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DRV8899-Q1: Smart tune Ripple Control Decay Mode Ivalley setting

Part Number: DRV8899-Q1
Other Parts Discussed in Thread: DRV8889-Q1,

Tool/software:

Hi Team,

Could you tell me sequential of setting Ivalley at Smart tune Ripple Control Decay Mode?

Especially, Customer want to know about relation between Itrip and Ivalley.

Please provide some material if we have.

Best Regards,

Yusuke

  • Hi Okamoto-san,

    Could you tell me sequential of setting Ivalley at Smart tune Ripple Control Decay Mode?

    Especially, Customer want to know about relation between Itrip and Ivalley.

    The Ivalley is a fixed parameter in this device. It is 19mA + 2% of ITRIP for the DRV8889-Q1 and the DRV8899-Q1 drivers. Thank you.

    Regards, Murugavel 

  • Hi Murugavel,

    Thank you for your support.

    Could you tell me which page does it is stated?

    Our customer want to know.

    Best Regards,

    Yusuke

  • Hi Okamoto-san,

    It is not mentioned in the datasheet. Thank you.

    Regards, Murugavel 

  • Hi Murugavel,

    According to datasheet, Ivalley seemed to below of Itrip.

    Isn't Ivalley = Itrip(2%)-19mA?

    "It is 19mA + 2% of ITRIP"

  • Hi Okamoto-san,

    Ivalley = ITRIP - (19mA + 2% of ITRIP). Sorry for not being clear in the previous response. Thank you.

    Regards, Murugavel   

  • Hi Murugavel,

    Our customer measured the Itrip and Ivalley however the current value is not math following equation:

    Ivalley = ITRIP - (19mA + 2% of ITRIP)

    【Measured value】

    Itrip setting:50A

    Ivalley41mA

    Why it was not match?

    Best Regards,

    Yusuke 

  • Hi Okamoto-san,

    Itrip setting of 50 mA is at the extreme low end of the Itrip setting for this device which has a maximum IFS setting of 1 A. The DRV8899-Q1 is a 1 A device and cannot provide the desired accuracy at the bottom end of the scale because offset currents will dominate and device to device variations will be pronounced. What is the end application that requires IFS = 50 mA? Do we have a datasheet for the stepper with L and R values? What is the measurement method adopted by the customer? Was there a waveform capture? Thank you.

    See below waveform captured at 100 % of maximum IS, IFS = 1 A, showing ripple amplitude at 38 mA which is very close to the expected (19mA + 2% of ITRIP).

    See below waveform captured at 50 % of max IFS, IFS = 500 mA, showing ripple amplitude at ~ 20 mA which is very close to the expected value.

    See below waveform captured at 25 % of max IFS, IFS = 250 mA, showing ripple amplitude at ~ 19 mA which is very close to the expected value.

    I did set IFS = 50 mA with my sample - see below capture. The ripple was ~ 18 mA.

    Regards, Murugavel