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PCA9306: Please look at this question for PCA9306, thanks.

user4365766
Expert 1980 points
Part Number: PCA9306

Hi TI：

I saw there had the below description in the TI PCA9306 datasheet, it required a 200k ohm pull-up resistor between the Vdpu and Vref2/En, must the resistor be 200k for 3.3V/2.5V? what is the reason of  this value for this resistor, not other value? Would you please share some information for this resistor? Thanks.

  • 0
    TI__Guru 73471 points

    Hey User4365766,

    I added a section in the datasheet (8.1.8) to try to explain the reason for the 200k resistor. Figure 6 of the datasheet also shows the functional block of the Vref1 and Vref2 pins and why 200k resistor is used.

    Essentially its used to limit current to generate the biasing voltages for the device. Equation 5 of the datasheet shows the effect of changing the biasing resistor (you get a larger Ibias with a lower Rcc). 200k is not a required value but a suggested value. You could use a 1k resistor but get 200x more Ibias and basically increase the power consumption of the device. I can't think of a reason why you would want a lower value resistor other than to save on cost of buying resistors in bulk.

    -Bobby