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    Resistors for BMP390

    dgok
    New Poster

    Resistors for BMP390

    The connection diagram for BMP390 recommends 4.7k resistors connected between the SDA and VDDIO. If the board I am designing already has 100k resistors connected between those two lines in parallel are the 4.7k resistors necessary? Also will the sensor still function as normal with 100k instead of 4.7k?

    3 REPLIES 3
    BSTRobin
    Community Moderator

    Re: Resistors for BMP390

    Hello dgok,

    If the board I am designing already has 100k resistors connected between those two lines in parallel are the 4.7k resistors necessary?
    Reply:What is the purpose of this design?

    Also will the sensor still function as normal with 100k instead of 4.7k?
    Reply:I2C interface equipment needs to follow the hardware design. You can refer to the I2C interface specification. Excessive resistance will greatly reduce the I2C communication rate.

    dgok
    New Poster

    Re: Resistors for BMP390

    I am designing an AHRS sensor that connects to a Raspberry Pi. There is a voltage translator that converts the 3.3 V power supply from the Raspberry Pi to 1.8 V for the components such as the pressure sensor to operate at their typical input voltage. The datasheet for the translator recommends 200k pull-up resistors between SDA and SCL lines. Right now my design has 100k resistors and if I were to follow the connection diagram for BMP390 I would be adding the 4.7k resistors in parallel with the 100k resistors that are already in the design, which is why I'm asking if the 4.7k resistors are necessary when I already have the other 100k resistors. 

    BSTRobin
    Community Moderator

    Re: Resistors for BMP390

    Hello dgok,

    I think it is not good way that you want to convert 3.3V, 1.8V by resistance, the recommended way is to use a special voltage conversion chip.

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