TL081 vs TL071

  • Thread starter Michael A. Covington
  • Start date
M

Michael A. Covington

Guest
What is the difference between these op-amps? The latter is billed as
"low-noise" but they have the same noise specification (18 nv/sqrt(Hz)), as
well as nearly all the same other specifications ('81 has less offset
error). And the same price (48 cents).

I've been using them both as general-purpose op-amps for a long time and
haven't noticed any difference between them. Are they generally well
regarded? What do people prefer as an all-purpose, default-choice op-amp
these days (in place of the old 741, which I always thought was too noisy)?
 
"Michael A. Covington" <look@ai.uga.edu.for.address> wrote in message
news:411ef6ba$1@mustang.speedfactory.net...
What is the difference between these op-amps? The latter is billed as
"low-noise" but they have the same noise specification (18
nv/sqrt(Hz)), as
well as nearly all the same other specifications ('81 has less offset
error). And the same price (48 cents).

I've been using them both as general-purpose op-amps for a long time
and
haven't noticed any difference between them. Are they generally well
regarded? What do people prefer as an all-purpose, default-choice
op-amp
these days (in place of the old 741, which I always thought was too
noisy)?
Click to expand...
5532 series for audio apps? The TL082 was sold by Rat Shack but the
package would come with either that or a LF353. I guess they were
interchangeable. I would not use a 741 for decent Hi-Fi audio apps.
 
Thanks. I should add that I'm not looking for the ideal audio amp -- I have
others for that. Rather, I'm trying to settle on something better than the
741 as a cheap, abundant op-amp for a wide range of non-critical uses. Part
of the appeal of the TL081/2/4 (or TL071/2/4) is that it's easy to remember
the numbers (single, dual, quad).
 
"Jamie" <jamie_5_not_valid_after_5_Please@charter.net> wrote in message
news:10huu06mbocnae8@corp.supernews.com...
i could be wrong but i think the 71 is a bipolar input type
and the 81 is the cmos high gain input with a much better
linearity to it.
Click to expand...
They seem to have the same circuit diagram.
 
i could be wrong but i think the 71 is a bipolar input type
and the 81 is the cmos high gain input with a much better
linearity to it.



Michael A. Covington wrote:

What is the difference between these op-amps? The latter is billed as
"low-noise" but they have the same noise specification (18 nv/sqrt(Hz)), as
well as nearly all the same other specifications ('81 has less offset
error). And the same price (48 cents).

I've been using them both as general-purpose op-amps for a long time and
haven't noticed any difference between them. Are they generally well
regarded? What do people prefer as an all-purpose, default-choice op-amp
these days (in place of the old 741, which I always thought was too noisy)?
Click to expand...
 
"Jamie" <jamie_5_not_valid_after_5_Please@charter.net> wrote in message
news:10huu06mbocnae8@corp.supernews.com...
i could be wrong but i think the 71 is a bipolar input type
and the 81 is the cmos high gain input with a much better
linearity to it.
Click to expand...
They are all fet input.

The 61 was low current (or low offset, I forget..) the 71 was low noise, and
the 81 was low cost.

Same for 62/72/82 and 64/74/84
 
"Dave VanHorn" <dvanhorn@cedar.net> wrote in message
news:u4udnfJlWvDkfoLcRVn-pw@comcast.com...
They are all fet input.

The 61 was low current (or low offset, I forget..) the 71 was low noise,
and the 81 was low cost.

Same for 62/72/82 and 64/74/84
Click to expand...
Yes. But as the OP noted, and as was noted in an earlier thread on exactly
the same topic, the specs for the 7x and 8x are virtually identical these
days. "Low noise" and "low cost" seem to no longer be differentiators.

My own theory - unsupported by any evidence other than the existence of
multiple part numbers for seemingly the same part, along with historical
anecdotes about the parts behaving differently - is that they used to be
different, but at some point the mfrs decided that the "low noise" process
had gotten cheap enough or the "low cost" process had gotten quiet enough
that they just started using the same innards for both.

Again, that's just a theory; would be nice to hear from someone at TI.
 
My own theory - unsupported by any evidence other than the existence of
multiple part numbers for seemingly the same part, along with historical
anecdotes about the parts behaving differently - is that they used to be
different, but at some point the mfrs decided that the "low noise" process
had gotten cheap enough or the "low cost" process had gotten quiet enough
that they just started using the same innards for both.

Again, that's just a theory; would be nice to hear from someone at TI.
Click to expand...
I need to look at my old data books! My dim recollection is that when I
settled on the TL081 back in the 1980s, it was quite distinct from the
TL071. (Maybe it just cost less.) But Horowitz and Hill 1989 already show
the same numbers for the specs of both chips (actually appreciably less
offset on the '81; no visible advantage to the '71 though they tag it "low
noise").
 
