power MOSFET, turning the MOSFET on and providing a low-resistance power supply path from the battery to the load. If the battery is reversed, a depletion mode device shorts the gate and source of the MOSFET, turning it off and disconnecting the load from the battery.
Claims11
A device for protecting a load from a reversed voltage condition, said device comprising:
- an input terminal for connection to a positive terminal of a power source and a load terminal for connection to a load to be supplied by said power source;
- an N-channel MOSFET connected between said input terminal and said load terminal, a source and a body of said MOSFET being coupled to said input terminal and a drain of said MOSFET being coupled to said load terminal;
- a charge pump for increasing the voltage at a gate of said MOSFET to a level above the voltage at said input terminal, said charge pump being supplied by supply circuitry coupled to said load terminal;
- and
- a depletion mode MOSFET connected between said input terminal and said gate of said N-channel MOSFET.
2 more elements
A reverse battery protection device comprising:
- an input terminal for connection to a battery terminal, said input terminal to be connected to a positive terminal of a battery when said battery is properly connected and to a negative terminal of said battery when said battery is reverse connected;
- a load terminal for connection to a load;
- an N-channel MOSFET connected between said input terminal and said load terminal, a body-to-drain diode within said MOSFET being forward directed from said input terminal to said load terminal;
- and
- a means for setting the voltage at a gate of said MOSFET at a first level above a voltage at said input terminal so as to turn said MOSFET on when said battery is properly connected and for setting the voltage at said gate of said MOSFET at a second level which is below said first level so as to turn said MOSFET off when said battery is reverse connected.
2 more elements
Dependencies are inferred from the claim text.