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LM3886 current into pin 7

Daniel Joffe
Prodigy 30 points

Measurement shows typical current into pin 7 is about 4 mA. What range of current can one expect for this pin?

Is there a model that shows this current? Is there a schematic snippet that gives a good indication of what goes into this current inside the chip?

  • 0
    TI__Guru 52115 points
    Hi Daniel,

    I will take a look at this issue and get back to you soon.

    Andy
  • 0 in reply to Andy Liu (BMS)
    Prodigy 30 points
    Thanks...any guess on the timetable?
  • 0 in reply to Daniel Joffe
    TI__Guru 52115 points

    Hi Daniel,

    Here are some comments I got from my colleague on your question:

    It depends on supply voltage and output voltage swing on output.
    Ignd on Pin 7 in DC component is as follow for both in Mute and Un-Mute mode.
    V+/V- (+/- V)     Idcgnd(mA)
    10                    -0.38
    20                    -1.8
    30                    -3.2
    40                    -4.2
    When in Un-Mute mode, there is an additional current flow on Pin 7 about current flow on Mute ckt resistor 10k. This current will be Vout swing/10k. So if the Vout swing is +/-10Vpp, Iacgnd for this portion is +/-10/10k=+/-1mA. If assuming +/-20% of resistor variation due to process variation, 10k becomes 8k Ohms.

    So total Ignd current will be: Total Ignd=Idcgnd +/- Iacgnd
    If customer uses +/-40V supply voltage, Idcgnd will be about 4.2mA. This will vary about +/-20% as well.
    And Iacgnd will be (+/-40 – Vclip)/8k=+/-4.8 mA in case of no load and 1.6V of Vclip.
    So Ignd=4.2mA +/- 4.8mA -->+0.6mA to -9mA

    Andy