"Jamie" <jamie_5_not_valid_after_5_Please@charter.net> wrote in message
news:10hvn1hh85u2k40@corp.supernews.com...
yes, they have the same lay out, they are pin for pin compatible.
but that does not mean they are the same in electrical ratings
like gain, BandWidth etc.
Click to expand...
I mean the schematic of the chip itself is published in the data sheets and
is the same for both. Also, the numbers that indicate performance are
practically identical.
 
yes, they have the same lay out, they are pin for pin compatible.
but that does not mean they are the same in electrical ratings
like gain, BandWidth etc.


Michael A. Covington wrote:

"Jamie" <jamie_5_not_valid_after_5_Please@charter.net> wrote in message
news:10huu06mbocnae8@corp.supernews.com...

i could be wrong but i think the 71 is a bipolar input type
and the 81 is the cmos high gain input with a much better
linearity to it.


They seem to have the same circuit diagram.
Click to expand...
 
Yes. But as the OP noted, and as was noted in an earlier thread on
exactly
the same topic, the specs for the 7x and 8x are virtually identical
these days. "Low noise" and "low cost" seem to no longer be
differentiators.
Click to expand...
This was originally done back in the late 70's or early 80's and that was
the official word from TI.
 
See the thread from January of this year "Singing the praises of the
LM324",
too. It's often-villified for crossover distortion (there *are*
workarounds)
but it works very well for DC-ish applications from rail to rail.

Tim.
Click to expand...
Well, the Xover distortion can be a really hideous nasty surprise, if you
don't know about it in advance.
 
"Michael A. Covington" (look@ai.uga.edu.for.address) writes:
"Michael Black" <et472@FreeNet.Carleton.CA> wrote in message
news:cfr208$vb$1@freenet9.carleton.ca...

"Michael A. Covington" (look@ai.uga.edu.for.address) writes:
What is the difference between these op-amps? The latter is billed as
"low-noise" but they have the same noise specification (18 nv/sqrt(Hz)),
as
well as nearly all the same other specifications ('81 has less offset
error). And the same price (48 cents).

It took a bit of digging, but I pulled out the brochure TI sent out when
these devices were just introduced, dated 1977. Well, I knew where it
was,
but the specific box was under some others.

TL081 = 47nV
TL071 = 18nV

AHA! Nowadays both are specified as 18 nV/sqrt(Hz).

I'll bet nowadays they are the same chip! Originally they weren't.



Of course, that now leads to the question of when this occurred. Do
Click to expand...
we all have the low noise ones in our junkboxes, or is a relatively recent
change?

I don't have a complete sequence of TI literature (or any company's literature
for that matter) in order to check year by year, or even decade by decade.

Michael
 
TL081 = 47nV
TL071 = 18nV

AHA! Nowadays both are specified as 18 nV/sqrt(Hz).

I'll bet nowadays they are the same chip! Originally they weren't.

Of course, that now leads to the question of when this occurred. Do
we all have the low noise ones in our junkboxes, or is a relatively recent
change?
Click to expand...
The chart in The Art of Electronics, 1989, lists them both as 18 nV/sqrt(Hz)
but describes the '71 as "low noise." Does anybody have the earlier edition
of The Art of Electronics?
 
"Michael Black" <et472@FreeNet.Carleton.CA> wrote in message
news:cfr208$vb$1@freenet9.carleton.ca...
[snip]

It doesn't seem to say much about why the two devices differ, ie if
one is a hand selected from the larger pool.
Click to expand...
Or if the opamp chip was laser trimmed or whatever had to be done to get
the tighter specs.

Michael
Click to expand...
 
"Dave VanHorn" <dvanhorn@cedar.net> wrote in message
news:KO-dnXQiz6LmsrzcRVn-tw@comcast.com...
See the thread from January of this year "Singing the praises of the
LM324",
too. It's often-villified for crossover distortion (there *are*
workarounds)
but it works very well for DC-ish applications from rail to rail.

Tim.

Well, the Xover distortion can be a really hideous nasty surprise, if
you
don't know about it in advance.
Click to expand...
I thought it weas SOP to put a 6.8k resistor from output to ground (or
was it + supply) to alleviate this problem.
 
I thought it weas SOP to put a 6.8k resistor from output to ground (or
was it + supply) to alleviate this problem.
Click to expand...
IIRC it's +, and I remember 2.2k.. OTOH, I rarely use them.
The TL074's are my favorite GP chips.

How many schematics do you see with 324's specified, and how many have
anything there to kill the xover distortion?
 
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