Why Is the DUT Voltage Measured Alternately in Groups of Four in SET IOL System?

Updated May 28, 2026

Reported In

Other

Hardware: SET IOL

Issue Details

In SET IOL system, I observe that DUT voltage measurements do not occur simultaneously for all channels.
Instead, when using a total of 8 DUTs, the system measures the voltage of DUT 1–4 and DUT 5–8 alternately.
I want to understand why the measurements are performed in this manner.

Solution

When IOL system was originally developed, silicon (Si) devices were widely used, and the body diode voltage drop was measured to calculate the junction temperature.

With the introduction of silicon carbide (SiC) devices, the body diode voltage drop increased to more than 2.5 V per DUT.
As a result, measuring all 8 DUTs simultaneously would require a total voltage exceeding 20 V.

Since 20 V is the maximum measurement range supported by the IOL system measurement unit, the stress conditions remain unchanged, but the measurement method was modified.
To stay within the measurement voltage limit, the system measures DUT 1–4 and DUT 5–8 alternately instead of measuring all 8 DUTs at once.

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