Variable liftoff voltage process field device
First Claim
1. A field device, comprising:
- field device circuitry configured to measure or control a process variable;
a first process control loop terminal configured to couple to a two-wire process control loop, the two-wire process control loop carrying a loop current;
a second process control loop terminal configured to couple to the two-wire process control loop;
a switching regulator having an input and an output, the output coupled to the field device circuitry and arranged to provide power to the field device circuitry; and
a variable voltage source having an input electrically coupled to the first process control loop terminal, and a voltage output coupled to the input of the switching regulator and a control input, wherein the voltage output is a function of the control input, wherein the voltage output changes inversely to the loop current flowing through the two-wire process control loop.
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Accused Products
Abstract
A field transmitter includes field device circuitry configured to measure or control a process variable. A first process control loop terminal is configured to couple to a two-wire process control loop which carries a loop current. A second process control loop terminal configured to couple to the two-wire process control loop. A switching regulator has an input and an output. The output is coupled to the transmitter circuitry and arranged to provide power to the transmitter circuitry. A variable voltage source having an input electrically coupled to the first process control loop terminal, and a voltage output coupled to the input of the switching regulator and a control input. The voltage output is a function of the control input.
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Citations
15 Claims
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1. A field device, comprising:
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field device circuitry configured to measure or control a process variable; a first process control loop terminal configured to couple to a two-wire process control loop, the two-wire process control loop carrying a loop current; a second process control loop terminal configured to couple to the two-wire process control loop; a switching regulator having an input and an output, the output coupled to the field device circuitry and arranged to provide power to the field device circuitry; and a variable voltage source having an input electrically coupled to the first process control loop terminal, and a voltage output coupled to the input of the switching regulator and a control input, wherein the voltage output is a function of the control input, wherein the voltage output changes inversely to the loop current flowing through the two-wire process control loop. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of powering a process field device, comprising:
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coupling first and second process control loop terminals of the field device to a two-wire process control loop, the two-wire process control loop carrying a loop current; receiving an input voltage at a switching regulator; providing power to field device circuitry from an output of the switching regulator from the input voltage; and controlling the input voltage to the switching regulator, wherein the input voltage to the switching regulator varies inversely to the loop current flowing through the two-wire process control loop. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification