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LM4865: LM4865

Rohini E
Intellectual 610 points
Part Number: LM4865
Other Parts Discussed in Thread: TLV320DAC3120, TAS2505

Hi Team,

We are using DAC(PCM175x) and Power Amplifier(LM4865) in our audio section

In datasheet we didn't get info about the current consumption of the power amplifier.  We are using 5V for our complete audio section.

We measured upto 370mA is taken by power amplifier at maximum volume. A new requirement came from customer to support supply with AA(700mAh) standard batteries made a challenge. Even with 3 batteries (1200mAh) we tried which makes supply as 4.7V when using batteries

1. we tried few ways like reducing the gain of amplifier using DC pin

2. Reducing supply voltage to 4.5V(Amplifier operating Voltage -2.7 to 5.5 & DAC operating Voltage -4.5 to 5.5).

In both the cases volume is enough for us. but current consumption to the max it is 310mA, making our system to reset again and again. We are not seeing this issue with headphones at anytime.

We request you to provide your thoughts on our test cases and include your solutions while testing LM4865


Here I have attached the schematics of the Audio section

Thanks & Regards

E.Rohini

  • 0
    TI__Guru** 110925 points

    Hi Rohini,

    Perhaps using a Class-D amplifier would help reducing current consumption.

    From your description I think you use PCM175x to feed audio into LM4865 which can change between speaker and headphone. Have you considered using a DAC that has integrated speaker and headphone drivers? TAS2505 and TLV320DAC3120 could be a couple options. The difference is that you would need a controller to setup the DAC.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators