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60
4.
BASIC OPERATION
IM FG410-01EN
c) Difference between normal and extended variable duty range
d) Duty and frequency limitations for standard variable duty range
The duty setting range is limited to the following range according to the frequency.
For example, the variable range at 3 MHz is limited to 10% to 90%.
If the above limitation according to the frequency setting is not satisfied, the duty is
adjusted.
Variable Range Characteristics
Normal Setting range: 0.0100% to 99.9900%
• Range in which the duty can be changed with little jitter and no pulse loss
• The higher the frequency, the narrower the duty setting range.
• At 15 MHz, the duty is fixed to 50%.
Extended Setting range: 0.0000% to 100.0000% (independent of the frequency)
• Jitter of 2.5 ns rms or less typ., duty can always be changed from 0% to 100%.
• If the high-level or low-level pulse width is less than 8.4 ns, the pulse may at
times vanish. However, on average, the duty is equivalent to the set duty.
• When 0% is set, the waveform is fixed on the low-level side, and when 100% is
set, it is fixed to the high-level side. In either case, the pulse stops being output.
Frequency (Hz) / 300,000
≤
Duty (%)
≤
100
−
Frequency (Hz) / 300,000
Check
In the case of the extended variable duty range, the pulse may at times vanish,
and thus the frequency may become lower than the set frequency. Do not use
the extended variable duty range for applications that require that a constant
frequency be maintained.