Constant current sources with programmable voltage source
First Claim
1. A circuit for providing a constant current to a load, comprising:
- a constant current source for connection to the load and having a control signal input for receiving a signal indicative of the desired current to be provided, said current source providing a constant current to the load when the voltage across said current source exceeds a predetermined value;
a digitally programmable voltage source for coupling to the load and for coupling to said current source and having digital inputs and a voltage output, said voltage source providing the voltage impressed on said current source and the load, said voltage source providing an output level representative of an applied digital value provided to said digital inputs;
means for monitoring the difference between the voltage across the load and the voltage supplied by said voltage source; and
means coupled to said monitoring means and said voltage source digital inputs for changing said programmed value of said voltage source to increase said output voltage level when said difference is below a given level.
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Accused Products
Abstract
An implant for stimulating the vagus nerve receives commands over a radio frequency link. The communication protocol uses asynchronous communications devices with parity checking and echoing of communicated characters and passwords to improve communication error checking. The implant disables a voltage convertor used in providing the stimulation signal at periodic intervals to monitor for communications attempts. The implant provides radio frequency marker pulses before providing stimulation signals of certain frequencies. During the providing of stimulation signals the implant monitors the voltage overhead present between the voltage source and the load and adjusts the overhead to a desired level. The implant changes the voltage applied to certain internal components during stimulation periods to allow full power operation during those intervals and reduced power levels at other intervals. The implant is reset by the placing a magnet in a given location in conjunction with the application of a radio frequency transmission for a given period.
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Citations
6 Claims
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1. A circuit for providing a constant current to a load, comprising:
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a constant current source for connection to the load and having a control signal input for receiving a signal indicative of the desired current to be provided, said current source providing a constant current to the load when the voltage across said current source exceeds a predetermined value; a digitally programmable voltage source for coupling to the load and for coupling to said current source and having digital inputs and a voltage output, said voltage source providing the voltage impressed on said current source and the load, said voltage source providing an output level representative of an applied digital value provided to said digital inputs; means for monitoring the difference between the voltage across the load and the voltage supplied by said voltage source; and means coupled to said monitoring means and said voltage source digital inputs for changing said programmed value of said voltage source to increase said output voltage level when said difference is below a given level. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification