Control
Board
4-8
Power
Supply
Supervisor
Circuit
The
power
supply
supervisor
circuit (U14), a MAX691, generates a Reset
signal
and
a
Reset\
signal for
the
main
microcontroller
(US)
if
the
power
supply
voltage
to
the
Control
board
drops
below
4.65
V.
It
also generates a
voltage sensitive chip select for
the
PSD412 (U6)
and
the
PSD413 (U3).
The
low
voltage
threshold
(4.65
V)
places U3
and
U6
in
sleep
mode
and
disables
the
2K x 8 external static RAM.
AID
and
D/A
Conversion
Each
8OC562
microcontroller
(US
and
U11) contains
an
8-channel
multiplexed
8-bit
AID
converter. Resolution
of
voltage
and
current
sense
inputs
is
enhanced
by
incorporating
gain
scaling relays
in
the
sense
circuits
on
the
Power
Supply
IRF
board
and
prescaling
based
on
the
expected
input
voltage
or
current
values.
An
MP7226
quad
D I A converter (UI5)
provides
4-channel 8-bit D I A
capabilities for
the
feedback microcontroller
to
output
0 to 5 V
dc
analog
voltages.
Waveform
Generation
(T_ON
ASIC)
A
dedicated
89C54 microcontroller (U9) generates
the
RF
drive
waveforms
(T_ON\)
for
the
RF
output
amplifier
on
the
power
supply
IRF
board.
The
microcontroller functions
as
an
application-specific
integrated
circuit,
or
ASIC,
performing
an
endless
series
of
repetitive tasks
while
enabled.
The
feedback microcontroller (U11)
holds
the
T_ON
ASIC (U9)
in
a reset
state
until
the
feedback microcontroller detects a
valid
activation request.
After
validating
the
request,
the
feedback microcontroller releases
the
T_ON ASIC
from
reset
and
communicates
a 4-bit
code
that
represents
the
generator
mode
to
be
activated.
The
acceptable activation codes
are
listed
below:
0:
Precise
bipolar
1:
Standard
and
Macro
bipolar
2: Low
and
Pure
cut
3:
Blendcut
7:
Desiccate
coag
8:
LCF
Fulgurate
coag
9:
Spray
coag
11:
Spark-controlled Blend
12:
Fulgurate
coag
Codes
4,5,6,10
and
13-15
are
unused.
Force
F)(TM-C
Service
Manual
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