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What does the "H" mean in Part Number UPC78M15H?

Discussion in 'Electronic Components' started by Tim, Apr 3, 2007.

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  1. Tim

    Tim Guest

    This part has been replaced with an off the shelf 78M15, but may be
    causing noise. Is there something special about the UPC78M15H?

    I did a spec sheet search on it, and found lots about the standard
    78M15, but not with the "H" on the end.


    - Tim -
  2. Ryan Weihl

    Ryan Weihl Guest

    high power, 15v/5A

  3. Ryan Weihl

    Ryan Weihl Guest

    look here:


  4. Tim

    Tim Guest

  5. Because they are confused.

    The "M" in the middle indicates lower current output.

    The "standard" part would be the 7815, which is about a 1amp 15volt regulator.
    A 78L15 has about 100mA output and is usuall/always in a to-92 package.
    The 78M15 is somewhere between the two, I would have guessed 500mA but
    it's been a long time since I looked it up, and I think is generally in
    a to-5 package.

    I think someone suggested the "H" was for a high current version because
    there was one device years ago that wasn't a three terminal regulator
    or something and did use a suffix to denote current.

    I don't have a clue what the "H" at the end is for. Suffixes are generally
    about package type or makeup (such as plastic or metal). The specifics
    might vary from manufucturer to manufacturer. I suppose the suffix
    might even indicate temperature range (consumer equipment is generally
    less fussy in this regard), but I can't say I've ever seen that in
    regards to three terminal regulators, and a glance at databook shows
    nothing in this regard.

  6. Tim

    Tim Guest

    This one is in a TO-220 case and has a heatsink on it. It runs very hot,
    hotter than any other component in the box, even the output trannies run
    cool compared to this regulator. You can almost burn yourself on the

    I was hoping that it was indeed a high power unit as that would explain
    the excessive heat generated from the normal one.

    - Tim -
  7. (Michael Black) wrote in
    I've seen several devices with an M variant in a TO126 package, kind of
    like a thin flat TO220. It's a nice package, I wish more devices used it.
  8. Ryan Weihl

    Ryan Weihl Guest

    accoring to that spec sheet it is a 78M15 in a to220 package.
    me saying 5A was an error and I removed that ansewr again

  9. Franc Zabkar

    Franc Zabkar Guest

    The list of uPC parts in my vrt databook would suggest that a H suffix
    generally denotes a SIP, SIL, or SILP package. A C suffix appears to
    be used for DIPs, G for MDIP, and V for SQP. Therefore I suspect that
    in your case the "H" also refers in some way to the package style. I
    suppose you could think of a TO-220 package as a "3-SIL" ???

    - Franc Zabkar
  10. jntel

    jntel Guest


    It's an obsolete NEC Electronics part.

    Hope it has more info than you have now.

  11. Ross Herbert

    Ross Herbert Guest

    I don't think the H means anything of consequence. I don't know why
    NEC used the M in the middle either. Originally, when Fairchild and
    Natsemi first started out with these 3 terminal regulators they used
    78L.. for the TO92 plastic "low" power version, 78M.. for the TO39
    "medium" power version and 78.. for the TO220 (1A max) version.

    The NEC version is an isolated TO220 plastic type which has a lower
    current rating (350mA) than the standard metal tabbed 78.. TO220
    version available from other manufacturers.

    Datasheet archive has a datasheet on the UPC78M00A series here

    The A simply denotes a better load regulation than the version without
    the A and you can substitute this part if preferred.

  12. The original 1A regulators were in TO-3 cases.

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  13. Ray King

    Ray King Guest


    The "H" probably means high voltage input. The heat produced by a series
    regulator is the same no matter what the part number.That is if it regulates
    to the same out put voltage. The series regulators are almost always the
    hottest semi in a circuit.
  14. Jeff Volp

    Jeff Volp Guest

    Years ago when I ordered those things, the H suffix meant the TO5/TO39 metal
    can package.

  15. Ross Herbert

    Ross Herbert Guest

    Since the linear monolithic regulator first appeared it has grown to
    encompass many and varied versions and packages. I will disregard all
    but the original versions in this discussion.

    Around 1970-71, before the 78/79 series appeared on the scene Natsemi
    had the LM340 series +VE regulator series which were available in both
    TO220 and TO3 cases. And before this Natsemi had the LM309 fixed 5V
    reg in both TO39 and TO3 cases. Bob Dobkin who worked for Natsemi was
    credited as the inventor of the monolithic linear voltage regulator.

    Subsequent to the LM340 series - around 1972 - Natsemi released the
    -VE equivalents to the LM340 series as the LM320 series, however these
    were only in the TO39 and TO3 cases initially, and sometime later they
    were available in the TO220 case. Both LM340 and 320 versions were
    eventually available in TO39, TO220 and TO3 packages (and also smd).

    I think I am correct in saying that the 78/79 series series
    regulators, came after the 340/320 series and were subsequently
    manufactured by Natsemi, Fairchild, Motorola and many others, and
    became accepted as the industry standard types. The internal circuitry
    of the original 78/79 series was almost identical to the original
    340/320 series and today Natsemi uses a common datasheet which
    includes both types. This seems to indicate they are now internally
    exactly the same.
  16. Ross Herbert

    Ross Herbert Guest

    Yep, Natsemi did use the H to denote their TO39 versions - not the M
    as I said in another post.
  17. That's the way I remember it, that there was the 309 and the 340 series
    and then sometime later the 78XX numbering arrived. I'm not even sure
    I remember TO-220 cases in the beginning.

  18. Tim

    Tim Guest

    Well now I'm getting more confused. The part number listed in the
    service manual, that is on it's way to me, is UPC78M15H. I had the guy
    that is sending it check for that info. The part was made by NEC, the
    same manufacturer that makes the 78M15 that is in there now. The PC
    board is made for a TO-220 style pinout and heat sink, complete with
    mounting holes.

    Am I correct in remembering that a T039 id a round metal can about 1/4
    inch across or so, and would have the 3 pads at 120 degree intervals?

    - Tim -

  19. I remeber a lot of surplus TO-3 parts hit the surplus market about 6
    months to a year after the T)-220 parts hit the streets. They were
    finally cheap enough for hobby work. You didn't mind buying them by the
    dozen, instead of asking, DO I REALLY need a regulator for this?

    The Online NTE cross reference should list some of the early
    variations, if they can still supply replacement parts.

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  20. Tim

    Tim Guest

    Their X ref specs the NTE 968 for the entire *78*15* lineup. Although it
    does say the output is in excess of 1 amp when heat sinked properly.

    I did see someone selling the actual UPC78M15H on the net at about $12
    US. A bit steep for a 2 dollar part.

    - Tim -
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