TL082IDR

Hello Ron,

Thank you for the explanation. 

Let me confirm about "20nA spec was based on characterization data where Ta=Tj=85C".

Normally, Tj is higher than Ta due to self-heating of device.  If it keeps input bias current to 20nA, I guess Ta should be lower than 85C, right?

Regards,

Hide

Hide,

Yes you are correct. In most applications the TL082 does not dissipate much heat so the difference will be small.
Typically the input current is much less as seen in figure 17 of the data sheet..

Regards,
Ron Michallick

Hello Ron,

It seems to me that the difference is not small...

Power dissipation = 1.4mA * 30V * 4ch = 0.168W  --- (TL084, 4ch)

Theta Ja = 86C --- (TL084, SOP14)

Tj - Ta = 86 * 0.168 = 14.448C

If above calculation is correct, Ta shoule be below 71C (85C - 14C) to keep 20nA_Max input bias current, is that right?

Regards,

Hide

Hide,

Yes, the formulas are correct.

There are two power formulas for output current.
If current flows out of TL082, power = ('VCC+' - 'Vout' ) * Iout
If current flows in to TL082, power = ('Vout' - 'VCC-' ) * Iout

Regards,
Ron Michallick

Ron,

Let me confirm if I understand this correctly.

1) In case of using TL082 where Ta=85C, Tj will be around 100C, right?

If above my understanding is right, I have a following question;

2) If I use TL082 where Ta=85C and Tj=100C, which parameter lose coverage specified on the datasheet? (ex. Input bias current?, Input offset current?)

3) On the above parameter that lose of datasheet (ex. Input bias current?, Input offset current?), can I get estimate value? (estimate value where Ta=85C and Tj=100C)

Regards,

Hide

Hide,

1) Right.

2) The input current specs would seem to be increased by 167%, but the tighter 25C spec over rides 85C spec; so the increase is just 14%.
2) The open loop gain spec, AVD would drop by 10%

3) IIB @100C max = 22.8nA;  IIO @100C max = 2.28nA
3) AVD @100C min = 22.5V/mV