201
Chapter 4 Remote Interface Reference
Pulse Width Modulation (PWM) Commands
4
• The duty cycle deviation is also limited by the minimum pulse width
(Wmin):
Duty Cycle Deviation < Duty Cycle – 100 X Wmin ÷ Period
and
Duty Cycle Deviation <
100 – Duty Cycle – 100 X Wmin ÷ Period
where:
Wmin = 40 ns for period <
10 s.
Wmin = 200 ns for period > 10 s, but <
100 s.
Wmin = 2 µs for period > 100 s, but <
1000 s.
• The duty cycle deviation is also limited by the current edge time
setting.
Duty Cycle Dev < Duty Cycle – (160 X Edge Time) ÷ Period
and
Duty Cycle Dev <
100 – Duty Cycle – (160 X Edge Time) ÷ Period
•
If you select the
External
modulating source (
PWM:SOUR EXT
command
), the deviation is controlled by the ±5V signal level present
on the rear-panel Modulation In connector. For example, if you have
set the duty cycle deviation to 5 percent, a +5V signal level
corresponds to a 5 percent deviation, that is an additional 5% of
period added to the pulse duty cycle. Lower external signal levels
produce less deviation, and negative signal levels reduce the duty
cycle.
Note: The operation of the PWM:DEV:DCYC command is affected by the
FUNC:PULS:HOLD command (see “Pulse Configuration Commands” on
page 184 for further information). The FUNC:PULS:HOLD command
determines whether pulse width (the default) or pulse duty cycle values
are to be held constant as the period is varied. If the width is held, so is
the width deviation. If the duty cycle is held, so is the duty cycle deviation.
If pulse width and width deviation are being held, duty cycle deviation
values specified with the PWM:DEV:DCYC command are automatically
converted to the equivalent width deviation in seconds.
33210A users guide.book Page 201 Wednesday, July 16, 2008 11:16 AM
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