OPA860 , the OPA660's successor?

Bricolo · 26th July 2005, 04:38 PM

TI announced a new Wide-Bandwidth, Operational Transconductance Amplifier (OTA) and Buffer, the OTA860.

Here's the product page
http://focus.ti.com/docs/prod/folder...0.html#samples

This one seems interesting, for I/V stages, like the discontinued OPA660 and the AD844

Datasheet: http://www-s.ti.com/sc/ds/opa860.pdf

carlosfm · 26th July 2005, 06:10 PM

+/- 6.5V max. PSU voltage...

Bricolo · 26th July 2005, 09:58 PM

like the OPA660

Charles Hansen · 27th July 2005, 07:27 PM

Quote:

Originally posted by Bricolo
This one seems interesting, for I/V stages, like the discontinued OPA660 and the AD844.

Too bad they screwed it up.

The OPA660 had an open-loop buffer that was identical to the input stage of the OTA section. This could be used to make a very nice diff amp. The new part has a closed-loop (high feedback) buffer and so this option no longer exists. Besides, the closed-loop buffer won't sound as good as the old open-loop one.

Oh, well...."progress" as usual???

Joseph K · 27th July 2005, 08:07 PM

Quote:

This could be used to make a very nice diff amp.

In fact. I had been always asking myself, what would have Jocko to tell about such an input, hanged between a schott transformer and a HC86, in place of the opa601...?

Joseph K · 27th July 2005, 08:35 PM

Also, it seems to be that they somehow reorganized the inner bias current distribution, so now with less bias it has higher transconductance. Though the old version was capable of a higher maximum value [while consuming twice as much]
Do I guess it right that this translates into higher [at max bias] distortion figures with the new one, in case of an I/V converter?
Of course, from the datasheet you can read much better values..

Ciao, George

Charles Hansen · 28th July 2005, 04:24 AM

Nice schematic. I think it would sound good. Unfortunately *both* the OPA660 and the BUF601 are discontinued. Too bad that TI bought out B-B and makes such stupid decisions.

kevinkr · 28th July 2005, 05:11 PM

Part is end of life, however there are lots of vendors that still have stock on these parts if you want to acquire some.
Try Avnet, Arrow, Digikey and Newark electronics in the states. Go to TI site for international distributors.

Interestingly a TI rep told me some weeks ago when talking about the new OPA880 that their policy generallywas not to obsolete older parts as long as there was reasonable demand, but I guess the policy changed in regards to this part at least.

A lot of process improvements apparently have resulted in better linearity due to improved performance in the transistors themselves. (Quoted)

Kevin

26th July 2005, 04:38 PM	#1
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	OPA860 , the OPA660's successor? TI announced a new Wide-Bandwidth, Operational Transconductance Amplifier (OTA) and Buffer, the OTA860. Here's the product page http://focus.ti.com/docs/prod/folder...0.html#samples This one seems interesting, for I/V stages, like the discontinued OPA660 and the AD844 Datasheet: http://www-s.ti.com/sc/ds/opa860.pdf __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease

26th July 2005, 09:58 PM	#3
Bricolo diyAudio Member Join Date: Nov 2002 Location: Grenoble, FR	like the OPA660 __________________ Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease

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26th July 2005, 06:10 PM	#2
carlosfm Banned Join Date: Mar 2003 Location: Lisbon, Portugal	+/- 6.5V max. PSU voltage...

27th July 2005, 08:35 PM	#6
Joseph K diyAudio Member Join Date: Dec 2004 Location: gran sasso	Also, it seems to be that they somehow reorganized the inner bias current distribution, so now with less bias it has higher transconductance. Though the old version was capable of a higher maximum value [while consuming twice as much] Do I guess it right that this translates into higher [at max bias] distortion figures with the new one, in case of an I/V converter? Of course, from the datasheet you can read much better values.. Ciao, George

28th July 2005, 04:24 AM	#7
Charles Hansen diyAudio Member Join Date: May 2003 Location: Colorado	Nice schematic. I think it would sound good. Unfortunately both the OPA660 and the BUF601 are discontinued. Too bad that TI bought out B-B and makes such stupid decisions.

28th July 2005, 05:11 PM	#8
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Part is end of life, however there are lots of vendors that still have stock on these parts if you want to acquire some. Try Avnet, Arrow, Digikey and Newark electronics in the states. Go to TI site for international distributors. Interestingly a TI rep told me some weeks ago when talking about the new OPA880 that their policy generallywas not to obsolete older parts as long as there was reasonable demand, but I guess the policy changed in regards to this part at least. A lot of process improvements apparently have resulted in better linearity due to improved performance in the transistors themselves. (Quoted) Kevin

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