Covidien Force FX, Service Manual

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Control Board
4-10
Force FX Electrosurgical Generator C Service Manual
Each code generates a unique waveform pattern to be delivered to the RF output stage
of the generator. The T_ON ASIC reads and evaluates the code and, if the code value is
acceptable, repetitively generates the appropriate waveform until the activation request
ends. After the request ends, the feedback microcontroller places the T_ON ASIC back
into reset.
If the code received by the T_ON ASIC is not valid, the internal program sets an error flag,
deactivates all output signals, and remains in an error state until the system is reset.
T_ON Average Check
The T_ON waveform generator output waveform is integrated in hardware and returned
to the main microcontroller as an analog value called T_ON average. The T_ON average is
different for each distinct output mode of the T_ON waveform generator. The main
microcontroller continually checks the T_ON average for compliance with the calibrated
value to ensure that the T_ON waveform generator is operating properly.
The T_ON average signal rests at 5 V when the generator is not activated and drops to
the calibrated value when activation occurs. The main microcontroller checks to make
sure the T_ON average signal is within ± 15 counts of the calibrated value.
During wak control in the coag modes, the T_ON average rises an indeterminate amount.
Due to this unknown, the T_ON average is allowed to rise to 253 counts, which
guarantees the T_ON waveform generator is still operating. The T_ON average is still not
allowed to drop below the lower limit of 15 counts mentioned above.
Audio Alarm
The audio alarm circuit is located on the Footswitch board. The audio alarm is controlled
by software and hardware.
• Software control is provided by the UP_TONE\ (microcontroller tone) and LO_TONE
signals generated by the main microcontroller in response to activation inputs, alarms,
and at power-up. These signals connect from the Control board to the Power Supply/
RF board through the 96-pin connector and then from the Power Supply/RF board to
the Footswitch board through the 16-pin footswitch ribbon connector.
• Hardware control is provided by the RF_TONE\ signal generated in the RF output
stage by RF sensing circuitry on the Power Supply/RF board.
Serial Interface
The RS-232 serial port is a software-polled interface to the main microcontroller (U5). It is
used for diagnostics and calibration. Transmission and receipt of command strings do not
stop real time processing, except as single characters are read from or written to the
serial port. The serial port is configured to 9600 baud, 8 data bits, 1 stop bit, with no
parity. This timing is derived from the main microcontroller oscillator frequency of
11.0592 MHz.