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DRV2625: DRV2625 VDD versus LRA waveform Vpp

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Replies: 31

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Part Number: DRV2625

Hi

We set overdrive voltage = 3Vpeak as attached excel

But we find when we change DRV2625 VDD voltage, the waveform Vp/Vpp also change as below table

Is it normal? Since as I know the Vp should limit at Vpeak setting

Thank you~~

Haptic_VDD(V) Waveform Vp(V) Waveform Vpp(V)
4.4 3.42 6.84
4.2 3.34 6.68
4 3.3 6.6
3.8 3.22 6.48
3.6 3.14 6.32
3.5 3.1 6.2
3.4 3.06 6.12

8132.DRV2624 and DRV2625 Configuration Tool and Design Equations-AWA_modified.xlsx

  • In reply to Poki Huang:

    Hey Poki,

    Can you set your oscilloscope for 500kS/s at 20s/div and record the waveform you get again.

    Could you also show me a waveform of the auto-calibration

    And could you explain the set-up in that last picture and what DRV2605EVM is doing in that circuit.

    I will look at your code closer but at first look it seems to be configuring everything correctly

    Best,

    Carson

  • In reply to Carson Allen:

    HI Carson:

    Could you provide the frequency of your DRV2625 EVB LRA?

    And any ittems at initialization/work mode that we need select or just follow Console default?

    I attached console default chart, please help checksetting.zip

    Thank you~~

    Poki

  • In reply to Poki Huang:

    Hi Carson:

    I use DRV2625 EVB with its own LRA to measure

    I use 20s/div and 50kS/s(our oscilloscope no support above 100kS/s at 20s/div)

    But the result is the same, Vpp will change with VDD, and Vpp(Vp) over setting clamping voltage

    you can check below chart

    Rated voltage=1.8V, clamping voltage=3V, VDD=3.6V/4.4V

    Rated voltage=1.8V, VDD=4.4V,  clamping voltage=3V/4V

    What the reason you use 20s/div to measure?

    And could you provide your test waveforms for us?

    Because I want to check what the Vpeak you measure

    Thank you~~

    Poki

  • In reply to Poki Huang:

    Hi, Poki,

    I will follow up this case for now.

    I have some questions regarding the device behavior.

    - Are you changing the VDD level on the fly? I mean, do you configure the device and then adjust the VDD level? Have you tried to change the VDD level and then configure the device? Do you have the same results?

    - Do you have the same results in open and closed loop modes?

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodriguez S.:

    Hi Luis:

    Yes I change the VDD level and then configure the device

    The result is the same

    I do open loop but get the same result as below chart

    And could you help provide your test waveforms for us?

    Thank you~~

    VDD=3.6V, Vpp=6.44V

    VDD=4.4V, Vpp=6.68V

  • In reply to Poki Huang:

    Hi, Poki,

    Sorry for the delay. We are still working with our team in order to understand this case. I will come back with details as soon as possible.

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodriguez S.:

    Hi, Poki,

    One question regarding your captures, do you measure the output through output filters like the one mentioned in section 5 of this document?

    https://www.ti.com/lit/ug/slou432a/slou432a.pdf#page=10

    Best regards,
    Luis Fernando Rodríguez S.

  • In reply to Luis Fernando Rodriguez S.:

    Hi Luis:

    Yes we measure the output through output filters like the one mentioned in section 5 of this document

    Actually present test we use DRV2625 EVB, measure output from EVB SCH TP1 and TP8

    Poki

  • In reply to Poki Huang:

    Hi Luis:

    Any feedback about this?

    Thank you~~

    Poki

  • In reply to Poki Huang:

    Hi, Poki,

    Sorry for my late response. We have contacted our main haptics driver designer in order to get more details about this phenomenon.

    So, basically, when the VDD level is modified, we should see an increment in the output voltage in PWM format as you clearly see in your scope capture. We should expect to see a maximum of 2 times VDD (a Vpk-pk level from -VDD to +VDD). However, the internal algorithms modify the duty cycle when the VDD level is modified, so the resultant overdrive and rated voltage values are the same.

    The captures you shared seems to be in PWM format. So, in order to see that the output voltage is not modified, you need to filter the PWM switching frequency (a 20KHz-40KHz low-pass filter is usually used for this purpose). You may use an effect from the ROM libraries (like the buzz effect) in order to prove this.

    I hope this makes sense. Please let me know if you have additional questions or coments.

    Best regards,
    Luis Fernando Rodríguez S.

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