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TL072: 10dB increase in noise when using TL072CP vs. TL072IP

Jesse Honig
Prodigy 10 points
Part Number: TL072
Other Parts Discussed in Thread: TL082

Hello -

In a small amplifier circuit I have designed, I am reliably getting 10dB more noise on the FFT when using the TL072CP as opposed to TL072IP. In the data sheet I can only see a few small differences. Can this point to an error in my schematic or layout?

Thanks,

JH

  • 0
    Guru 140200 points

    Hi JH,

    can you show your FFT and a schematic of your circuit?

    Kai

  • 0
    TI__Guru**** 151036 points

    JH,

    TL072CP and TL072IP have different internal silicon dies; they are both functionally equivalent, but not exactly the same. My sample data shows slightly less noise on TL072IP. I observed a difference of 1.5dB. 

    Does "reliably getting" mean that many samples were tested? Is the increased noise wideband or 1/F profile.

    The noise specification in data sheet is typical only. For low noise critical circuits it is recommended to use a device that has maximum limits for noise specifications.

  • 0 in reply to Ron Michallick
    Guru 48395 points

    There are precious few op amp datasheets with max noise numbers and none with a range of 1/f corners reported (to my knowledge). This won't help you with the TL082, but there were some odd comments previously - 

    I did work with the designer to try to fill all that out in burst of BurrBrown higher speed op amp introductions - via simulation of course - then you need -

    1. Really good process models with their variations and temperature effects

    2. An incredibly patient designer to run worst case sims at the cadence level. 

    Here is an example with a pretty good (but very dense) spec table format that was later abandoned as being too time consuming. - setting the condition to >1MHz sidesteps the 1/f corner variation question - but here is full worst case detail for the input noise terms - not many datasheets left with this level of detail. - and certainly not the legacy op amps like the TL082.