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LM747H

Jun Huang1
Prodigy 100 points

Other Parts Discussed in Thread: LM741, LM747QML, LM747, TLE2021, TLE2071, TLE2061, TLE2081, MC33078, LF412, LF412-N

I need help with finding a direct replacement for LM747H, TO-100. I was suggested to use LM747H/883. But the LM747H/883's GBP is not as good as the LM747H's. Thanks.

  • 0
    TI__Guru 66726 points

    Hello Jun,

    Technically, the LM747H did not even have a GBW spec.The column is blank.

    The LM747H and the LM747H/883 both use the same die - so the basic AC performance should be similar.

    The "Open Loop Transfer Characteristics vs. Frequency" plot infers a BW of about 0.9 to 1MHz - which is about right for a LM741 type device. This would be considered a "Typical". The LM747AH spec was inferred from the slew rate...I'm not thrilled with that.

    The /883 version BW is just heavily padded to pass the MIL-STD-883 specifications. AC-wise it should be identical to the LM747H.

    Regards,

  • 0 in reply to Paul Grohe
    Prodigy 100 points

    I was informed by a TI support representative that the LM747H/883 is obsolete. I guess I need to re lay out the board with LM741.

  • 0 in reply to Jun Huang1
    TI__Guru 66726 points

    Hello Jun,

    Hmm... The website shows it in full production...

     http://www.national.com/popr/LM747QML.html

    It would probably be a good idea to use a newer device. The LM747 is over 35 years old....I would not expect it to be around for many more years.

    Any particular reason you are using the 741? Trim pins? Comp pins? Metal can? Do you need the full temp range (to -55°C).

    Regards,

  • 0 in reply to Paul Grohe
    Prodigy 100 points

    Cuz it's full temp range. Due to physical constrain, I'm also thinking of using LF412. what's your suggestion?

  • 0 in reply to Jun Huang1
    TI__Guru 66726 points

    Do you need a metal can? Do you need to go to -55?

    The industrial range is -40 to +125 - which is just 15°C short on the cold end. IF you can use the -40 to 125 range - you have many, many more options.

    We do have Enhanced Package "EP" and "extended industrial" devices - which are "military" temp range, but without the military pedigrees and prices.

    The TL06x, 07x and 08x family has extended temp range devices - usually in ceramic packages.

    The following families also have extended temp ranges with specs >= to the LM741:

     TLE2021/2/4

     TLE2061/2/4,  TLE2071/2/4, TLE2081/2/4

     MC33078

     LF411MH or LF412MH

    Regards,

     

  • 0 in reply to Paul Grohe
    Prodigy 100 points

    I do need metal can. It would be painful to re layout the legacy product. Although the original is TO-100, but I can micky-mouse the TO-5 to get it to work. I notice that the output current of the LF412 is not listed on the spec sheet. Is there any reason why it's omitted?

     

    thank you and regards,

    Jun

  • 0 in reply to Jun Huang1
    TI__Guru 66726 points

    Look at the National (LF412-N) version - there are output current limit graphs on page 5.

     http://www.ti.com/product/LF412-N

    Regards,

  • 0 in reply to Paul Grohe
    Prodigy 100 points

    oh, got it.

     

    thank you and have a nice weekend!

  • 0 in reply to Jun Huang1
    Guru 21975 points

    Jun,

    Just in case it is any help, the OPA2111BM is still available (TO-99 metal can). It is a dual JFET-input device with '747-like speed. Very expensive but still available. :)

    Regards, Bruce.

  • 0 in reply to Bruce Trump
    Prodigy 100 points

    holy macro! it's $61 each. I'll try the LF412 first and see if the board passes. thank you anyways.