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TCA9517: Power-related questions

Taemin Ahn
Intellectual 795 points
Part Number: TCA9517
Other Parts Discussed in Thread: PCA9518,

Hi team

I designed the power of the master terminal as shown below.
The two 3.3V have different voltage sources. But the voltage level is the same.
Please check if there is a problem.
Also check that the PCA9518 can operate in the same way.

Thanks,

TM

  • 0
    TI__Guru 62920 points
    Hi Taemin,

    Yes, this connection is ok for both devices. Of course, both 3.3-V rails just be fully powered for communication to work. When the PCA9518 is used, the VCC pin should connect to 3.3 V.

    Regards,
    Max
  • 0
    TI__Guru* 78111 points

    Hey TM,

    Just to make sure I understand correctly, are you planning to have PCA9518 in contact with TCA9517 B side? You've stated that you expect PCA9518 to be using 3.3V so this does bring up concern with me. TCA9517 uses a static voltage offset on B side and PCA9518 also uses a static voltage offset (both sides). If B side of TCA9517 and PCA9518 are connected we could run into problems.

    If this is the case, I would recommend you flip the TCA9517 so the B side is seeing 5V and A side sees 3.3V. This will also allow for the device to perform better (this device prefers B side to be equal to or larger than A side but can work without meeting that condition).

    -Bobby