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Original question:

PCA9539: Reset Connection

PCA9539: Schemetic review request

KHR
Prodigy 40 points
Part Number: PCA9539

Hi, I ask to review the circuit diagram about PCA9539.

PCA9539 Ref. Des : U72, 73, 74

I will be waiting for the reply.

Thank you !!Connect_RG_20210826.pdf

  • 0
    TI__Guru 74262 points

    Kim,

    An engineer has been notified of this thread and will respond by tomorrow.

    Regards,

    Eric Hackett 

  • 0
    TI__Guru 73181 points
    PCA9539 (U72, U73, U74)
    Checked: Status: (Good, Bad, Okay, ?) Comments:
    Schematic pinout matches datasheet Good
    Decoupling Cap on Vcc ? Decoupling Cap is missing
    SCL/SDA on schematic pin out matches SDA/SCL net name Good
    RESET biased correctly ? Verify that RESET is not being over biased above Vcc logic. Refer to 8.2.1.1 RESET Errata
    Unique Addresses between the other IO expanders Good
    P-Ports are properly Biased ? U74 pins 17-20 are floating, this can be okay if device is programed to have pins set to an output, if left an input then you need to bias the pin to either GND or Vcc with a resistor. (otherwise shoot through current and higher supply current)

    -Bobby