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LM3886: Need a Clarification on AUDIO amplifiers (LM3886)

Sowmiya annamalai
Prodigy 200 points
Part Number: LM3886
Other Parts Discussed in Thread: TLV320AIC20,

Hi,

In our design, we have a CODEC (TLV320AIC20) HDSO+/- output connected to an audio power amplifier(LM3886) to drive a 4ohms or 8ohm speaker. This audio power amplifier supply is directly connected to an aircraft DC bus supply i.e 18Vdc to 32.2Vdc with ambient operating temperature conditions as -20 deg C to +55 deg C.

 

  1. We need a power level of “2W into an 8 Ohm speaker “or “5W into a 4 Ohm speaker” for full operating temperature conditions i.e, -20 deg C to  +55 deg C. As per the figure-37 in the datasheet of LM3886, output power graph started from +/- 9V  supply and I was not clear on power levels to be taken at +/-9V.  This Confusion is because at Some places of datasheet it was mentioned as 18V min supply and  Some other places of  datasheet it was mentioned as 20V min supply. So requesting you Conform on the guaranteed power levels at 18V operating condition in both extreme ends of temperature.
  • 0
    TI__Mastermind 19410 points

    Hi,

    18V is typical value that are measured at 25°C and represent the parametric norm. 20V is specified to AOQL (Average Outgoing Quality Level).

    I do not have the power data on 18V at high and low temperature, since the device is very old, I can not deep in more data.

    The Figure 37 in datasheet shows the power capacity vs supply power at THD<0.1%.

    Regards,

    Derek 

  • 0 in reply to Yanming Gong
    Prodigy 200 points

    Hi,

    Based on your response, LM3886 minimum recommended VCC is 20V.

    If I can generate -2V  with a small switching inverting regulator for –VCC pin and 18V on + VCC pin ,which will create a difference of 20V. will this work? (Requesting to refer attached Audio Amplifier.png image)

    Requesting to suggest a better option for -2V generation from 18V to 32.2Vdc aircraft bus supply.(refer -2V regulator.png image )

    Please make sure the approach is reliable.

  • 0 in reply to Sowmiya annamalai
    TI__Mastermind 19410 points

    Hi,

    According to datasheet graph, in my opinion I think it is fine. 

    Regards,

    Derek