Inductor Current Linearity With Varying Load - Tektronix Keithley DMM7510 User Manual

Model DMM7510 7½ Digit Multimeter User's Manual
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

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
DMM7510-900-01 Rev. C / September 2019
Ripple noise on the output voltage
Section 10: Capturing and analyzing waveforms
(on page 10-4).
10-11