Application of oscilloscope in switching power supply

August 02, 2025

Power supply is a crucial component in all electronic devices. It can be categorized into switching power supplies, linear power supplies, and others. Among these, switching power supplies have become the dominant architecture in digital computing and network communication systems due to their efficiency and compact design. The performance of a switching power supply directly affects the overall functionality of the system. Therefore, accurate power analysis is essential during R&D and production testing. The SDS2000 Super Phosphor Oscilloscope from SIGLENT comes with an advanced power analysis module that enables precise measurements for most power-related parameters. In this article, we will explore the power analysis capabilities of the SDS2000 by examining the input module of a power demo board. As an example, let's take the STBX power demo board. Figure 1 shows its physical layout:
Figure 1: STBX Power Demo Board
The schematic diagram of the STBX circuit is shown in Figure 2:
Figure 2: Schematic Diagram of STBX Circuit
Before starting the power analysis, itâ€™s important to ensure that the oscilloscope, power demo board, and probes are all functioning properly. Once everything is confirmed to be in working order, you can proceed with the analysis. To begin, we used the SDS2304 oscilloscope along with a differential probe and a current probe to measure the voltage and current waveforms at the power input. The results are shown in Figure 3. The red curve on channel 2 represents the voltage waveform, while the green curve on channel 4 represents the current waveform. With the SDS2000â€™s powerful parameter measurement features, we were able to easily determine key values such as peak-to-peak, RMS, maximum, and minimum for both voltage and current. The figure displays the peak-to-peak value and frequency of both signals.
Figure 3: Input Waveform Measurement
It's important to note that different voltage and current probes may have varying transmission delays. This timing difference can significantly affect the accuracy of power measurements. To ensure precision, the "delay deviation correction" feature must be used to balance the delay between the voltage and current probes. This step is critical and should be performed before any power measurements are taken.
Figure 4: Power Analysis Options
As shown in Figure 4, the SDS2000 offers a comprehensive power analysis module that supports various analytical methods, including power quality, current harmonics, inrush current, switching loss, conversion speed, modulation, output ripple, and transient response. These tools give engineers greater flexibility and control when analyzing real-world power systems. This article will focus on power quality analysis, current harmonic analysis, and inrush current analysis, which are particularly useful in evaluating the performance of switching power supplies.
Stationary Accessories
Customizable stationary accessories,planner sticker sets,notebook sticker sets
Lion Paper Products (Jiaxing) Co.,Ltd , https://www.lion-paper.com