Key considerations for ESD clamps are listed in this slide, plus graphs illustrating the two types of breakdown voltage. The first of these is the normal zener diode I-V relationship. Breakdown voltage is highlighted at the current ramp. The second is specific to TI components, illustrated by the I-V curve of a Snap Back which breaks down at Vbr, and then snaps back to Vsb. Side-by-Side Comparison of the two graphs makes it possible to visually see why Snap Back is a better solution than the normal Zeners.