TL082: clarification on test methods

KlausWawrzyniak

Part Number: TL082
Other Parts Discussed in Thread: TL072, , TINA-TI

Hello,

(a) I need further explanation on the test methods mentioned in the datasheet (SLOS081M) for figure 6-28 (No Phase Reversal):

does this figure belong to test Figure 1 (figure 7-1)?

Or is this test done with a series resistor in the feedback loop between output to input? If so, please specify resistor value.

(b) in the same datasheet figure 6-28 belongs to chapter 6.16, which gives specification for the TL08xH (so the H version).

Do you have a figure for the non-H version of the TL082, similar to figure 6-28?

How does the TL082, A, B device behave in unity gain mode (no resistor in the feedback path)?

Thanks, best regards,

Klaus

over 2 years ago

+1 Ron Michallick over 2 years ago

TI__Guru**** 150706 points

Hello Klaus,

Figure 7-1 is used for 6-28, unity gain (OUT connected directly to IN-), there was no classic phase inversion.

For TL082 (no-H) see data sheet for TL072, section 9.3 (two pages). You will see effect for classic phase reversal expected on TL082 (no-H). Classic PR is when one input voltage that is within supply rails causes the output to change phases regardless of other input voltage. This occurs due to input stage headroom loss AND a JFET parasitic diode current flow.

For TL082H, there will still be headroom loss, but the NMOS input stage doesn't have the same parasitic diode as the TL082 (no-H). In unity gain there could be some remnant phase reversal when input is too close to V-. The output could rise until IN- comes back into a operational common mode range. So output voltage for bottom of output curve may vary a little amplifier to amplifier. In no case, should output jump up to about +10V. So in unity gain PR is limited, but recommended input common mode range should always be used. See table 6-5

0 kai klaas69 over 2 years ago

Guru 140200 points

Hi Klaus,

the phase reversal of the TL082 can even be seen in the TINA-TI simulation, allthough not necessarily taking place at the correct input voltage:

klaus_tl082.TSC

Keep in mind, that the TL082 and TL082H are no RRIO OPAmps (input output rail to rail). So they might not be the best choice in a single supply application.

Kai