2 Initial Examination of TMCS11xxEVM with CB70-14-CY Copper Lugs

The TMCS11xxEVM comes with a pair of CB70-14-CY 90A rated copper lugs included in the kit to provide a safe transfer of current into the EVM, provided the correct gauge cabling is used for the given signal. These lugs allow the user to move from one sensitivity variant of the chosen product family to another relatively quickly by simply screwing down to the desired variant, and ensuring a secure connection prior to energizing the system. They also allow for re-use, as the user's cabling is also screwed down into the terminal rather than soldering a one-time use design. Figure 2-1 shows a single panel of the EVM in the standard orientation as described in the TMCS1123 User's Guide without cabling attached.

Figure 2-1 TMCS1123EVM Portion, A1 Variant, Standard Configuration, Sensitivity = 25mV/A

When this system was initially developed, varying copper weights were explored on a singular version of the paneled product to ultimately arrive at the 4oz final version available for use today. Figure 2-2 and Figure 2-3 demonstrate measured board performance for 3oz and 4oz pours, respectively, and while performance between these variations is similar, 4oz copper was ultimately chosen for the marginal improvement seen above the 60A mark.

Figure 2-2 TMCS1123EVM Thermal Response Curves for 2 Sample Devices, 3 Oz Copper, >60 Amperes

Figure 2-3 TMCS1123EVM Thermal Response Curves for 2 Devices, 4Oz Copper, >60 Amperes

At the 80A maximal point for the device,the observation is that there is roughly a 5°C improvement between the mean points of the measurement between 3oz and 4oz pours. As shown, the EVM, equipped with 4oz planes, is capable of up to approximately 93A of current capacity prior to the junction temperature reaching the absolute maximum rating of 165°C, but copper thickness can vary by lot within the build specification, due to several factors: base copper thickness tolerance, the selected start copper thickness used by the vendor, and the number of cleaning processes used by the vendor to name a few. As such, sufficient headroom is taken to make sure the device operates within the given specification (this is demonstrated in the copper weight section), even for potential worst case scenarios.