PMA2
Modulation Analysis
Modulation Analysis
functions produce a time domain display, which represents the modulated
parameter in a time-vs.- time graphical plot. They are convenient tools for
intuitively viewing the time domain response of the entire control
loop, including any time constants added by the pulse width modulator.
Modulation Analysis can be performed for duty cycle, period, frequency,
and pulse width.
| The width of every pulse in a PWM power
supply’s control circuit is measured |
The time value of each pulse width
is displayed on the vertical axis |
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Soft Start |
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In this example, PMA2 on a WavePro DSO acquires a 20 ms
record of every gate drive pulse from the time a power supply is turned on until it reaches steady
state.
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Modulation Analysis displays the pulse width value of
every cycle on the vertical axis as it occurs. The soft start circuit’s
performance is readily observed.
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The 5 volt supply is
monitored as it increases from 0 volts to a regulated +5 volt level.
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The zoom feature allows
each gate drive to be individually examined.
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CLICK
ON IMAGE TO ZOOM
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Step Response |
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PMA2 on a WavePro DSO examines the change in gate drive pulse
widths as a power supply’s load steps from full to minimum.
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Modulation Analysis displays the pulse width value of every cycle
on the vertical axis as it occurs. The circuit’s response to a step
change can be observed.
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Zoom traces can be used to view individual gate drive pulses and
observe their behavior before and after a large load change.
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WavePro SMART Trigger allows the gate drive signal acquisition to
start on the first gate drive pulse that occurs after the load
changes from maximum to minimum.
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CLICK
ON IMAGE TO ZOOM
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