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Old 15th July 2012, 07:26 PM   #1
ncdrawl is offline ncdrawl  United States
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Default Drop in replacement for BB OPA 627??

What are some drop in replacements for these, and are there , in your opinion any that are better sonically?
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Old 16th July 2012, 04:36 AM   #2
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The OPA827 is often suggested as a lower-cost replacement for the OPA627 with essentially identical performance "where it matters" - but there are many opinions as to whether that's true or not.

Dale
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Old 16th July 2012, 06:49 AM   #3
Calvin is offline Calvin  Germany
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Hi,

the OPA827 seems to be a ghost, anybody knows, but no one has a proof it exists in real life . Maybe things improved but at the time I had a certain interest in that chip TI littlebritish-like always said: "TI says noooo"
Itīd be an improved replacement to the 627, but only available in SO-8 and MSOP-8 SMD casings.
The AD8610 and its Dual brother AD8620 are also possible replacements made by Analogdevices (ADI). The ADIs only allow for lower supply voltages of +-13V and are only available in SMD SOIC-8 and MSOP-8.

jauu
Calvin
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Old 16th July 2012, 07:00 AM   #4
jcx is offline jcx  United States
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nobody's matching the OPA627's noise and input common mode mode impedance linearity - not that you can find much on input impedance linearity unless Groner has tested it for us SG-Acoustics · Samuel Groner · IC OpAmps
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Old 16th July 2012, 08:14 AM   #5
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Quote:
Originally Posted by Calvin View Post
Hi,

the OPA827 seems to be a ghost, anybody knows, but no one has a proof it exists in real life . Maybe things improved but at the time I had a certain interest in that chip TI littlebritish-like always said: "TI says noooo"
Itīd be an improved replacement to the 627, but only available in SO-8 and MSOP-8 SMD casings.
Maybe I don't understand your post, but my distributor stocks the OPA827 for 7USD; thousands in stock. Easily mounted on single or dual adapters.
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Old 17th July 2012, 10:10 AM   #6
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Default But... but... but... we need more info :P

Quote:
Originally Posted by theAnonymous1 View Post
Maybe I don't understand your post, but my distributor stocks the OPA827 for 7USD; thousands in stock. Easily mounted on single or dual adapters.
I believe what Calvin was refering to, was that it is not available in the PDIP size, that is easy for D.I.Y. Ofcourse, many have now started to use SO-8 to DIP adaptors and a small toaster over....

Calvin can correct me if I am wrong though

You also need to know if your circuit is running it in unity gain or not.

Newer alternatives, but in soic & PDIP (some)... um... but not in the same class, as in "precision Amplifier", would be one of their newer Audio chips. I am not sure if your design though can accomodate them or not.
You can try:
OPA1641
OPA1632 is also stable at Gain = 1
OPA827
LME49710
LME49870 able to use up to 44v while still having a low nV/rtHz.

Btw, you do not mention in what it is being used, what voltage range it is used in, since there are some nice chips, but have a lower voltage range than the older families. Also, are you using it in a headphone amp design, is it portable, or in a bigger assembly, what will it be driving. There are many parameters to look at. Are you looking for single channel only or can a dual be added? there are many things unanswered, so the parts I have mentioned, are geared toward single channel and "audiophile" and from the T.I. range (National is now part of T.I.), plus I tried to keep the GBW typ(MHz) in the same ball mark (for most), since if you get a faster one, you might get oscillation and other issues if your circuit has not accounted for everything. I am sure there are plenty more and much more knowledgable members that can advise you better. I also tried to keep it to "newer" designs and also available as a PDIP/Soic

Now, can some else please comment too.... :-) I love seeing suggestions.
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Old 17th July 2012, 11:31 AM   #7
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Don't forget the LME49990 and LME49880.
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Old 17th July 2012, 08:13 PM   #8
jitter is offline jitter  Netherlands
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The closest non-TI/BB (and cheaper) drop-in replacement for the OPA627AU (the SMD-version) must be the AD ADA4627-1.
With an SO-8 to DIP adapter you could use it to replace the OPA627AP/BP too.
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Old 17th July 2012, 08:17 PM   #9
jitter is offline jitter  Netherlands
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Quote:
Originally Posted by Aries1470 View Post
many have now started to use SO-8 to DIP adaptors and a small toaster over....
Why a toaster oven? An SO-8 can easily be soldered by hand.
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Old 18th July 2012, 06:32 PM   #10
Calvin is offline Calvin  Germany
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Hi,

@theAnonymous1
When I was interested in the OPA827 it wasnīt available for over half a year. Obviously avaliability improved.

But just saw this at the TI E2E community:
Theme: unusually high distortions of original OPA827 in noninverting buffer mode.
"All stock of the old devices has been purged out of TI and distributor stock. Any newly shipped OPA827 will be the new type.
To explain further, this was a very interesting case. The behavior of the earlier version was first identified as an input bias current that changed each time the op amp was powered on. It had the appearance of a "warm up" phenomenon, requiring 10 to 20 seconds to stabilize to a low value, but actually did not relate to a die temperature change. It also caused distortion to increase with higher source impedance in non-inverting configurations.
This behavior was eliminated with a minor wafer processing change. There was no change made to the circuit of the OPA827. With this processing change, the OPA827 is now an excellent performer with high source impedance. Its silicon-on-insulator isolation fabrication eliminates the voltage-variable input capacitance effects that can cause distortion with common with junction-isolated op amps."

Maybe its now time to evaluate the OPA827 again?

jauu
Calvin
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