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US 8,283,947 B1Granted
High voltage tolerant bus holder circuit and method of operating the circuit
AssigneeNXP B.V.
InventorsJayarama Ubaradka, Dharmaray M. Nedalgi
Life of this patent
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Abstract
A high voltage tolerant bus holder circuit and method of operating the bus holder circuit utilizes first and second control transistors connected in parallel between a control terminal of a pull-up transistor and a bus. The first control transistor is used to turn on the pull-up transistor during a pull-up mode of operation. The second control transistor is used to turn off the pull-down transistor when a voltage on the bus exceeds a threshold.
Claims20
A bus holder circuit comprising:
- first and second pull-up transistors connected in series on a first current path between a bus and a high voltage rail;
- a first pull-down transistor on a second current path between the bus and a low voltage rail;
- and
- first and second control transistors connected in parallel between a control terminal of the second pull-up transistor and the bus, the first control transistor being used to turn on the second pull-up transistor during a pull-up mode of operation, the second control transistor being used to turn off the second pull-up transistor when a voltage on the bus exceeds a threshold.
1 more element
A bus holder circuit comprising:
- first and second pull-up transistors connected in series on a first current path between a bus and a high voltage rail;
- first and second pull-down transistors on a second current path between the bus and a low voltage rail;
- and
- first and second control transistors connected in parallel between a control terminal of the second transistor and the bus, the first control transistor being used to turn on the second pull-up transistor during a pull-up mode of operation, the second control transistor being used to turn off the second pull-up transistor when a voltage on the bus exceeds a threshold.
1 more element
A method of operating a bus holder circuit, the method comprising:
- turning on first and second pull-up transistors connected in series on a first current path between a bus and a high voltage rail during a pull-up mode of operation of the bus holder circuit using a first control transistor connected to a control terminal of the second pull-up transistor and the bus;
- turning on a first pull-down transistor on a second current path between the bus and a low voltage rail during a pull-down mode of operation of the bus holder circuit;
- and
- turning off the second pull-down transistor when a voltage on the bus exceeds a threshold using a second control transistor connected in parallel with the first control transistor between the control terminal of the second pull-up transistor and the bus.
1 more element
Dependencies are inferred from the claim text.