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  • TI Thinks Resolved

DRV2625: DRV2625 measured waveform by different LRA setup

Intellectual 940 points

Replies: 19

Views: 115

Part Number: DRV2625

Hi

What is the correct setup for LRA when measure waveform? Seems different setup will get different waveform

We use two setup, one is fix LRA(sticky LRA bot side on loading plate), the other is hold on hand with press the pad of LRA

We test waveform strong click 100% and soft bump 100%

Thank you~~

 fix LRA(sticky LRA bot side on loading plate),

hold on hand with press the pad of LRA

 strong click 100% -- fix LRA(sticky LRA bot side on loading plate),

 strong click 100% --hold on hand with press the pad of LRA

soft bump 100% -- fix LRA(sticky LRA bot side on loading plate),

soft bump 100% -- hold on hand with press the pad of LRA

  

  • Hey Poki,

    Something similar to the first way you mentioned and showed except you dont want to stick it to something with another LRA already on it, this is due to dampening caused by the other LRA and will alter the closed-loop feedback of the system. Also under whatever you stick the LRA you would want to put foam to isolate it from the rest of the table. Here is a picture of what the proper set-up of an external LRA:

    You could take off one of the pieces of metal from one of the EVMs you have and create this exact set up.

    Best,

    Carson Allen

    LPAA Applications

  • In reply to Carson Allen:

    Hi Carson:

    Thanks for feedback soon

    Any good way tak off metal from EVM? the tape is very strong^^

  • In reply to Poki Huang:

    Hi Carson:

    Or can we just remove this LRA that already on it?

    And the ERM can still on it?

    thank you~~

  • In reply to Poki Huang:

    Hey Poki

    You can just remove the LRA that is already on it and Leave ERM

    Best,

    Carson

  • In reply to Carson Allen:

    Hi Carson:

    OK, I will remove the LRA and re-test

    But can I know first that what the strong click 100% and soft bump 100% wavefrom look like?

    Is it similar to present fix LRA waveform? Or totally different due to other LRA on it?

    Or do you have this two waveform can provide?

    thank you~~

  • In reply to Poki Huang:

    Hey Poki, 

    If you look on page 7/Figure 6 on DRV2625 Datasheet you will see what Strong Click is supposed to look like.The first waveform you provided resembles it and you can check to see if the voltage amplitudes match with your set overdrive clamp voltage for the overdrive portion and rated voltage for the lower middle portion.

    I will need to create a recording of my own for the soft bump and get back to you on that.

    Best,

    Carson

  • In reply to Carson Allen:

    Here is what the soft bump should look like, which is what your fixed LRA soft bump recording looks like

  • In reply to Carson Allen:

    Hi Carson:

    Thanks feedback

    I remove the original LRA on EVM with loading and the waveform are the same

    My waveform is looks like with datasheet page 7/Figure 6 and you provided

    But there is still a little different, do you know why? And is it acceptable?

    Thank kyou~~

    Poki

  • In reply to Poki Huang:

    Hey Poki,

    The Datasheet and my recordings used a different LRA than you are using which also means we are using a different rated voltage, clamp voltage, and operating frequency. This would account for any differences in the recordings besides just testing environment and actuator variance which is fine, as long as the haptic effect you feel is what is desired there is no requirement to perfectly match the recordings provided.

    Best,

    Carson

  • In reply to Carson Allen:

    Hi Carson:

    I found a strange situation

    We use the same setup to measure again, but the waveform become unstable

    Could it come from measurement error? Or the driving waveform really become unstable?

    Could you provide some recommand for me to do test?

    Thank you~~

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