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PCA9306: Asking for the PCA9306 power consumption information

SHH
Mastermind 32196 points
Part Number: PCA9306

Hi Team,
Customer is asking for the PCA9306 power consumption data.
Would you please help for Pd and Pc information?


BR,
SHH

  • 0
    TI__Guru 73331 points

    Hello SHH,

    I can give you an estimate on Pc if you can provide the schematic (pull up resistor on Vref2 and the Enable) and voltage levels of Vref1 and Vref2.

    I suspect Pd will likely be around 0.090W (0.7V*128mA) <-- 0.7V is the expected Vth and voltage drop across the Vref1 and Vref2 pins while 128mA is the maximum continuous channel current allowed. This would be worst case scenario.

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    TI__Mastermind 32196 points

    Hi Bobby,

    thanks for reply.

    could you please base on datasheet figure 7 and figure 8 to provide example on how to calculate the Pc?

    BR,

    SHH

  • 0 in reply to SHH
    TI__Guru 73331 points

    Hey SHH,

    Lets call the current from Vref2 into Vref1 to be Icc.

    Icc can be approximated by taking [3.3V-(Vref1+0.7V)]/200k. You can see here if the 3.3V were larger the Icc would become larger. In this example though, it will be about 4uA.

    Constant power coming from Vref2 through Vref1 will be:

    Pcc=Vth*Icc

    In this example: 4uA*0.7V is about 2.8uW.

    If you want to calculate the power from SDA/SCL, we can do a worst case scenario where SDA/SCL one either side holds low (simpler and easier to calculate).

    IoL=Vref1/Rpullup1+Vdpu/Rpullup2

    Power = Ron*IoL^2

    Where Ron is can be found on table 6.5, worse case scenario is when VoL is Venable - ~Vth or about 140 ohms. In most cases it will be much lower (I think 10 ohms would be a better value to use in my opinion).

    Once you calculate the power from SDA/SCL, you can multiply it by 2 because there are two lines (SDA and SCL). You can then add this to the Pcc we calculated earlier. This will give you the total power across the device.

    Thanks,

    -Bobby