capacitor Esd waveform

[dark]

Hi board,

If ESD even strucks the powersupply port , and it has a TVS (1.5KE440)to clamp the voltage to Vc=631V . Then I need to know how to select the voltage rating of Electrolytic capacitor , I have a capacitor in the circuit 470uF 150V exposed to this ESD event .Is the esd event too low energy to cause any damage to above mentioned capacitor .

Thanks

 

[ronsimpson]

The ESD does not have enough power to charge up a 470uF cap.

 

[cowboybob]

Since the range of ESD voltage/current potentials are infinite, there is no real way way protect against all possible instances. The value cap you have was chosen for it's efficacy in filtering the supply output. The TVS for most common EDS events.

The really big one that takes out the TVS most likely will take out the cap as well. These simply can't be protected against.

Well, not exactly.

You could unplug the device and never use it. But even then, lightning is known to follow no predictable transit pattern.

I wouldn't worry about it much.

 

[ronsimpson]

A large capacitor (470uF 150V) has inductance and resistance that limits how fast it will charge. It is certainly possible to put 1000 volts for 10ns on the capacitor with out huge current flow. The TVS can not withstand over 631 volts for long periods of time but will respond to fast spikes.

 

[kubeek]

Is the esd event too low energy to cause any damage to above mentioned capacitor .Thanks

Depends what you imagine as an ESD. Consider lightning, which is a kind of ESD too, but a completely different energy level than a human body model used for normal ESD assesment.

 

[dark]

Thanks for the replies , Please find the attached image for waveform.
**broken link removed**