System and power converter issues are frequently related to a converter’s switching characteristics, which are most easily observed at the switching node. In this video, Steve Sandler discusses the measurement and interpretation of switch node waveforms as observed in point-of-load regulators or POLs. He discusses the instrumentation requirements for measuring switch-node waveforms, why switch-node waveforms should be viewed using different time scales, and the impact of scope probes on measurements.
With those measurement requirements as background, Sandler examines how switching frequency and duty cycle affect power supply stability as well as EMI.
Measurements taken at the switch-node reveal information about power supply stability, noise, and EMI and how these characteristics are affected by switching frequency and duty cycle.