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TCA9539-Q1: TCA9539QPWRQ1 review schematic

Part Number: TCA9539-Q1

Hi, Support Team

We will use TCA9539-Q1 as below chart: have any concern?

if any suggestion, Please advise me.


Best regards,


  • The schematic does not show any pull-up resistors on SDA/SCL. I guess they are elsewhere.

    I do not understan RES1007. Is EXIO1_VCC connected directly to a power supply? If not, then you must remove the resistor.

  • Hi Lawrence,

    Clemens already pointed out the major concerns here. 

    The TCA9539-Q1 as well as any of our other IO expanders all require pull-up resistors on the SDA and SCL lines.  Are there pull-up resistors present on the SDA and SCL lines? I am assuming they are present on another page of the schematic. 

    Also with resistor R1007, what is the purpose of this resistance? 10kohm is quite large, and I would expect current limitations to the device if a heavy load or multiple p-ports would be driving at the same time. The continuous current through VCC could be a maximum of 160mA, most likely less than this current since this is the abs. max rating. On average, maybe 50mA - 75mA would be the current draw requirement for this device when driving and receiving multiple signals.