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Replacing an old buffer

Tammam OBEID
Prodigy 40 points

Other Parts Discussed in Thread: LME49600, OPA549, OPA548, OPA547

Hello everyone,

I have a question and I hope that you can help me through it. I have an old circuit that have an old buffer LH0063. I am looking for a buffer that I can use to replace the existing LH0063 by a TI product.

Hope that you can help me

Thank for your time and help

  • 0
    TI__Expert 3840 points

    Hi Tammam,

    I am looking for an appropriate representative from the responsible product line for a suggested replacement. In the meantime, I have looked up this part and see that it is close in performance to the LME49600, although the packages are very different. Will you be doing a PCB update such that the package type will not be an issue? 

    Do you have specific performance metrics that you need to meet that you could share with us? ie supply voltage, load, maximum output current required, slew rate required, etc.

    Until I get a response, could you please take a look at the LME49600 and see if this might meet your needs?

    Thanks and Best Regards,

    JD

  • 0 in reply to John De Celles
    TI__Expert 3840 points

    Hi Tammam,

    From what I've been told, the LH0063 has been obsoleted for quite some time now. There is also not a "direct" replacement, but the parts that are similar are listed below:

    1. LME49600

    2. OPA633

    3. OPA547, OPA548, OPA549.

    Best Regards,

    JD

  • 0 in reply to John De Celles
    Prodigy 40 points

    Hi John,

    First I would like to thank you for your help.

    My circuitry is simple; I have a pulse generator that is made of a square wave generator and an injection capacitor with a value between 10pF and 200pF. The output of the pulse generator is driven into a load that could have: an impedance between 30Ohms and 200Ohms, and a capacitance between 10pF and 10µF.

    To maintain the quality of the pulse signal before it is feed into the load a buffer is a must.

    Thank you for your help

    Best regards

    TO

  • 0 in reply to John De Celles
    Prodigy 40 points

    Hello,

    I have ordered the LME49600 and the LME49710. Well I am confused since i though that I could create a buffer/amplifier from each on the LME separately, but in the application note their is a combination of more than one LME component to create an audio amplifier that is close to what I need but way more complicated then what is asked from me to implement.

    So can any one helps me in this?

    Best regards,

    Tammam

  • 0 in reply to Tammam OBEID
    TI__Expert 3840 points

    Hi Tammam,

    You should just be able to use the LME49600 as a buffer as indicated in the diagram below:

    Or, you can use the LME49710 with the LME49600 as a current driver/buffer for the LME49710 in its feedback loop, as shown below:

    Is this circuit above, what you are referring to when you say it is too complicated?

    The benefit of using the LME49710 allows for a feedback loop and the ability to have gain. Using the LME49600 by itself provides only current drive; ie a gain of 1.

    If either of these options don't work, there were other ICs previously recommended that might also work.

    If I haven't cleared up the confusion or you have more questions please let me know.

    Best Regards,

    JD

  • 0 in reply to John De Celles
    Prodigy 40 points

    Dear Mr JD;

    I would like to than you for your precious informations. Currently I am testing both circuitry that you gave me and the others that are in the application notes in the datasheets of the LME49600 and LME49710.

    For me the circuits are not complicated but I have a limited area on the PCB and limited number of IC's to use.

    However, I will keep you updated with the advancement of the circuitry specially that I am trying to pass the LME's to single-supply operation mode.

    In addition to that I am still waiting the validation of an order by TI for: OPA547T-1G3 and OPA633KP (order number: 2172105). To be able to do more tests.

    Thank you fro your help and time.

    Best regards;

    TMO