TI Jfets

[Also Wik]

What's the difference between what TI.com calls a TL071 " low noise jfet operational amplifier", and a "General Purpose" op-amp?

[Also Wik]

No difference between "low noise jfet" and "General Purpose jfet"? 

[Peter Snowberg]

More words? 

The TL071 and which other opamp?

Names are a funny thing. As things have improved in the chip industry, what was once called low noise is now just general purpose. The TL071 does have lower noise than the TL081 for instance, which is more of a general purpose JFET opamp. The trade-off for low noise parts is usually more cost.

[Also Wik]

Well, I did a "TL071" search at TI.com, and 2 things popped up. One said " LOW-NOISE JFET-INPUT OPERATIONAL AMPLIFIER" and the other is " LOW-NOISE JFET-INPUT GENERAL-PURPOSE OPERATIONAL AMPLIFIER"... also the "packaging" letter is different... one is "P" and the other is "D". What does this mean? 

[Elektrojänis]

The TL071 does have lower noise than the TL081 for instance, which is more of a general purpose JFET opamp.

It's quite funny actually... Have you ever compared the noise figures in the datasheets of TL071 and 072?

TL07x (page 9): http://focus.ti.com/lit/ds/symlink/tl071.pdf
TL08x (page 7): http://focus.ti.com/lit/ds/symlink/tl081.pdf

Look for the Equivalent input noise voltage and current in both... Hmmm... Can anyone explain this?

also the "packaging" letter is different... one is "P" and the other is "D". What does this mean? 

D is surface mount: http://focus.ti.com/lit/ml/msoi002c/msoi002c.pdf
P is "through circuit board": http://focus.ti.com/lit/ml/mpdi001a/mpdi001a.pdf

For usual DIY purposes "P" is good.  Surface mount (D) is harder to work with without special tools.