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Signal Settings
Touch Signal to recall signal settings dialog box:
A. Set the input voltage source
B. Set the input current source
C. Set the expected current value, the range is 100 mA - 500
A. The oscilloscope will set the trigger level to expected
current/20 and the vertical scale of the current channel to
expected current/3.
D. Set the maximum effective input voltage (Vrms), the range is
1 V - 1 kV. The oscilloscope will set the vertical scale of the
voltage channel to maximum input voltage/6.
E. View the connection guide
F. Return to previous menu
25.5 Switching Loss
Switch loss analysis can be used to calculate the power dissipated in the switching
period.
Deskew Calibration
A relatively small skew can cause a large measurement error of switching loss,
especially during the on phase when the voltage is close to zero and the non-on phase
when the current is close to zero. This is a typical oscilloscope dynamic range limitation
when trying to measure weak voltage and (or) current in the presence of relatively large
switching voltage and (or) current.
To correct the skew between the oscilloscope channels or probes, the deskew
procedure should be performed once initially, and re-run when any part of the hardware
setup changes (for example, a different probe, different oscilloscope channel, etc.) or
when the ambient temperature changes. The deskew procedures by using a deskew
fixture is as follows.
A. Demagnetize and zero-adjust the current probe
B. Set up connections to the deskew fixture according to the deskew fixture instructions.
C. Connect the +ve and -ve probes of the high voltage differential probe to the
appropriate voltage terminals of the deskew fixture, and connect the probe to the
scope.
D. Connect the current probe to the deskew fixture current loop with the direction of the
arrow indicating the direction of the current flow, and connect the current probe to the
scope.
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T3DSO2000A Manual. Page 153
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