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PCA9306: Unable to communicate

Allen yang
Expert 1155 points
Part Number: PCA9306
Other Parts Discussed in Thread: TCA9617B

Tool/software:

Hi Team,

The design has 2 PCA9306 to power 2 devices. They are U102, U108443,

U102 cannot communicate.

Is there a problem with this design?

  • 0
    TI__Guru 54198 points

    Hi Allen,

    PCA9306 is not a buffer. It is a passive level translator. 

    Do you have the schematic of U102 and U108443? 

    A scope capture can also help to determine what is the fail mode. 

    Regards,

    Tyler

  • 0 in reply to Tyler Townsend
    Expert 1155 points

    Hi Tyler,

    Is the connection method shown below feasible?

    When using the PCA9306 for level shifting with a 3.3V input signal, does it mean there is no buffer function?

    Please recommend an IC that provides both level shifting and buffer functions.

  • 0 in reply to Allen yang
    TI__Guru 54198 points

    Hi Allen,

    PCA9306 is not a true buffer with re-driving circuitry. It is a passive level translator. 

    A buffer like TCA9617B could work here with VCCA = VCCB = 3.3 V. 

    However, what is the VIL of the PCIe SW, i2c expander, and BMC? 

    Can we confirm that BMC VIL = 0.30 x VCC = 0.3 x 3.3 = 0.99 V? 

    Why do we need level translation if PCA9306 is being used from 3.3V to 3.3V? 

    Is there a scope capture to capture the fail mode? 

    Regards,

    Tyler