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Original question:

OPA656: Please tell me the difference between the parts numbers.

OPA656: I want to check the specs of OPA656U/2K5 and OPA656UB/2K5

akira.ono
Prodigy 60 points
Part Number: OPA656
Other Parts Discussed in Thread: OPA814,

Hi TI team,

I noticed something strange when it checked the Datasheet.

www.ti.com/.../opa656.pdf

OPA656UB/2K5 is a Hi-Grede model of OPA656U/2K5, but the spec below seems like OPA656UB/2K5 is Down-Spec.

Max. Input Bias Current(pA) for VCM=0V, TJ=25℃

OPA656U/2K5: +-20pA

OPA656UB/2K5: +-450pA

Is +-450pA the correct value?

I also noticed that there are two Input Bias Currents with the same content. Is this Typo?

Also, in Section 7.6, are CMRR and PSRR OK to compare with Electrical Characteristics (continued)? There was no (continued) in the item 7.6.

Thanks and Best Regards,

Akira Ono

  • +1
    Guru 48395 points

    Are you sure you want to be looking at this device, it looks to be going away, 

    https://e2e.ti.com/search?q=opa656%20ltb&category=forum

    The OPA814 is the upgrade, 

  • +1
    Guru 281870 points

    450 pA is the 70 °C value. At 25 °C, the B version has 5 pA.

    The "(continued)" means that it belongs to the same table from the previous page. Section 7.6 is not spread over multiple pages.

  • +1
    TI__Genius 16776 points

    Hello Akira-san,

    Thank you for requesting clarity on the OPA656 Electrical Characteristics for the high-grade and non-high-grade versions.  The OPA814 has improved (& upgraded) performance compared to the OPA656; these improvements are also over the wider TA = –40°C to +85°C temperature range.  

    Unless the design has strict need for the minor performance difference of OPA656xB compared to OPA814, the recommendation is to design with the new OPA814.  The OPA814 device performs near to the high-grade strictly-tested OPA656xB device, but without the need to for separate testing to determine if the part is "high-grade" or not "high-grade."  Instead of designing a separate high-grade OPA814xB, the new OPA814 was upgraded to be a replacement for either the OPA656x or the OPA656xB.

    Please evaluate the OPA814 for your design and let our HSAMPs team know if you have additional questions.

    As for the clarifying questions, Clemens already addressed the key points.  While it may be extra information for Input Bias Current to be present in two table rows, the information is correct for TYP and MAX values.  Section 7.6 exists to highlight the differences between high-grade DC specifications and the regular DC specifications present in the Electrical Characteristics Section 7.5.  All values in the Section 7.6 table have corresponding values in the Section 7.5 table which are available for comparison.

    I strongly suggest evaluating the OPA814 for your design, which is likely to be the right part considering the reduced availability of the OPA656.  The OPA656 has entered "Last Time Buy" and has been upgraded by the OPA814.  The performance differences between OPA814 and OPA656xB are minor compared to the improvement between OPA814 and OPA656.  I believe you would be buying the OPA814DR, which is the upgrade and replacement to the OPA656U.  The OPA814DR comes in 3k unit Large Tape & Reel.

    Best,

    Alec