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ISO6721-Q1: Can ISO6721-Q1 be used for level shifting from 2V to 3.3V?

Kazuya Nakai59
Guru 21645 points
Part Number: ISO6721-Q1

Hello guys,

One of my customers is considering using ISO6721-Q1 for for level shifting from 2V to 3.3V with isolation.

At this moment, they have the following questions?
Could you please give me your reply?

Q1.
Can ISO6721-Q1 be used for level shifting from 2V at VCC1 to 3.3V at VCC2 though the device datasheet says VCC1 voltage ranges are 1.71V~1.89V and 2.25V~5.5V?

Q2. 
If Q1 answer is No, could you please tell me any device which can be used for level shifting from 2V to 3.3V with isolation?

Your reply would be much appreciated.

Best regards,
Kazuya. 

  • 0
    TI__Genius 17815 points

    Hello,

    Thank you for your question.

    I have answered your questions below:

    1. Can ISO6721-Q1 be used for level shifting from 2V at VCC1 to 3.3V at VCC2 though the device datasheet says VCC1 voltage ranges are 1.71V~1.89V and 2.25V~5.5V?
      1. No, the level shifting would be limited to the conditions in the recommended operating conditions.
      2. The supply voltages of the ISO6721-Q1 can be different voltages within the recommended operating conditions listed in the datasheet. Since the isolation barrier separates the two sides from each other, each side can be independently powered with different supplies. This means that the VCC voltage selected should be in the ranges listed under the recommended operating conditions.

      3. Since 2V for VCC1 is outside the ranges described in the image above (2V is greater than 1.89V), the channel outputs would be in undetermined states.

    2. If Q1 answer is No, could you please tell me any device which can be used for level shifting from 2V to 3.3V with isolation?
      1. I believe we do not have any digital isolators that are compatible with 2V for VCC1 or VCC2. Most of our isolators support VCC of 1.8V, 2.5V, 3.3V, and 5V.
        1. The ISO6721-Q1 supports 1.8V, 2.5V, 3.3V, and 5V. 

    Regards,
    Aaditya Vittal

  • 0 in reply to Aaditya V.
    Guru 21645 points

    Hello Vittal,

    Thank you very much for your reply and I'm sorry to be late my response.

    I understood that TI digital isolator VCC1/2 voltage range don't support 2.0V.
    The customer has one question about ISO6721as the follow.
    Could I ask you it?

    Q. Why TI digital isolator VCC1/2 voltage range can not support 2.0V?
         Is the reason come from process spec limitation?

    Thank you again and best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Mastermind 29535 points

    Hello Kazuya, 

    These ranges are designed around standard supply for logic circuits, 1.8V, 3.3V, and 5V. The range in between is an uncharacterized range and it is not recommended to operate here. The reason for the gap is mostly because it follows the voltage standard for TI's devices. 

    Best,
    Andrew