Model DMM7510 7½ Digit Multimeter Application Manual
Section 7: Capturing and analyzing waveforms
DMM7510-904-01 Rev. D March 2021
7-11
Using SCPI or TSP commands
Use the command sequence for the ripple noise on the output voltage test to acquire the switching
voltage waveform. Refer to
Ripple noise on the output voltage
(on page 7-4).
Inductor current linearity with varying load
The inductor current is expected to be a linear triangular waveform with varying amplitude, depending
on the loading at the output terminals. The current increases linearly when energy is stored into the
inductor and decreases when energy discharges from the inductor. Any nonlinearity in the slope of
the triangle waveform indicates inductor saturation, which is likely caused by overloading the output.
For this test, you:
•
Connect the 3
Ω load resistor to the output terminals of the buck converter
•
Connect test leads to the output terminals of the buck converter
•
Supply 12 V to the input terminals of the buck converter
•
Reset the instrument
•
Select the digitize current function and set sample rate to 500 kilosamples per second
•
Set sample count to 50
•
Display the graph
•
Repeat these steps with 4
Ω and 8 Ω resistive loads to see the change in the inductor current
Inductor current measurement device connections
You can use either the front or rear inputs. Ensure that the front-panel TERMINALS switch is set
correctly (
F
displayed for front;
R
displayed for rear). You must use either the front terminals or rear
terminals. You cannot mix connections.
Both front-panel and rear-panel connections are safety banana jacks. You can make these
connections with two insulated cables with banana plugs.
Connect the test leads as shown in the following figure.
