In a small board where space is important I need to place ESD protections near some 3.3V bus with I/O lines (4 pin: 3.3V, GND, digital input, digital output).

The most sensitive IC to protect is an xmega32A4. I'm going to use a USBLC6-2SC6 due to its very small package. I'm concerned about clamping voltage: using standard bidirectional 3.3V TVS, the clamping voltage can be as low as 5.7V @ 10A (example SD03C) while USBLC6-SC6 offers only 17V @ 5A.

How can I decide if this is enough or not? Is there any information in the xmega datasheet that I can use?