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LM385: Could it be retiring?

Discussion in 'Electronic Design' started by Joerg, Apr 23, 2007.

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  1. Joerg

    Joerg Guest

    Checked a few micro-power shunt references this morning. The ROHS
    compliant versions of the LM385 were called "mature" on the Arrow web
    site and that word always makes my neck hairs stand up. Could this mean
    it's headed for lalaland? If so, which micro-power shunt refs are
    engineers using instead these days? The TLV431 is kind of out in my
    case, too much cathode current.
  2. D from BC

    D from BC Guest

    Digikey has 0.6uA listed for the cathode current for
    digi#296-18865-1-ND it's a TL431BCDBR
    Or just type in TL431 as a keyword..Looks like there's versions that
    need an idle Ic up to 1mA.. an alternative...I think I saw a micropower op amp with a
    built in reference IC that can be turned into a shunt reg..
    Can't remember the IC #...
    But I recall finding similar IC's that had a flea power op amp but
    then the fk'n build in reference was just a hog.

    I just took a quick peek at this voltage reference ISL60002.. It's not
    a shunt reg... just a Vref that draws 400nA...
    Take it as a clue that there's gotta be something much "lighter" than
    the TL431.
    Maybe make a shunt reg with a flea reference + flea op amp + mosfet?

    D from BC
  3. Joerg

    Joerg Guest

    A lot of the info in those tables isn't correct. The lowest cathode
    current version of the 431 I have ever seen is 50uA. But down there the
    selection of vendors shrinks and it consequently begins to become
    expensive, meaning >15c. The run-of-the-mills TL431 varieties are
    between 400uA and 1mA min.

    There are some boutique chips like that. Unfortunately they also carry
    boutique price tags :-(
  4. Steve

    Steve Guest

    I use LM4040, but its 60 uA min vs the 10-20u of your 385. The SC70 package
    is nice, though .

    National's site shows 385 in full production for all its variants, maybe its
    not doomed...

  5. D from BC

    D from BC Guest

    Yup..that ISL60002 is about $8.00CAD!!! But I mentioned it as a
    benchmark example.

    Is anyone going to tell Digikey than the TL431 tables are wrong???
    They should have a reward program where customers get a credit for
    reporting errors..
    A free bag of flea power shunt regulators for every reported error! :)

    D from BC
  6. The LM385 is a "High Side Adjustable Current Reference" vs. the TL431
    family which has a low side reference. Is there any other HSACRs with low Ik
    beside the LM385 in a SMD? The LM385 do not come in SMD so they probably
    will be phased out.
  7. John Fields

    John Fields Guest

    National's web site says all versions are in full production, TI's
    says they're active, and ON semi has zillions of 'em so probably not
    to worry for a while.
  8. Joerg

    Joerg Guest

    It does come in SOT-23 and also TSSOP. LM385M3X-1.2 would be the SOT-23
    version from National, for example.
  9. Joerg

    Joerg Guest

    Yes, they list them as active. I am just wondering why Arrow calls them
    "mature". Usually that isn't a good sign. Also, I've had instances in
    the past, like with a log amp chip, where there was full production
    indication and then suddenly poof. As if someone had turned the lights
    off. The purchasing manager came down the hallway, all red in the face.

    I have used the LM4040 on the design that I am wrapping up right now but
    on this next one 60uA would be too much. That low power requirement
    bites everywhere. For example, I'd really like to use a chunk of a LP339
    as a linear amp but there isn't much info around to calculate the loop
    stabilization. Just hanging 1uF at the output is kind of crude and won't
    work here anyway.
  10. ["Followup-To:" header set to]
    Why doesn't the adjustable version come in SOT-23?

  11. Joerg, Where did you find the adjustable LM385 in a SOT-23 pack??
  12. Joerg

    Joerg Guest

    The adjustable only comes in SOIC, AFAIK. That would be LM385BM. Digikey
    has some but they are kind of pricey.
  13. Joerg

    Joerg Guest

    No idea. Maybe the die area is too large but I can't really imagine that
    on a 20uA device. It does come in SOIC though.
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