Controller for nerve stimulation circuit and associated systems and methods

Abstract

Disclosed is a voltage monitoring circuit for use in detecting if a voltage supplied to current-generating circuit is sufficient to allow the current-generating circuit to produce a desired current. In one embodiment the circuit is designed for use in an implantable device that is configured to deliver therapeutic pulses to a patient. The voltage monitoring circuit is configured to produce a signal if a supplied voltage is insufficient to allow a current-generating circuit to deliver a requested current to a set of electrodes. In one embodiment, the voltage monitoring circuit detects a change in a difference between the voltage at a node in the current-generating circuit and the supplied voltage.

1 - 29 . (canceled) 
     
     
         30 . A circuit, comprising:
 a voltage regulator to produce a variable supply voltage based on an input voltage;   a current-generating circuit to supply a requested current to one or more electrodes, wherein the current-generating circuit includes a transistor coupled to the variable supply voltage;   a reference current circuit coupled to the voltage regulator, the reference current that, in operation, produces a voltage that tracks the variable supply voltage; and   a comparator including
 a first input coupled to the reference current path to sense the voltage that tracks the variable supply voltage, and 
 a second input coupled to the transistor in the current-generating circuit to sense a voltage drop across the transistor, 
 wherein the comparator, in operation, produces an indication when the voltage at the second input exceeds the voltage at the first input. 
   
     
     
         31 . The circuit of  claim 30 , wherein:
 the voltage regulator is a programmable voltage regulator; and   wherein the circuit further comprises:   a control circuit coupled to the programmable voltage regulator and the voltage monitoring circuit, wherein the control circuit, in operation, controls the voltage regulator based on the indication to increase the variable supply voltage provided to the current-generating circuit.   
     
     
         32 . The circuit of  claim 30 , wherein the indication is provided by the comparator when the variable supply voltage produced by the voltage regulator is insufficient for supplying the requested current. 
     
     
         33 . The voltage monitoring circuit of  claim 30 , wherein the first input is connected to a node that is located between a reference transistor in the reference current path, and a constant current source. 
     
     
         34 . The voltage monitoring circuit of  claim 30 , wherein:
 the current-generating circuit includes a set of transistors connected in parallel, the current-generating circuit, in operation, produces the requested current; and   the second input is connected to a node located between the set of transistors connected in parallel.   
     
     
         35 . The circuit of  claim 30 , wherein:
 the current-generating circuit includes serially connected transistors that produce the requested current; and   the second input of the comparator is connected to a node between the serially connected transistors.   
     
     
         36 . A method of operating a circuit, the method comprising:
 producing a variable supply voltage based on an input voltage;   operating a current-generating circuit to generate a requested current, wherein the current-generating circuit includes a transistor coupled to the variable supply voltage; and   producing an indication when a second voltage exceeds a first voltage, wherein
 the first voltage is based on the variable supply voltage, and 
 the second voltage corresponds to a voltage drop across the transistor in the current-generating circuit. 
   
     
     
         37 . The method of  claim 36 , wherein the first voltage tracks the variable supply voltage. 
     
     
         38 . The method of  claim 36 , wherein producing the indication includes indicating that the variable supply voltage produced by the voltage regulator is insufficient for supplying the requested current. 
     
     
         39 . The method of  claim 36 , further comprising adjusting the variable supply voltage based on the indication. 
     
     
         40 . The method of  claim 38 , wherein adjusting the variable supply voltage includes increasing the variable supply voltage. 
     
     
         41 . The method of  claim 36 , wherein:
 producing the variable supply voltage includes operating a voltage regulator to produce the variable supply voltage based on an input voltage; and   producing the indication includes operating a comparator having
 a first input that, in operation, receives the first voltage, and 
 a second input that, in operation, receives the second voltage. 
   
     
     
         42 . The method of  claim 41 , further comprising:
 operating a reference current circuit to produce the first voltage for tracking the variable supply voltage; and   providing the first voltage from the reference current circuit to the first input of the comparator.   
     
     
         43 . The method of  claim 42 , wherein providing the first voltage includes providing the first voltage from a node located between a reference transistor and a constant current source. 
     
     
         44 . The method of  claim 41 , wherein operating the voltage regulator includes adjusting the variable supply voltage based on the indication. 
     
     
         45 . The method of  claim 41 , wherein:
 the current-generating circuit includes a set of transistors connected in parallel and that, in operation, produces the requested current; and   wherein the method further comprises:   providing to the second input of the comparator the second voltage from a node between the set of transistors.   
     
     
         46 . The method of  claim 41 , wherein:
 the current-generating circuit includes transistors connected in series and that, in operation, produces the requested current; and   wherein the method further comprises:   providing to the second input of the comparator the second voltage from a node between the series-connected transistors.   
     
     
         47 . A system for delivering therapeutic pulses to a patient, comprising:
 a connector for providing a current to one or more electrodes for delivering the therapeutic pulses;   a programmable voltage regulator to produce a supply voltage;   a current-generating circuit coupled to the electrode connection and the voltage regulator, the current-generating circuit to supply the current to the electrode connection according to a targeted level, wherein the current-generating circuit supplies the current based on the supply voltage;   a voltage monitoring circuit to generate an indication when the supply voltage is insufficient to produce the current at the targeted level; and   a control circuit coupled to the voltage monitoring circuit and the programmable voltage regulator, the control circuit that, in operation, controls the programmable voltage regulator to increase the supply voltage in response to the indication.   
     
     
         48 . The system of  claim 47 , wherein:
 the current-generating circuit includes a transistor coupled to the variable supply voltage; and   the voltage monitoring circuit includes
 a reference current circuit coupled to the programmable voltage regulator, the reference current circuit, in operation, produces a voltage that tracks the supply voltage; and 
 a comparator including
 a first input coupled to the reference current path to sense the voltage that tracks the variable supply voltage, and 
 a second input coupled to the transistor in the current-generating circuit to sense a voltage drop across the transistor, 
 wherein the comparator, in operation, produces the indication when the voltage at the second input exceeds the voltage at the first input to indicate that the supply voltage produced by the voltage regulator is insufficient for supplying the targeted level of the current. 
 
   
     
     
         49 . The system of  claim 48 , wherein:
 the reference current path includes a reference transistor connected to a constant current source;   the transistor is one of a set of transistors included in the current-generating circuit to produce the requested current;   the first input of the comparator is connected to a node between the reference transistor and the constant current source; and   the second input of the comparator is connected to a node between transistors in the set of transistors.