lm4991+problem

Discussion in 'The Projects Forum' started by ekremhb, Nov 9, 2009.

  1. ekremhb

    Thread Starter New Member

    Nov 9, 2009
    2
    0
    I want make my mp4 player 3w sound amlifier whit
    lm4991 and design my circut base of own pdf but I have not listen
    any sound from speaker or not any sound what is the problem


    Can you help me

    supply voltage 3,7 lion cell speaker 8 ohm 3w

    Regards
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    From page 2 of National Semiconductor's datasheet:

    [​IMG]

    Did you build your circuit according to that schematic?
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The datasheet for the LM4991 shows that it works when its supply is as low as 3.7V but its output power into 8 ohms is low. It is only 0.7W at 1% clipping distortion which will be audible. Its output power at clipping (low distortion) is only 0.58W which is less power than a cheap clock radio. Its power output will be less as the battery charge becomes less than 3.7V.
     
  5. ekremhb

    Thread Starter New Member

    Nov 9, 2009
    2
    0
    Yes I am build same circuit
    and pin 1 is tied to gnd for lm4991 to on state
     
    Last edited: Nov 24, 2009
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