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DRV2605LEVM-MD: voltage and frequency that are used to get mentioned amplitudes

Gerald
Genius 9575 points
Part Number: DRV2605LEVM-MD
Other Parts Discussed in Thread: DRV2605L

Hi Experts,

Our customer bought the drv2605levmd. He would like to know some information in regards of that. He is running 4 LRA Motors with two amplitudes: 154 and 179

He basically want to know what is the voltage and frequency that are used to get those amplitudes
example : amplitude = 154 , Voltage= ? , frequency =?

If there is an equation to compute it, please advise. Thank you.

Kind regards,
Gerald

  • +1
    TI__Genius 16870 points

    Hi Gerald,

    I assume that the customer is using Real Time Playback mode (RTP) based on your question.

    In closed loop(CL) mode the DRV2605L algorithm will actively track the resonant frequency and drive the LRA at that frequency. the initial guess of the frequency is stored in register 0x1B DRIVE_TIME[4:0], and the value that is measured by the auto resonance tracking algorithm is stored in register 0x22 LRA_PERIOD[7:0]

    In Open loop(OL) mode the device will not track the frequency and drives the LRA at the frequency found during auto calibration, this frequency is stored in register 0x20 OL_LRA_PERIOD[6:0]

    in RTP mode the amplitude value (154,179) correspond to a fraction of the RATED_VOLTAGE or OD_CLAMP voltage/ (based on the settings, OL or CL mode)

    for example; if the customer is using Closed Loop mode, and BIDIR_INPUT = 0, and for example has a RATED_VOLTAGE of 2Vrms. then 

    (154/255) x 2Vrms = 1.2 Vrms , and (179/255) * 2Vrms = 1.4 Vrms.

    Regards,
    Arthur

  • +1 in reply to Arthur Brown
    TI__Genius 16870 points

    Also to read more on the RTP mode amplitudes please read sections 8.5.8.1 to section 8.5.8.1.3  of the data sheet https://www.ti.com/lit/ds/symlink/drv2605l.pdf