On Sat, 06 Feb 2010 14:46:31 -0500, Hammy wrote:

On Sat, 06 Feb 2010 10:15:29 -0800, Mycelium
g wrote:

On Sat, 06 Feb 2010 12:07:56 -0500, Hammy wrote:


The rms current rating was probably exceeded for the ambient temp it
overheated and Kabloowee!


Properly operating ceramic capacitors do not experience ANY heavy
current. If they are experiencing current, they are already bad.

Sure they are 10 and 22uF MLCC's (X5R) are used all the time in the
output of SMPS's so they do carry large RMS currents. That cap looks
like a large 1206 or bigger package which means it's probably a 10 or
22uf cap.

No, ya dippy dope, that is NOT a 22uF cap! That is more likely a
standard 0.01uF cap.

Now, re-do using the right math.

You are attributing storage cap nomenclature and specs with ceramic
caps, which have entirely different purposes and operating spec
declarations.

If your SMPS is switching at 500kHz are faster you don't need large
Aluminum's for hold-up in between such small switching periods.

You are still in the wrong realm.

From just one of the numerous application notes out there on MLCC's as
output caps for SMPS's.

No... as filtration on the outputs, not as the storage itself, and in
the cases where it is "the storage cap", it is usually a high voltage
application, where the output is in mA.

"Because the ESR of ceramic capacitors is low, the capacitor
temperature rise due to ripple current dissipation is usually
negligible.

Oh, boy... you are good at quoting. You are apparently not that good
at interpreting what you are reading.

Good design practice dictates that we always confirm this
and verify that the output capacitor RMS current and temperature rise
are within the manufacturer's suggested limit.

That cap in the photo is NOT an output cap in ANY circuit, you dippy
twit!

The maximum RMS ripple
current seen by the output capacitor occurs at the maximum input
voltage…."

No ****.

Sounds to me like they are working while they carry high rms current.

Sounds to me like you are lost in a lost world as it relates to the
application that cap is being used for, much less its value, idiot.