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ISO7220A: OUTx power-up state with VCCI unpowered

Part Number: ISO7220A

Is the initial OUTx state known when VCCO is powered normally (say 3.3V), and VCCI is unpowered?

I have an application where the VCCI domain may not be powered when the VCCO domain is active. I am wondering if the OUTx outputs start in a deterministic, known state when the VCCI domain is unpowered. In this case VCCI and INx will be at the GNDI level.

Referring to the Functional Block Diagram in section 8.2, page 23 of the data sheet, it appears the initial state will depend on the power-up state of the NOR latch in the lower frequency channel and does not necessarily start in a defined state when only VCCI is applied.

  • Hi Matthew,

    When input side is unpowered and the output side is powered, the output state will go to the default state (HIGH).
    This is also valid if both sides are powered and INx is floating or open (OUTx will be HIGH).
    Please refer to Table 2 under Section 8.4 (Device Functional Modes) of the ISO7220A datasheet for more information regarding the same.

    Regards,
    Anand Reghunathan
  • In reply to Anand Reghunathan:

    Thank you for pointing me at Table 2 in Section 8.4, I overlooked it and that clearly answers my question.

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