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DRV2605L-Q1: May I know if the full-bridge switch tube that controls the current output inside the chip operates when the repeated write register keeps the chip from output?

Hazel Sun
Expert 6535 points
Part Number: DRV2605L-Q1

Hi team,

May I know if the full-bridge switch tube that controls the current output inside the chip operates when the repeated write register keeps the chip from output? 

thanks

  • 0
    TI__Mastermind 31365 points

    Hi Hazel,

    I'm not sure I understand your question. Do you want to know if the output driver is disabled/in a high-z state when you write a certain register? Which register are you referring to?

    Thank you,
    Jeff McPherson

  • 0
    Prodigy 30 points

    Hello Jeff

    Our MCU read 0x1A register every 20ms. Does this impact the state of full-bridge?

    Actually, our question is about the nosie around 400Mhz, which we found it during RE test and confirmed it's from DRV2605L-Q1.

    There is no such nosie when we stop I2C communication between MCU and DRV2605L-Q1 by removing the pull-up resistor of SCK or pulling EN down.

    Do you have the idea about this noise? Thank you so much for your support!

  • 0 in reply to yang leo
    TI__Mastermind 31365 points

    Hi Yang,

    Reading the register will not change the state of the output bridge.

    The noise is likely EMI radiation from the I2C bus. You can try to reduce this noise by slowing the edge rate with a small series resistor, but take care not to violate the I2C timing specs. 

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 30 points

    Hello Jeff

    Thank you for your quick response.

    Do you mean slow down the rising time of I2C? Can we do it by increasing the resistance of pull-up resistor? (We use 4.7k now)

    BTW, previously, the frequency of SCL is 420KHz which exceeds the spec of DRV2605L-Q1(maximum is 400KHz in the spec), we adjust it to 100KHz, but seems no good effect.

    Look forward to your reply.

  • 0 in reply to yang leo
    TI__Mastermind 31365 points

    Hi Yang,

    You can increase the pull-up resistor to increase the RC constant, that will slow the edge rate. Does the 400MHz noise remain when using 100kHz I2C?

    Best regards,
    Jeff McPherson