Drain-to-Source Voltage Measurement Discrepancies with MSO58 with TIVH05L and THDP0200 probes

Hello, out lab is using the MS058 OScope to measure the drain to source voltage on an LLC converter with a front end PFC circuit. We are seeing some discrepancy in our measurements when using two different probes. I was hoping to get some advice on this topic. The summary of the two probes is below:

- using a TIVH05L IsoVu probe with the SQPIN 500X tip the turn off VDS measurements show the voltage overshoot to be ~500V.

- using a THDP0200 the measurements are showing significantly higher overshoot voltages (~650V).

Any recommendation on which measurements are accurate and what explains the discrepancy between the two measurements?

Hello,

The SQPIN500X has a Differential Input Voltage range of +/- 500V at 2X. This probe showing overshoot voltage to be around 500V means that the probe could be clipping the signal and you aren't seeing all of the data. However, this is a very good probe for your application. I would suggest using the WSQPIN1000X tip cable, with a +/- 1000V range at 2X. This probe tip will give a larger differential range to avoid this clipping.