MLCC experience/suggestions?

[starfire]

Does anyone have any experiences (good or bad) with using MLCC-type caps for
input power / voltage regulator applications? I'm using 22uF Tantalums
right now and have reduced (but not eliminated) some heavy switching
transients. The MLCC looks good in terms of no polarization and reduced
package size for the capacitance rating.

Is there a source for these caps (in 47uF or 100uF flavors) at prices lower
than DigiKey? DigiKey wants $23.48 for ten 100uF, 6.3V caps. I realize
this is a relatively new technology but has anyone run across a more
inexpensive source?

Thanks.

Dave

 

[Eeyore]

Does anyone have any experiences (good or bad) with using MLCC-type caps for
input power / voltage regulator applications? I'm using 22uF Tantalums
right now and have reduced (but not eliminated) some heavy switching
transients. The MLCC looks good in terms of no polarization and reduced
package size for the capacitance rating.

Is there a source for these caps (in 47uF or 100uF flavors) at prices lower
than DigiKey? DigiKey wants $23.48 for ten 100uF, 6.3V caps. I realize
this is a relatively new technology but has anyone run across a more
inexpensive source?

There's nothing new about MLCCs !

What do you want 100uF for ?

Graham

 

[Nico Coesel]

Does anyone have any experiences (good or bad) with using MLCC-type caps for
input power / voltage regulator applications? I'm using 22uF Tantalums
right now and have reduced (but not eliminated) some heavy switching
transients. The MLCC looks good in terms of no polarization and reduced
package size for the capacitance rating.

Is there a source for these caps (in 47uF or 100uF flavors) at prices lower
than DigiKey? DigiKey wants $23.48 for ten 100uF, 6.3V caps. I realize
this is a relatively new technology but has anyone run across a more
inexpensive source?

Perhaps smaller sizes are cheaper in the end. I've been using MLCC for
several years now. They work fine and I like the fact MLCC is not
prone to burn a hole in the PCB. Another positive thing about MLCC is
that they are better for the environment. Mining tantalum does a lot
of damage to the plants and animals.

 

[Eeyore]

Mining tantalum does a lot
of damage to the plants and animals.

Does it ?

Can you explain how it does that ?

Graham

 

[John Larkin]

Does anyone have any experiences (good or bad) with using MLCC-type caps for
input power / voltage regulator applications? I'm using 22uF Tantalums
right now and have reduced (but not eliminated) some heavy switching
transients. The MLCC looks good in terms of no polarization and reduced
package size for the capacitance rating.

Is there a source for these caps (in 47uF or 100uF flavors) at prices lower
than DigiKey? DigiKey wants $23.48 for ten 100uF, 6.3V caps. I realize
this is a relatively new technology but has anyone run across a more
inexpensive source?

Thanks.

Dave

Ceramics are great, and values like 10 or 22 uF are affordable. But a
lot of regulators will oscillate into a big ceramic load, including
most LDOs and LM337.

John

 

[Nico Coesel]

Does it ?

Can you explain how it does that ?

I can't understand why I even bother to post this *, but here it goes:
First hit with Google:

http://www.cellular-news.com/coltan/

* I must be in a really good mood since we're about to have lasanga
for dinner.

 

[Eeyore]

I can't understand why I even bother to post this *, but here it goes:
First hit with Google:

http://www.cellular-news.com/coltan/

Poor gorillas.

I've never specced a tantalum cap in my life. I've always been slightly puzzled
why they're so popular in cellphones.

Graham

 

[starfire]

Ceramics are great, and values like 10 or 22 uF are affordable. But a
lot of regulators will oscillate into a big ceramic load, including
most LDOs and LM337.

John

Now that's EXACTLY the kind of information I was looking for! Thank you!

So often people get sidetracked by picking on the exact verbiage used to
format the questions that they overlook the context of the question...

