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TLV320DAC3100: How can I connect it to a single ended speaker

Gustavo Vargas
Prodigy 20 points
Part Number: TLV320DAC3100

Hello team,

In this application my customer is using HPL output as a line driver (600ohm) and also the power output to drive a 1W 8ohm speaker. The speaker is pre-wired inside a hand-held and one side is tied to ground, so only one side of it can be drived. How can we connect the class-D differential output to this speaker?

I guess we could connect both SPKP together and drive the speaker with it. In this case what should we do with both SPKM pins?

Do I need filters of DC-block in between SPKP pins and the speaker? 

Also, as an extra question, there is any case where the MCLK is mandatory or we can always use BCLK and PLL to generate the internal clock?

Thank you!

  • 0
    TI__Guru* 84915 points

    Hi, Gustavo,

    Welcome to E2E and thank you for your interest in our products!

    Unfortunately, the Class-D driver is a fully differential amplifier and the single-ended connections are not recommended. Both outputs are required in order to remove the Class-D switching frequency. In addition, a single output would only provide the half-cycle of the output signal.

    Regarding your question about the MCLK, the MCLK is not mandatory in case you are using the device in slave mode (BCLK and WCLK as inputs). BCLK can be used as main clock to generate the internal sampling rate.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 20 points

    Hi, Luis,

    Thank you for your reply. However, I must find a way to connect to such single-ended speaker. There is any way to convert the output to a single-ended fashion? With some magical external parts?

    I do understand I will lose at least 50% of my power (speaker is only 1W anyway), and also increase noise, but, for this application, I must use this speaker and I do not have any control over how it is wired.

    So, when you say connecting both SPKP together to one side of the speaker and the other side to the ground is "not recommended" do you mean I will have noise and waste energy or do you mean I will short device's life due to forcing it to work out of specification?

    If the second then we stop now! If the former I'm afraid we will go ahead and produce boards.... but in this case any recommendations on what to do with both SPKN pins?

    Thank you!

  • 0 in reply to Gustavo Vargas
    TI__Guru* 84915 points

    Hi, Gustavo,

    I don't think the single-ended solution will short the device life. But I actually think that the output signal will be only valid for the half cycle. I mean, if we suppose that the output is a sine wave, the output won't be capable to provide the negative half cycle of the signal. Basically, the positive half cycle is provided by SPKP and the negative half cycle is provided by the SPKM.

    Let me know if you have additional questions or comments.

    Best regards,
    Luis Fernando Rodríguez S.