[sdiy] Happenin' new opamp

[Roman Sowa]

Great news!
Thanks for sharring.
Guess the "little secret" is not secret anymore.

Roman

W dniu 2018-04-19 o 15:10, Mattias Rickardsson pisze:
> I'm throwing in some news (for me at least) about the fairly new 
> OPA1678/79 low-noise rail-to-rail FET-input op-amps that I was trying as 
> substitutes for the OPA1652/54, which has a price more than twice as 
> high. The specifications are remarkably similar, and by accident I got 
> in contact with TI's John Caldwell. He writes:
> 
> "I’ll let you in a on a little secret, the silicon is identical between 
> the two devices. OPA1652 was released by another engineer before me, and 
> when I took over the portfolio of audio op amps I personally felt that 
> OPA1652 was too expensive to address the bulk of audio opportunities. 
> For that reason, we made some changes to the production testing (used 
> new test hardware that let us test more units faster) to reduce the 
> manufacturing cost and re-released the device at a lower price point.
> Fun fact: the OPA1652 / OPA1678 has the lowest broadband voltage noise 
> of any FET-type input amplifier in TI’s portfolio. It even has lower 
> broadband voltage noise than the much more expensive OPA827."
> 
> I don't know if this was known before, but anyway great to have the same 
> brilliant chip for a fraction of the price... and isn't it a great 
> attitude about quality product sales? :-)
> 
> Regarding the inputs, which they don't mention being FET in the OPA1678 
> datasheet:
> 
> "We received your feedback on the OPA1678 datasheet. With regards to 
> mentioning the input device type, the OPA1678 is fabricated on a CMOS 
> process, so yes the device type is indeed a FET (MOSFET). This is also 
> shown in the simplified diagram of the internal architecture on the 
> first page.
> Calling it a “FET” input sometimes raises confusion between whether or 
> not the devices is JFET or CMOS and I wanted to avoid that when I wrote 
> the OPA1678 datasheet."
> 
> /mr
> 
> 
> On 4 June 2017 at 17:39, Tim Ressel <timr at circuitabbey.com 
> <mailto:timr at circuitabbey.com>> wrote:
>  >
>  > I started out with the LM4562. Very nice, but as you say, high 
> cabbage factor. Then I went to the LME49723. Noise is higher but amp is 
> cheaper. If you really want to break the bank, go with the AD797. Super 
> low noise, super high price.
>  >
>  > --timbo
>  >
>  >
>  > On 6/4/2017 2:29 AM, John P Shea wrote:
>  >
>  > 4x the price:
>  >
>  > http://www.ti.com/lit/ds/symlink/lm4562.pdf 
> <http://www.ti.com/lit/ds/symlink/lm4562.pdf>
>  >
>  > DIP & SOIC
>  >
>  > Regards,
>  > JPS
>  >
>  > On Sun, 4 Jun 2017 at 12:21 pm, Tim Ressel <timr at circuitabbey.com 
> <mailto:timr at circuitabbey.com>> wrote:
>  >>
>  >> It seems to be a popular amp. Mouser got 2500 of the SOICs in and blew
>  >> through them in days. They have 7K on order. I think they will become my
>  >> go-to amp for audio stuff. I'd write TI and ask for the QFN package.
>  >>
>  >> --tim
>  >>
>  >>
>  >> On 5/24/2017 10:09 AM, paula at synth.net <mailto:paula at synth.net> wrote:
>  >> > Tim,
>  >> >
>  >> >  hey that's neat, though I feel the reverse, s shame it's not in a
>  >> > smaller 3x3 QFN package. The VSSOP is close though.
>  >> >
>  >> >  Thanks for the heads up :)
>  >> >
>  >> > Paula
>  >> >
>  >> >
>  >> > On 2017-05-23 21:30, Tim Ressel wrote:
>  >> >> Hey,
>  >> >>
>  >> >> Writing to say the OPA1678 from TI is a pretty nice little amp. Low
>  >> >> noise, low distortion, low bias current, low cost. Is a dual; OPA1679
>  >> >> is a quad. SMT only, sad to say, but that be the times we live in.
>  >> >>
>  >> >> http://www.ti.com/lit/ds/symlink/opa1678.pdf 
> <http://www.ti.com/lit/ds/symlink/opa1678.pdf>
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>  >>
>  >> --
>  >> --Tim Ressel
>  >> Circuit Abbey
>  >> timr at circuitabbey.com <mailto:timr at circuitabbey.com>
>  >>
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>  > --
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>  > Circuit Abbey
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