Low power physical layer for a bus in an industrial transmitter
First Claim
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1. A process variable transmitter, comprising:
- connections that are mateable and demateable with an accessory load;
the connections including a bus contact and a common contact;
a transmitter circuit having a common conductor coupled to the common contact, and having a supply conductor, and having a serial input and a serial output;
a receiver circuit coupled to the serial input and coupled to the bus contact by a serial bus;
a supply limiter circuit drawing a supply current from the supply conductor and providing a stored energy output;
the supply limiter circuit providing a supply current limit;
a recessive driver circuit drawing a drive current from the stored energy output and coupling the drive current to the serial bus, the recessive driver circuit providing a drive current limit; and
a dominant driver circuit coupled between the serial output and the serial bus;
the dominant driver circuit having a dominant state in which it conducts the drive current to the common conductor, and an inactive state in which the drive current is available to the accessory load.
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Abstract
A process variable transmitter connects a serial bus to an accessory load. A supply limiter circuit provides a first supply current limit and provides a stored energy output. A recessive driver circuit draws a drive current from the stored energy output and couples the drive current to the serial bus. The recessive driver circuit provides a drive current limit. A dominant driver circuit has a dominant state in which it conducts the drive current, and an inactive state in which the drive current is available to the accessory load.
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Citations
24 Claims
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1. A process variable transmitter, comprising:
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connections that are mateable and demateable with an accessory load;
the connections including a bus contact and a common contact;a transmitter circuit having a common conductor coupled to the common contact, and having a supply conductor, and having a serial input and a serial output; a receiver circuit coupled to the serial input and coupled to the bus contact by a serial bus; a supply limiter circuit drawing a supply current from the supply conductor and providing a stored energy output;
the supply limiter circuit providing a supply current limit;a recessive driver circuit drawing a drive current from the stored energy output and coupling the drive current to the serial bus, the recessive driver circuit providing a drive current limit; and a dominant driver circuit coupled between the serial output and the serial bus;
the dominant driver circuit having a dominant state in which it conducts the drive current to the common conductor, and an inactive state in which the drive current is available to the accessory load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification