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Original question:

TCA9617A: VCCA margin over VCCB

TCA9617A: VCCA and VCCB connected to the same 3.3V together

Kelly Bai
Intellectual 1330 points
Part Number: TCA9617A

hi team,

as datasheet says VCCB should be higher than VCCA, but the figure 13 in the datasheet shows VCCA and VCCB are connected together.

so can we connected VCCA and VCCB in to the same power supply? thanks.

  • 0
    Guru 316640 points

    This is allowed.

    The datasheet allows VCCA = VCCB. And as shown in the linked question, VCCA being higher by up to 0.5 V is harmless.

  • 0
    Prodigy 20 points

    Hi Clemens,

    Thx a lot for confirming that VCCA and VCCB being using the same power supply is allowed. 

    And please let me use this opportunity to make another question clearer. In the TCA9617A, it states that "VCCB should always be higher than VCCA. VCCB cannot be lower than VCCA even when the device is disabled." 

    But as your comments above, do you mean that VCCA being higher than VCCB  by up to 0.5V is acceptable?

    BR,

    Jon

  • 0 in reply to Cai Jun
    Guru 316640 points

    The statement in the datasheet is simplified. See the linked question.

  • 0 in reply to Cai Jun
    TI__Guru 72591 points

    Cai,

    Clemmen's response is correct. The TCA9617 (both A and B) allow for VCCA=VCCB as long as the recommended operating voltage is being followed. 

    Clemen's response about the 0.5V margin is related to why VccA should not be larger than VccB. In the A version, there is a leakage path from A side to B side, to get this leakage path to actually leak, you would need to have VccA larger than VccB by a threshold voltage, 0.5V is close to that value.

    -Bobby