Figure 6.1 RF Drive Signals
6-8
SP_PCON: (Scaler to calibrate Spray power)
SET for Spray activation to rescale SE_Pcon for
Spray calibration and control.
T_RLY:
Tank Relay selects either the Spray or ABC™
transformer primary. set when Spray is acti
-
vated.
XSLO:
Transformer Sense input must be low. If the
harness from the Handsense PCB to the
Power Control PCB is not connected or bro-
ken, this signal is pulled up and will inhibit
single ended operation.
A_SNS:
Arc Sense - A pulsed signal that pulses high any
-
time the ABC™ output exceeds a reference
level. Four or more pulses indicates an open
circuit on ABC™ and less than four pulses
indicates the ABC™ output is loaded.
ABC_OV: ABC™ Over Voltage
Pulses if the ABC™ output exceeds 3500 Vpk
and 192 consecutive pulses will cause ABC™
to be inhibited. If a failure occurs that
latches ABC™ in the Active Mode, this signal
will inhibit RF at power levels greater than
approximately 45W.
SE_EN: Single Ended drive control.
When this signal goes low, it allows C10 to start
charging up and RF drive to the Single Ended
Amplifier occurs.
SE_PW: Single Ended Pulse Width -
RF drive to the Single Ended Amplifier starts
when SE_EN goes low and stays on until this
signal transitions high. When this signal tran
-
sitions high, RF drive is terminated for one
cycle.
FB1 & FB2 DRV: (Full Bridge drive)
RF drive for the Full Bridge Amplifier. The full
bridge amplifier requires two drive signals
that are 180° out of phase with each other.
The rate is 461KHz and the duty cycle of the
signal varies with the mode requested. These
signals are active in Cut, Blend, Bipolar, and
Pinpoint.
FB1 & FB2 RST: (Full Bridge Drive Reset)
Reset signals for the amplifier drive transformers
on the full bridge amplifier. The FB1 RST
follows the FB1 DRV and has pulse duration
of about 200nS. FB2 RST follows FB2 DRV
and has a pulse duration of about 200nS.
SE_DRV: (Single Ended Drive)
RF drive for the single ended amplifier. This
signal is active when Spray and ABC™ modes
are active.
6.3.3 Power Control - I/O Signals
The following signals are in addition to those
described for U7.
PW_MEA: Pulse Width Measured
An average DC voltage of the Spray and ABC™
drive cycles. The Monitor microcontroller
verifies that the measured pulse width is cor
-
rect for the power setting.
FB_MON: Full Bridge Monitor
An average DC voltage of the Full Bridge
Amplifier drive to allow the monitor
microcontroller a means of verifying the duty
cycle of the RF drive.
IMEA: Current Measured
The monitor microcontroller verifies that the
output current is within limits.
6.3.4 ABC™ Arc Sense
ABC™ has two modes - Active and Target. The
active mode is enabled when a load is sensed and
only in the active mode will the power control dial
have any effect on the output voltage or power.
When a load is not present, the target mode is
enabled where the RF Output voltage is fixed and
the repetition rate increased. The Target mode
also has two modes - Target Pulses and Booster
Pulses.
The ABC™ mode is quite similar to Spray in the
sense that the output is a damped sinusoidal wave
-
form. The waveform is heavily damped when a
heavy load is on the output and lightly damped
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