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Old 26th July 2005, 04:38 PM   #1
Bricolo is offline Bricolo  France
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Default 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
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Old 26th July 2005, 06:10 PM   #2
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+/- 6.5V max. PSU voltage...
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Old 26th July 2005, 09:58 PM   #3
Bricolo is offline Bricolo  France
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like the OPA660
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Old 27th July 2005, 07:27 PM   #4
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Default Re: OPA860 , the OPA660's successor?

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???
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Old 27th July 2005, 08:07 PM   #5
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Default SP-diff

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...?
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File Type: pdf opa660_spdiff.pdf (13.0 KB, 305 views)
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Old 27th July 2005, 08:35 PM   #6
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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
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Old 28th July 2005, 04:24 AM   #7
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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.
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Old 28th July 2005, 05:11 PM   #8
kevinkr is offline kevinkr  United States
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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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