Power supply input circuit for field instrument
First Claim
Patent Images
1. A field instrument in a process control system, the field instrument comprising:
- communication loop input terminals coupleable to a communication loop for receiving a power signal having a first polarity or a second polarity, opposite the first polarity;
a peripheral device;
a peripheral device accessing circuit, coupled to the peripheral device; and
a supply input circuit coupled between the peripheral device accessing circuit and the communication loop input terminals, including a transistor bridge rectifier configured to receive power solely through the communication loop input terminals from the power signal and comprising a first set of transistors which provide power to the peripheral device accessing circuit when the power signal is of the first polarity and a bias circuit biasing the first set of transistors to be in a saturated state when the power signal is of the first polarity.
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Abstract
A field instrument includes an input circuit having a transistor bridge rectifier which is couplable to a power supply. The transistor bridge rectifier is configured to provide power from the power supply to a remainder of the field instrument.
82 Citations
25 Claims
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1. A field instrument in a process control system, the field instrument comprising:
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communication loop input terminals coupleable to a communication loop for receiving a power signal having a first polarity or a second polarity, opposite the first polarity; a peripheral device; a peripheral device accessing circuit, coupled to the peripheral device; and a supply input circuit coupled between the peripheral device accessing circuit and the communication loop input terminals, including a transistor bridge rectifier configured to receive power solely through the communication loop input terminals from the power signal and comprising a first set of transistors which provide power to the peripheral device accessing circuit when the power signal is of the first polarity and a bias circuit biasing the first set of transistors to be in a saturated state when the power signal is of the first polarity. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A field instrument, comprising:
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a peripheral device; a peripheral accessing circuit; and an input circuit, coupled to the peripheral accessing circuit and being powered by a communication loop, the input circuit receiving power from the communication loop and providing power to the peripheral accessing circuit and having a voltage drop thereacross of within approximately 0.4 volts or less. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A transmitter in a process control system, the transmitter comprising:
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communication loop input terminals coupleable to a communication loop for receiving a power signal having a first polarity or a second polarity, opposite the first polarity; a sensor sensing a process variable and providing a sensor signal indicative of the process variable; a transmitter circuit, coupled to the sensor, receiving the sensor signal and providing an output signal through the communication loop input terminals indicative of the sensor signal; and the transmitter circuit including; a transistor bridge rectifier coupled to the communication loop input terminals and being configured to receive power solely through the communication loop from the power signal, the transistor bridge rectifier including a pair of transistors which provide sole power to a remainder of the transmitter circuit when the power signal is of the first polarity and including a bias circuit biasing the pair of transistors in a saturated state based on at least an input voltage to the transistor bridge rectifier.
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15. A process control system, comprising:
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communication loop input terminals coupleable to a communication loop for receiving a power signal having a first polarity or a second polarity, opposite the first polarity; a controllable device controlling a process parameter; a control circuit, coupled to the controllable device, providing an output signal to control the controllable device and providing a communication signal through the communication loop input terminals, the control circuit including; a transistor bridge rectifier circuit configured to receive power solely through the communication loop input terminals from the power signal, the transistor bridge rectifier including a pair of transistors which provide sole power to a remainder of the control circuit when the power signal is of the first polarity and including a bias circuit biasing the pair of transistors in a saturated state based on at least an input voltage to the transistor bridge rectifier.
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16. A field instrument in a process control system, the field instrument comprising:
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communication loop input terminals coupleable to a communication loop for receiving a power signal having a first polarity or a second polarity, opposite the first polarity; a processing circuit receiving an input, performing a calculation based on the input, and providing an output based on the calculation; and a supply input circuit coupled to the processing circuit and the communication loop input terminals, the supply input circuit including a transistor bridge rectifier configured to receive power solely through the communication loop input terminals from the power signal and comprising a first set of transistors which provide sole power to the processing circuit when the power signal is of the first polarity and a bias circuit biasing the first set of transistors in a saturated state when the power signal is of the first polarity. - View Dependent Claims (17, 18)
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19. A field instrument in a process control system, the field instrument comprising:
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communication loop input terminals coupleable to a communication loop; a sensor for sensing a process variable; a two wire transmitter coupled to the sensor; and a supply input circuit coupled between the two wire transmitter and the communication loop input terminals, including a transistor bridge rectifier configured to receive power solely through the communication loop input terminals and provide power to the two wire transmitter.
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20. A field instrument in a process control system, the field instrument comprising:
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communication loop input terminals coupleable to a communication loop; a controllable device for controlling a process parameter; a process variable control circuit coupled to the controllable device; and a supply input circuit coupled between the process variable control circuit and the communication loop input terminals, including a transistor bridge rectifier configured to receive power solely through the communication loop input terminals and provide power to the process variable control circuit.
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21. A field instrument in a process control system, the field instrument comprising:
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communication loop input terminals coupleable to a communication loop; a peripheral device; a peripheral device accessing circuit, coupled to the peripheral device; a supply input circuit coupled between the peripheral device accessing circuit and the communication loop input terminals, including a transistor bridge rectifier configured to receive power solely through the communication loop input terminals and provide power to the peripheral device accessing circuit; and an active bias circuit, coupled to the transistor bridge rectifier, biasing the transistor bridge rectifier based on a desired input parameter. - View Dependent Claims (22, 23, 24, 25)
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Specification