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DRV5057: Linear magnetic flux density sensing range

Shotaro Sakai
Expert 3060 points
Part Number: DRV5057
Other Parts Discussed in Thread: DRV5055

Hello team,

My customer and I have a question about linear magnetic flux density sensing range of DRV5057. According to the below thread, it is depending on Vcc value.

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/953761/drv5057-about-linear-magnetic-sensing-range

But DRV5055 (liner hall sensor) does not the characteristic. Why the characteristic is different between DRV5057 and DRV5055?

↓ Linear magnetic sensing range of DRV5055

Best regards,

Shotaro

  • 0
    TI__Mastermind 23005 points

    Hello Shotaro-san,

    Thanks for posting to the sensing forum! Not sure I understand the question is here, are you asking why DRV5055 is characterized at both a Vcc of 5V and 3.3V for the linear magnetic sensing range but DRV5057 is only characterized at 5V?

    And you are asking why the characteristic values you obtained in the previous thread at 3.3V are different from the linear magnetic sensing range on the DRV5055 datasheet?

    Just trying to understand the question better so that I may address it thank you for your patience!

    Best,

    Isaac

  • 0 in reply to Isaac Lara
    TI__Expert 3060 points

    Hello Issac-san,

    Thank you for supporting!

    I want to know the reason why the rate of changing linear magnetic sensing range is so deferent between DRV5057 and DRV5055.

    DRV5057A1/Z1 ±35mT@3V (E2E), ±21mT@5V (Datasheet)

    DRV5055A1/Z1 ±22mT@3V (Datasheet), ±21mT@5V (Datasheet)

    At 5V Vcc, both have same range. But at 3.3V, the value is so different. I cannot explain this point to my customer. This is the background of the question.

    Best regards,

    Shotaro

  • 0 in reply to Shotaro Sakai
    TI__Mastermind 23005 points

    Hello Shotaro-san,

    Thank you for the clarification and the background on the question. It looks like I may need to reach out to the design team for some more insight on this question, unfortunately today is a holiday here in the U.S. so nobody is in the office. I will reach out to the team tomorrow and hopefully have an answer for you then. I appreciate your patience and I will keep you updated!

    Best,

    Isaac

  • 0 in reply to Isaac Lara
    TI__Mastermind 23005 points

    Hello Shotaro-san,

    Thanks for the patience here as I looked into this issue for you. The first thing to note is that these two devices are different from each other, DRV5055 uses a ratiometric device architecture, which means that it uses the same Vcc voltage reference for the ADC converter, this means that the device scales the Quiescent voltage and sensitivity linearly with the power-supply. This allows the ADC to convert the signals consistently regardless of shifts in the power supply.

    DRV5057 is not a ratiometric device hence why you see a shift in the linear range at different voltages in comparison to DRV5055.

    I hope this answers your question and please let me know if there are any other items I can help out with. Thanks!

    Best,

    Isaac

  • 0 in reply to Isaac Lara
    TI__Expert 3060 points

    Hello Issac-san,

    I understood the architecture difference between DRV5055 and DRV5057.

    Do you know why min/max BL (Linear magnetic sensing range) value is not defined?

    Best regards,

    Shotaro

  • +1 in reply to Shotaro Sakai
    TI__Mastermind 23005 points

    Hello Shotaro-san,

    I am not 100% sure why this wasn't included in the datasheet, but DRV5055 was not tested for BL and simply calculated using VL, VQ, and S. The formula used for the calculation was included in the datasheet (page 11), and using the maximum values for each of the specs mentioned a minimum value was calculated, so using typical values allows you to calculate a typical value.

    I believe something similar may have been done for DRV5057 where these values were simply calculated but in this instance using the typical values. A range could be calculated using the other min and max specs.

    Best,

    Isaac