TVS/ESD Diode on VBUS Line USB C

[OneGeekGuy]

Hi everyone,

I was using some time ago the famous USB PD controller STUSB4500. I am designing another PCB this time with another controller and I wanted to explore another alternatives for ESD/Surge/Lighting protection. While I was checking what I need, I went again to the recommended schematic for the STU and they recommend using ESDA25P35 for the VBUS line.

If we take a look at the IEC6100-4-5, we see and unless I am wrong, that line to ground testing, level 2 is 2kV, considering a surge resistance of 42Ohm, this results into max Surge current of 47A aprox.

The STUSB4500 has an absolute max voltage on VDD of 28V.

If we take a look to the TVS datasheet, we would see that Vcl at Ipp of 35A is 41V.

Then this means that during the pulse, the max voltage the VDD pin will see for a short time will be 41V. Is this correct? Would not be better to reduce the Vcl getting a diode with lower Rd, or I am being too conservative?

Thanks and regards!