FreeLists / si-list / [SI-LIST] Re: ESR too low?

["Calvo, Oscar A (FL51)" <Oscar.A.Calvo@xxxxxxxxxxxxx>]

In one of their slides they showed that you could actually get rid of the
tantalum bulk capacitors altogether by using this Turbo Trans feature and by
increasing the total ceramic capacitance.


-----Original Message-----
From: Henson, Bradley S [mailto:Bradley.S.Henson@xxxxxxxxxx] 
Sent: Wednesday, November 09, 2005 2:17 PM
To: Oscar.A.Calvo@xxxxxxxxxxxxx; electronbob2@xxxxxxxxxxxxx;
matusov@xxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: RE: [SI-LIST] Re: ESR too low?

This is an interesting problem. Modern high current/low voltage chips
require giant step load currents (e.g. 25A) at very low impedance to
stay within voltage tolerance. Regulators take hundreds of ns or
microseconds to respond to load transients. This drives us to need very
low esr bulk caps to supply virtually all of the demand while the
regulator loop responds. If you speed up the regulator response, you
simply move the transient problem to the input of the regulator, albeit
there should be more noise tolerance there possibly. I would also think
you are not going to be able to get rid of the need for a considerable
amount of very low esr bulk capacitance even with pretty fast response
times, at least with the regulator speeds I've seen.

-----Original Message-----
From: Calvo, Oscar A (FL51) [mailto:Oscar.A.Calvo@xxxxxxxxxxxxx] 
Sent: Wednesday, November 09, 2005 10:58 AM
To: electronbob2@xxxxxxxxxxxxx; matusov@xxxxxxxxxxxx;
si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: ESR too low?



I just attended a TI Web-seminar in where they talked about their new
line of PTH power modules which include a new feature that they call
Turbo Trans. Turbo Trans allows the user to custom tune the module to
meet a specific transient load requirement. Tuning is accomplished with
a single external resistor. They claim that by using TurboTrans one can
achieve a reduction in bulk output capacitance which leads to an
increase in ESR.

Has anyone had any experience using this feature?

The link below has more information.

http://www.ti.com/corp/docs/landing/t2/index.htm




-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Bob McNamara
Sent: Wednesday, November 09, 2005 11:51 AM
To: matusov@xxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: ESR too low?

[For anyone else trying to follow the link, it should be
http://focus.ti.com/docs/toolsw/folders/print/swift-sw.html]

Thanks, I hadn't seen that software before.  It's missing the ability to
optimize what I really care about as a user of the regulator - the
closed loop output impedance.  I claim that if you optimize the closed
loop response, one consequence is that you'll have adequate phase
margin.  On the other hand, optimizing the open loop response won't
guarantee me the best closed loop response.

Bob McNamara
Broadcom Corp.

--- Mikhail Matusov <matusov@xxxxxxxxxxxx> wrote:

> > Now if only the vendors would supply such a tool...
> 
> Have you seen the TI SWIFT Designer Software: 
> http://focus.ti.com/docs/toolsw/folders/print/swift-sw.htm
> 
> 
> 
> =======================
> Mikhail Matusov
> Hardware Design Engineer
> Square Peg Communications
> Tel.: +1 (613) 271-0044 ext.231
> Fax: +1 (613) 271-3007
> http://www.squarepeg.ca

------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl?Si-List_FAQ

List technical documents are available at:
                http://www.si-list.org

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl?Si-List_FAQ

List technical documents are available at:
                http://www.si-list.org

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List FAQ wiki page is located at:
                http://si-list.org/wiki/wiki.pl?Si-List_FAQ

List technical documents are available at:
                http://www.si-list.org

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu