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LMC6081: Input bias current specification SOIC package

Klaus Bahner
Prodigy 60 points
Part Number: LMC6081
Other Parts Discussed in Thread: OPA928

Hi there,

the datasheet lists a maximum input bias current for of the LMC6081AIM (SOIC package) of 100 pA, and for the versions in a PDIP package of 4 pA. The column with the typical parameters does not distinguish between the packages, neither does Figure 6 Input Bias Current vs Temperature.

So the question is whether there really is a difference between packages or whether this is just a testing limit. In case there is a difference, is it correct to assume that the typical input bias current is also a factor 25 higher for the SOIC package compared to the PDIP package. 

Since the PDIP package version has a current status of LIFEBUY it's not an option to use it, because this is for a new design.

Best regards,
Klaus

  • 0
    Guru 272770 points

    As far as I can see, there are no differences between the packages; "LMC6081AM" refers to the LMC6081-MIL, which is tested for higher temperatures.

  • 0 in reply to Clemens Ladisch
    Prodigy 60 points

    OK, this sounds good. How does one know though, that LMC6081AM refers to the MIL version? In the orderable parts section of the (latest) datasheet the letter M seems to designate PDIP instead of SOIC (Letter N).  The LMC6081-MIL product page on ti.com lists "DIESALE" as the only available option, which again according to the datasheet has the designation LMC6081-MDA - not LMC6081AM. I find this quite confusing ...

  • +1 in reply to Klaus Bahner
    TI__Guru 63050 points

    LMC6081AM temperature range is from -55C to 125C while for LMC6081AI from -40C to 85C - see below.  Since the leakage current roughly doubles every 10 deg C, increasing the maximum temperature from 85C to 125 C (by 40 deg C) results in IB increase by the factor of 2^(40C/10C)=16 (this is main reason behind 4pA vs 100pA max IB). Having said that for any new design I would recommend to use OPA928.

  • +1 in reply to Marek Lis
    Prodigy 60 points

    OK, that makes sense. Thanks for the clarification. I missed the difference in temperature specification for the AM vs. (A)I parts. I did actually look into the OPA928 and agree that it would fit my application much better. However, it is in preview only and I need to do prototyping now. Bad timing I guess ... 

  • 0 in reply to Klaus Bahner
    TI__Guru 63050 points

    Klaus,

    You may order pre-production samples of OPA928 by using following link: https://www.ti.com/product/OPA928#order-quality