I have a question about TVS diode selection. This kind of question is already discussed in previous questions.
For protecting vcc line of a controller with nominal VCC = 5V, 5%, maximum vcc = 6V. We normally choose esd diode with Vrwm=5V, for them Vbr = 5.8 to 7.8 and Vc = 12.5 to 15V (ESD9B5.0ST5G as a reference).
ESD diode manufacturer graphs also shows even though device is choosen from 5V operation, During testing, voltage across clamped can go up to ~50V(not sure can be lower but way higher than 5V), after some time they comes back to actual Vclamp voltage.
Is this ~50V clamping voltage is lethal to IC's(5V VCC pin)?
few answers i got it were first portion of ESD pulse where 8kV reaches is very low energy (few ns) and can't make much harm to IC's. In addition to that most of the IC's have basic ESD protection (have esd protection diodes on all pins which will induct during high voltage events, designer's work is to limit the current passed to those diodes during transient event)
we can't add series resisters in VCC pin of the IC, because it drops the voltage for the IC.
So, in those cases just connecting ESD diode across VCC line is worth?