Activation - ConMed Hyfrecator 2000 Service Manual

2000

3.3.4.1.6 Activation

Until the unit is activated, the Control microcontroller forces all drive signals to inactive states: HVPWM =
low, /GATEPWM = high, /TONE = low. Further, the Monitor microcontroller holds /HVENA inactive
(high), so the ACTIVE LED X3 is dark and the HV Regulator is idle. GATENA is held high, however, so
that the Monitor can detect activation, valid or otherwise, via the /GATE.M signal. The only visible
activities during this idle state are the two 4 MHz oscillators and the 10 msec LED & PSET cycle on the
PSETO & LED drive lines.
Although not externally visible, both microcontrollers are continuously performing fault detection tests, in
particular those that verify that no RF output is being generated. See Section 3.3.5 for descriptions of these
tests.
Activation starts in the following sequence:
1. /ACTIVE goes low in response to the user's closing the hand or foot switch.
2. After /ACTIVE is low for 20 msec, and there is no pending EEPROM write or power or mode change
process pending, the Control microcontroller begins generating /GATEPWM per the current mode and
HVPWM per the power setting, and turns on the /TONE signal.
3. Upon detecting gate drive activity on /GATE.M, the Monitor microcontroller pulls /HVEN low, thus
enabling the HV Regulator and turning on the ACTIVE LED.
Once activation has commenced, the Control microcontroller simply keeps its drive signals running, while
ignoring any further power or mode changes. Both microcontrollers continue their fault detection processes.
In particular, the Monitor is busy verifying that RF output is correct and that activation is accompanied by
an audible tone (TONEMON) and /ACTIVE.M being low. See Section 3.3.5 for descriptions of these tests
and fault shutdown processes.
Activation is normally terminated when the user releases the activation switch. Deactivation proceeds as
follows:
1. /ACTIVE goes high.
2. After 20 msec, the Control microcontroller returns HVPWM, /GATEPWM and /TONE to their idle
states, and re-enables power and mode change inputs.
3. Upon seeing /GATE.M activity cease and /ACTIVE.M go high, the Monitor takes /HVEN high to turn
off the ACTIVE LED and the HV supply, and restores idle state fault testing.
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