Surgical generator for ultrasonic and electrosurgical devices
View Patent ↗A control circuit of a surgical device is disclosed. The control circuit includes a first circuit portion coupled to at least one switch operable between an open state and a closed state. The first circuit portion communicates with a surgical generator over a conductor pair to receive a control signal to determine a state of the at least one switch.
1. A surgical device, the surgical device comprising:
an end effector to act on tissue; and
a control circuit configured for communication with a surgical generator, the control circuit comprising:
a conductor pair to communicate with the surgical generator;
a first circuit portion comprising:
a first switch configured to switch between an open state and a closed state;
a first resistor coupled in parallel with the first switch;
a second switch configured to switch between an open state and a closed state; and
a second resistor coupled in parallel with the second switch, wherein a combination of the first switch and the first resistor is coupled in series with a combination of the second switch and the second resistor;
a voltage reference coupled in parallel with the first circuit portion, wherein the control circuit is configured to receive from the generator and over the conductor pair an interrogation signal, wherein a state of at least one of the first switch or the second switch is determined from at least one characteristic of the interrogation signal;
a capacitor coupled in parallel with the first circuit portion;
a resistor coupled in series with the first circuit portion; and
a memory device coupled to the first circuit portion.
2. The surgical device of claim 1 , wherein the state of the first switch is determinable based on a slope of a voltage on the capacitor.
3. The surgical device of claim 1 , comprising an oscillator in communication with the at least one switch, wherein the state of the at least one switch is determinable based on a frequency of the oscillator.
4. The surgical device of claim 1 , comprising a one-wire multi-switch input device coupled to the at least one switch, wherein the state of the at least one switch is communicated to the generator over a one-wire communication protocol.
5. The surgical device of claim 1 , wherein the interrogation signal is a differential constant current pulse having a positive phase and a negative phase.
6. The surgical device of claim 1 , wherein the memory device comprises at least one one-wire electrically erasable programmable read only memory (EEPROM).
7. The surgical device of claim 5 , wherein the positive phase of the interrogation signal is a positive transition of the differential constant current pulse and the negative phase of the differential constant current pulse is a negative transition of the differential constant current pulse.