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TLV320AIC3120EVM-U: Audio Distortion

Scott Gaetjens
Intellectual 270 points
Part Number: TLV320AIC3120EVM-U
Other Parts Discussed in Thread: TLV320AIC3120

Hello,

We have a working prototype using this part.  All of the clocking settings are unchanged from how the default init script on the EVM sets them.  We are driving this speaker from the Class-D outputs: https://www.visaton.de/sites/default/files/dd_product/k50_8.pdf and are hearing distortion.  The speaker is rated for 2 watts which is higher than the TLV320 datasheet says the Class-D amps can deliver into an 8 ohm speaker (1.6W).  Any help would be appreciated.  Thanks.

  • 0
    TI__Mastermind 29745 points

    Hi,

    Since it's from the init script, the register settings should be ok and it was working with your prototype before.

    Can you measure the speaker impedance just to be sure and maybe try driving it from other source and see you hear the same distortion?

    Regards.

  • 0 in reply to pdjuandi
    Intellectual 270 points

    This issue has always been happening, I just ignored it until now since it wasn't the highest priority.  It's happening with the eval board and our prototype.  I have a really simple setup right now.  I'm connecting an 8 ohm speaker across the "SPLM" and "SPLP" connections on the eval board, setting the analog attenuation to zero in the GUI, and playing music from my laptop.  The speaker begins to sound distorted when I turn the Windows volume control up to around 60. 

    I also connected a 4 ohm, 15 watt passive studio monitor to SPLM and SPLP and it began to sound distorted around 85 in the Windows volume control.

    Since the Class D amplifier inside the TLV320AIC3120 is rated for delivering 2.5 watts into a 4 ohm speaker, I didn't think the GUI would allow me to configure the part in such a way as to exceed that limit.  There's no way my 15 watt speaker should be distorting with the eval board driving it, right?

  • 0 in reply to Scott Gaetjens
    TI__Mastermind 29745 points

    You mentioned hearing the distortion when windows volume going above 60 sounds like clipping issue.

    The class D output level is 2.2Vrms with 3.6V SPKVDD and 6dB gain, so it's very likely you are driving the device above that.

    For example you can use a sine tone to find your gain setting that does not result in distortion and use that.