I had a problem with switching transients on an LDO which a larger input
capacitor seemed to reduce. I had been using a 1uF ceramic on the
input-side and a 1uF ceramic on the output-side of a TC1108 LDO regulator.
Max current draw at 3.3VDC was about 100mA. Per great suggestions form this
group, I inserted a larger 22uF Tantalum on the input-side and the problem
was significantly reduced. While the switching transient was reduced to the
point of not causing a problem with board operation, it was still there, but
greatly reduced in amplitude. The voltage dip only dropped to about 2.5VDC
from the nominal 3.6VDC input and there was virtually no overshoot when the
transient ended about 2usec later. I had thought to increase the size of
the input cap to 47uF, 68uF, or even 100uF. I also just found out about
MLCC caps (I'm sorry... I must have been living a sheltered life ) and
saw the reduced size for the footprint as well as the non-polarized
components.

Since these components are relatively high cost ($23.48 for 10 parts from
DigiKey), would I be wasting time and money to try something like the 100uF
1206 device for the input-side LDO filtering?

Thanks.

Dave

 

[Eeyore]

Per great suggestions form this group, I inserted a larger 22uF Tantalum on
the input-side

Why a tantalum ?

Graham

 

[Winfield]

Ceramics are great, and values like 10 or 22 uF are affordable. But
a lot of regulators will oscillate into a big ceramic load, including
most LDOs and LM337.

You can solve that problem by adding a little series resistance.
DigiKey has a good stock of multiple sizes of SMD resistors with
resistances of 5, 10, 20, or 50 milli-ohms, or whatever your choice.

 

[starfire]

Why a tantalum ?

Graham

small size. only needed 6.3v working volts but needed small footprint.

Dave

 

[starfire]

You can solve that problem by adding a little series resistance.
DigiKey has a good stock of multiple sizes of SMD resistors with
resistances of 5, 10, 20, or 50 milli-ohms, or whatever your choice.

Is this to compensate for the lower ESR of the MLCC devices?

Dave

 

[Matt]

Does anyone have any experiences (good or bad) with using MLCC-type caps for

This paper may be of interest:

http://dkc1.digikey.com/us/en/mkt/NewT043/Panasonic/MLCC_whitepaper_081004.pdf

“ Improve Your Designs with Large Capacitance Value
Multi-Layer Ceramic Chip ( MLCC ) Capacitors â€
by George M. Harayda, Akira Omi, and Axel Yamamoto, Panasonic
Introduction
This paper explores how recent advances in ceramic material
and package technologies have now increased the choices for
a designer when selecting the best capacitor for by-passing /
de-coupling, filtering, and non-critical timing circuitry.
These technology improvements have made it possible to add
more capacitance ( 1 μF & greater ) into smaller case sizes
( 1206 down to 0402 ) while maintaining the largest possible
operating voltage ( 6.3 up to 25 V ), improving the electrical
performance, and lowering the cost of MLCC Capacitors.
No longer is a designer restricted to SMT / Chip Aluminum
Electrolytic ( ‘wet’ or ‘solid-polymer’ ) or Chip Tantalum
( ‘solid-polymer’ or ‘low ESR’ ). The superior equivalent
series resistance and inductance / impedance and reliability of
MLCCs can now be found in the higher capacitance values.
These improved MLCC mechanical and electrical attributes
will enable you to make your electronic products have smaller
size, less weight, better electrical performance, and a lower
cost; thereby making your products more competitive.

The datasheets for National LM3670 and LM3671 (LDO efficient DC-DC
regulators) have reference designs that call for MLCCs, and they provide
part numbers.

 

[starfire]

This paper may be of interest:

http://dkc1.digikey.com/us/en/mkt/NewT043/Panasonic/MLCC_whitepaper_081004.pdf

Excellent! Thanks very much. Very useful.

Dave

 

[John Larkin]

You can solve that problem by adding a little series resistance.
DigiKey has a good stock of multiple sizes of SMD resistors with
resistances of 5, 10, 20, or 50 milli-ohms, or whatever your choice.

I want a cap to have a low AC impedance, so it seems silly to add
another component just to make esr worse. It's better to use
regulators that are stable with low-z loads.

John