Polarised SMD Caps?

Lostcause · 21st March 2006, 04:07 PM

Does anyone know where I can get polarised 1uf Caps from?
Ideally they need to be X7R 0805's

Is there such a thing?

Thanks

Lee

anatech · 21st March 2006, 07:26 PM

Hi Lee,
Sounds like a Ceramic cap with a XR7 characteristic. They should be available but maybe not everywhere.

http://www.ttieurope.com/microsites/...w/products.cfm

This is one supplier.

-Chris

Lostcause · 21st March 2006, 08:46 PM

Quote:

Originally posted by anatech
Hi Lee,
Sounds like a Ceramic cap with a XR7 characteristic. They should be available but maybe not everywhere.

http://www.ttieurope.com/microsites/...w/products.cfm

This is one supplier.

-Chris

Cheers Ol' bean, so XR7 bears a reference to it being polarised?
I do have some XR7 ceramics but I've absolutely no idea if they are polarised or how the heck you would know which end was which, no markings at all!

Looks like a good Google session..........

Cheers

Lee

anatech · 22nd March 2006, 01:03 AM

Hi Lee,
Well, my point was that they were non-polar. A polarised ceramic cap makes no sense what so ever.

Quote:

how the heck you would know which end was which, no markings at all!

Which would be my point exactly.

If the cap is non-polar, why worry about it?

-Chris

davidsrsb · 22nd March 2006, 09:25 AM

Polarised 1uF SMD means either tantalum or alumimium. A 1uF tantalum is pretty small.

X7R is a ceramic dielectric type and is never polarised. Most 1uF ceramic will be Z5U or similar, which is really horrible for audio. You can get 1uF X7R, but will be fairly large and expensive. Even X7R is not that good on voltage coefficient, dielctric absorbtion etc.

Lostcause · 22nd March 2006, 09:36 AM

Quote:

Originally posted by davidsrsb
Polarised 1uF SMD means either tantalum or alumimium. A 1uF tantalum is pretty small.

X7R is a ceramic dielectric type and is never polarised. Most 1uF ceramic will be Z5U or similar, which is really horrible for audio. You can get 1uF X7R, but will be fairly large and expensive. Even X7R is not that good on voltage coefficient, dielctric absorbtion etc.

I wonder why they ask for polarised?
I've noticed on a tripath parts list that this is a ceramic X5R???
Are they contradicting themselves?

anatech · 23rd March 2006, 12:22 AM

Hi Lee,
I suspect they meant a polarized type for the charge pump and ceramics for bypass. A poly cap for the charge pump would work even better. The fact that it is non polarized will have no effect on the circuit.

They must mean X5R as X7R does not reach 1 uF. Time to e-mail them to clarify.

-Chris

TwoSpoons · 23rd March 2006, 04:45 AM

1uF, X7R

They do exist.

AndrewT · 23rd March 2006, 08:37 AM

Hi,
the polarised looks like they intended an SMD electrolytic or tantalum for the charge pump connections.

If there is room then a change to a small footprint metalised film could help performance.

Lostcause · 23rd March 2006, 08:43 AM

Quote:

Originally posted by AndrewT
Hi,
the polarised looks like they intended an SMD electrolytic or tantalum for the charge pump connections.

If there is room then a change to a small footprint metalised film could help performance.

Like this sort of thing?
They seem to be 4mm dia at the smallest but that would fit.
Cheers

Lee

21st March 2006, 04:07 PM	#1
Lostcause diyAudio Member Join Date: Aug 2005 Location: NW UK	Polarised SMD Caps? Does anyone know where I can get polarised 1uf Caps from? Ideally they need to be X7R 0805's Is there such a thing? Thanks Lee

23rd March 2006, 08:37 AM	#9
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, the polarised looks like they intended an SMD electrolytic or tantalum for the charge pump connections. If there is room then a change to a small footprint metalised film could help performance. __________________ regards Andrew T.

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21st March 2006, 07:26 PM	#2
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Lee, Sounds like a Ceramic cap with a XR7 characteristic. They should be available but maybe not everywhere. http://www.ttieurope.com/microsites/...w/products.cfm This is one supplier. -Chris

22nd March 2006, 09:25 AM	#5
davidsrsb diyAudio Member Join Date: Dec 2005 Location: Kuala Lumpur	Polarised 1uF SMD means either tantalum or alumimium. A 1uF tantalum is pretty small. X7R is a ceramic dielectric type and is never polarised. Most 1uF ceramic will be Z5U or similar, which is really horrible for audio. You can get 1uF X7R, but will be fairly large and expensive. Even X7R is not that good on voltage coefficient, dielctric absorbtion etc.

23rd March 2006, 12:22 AM	#7
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Lee, I suspect they meant a polarized type for the charge pump and ceramics for bypass. A poly cap for the charge pump would work even better. The fact that it is non polarized will have no effect on the circuit. They must mean X5R as X7R does not reach 1 uF. Time to e-mail them to clarify. -Chris

23rd March 2006, 04:45 AM	#8
TwoSpoons diyAudio Member Join Date: Oct 2004	1uF, X7R They do exist.

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