Medical device

Abstract

A medical device is described having a handle, a shaft coupled to the handle and an end effector coupled to the shaft. In one embodiment, the device includes an ultrasonic transducer and is arranged so that ultrasonic or electrical energy can be delivered to a vessel or tissue to be treated. Various novel sensing circuits are described to allow a measure of the drive signal to be measured and fed back to a controller. An active fuse circuit is also described for protecting one or more batteries of the device from an over-current situation.

1 .- 17 . (canceled) 
     
     
         18 . A medical device comprising:
 an end effector for gripping a vessel/tissue;   a drive circuit for generating a cyclically varying drive signal for driving energy into the vessel/tissue;   sensing circuitry for sensing a drive signal generated by the drive circuit; and   a controller responsive to the sensing circuitry and operable to control the drive circuit to control the energy delivered to the vessel/tissue;   wherein the drive circuit comprises an impedance element that is coupled to a reference potential and wherein the sensing circuitry comprises a divider circuit for obtaining a measure of the voltage across the impedance element and a bias signal generator for applying a DC bias signal to the voltage measure.   
     
     
         19 . A device according to  claim 18 , wherein the impedance element comprises a capacitor or a resistor. 
     
     
         20 . A device according to  claim 18 , wherein the sensing circuitry comprises DC blocking circuitry for preventing the DC bias signal from the bias signal generator from coupling with the drive circuit. 
     
     
         21 . A device according to  claim 18 , wherein the bias signal generator comprises a divider circuit connected between a reference voltage and a supply voltage of the controller. 
     
     
         22 . A device according to  claim 21 , wherein the divider circuit of the bias signal generator is connected to the supply voltage of the controller via a switch and wherein the controller is configured to open the switch when the controller does not require signals from the sensing circuitry. 
     
     
         23 .- 39 . (canceled)