Voltage rating on SMD capacitors

[akis]

I am using three SMD MLCC X7R 10uF/25V (total 30uF measured 40uF) at the output of a push-pull amp powered by +/-23V, the other side of the cap being a transformer.

On a purely resistive load I think I'd be within the voltage levels of the cap.

It is possible depending on the behaviour of the load on the transformer that higher voltages may develop even for very short periods of time.

Can these theoretical (not observed, just academic) voltages harm the capacitor? How could I check a random capacitor for "good operation" other than plugging it on the cap meter?

Thanks

[akis]

Re: Voltage rating on SMD capacitors

/bump

anyone?

[mariushm]

Re: Voltage rating on SMD capacitors

Never a good idea to get the voltage so close. Your voltage can go higher than +/- 23v for sure, depending on your mains voltage, load (transformers output more when there's little load usually)

But the worst thing is ... those ceramic capacitors won't be 10uF with 23v on them, they're probably going to be 3-5 uF if you're lucky.

Read up on it :

* http://www.maximintegrated.com/en/ap...ex.mvp/id/5527
*


* video EEVblog #626 - Ceramic Capacitor Voltage Dependency : https://www.youtube.com/watch?v=2MQyQUkwmMk
* video TDK Tech Tube : DC Bias Effect on Multilayer Ceramic Capacitors (MLCC) https://www.youtube.com/watch?v=weUrWSFJCgk


You would probably have to use 100v rated capacitors and probably aim for more capacitance.

[akis]

Re: Voltage rating on SMD capacitors

Alright I am reading and will now run some tests on my caps to see how they behave! What I was worried about was that reaching or exceeding the voltage ratings might cause irreversible damage, maybe even unnoticeable. like temperature coefficient worsening, or ESR worsening or whatever the capacitor meter won't tell me.