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DRV2605: audio-to-haptics function -- how is it different from an audio amplifier?

Brian Cherbak
Prodigy 30 points
Part Number: DRV2605

Hi there,

I'm considering using an LRA as a type of audio transducer. I saw that the DRV2605 has an audio-to-vibe function, which got me wondering: at that point, what's the difference between the DRV2605 and a small audio amplifier part? Does it have a built-in digital crossover or something, to prevent sending higher frequency content to an LRA? Is there any risk to it anyway (like tweeters)? Do you know of any application using LRAs to get a flatter response across the audible spectrum? Maybe even just speech?

Thank you for your time,

Brian

  • 0
    TI__Mastermind 20085 points
    Hi Brian,

    We will be responding soon further information.

    Best Regards
    José Luis Figueroa
    Audio Applications Engineer
  • 0
    TI__Mastermind 20085 points

    Hi Brian,

    Welcome to E2E, thanks for your interest in our products.

    The audio-to-vibe mode converts an audio input signal into meaningful haptic effects. This mode adds a vibratory bass extension to portable devices which allows users to feel the audio and visual contest. You can refer Audio-to-vibe Interface section of the datasheet to find further information. The DRV2605 audio-to-haptics extracts the low-frequency content and uses the magnitude of that content to drive LRAs. The device changes the magnitude of the drive voltage to the LRA with respect to the music. LRAs are always driven by their resonant frequency.

    Best Regards
    José Luis Figueroa
    Applications Engineer

  • 0 in reply to José Luis
    Prodigy 30 points

    Thanks José. 

    "The DRV2605 audio-to-haptics extracts the low-frequency content and uses the magnitude of that content to drive the LRAs" is the part that I think answers my question.

    We have been connecting LRAs to audio amplifiers and find that their frequency response is remarkably wider than their resonant frequency -- not full audio spectrum, but not bad in the voice range. Since our application isn't just for bass frequencies near the resonant frequency, perhaps we will consider just using a traditional audio amplifier.

    Thank you for your help!

    Brian

  • 0 in reply to Brian Cherbak
    TI__Guru** 101725 points
    Brian,

    The reason to drive the LRA at its resonant frequency is that this allows the device to get a better efficiency. The LRA movement strength and response is better at its resonant frequency than any other frequency, thus the driver needs less power to generate/stop the LRA movement.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Prodigy 30 points

    Hello Ivan,

    Thank you for your input -- yes, that makes sense. We are finding that, in order to produce high enough sound levels across speech frequencies for our application, we are close to or exceeding the LRA's max RMS power. That corroborates your input that we're using the LRA outside of its efficient range. We believe the solution will be to use the LRA for bass frequencies (with the DRV2605) combined with a different audio transducer, driven with a traditional audio amplifier, that together will produce a flatter frequency response across the speech audio range.

    Thanks again for your input!

    Brian