Covidien Force FX, Service Manual

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Control Board
Principles of Operation
Force FX Electrosurgical Generator C Service Manual
4-7
Main Microcontroller Memory
The Main Controller section includes a Xilinx TM* Spartan XC6SLX9 FPGA (U16), along
with a 4 Mbit SST39LF040 NOR Flash memory (U17) and Cypress TM* CY14B256LA
Nonvolatile RAM (NVRAM) (U18). The Cypress NVRAM and the SST NOR Flash memory
are interfaced to the controller through FPGA (U16).
The Cypress CY14B256LA-SP45XI is a fast static RAM, with a nonvolatile element in each
memory cell. The access time is typically 45ns. The memory is organized as 32 K bytes of
8 bits each. Data transfers from the SRAM to the nonvolatile elements (the STORE
operation) take place automatically at power-down. On power-up, data is restored to the
SRAM (the RECALL operation) from the nonvolatile memory.
The NOR Flash memory acts as a code memory for the Main Controller, which does not
have ROM memory.
Battery-Backed RAM
A socket on the Control Board contains a 3.0 V lithium button cell battery (BT) that
provides backup power to the DS T&R Real-Time clock (U6). The device has
several features, including 114 bytes of general purpose Nonvolatile RAM not dedicated
to any special function within the device. This NV RAM is used by the processor program
as battery-backed memory.
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.