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LP2981: Explicitly ordering new or legacy chips of LP2981

Eric Auer
Prodigy 10 points
Part Number: LP2981
Other Parts Discussed in Thread: LP2982, , , LP2985, LP2980-N, LP2992, TPS7A24, REG101

Tool/software:

Hi, I am searching for a way to explicitly order the "new chip" variants of LP2981 (3.3V) and LP2982 (5V) and of other LP298n voltage options. It seems that the distinction between old and new chips only is part of the CSO on the reels, but not of the MPN which could be used to order the selected variant from a distributor?

The new chips are easier to use with MLCC instead of tantalum output capacitors. The old chips technically need a series resistor for that use case, to avoid ringing when the load current changes. The new chips also have better specs. Both new and legacy chip share the same datasheet at the moment, both for LP2981 and LP2982, mentioning differences between legacy and new chips at several places.

Apparently, the nomenclature will be LP298n [A or blank] [I for normal temperature range] [M5 for SOT-23] [reel size code] - [n.n output voltage] / NOPB, which does not include an indication of the chip variant.

The CSO for LP2980 is DLN or GF8 for legacy chips and RFB for LP2980, new chip, according to your experts. I expect a similar distinction-by-CSO for LP2981 and LP2982, but fail to understand how to use that to explicitly order new chips from distributors?

Thank you for your hints!

  • 0
    TI__Expert 5942 points

    Hey Eric, 

    Thank you for your question here!  Some of our variants have an "M3" version this will only ship "new chip" material. For this case the closest device will be the LP2985-33DBVRM3 and LP2985-50DBVTM3 function extremely similar to the other LP298x devices, these will also ensure that your able to get "new chip" devices as well. 

    Let me know if you have any questions or if this doesn't solve the issue. 
    Thanks, 
    McKyla
  • 0 in reply to McKyla Beuttler
    Prodigy 10 points

    Hey McKyla, while both LP2981 and LP2981-N (why -N?) datasheets mention the same M3 nomenclature as for the LP2985 in theory,

    https://www.ti.com/lit/ds/symlink/lp2981.pdf

    https://www.ti.com/lit/ds/symlink/lp2981-n.pdf

    there is a practical problem: None of the Octopart search results actually include M3 when searching for LP298(1 or 0)(A or no A)-(33 or 50)DBV(R or T)M3.

    I only find hints about the new chip like the mention in one of the PCN listed on

    https://www.digikey.de/en/products/detail/LP2981A-33DBVR/296-17361-1-ND/691779

    which tells that one fab got added which produces only the new chip. So there still seems to be a mix of old and new chips being produced, with no way to explicitly order either? The product page on TI.com also does not distinguish both variants.

    In addition, while the -N datasheet does mention the M3 meaning, the list of orderable MPN in the same document only has LP2981AIM5-3.3/NOPB style names, but does not explain the IM5 part, as far as I can tell? See for example

    https://www.ti.com/product/LP2981-N/part-details/LP2981AIM5X-3.3/NOPB

    Thanks, Eric

  • 0 in reply to Eric Auer
    TI__Expert 5942 points

    Hey Eric, 

    Thank you for bringing these issues to my attention, these are of upmost importance to TI and myself to help resolve these issues. 

    The first issue you mentioned was the M3 being mentioned in the in the LP2981, LP2981-N, and LP2980-N datasheets. These M3 versions are not currently available for these generic part numbers. This language will be edited in these datasheets and should not be mentioned here. Before purchasing the devices, it is difficult to know if new or legacy chip material will be shipped since the easiest way is to check the label and it is possible to receive a mix. Other than the M3 variants another method to ensure only new chip material will be shipped is to work with your sales representative and let them know that you would only like new chip material. 

    On TI.com as well as the datasheet I can also see the confusion here on new vs. legacy chips being produced, for a period of time both the new and legacy chips will be produced and after a certain period only new chips will be produced. Right now both new and legacy chips are being produced until our customers purchasing this device have time to accept PCN updates.  

    The "-N" in some of the GPNs (generic part numbers) refer to the previous National Semiconductor parts. National was acquired by Texas Instruments in 2011. TI continued to support these National versions to continue to support customers designs. There are two version of some devices because prior to the acquisition both versions existed. For the most part both -N and non-N versions of these devices function extremely similarly. For the -N devices in the datasheet that have an IM5 this is the National code for the type of package and does not refer to any new or legacy chip versions. 

    Hopefully this helps answer your questions and provides some solutions to resolve this. 

    Thanks, 

    McKyla

  • 0 in reply to McKyla Beuttler
    Prodigy 10 points

    Hey McKyla, thank you for your added explanations. Do you have a specific roadmap regarding the timing of the transition from legacy to new chips?

    I could imagine that some customers  prefer the legacy chip for some reason, while the new chip is better for other customers and many might not care either way. For some, it would be useful to be able to explicitly order one of the variants.

    I assume you refer to buying directly from TI when referring to sales representatives who are able to make a choice in shipped chip variants? As mentioned, the distributors listed by Octopart do not seem to distinguish the variants.

    For new designs, it might be better to use completely different regulators, avoiding the issue of distinguishing chip variants. The LP298n series offered good load regulation and low noise. You may have pin-compatible alternatives already, but in every device family has unique advantages and disadvantages. The lower-noise LP2985 has the legacy/new chip thing of all LP298x, as does the LP2992.

    The TPS7A24 seems to be similar to the NEW LP2981 chip, but has twice the RMS output noise.

    The REG101 has very low noise, but relatively high prices.

    Thanks, Eric