Control Board
Principles of Operation
Force FX Electrosurgical Generator C Service Manual 4-7
Main Microcontroller Memory
An ST microelectronics PSD835G2 programmable systems device (U3) provides program
memory (512K x 8 external flash memory) and data memory (2K x 8 external battery-
backed static RAM) for the main microcontroller. Additional data memory is available
from these sources:
•256K x 8 microcontroller internal RAM
•4K x 8 external static RAM (U4) shared with the feedback microcontroller
Battery-Backed RAM
A socket on the Control board contains a 3.0 V lithium button cell battery (BT1) that
provides backup power for the 2K x 8 external RAM on the PSD835G2 device (U3) used
by the main microcontroller. The battery-backed RAM stores calibration constants, last
setup parameters, and temporary data.
Feedback Microcontroller
The feedback microcontroller (U11), like the main microcontroller, is an 80C562. It
receives commands from the main microcontroller and, when the generator is activated,
establishes the appropriate relay closures and activates RF output. It continually adjusts
the output signal of the generator by controlling the high voltage DC power supply and
the RF clock circuitry. It is primarily responsible for these functions:
• Scaling relay control and output relay control
•T_ON ASIC waveform control
•Leakage control (coag)
•Constant voltage, current, and power feedback control
• ECON initialization
• Real-time information update (actual voltage, current, power, impedance, effect
mode)
•Memory tests
•Communicating with the main microcontroller
Feedback Microcontroller Memory
An ST microelectronics PSD835G2 programmable systems device (U6) provides program
memory (512K x 8 external flash memory) and data memory (2K x 8 external static RAM)
for the feedback microcontroller. Additional data memory is available from these sources:
•256K x 8 microcontroller internal RAM
• 4K x 8 external static RAM (U4) shared with the main microcontroller.
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