How to Probe the Switch Node of a µModule Regulator

A common step in verifying if a power management circuit functions properly is to probe the switch node. But how does one perform that task on a power µModule regulator since the switch node is often not accessible? Using the LTM4611 as an example, Alan Chern explains how starting at the 42 second mark in this video he created.

With a bit of searching on the top of the µModule package, an oscilloscope probe can be used to inductively sense the switch node. Once triggered, the switch node duty cycle may be examined to verify that the step-down regulator is in operation. Varying the input voltage and watching for correct changes in the switch node waveform provides further evidence that the regulator is operating properly. While a step-down regulator was used in this example, this technique can also be applied to Battery Charger and LED Driver µModule regulators.




Willie Chan