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LM1971: About LM1971 output OPA...

Peter Tseng
Genius 5770 points
Part Number: LM1971
Other Parts Discussed in Thread: LF412, LF411, LF353

Dears,

My question is, the OPA behind the LM1971 output pin is necessary or not?

As the schematics, I think the OPA just is a buffer which without any gain adjust function.

Therefore, I can ignore it, am I right? 

BTW, since this is very old product that more than 10 years ago, is there any EOL plan for it in the near future?

Thanks.

  • 0
    TI__Mastermind 20085 points
    Hello Peter

    As you have mentioned the OPA is a buffer, But that should be used to avoid performance issues. For instance, this buffer helps to prevent audible clicks with attenuation changes, to prevent loading and subsequent linearity errors. You could refer the "Output Buffering" section of the datasheet to find further information about this.
    It seems that there is no any EOL plan for this device.

    Best Regards
    Jose Luis Figueroa
    Audio Applications Engineer
  • 0 in reply to José Luis
    Genius 5770 points
    Dear Sir,

    Thanks for the reply!
    BTW, since the OPA is necessary for certain consideration, is there any specific spec. request for the OPA selection?
    Thanks.
  • 0 in reply to Peter Tseng
    TI__Mastermind 20085 points
    Peter,

    The input impedance should be higher than 1 MΩ. You could use the following devices: LF411, LF353, LF412 and LM6041. They are mentioned in the datasheet.

    Best Regards
    José Luis Figueroa
    Audio Applications Engineer