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DRV8601: Do you have any sample waveform of OUT+ and OUT-?

Kazuya Nakai59
Guru 20640 points
Part Number: DRV8601
Other Parts Discussed in Thread: TPA6205A1, DRV8210

Hello guys,

One of my customers is about to evaluate DRV8601 on their own board with Figure 16. Pseudo-Differential Feedback with Internal Reference circuit.
They want to get input/output waveform example on the circuit if you have any waveform.

Do you have?

Your reply would be much appreciated.

Best regards,
Kazuya.

  • 0
    TI__Mastermind 31035 points

    Hi Nakai-san,

    I don't have a waveform on hand, but you can refer to Figure 13 as an estimate. The output is a Class-D switching amplifier, and so you should see the voltage switching similar to a PWM wave. After being filtered, or connected to the LRA load, you will see something closer to Figure 13.

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Guru 20640 points

    Hi Jeff,

    Thank you very much for your reply.
    The customer uses ERM. 
    In the case, is the output waveform similar to Figure 13?


    Also I think DRV8601 function is a fully differential amplifier.
    Does DRV8601 use same chip as TPA6205A1?

    Thank you again and best regards,
    Kazuya. 

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 31035 points

    Hi Nakai-san,

    Yes Figure 13 also applies to ERM.

    Both the DRV8601 and TPA6205A1 use a Class-D amp topology but they are not the same chip.

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Guru 20640 points

    Hi Jeff,

    Thank you very much for your reply.
    Could I ask you a few additional questions as the below?

    Q1.
    They use Figure 16 circuit to drive ERM with 10kHz PWM frequency.
    When PWM on duty is 50%, the ERM generates audio noise a little.
    We think that Cf (filter capacitor) value increasing is one of solution for the audio noise.
    Also we think higher PWM frequency would be another solution.
    Is our thought correct?

    Q2. 
    What is the highest PWM frequency which can be input to DRV8601?

    Q3.
    We think that DRV8210 can be used to drive ERM.
    What is advantage point of DRV8601 compare to DRV8210?

    Thank you again and best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 31035 points

    Hi Nakai-san,

    Q1) Check Section 8.2.1.2 for design procedures with Cf. If the noise is coming from PWM harmonics, then increasing the frequency could help, or lowering the cutoff frequency of the filter

    Q2) Let me confirm internally and get back to you on this question.

    Q3) DRV8210 belongs to a different group so I can't comment in detail on it, but the DRV8601 is intended for haptics while the 8210 is a more generic motor driver, but they both support a PWM input.

    Thank you,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    TI__Mastermind 31035 points

    Hi Nakai-san,

    To confirm #2, as long as your demodulated signal is in the audio band, there should be no limit to the PWM frequency. 

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Guru 20640 points

    Hi Jeff、

    Thank you very much for your reply.
    I understood.

    Thank you again and best regards,
    Kazuya.