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LM3886: replace from LM3876 to LM3886

Hirotaka Matsumoto
Guru 27585 points
Part Number: LM3886

Hi all

Would you mind if we ask LM3876 and LM3886?
Our customer would like to replace from LM3876 to LM3886.
So, there is some differences the pin 5 as follows;
-LM3876 : NC(+)
-LM3886 : V+

<Question1>
About LM3876, is it possible to conncect 5-pin NC(+) to V+?
(We can not judge whether 5-pin NC has internal connection or not on the datasheet.)

<Question2>
Is it possible to from LM3876 to LM3886 without the board layout changing?
Because there is no supply for 5-pin(V+) of LM3886, it occurred the partial contact of the amp.

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Guru** 102135 points
    HI Matsumoto-san,

    Q1 - It should be fine to connect LM3876 pin 5 to V+. The last datasheet available for LM3876 (SNAS090D) says the following: "†Connect Pin 5 to V+ for Compatibility with LM3886"
    Q2 - I think I didn't fully understand your question. Could you please repeat the question? Is my understanding correct that you ask if you can leave LM3886 pin 5 floating? Pin 5 on LM3886 must be connected to V+

    Best regards,
    -Ivan Salazar
    Texas Instruments
  • 0
    TI__Mastermind 30090 points

    Hello Matsumoto-san,

    Thank you for your questions,  I would be happy to answer them.

    Q1:  This was actually the intent of the original designers.  the +  in the parentheses is actually a footnote marker.  I have included a screen shot of the datasheet for the LM3876 below:

    Pin 5 is not internally connected on the LM3876,  but if the layout designers wanted flexibility with components,  they could connect pin 5 to V+ and use either the LM3876 or the LM3886.  

    Q2:  If the original layout has pin 5 connected to V+ there is no need for any modifications.  The LM3886 does require that pin5 be connected to V+  

    if the original layout did not connect pin 5 to V+ this would need to be changed, or pin 5 would need to be connected to V+ using a jumper

    best regards,

    -Steve Wilson