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Theory of Operation
SurgiStat Low-Power Electrosurgical Generator Service Manual
4-5
System Logic
When the user sets the power, the system logic determines what the pulse width needs
to be to deliver the requested output.
System Logic
The control logic uses a field programmable gate array as the generator “brain.” This
system interprets all inputs and delivers the correct corresponding outputs.
This system controls every operation of the generator.
A system clock circuit, composed of an oscillator, provides the basic operating frequency
of 5 MHz.
The reset circuit provides a single pulse when you turn on the SurgiStat generator. This
pulse resets the field programmable gate array to ensure proper operation.
SurgiStat Control Signal Inputs and Outputs
The following table lists the important input and output signals. From a troubleshooting
standpoint, the absence (and presence) of these signals will help you isolate problem.
Signal Name
Description
TEMP
This is an input signal from the temperature-sense circuit that informs
the system logic of the internal temperature of the generator.
AUDIO_DRV
This is an output signal from the system logic that generates the
activation tones for all modes of operation.
A 610 Hz square wave is generated when the cut or blend mode is
activated. A 910 Hz square wave is generated when the desiccation,
fulguration, or bipolar mode is activated.
This signal is used by the audio circuit.
ALARM_DRV
This is an output signal from the system logic that generates a
2 kHz / 1 kHz square wave for activating the alarm siren.
This signal is used by the audio circuit.
PFC_VSENSE_ACT
This is an input signal fro the PFC circuit to measure the high voltage.
PFC_ON
This is an output signal to the PFC circuit to enable the power-factor
corrector during RF activation.
PFC_VSENSE_GND
This is an input signal from the PFC circuit to measure the high voltage.
TAP_SEL
This is an output signal from the system logic that controls relays on
the main board. The relays select which secondary windings will be
used from the monopolar output transformer.
Summary of Contents for SurgiStat
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