Covidien Force FX, Руководство по обслуживанию

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Control Board
4-12
Force FX Electrosurgical Generator C Service Manual
Instant Response Algorithm
This mode is a closed loop control algorithm implemented in microcontroller firmware. It
is applied to the bipolar modes and the cut modes. It is not applied to the coag modes.
As tissue impedance increases from short circuit to open circuit, the algorithm
implements first constant current, then constant power, and finally, constant voltage. The
maximum output voltage is controlled to reduce capacitive coupling, reduce video
interference, and eliminate sparking. At low impedances, constant current protects
output circuitry. At high impedances, constant voltage control limits arcing and
electromagnetic interference.
Constant current: output voltage is held at constant output current according to
I = (P/R) ˆ(1/2)
where I is the output current, P is the power set by the user, and R is the constant current
to constant power impedance switchpoint.
Constant power: the power set by the user is maintained.
Constant voltage: the output voltage is maintained according to
V = (P*R) ˆ(1/2)
where V is the output voltage, P is the power set by the user, and R is the constant power
to constant voltage impedance switchpoint.
High Impedance Operation
The firmware algorithm clamps the output voltage to specific levels for high impedance
conditions. The clamp level is a function of the mode that is activated. This helps prevent
arcing and electromagnetic interference.
Analog to Digital Saturation
Analog to digital saturation works in conjunction with RF leakage current limiting. If the
analog to digital converter is saturated, the effect mode feedback loop reduces the
output voltage to allow for an unsaturated operating condition. The feedback loop
switches the control function to maintaining the analog to digital converter in the linear
operating range.