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ISO7220A-Q1: How to Isolate the positive and negetive voltage ?

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Replies: 7

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Part Number: ISO7220A-Q1

Hi

   In my design , I would like to use ISO7220 to isolate the negetive and positive signal,  the signal is send to MCU which is in the positive voltage domain.  Is the function right ?

  • Hi Liang,

    This application is correct as long as the signal and GND pairs are preserved on each side of the ISO7220A-Q1 as shown in the image below.



    The microcontroller's 3.3V supply can also be used to power the output side of the isolator. The input side must be powered by a 3V - 5.5V supply referenced to the input side ground, gnd2. Is a supply for this pin available?


    Thank you for posting to E2E!
    Manuel Chavez

  • In reply to Manuel Chavez:

    Hi Manuel,
    Thanks alot !
    Yes, gnd2 is avilable in the input side . I am clear about it , but I found there is another problem: the battary charge block in negetive voltage domain can not work , I need to solve it
  • In reply to liang ren:

    Hi Liang,

    What kind of problem is the battery charge block having? Is it powering on? A part number will be helpful in case there is a dedicated team to help us with that specific device.

    Regarding the previous conversation, I should have mentioned that the ISO7220A-Q1 is a very old part. Please consider designing with the newer, more capable ISO7720. The two devices are pin-to-pin compatible and the ISO7720 has higher isolation ratings.


    Thank you for your time,
    Manuel Chavez
  • In reply to Manuel Chavez:

    Thanks ,I will use ISO7720 in normal digital isolation. At the beigning , I would like to design two battary charger board , and the two board is conected in series inorder to generate negetive voltage, I can not use the input negetive power to charge the second board , otherswise using a switch to split the two board when charging , and connect when working . But this method will be difficult for battary voltage detect circut , because when charging I can use the passive balance IC to detect the battary voltage , but when discharge the balance IC has some negetive common voltage input , I think it will not work.
  • In reply to liang ren:

    Hi Liang,

    I understand that you would like to design with two battery charger boards connected at different operating times/modes. Can you please show this in a block diagram? It may be necessary for me to contact engineers in a power management team to help.


    Thank you,
    Manuel Chavez
  • In reply to Manuel Chavez:

    Hi Liang,

    Are the battery charger boards working now? Which devices are being used? I will await your response.


    Thank you,
    Manuel Chavez
  • In reply to Manuel Chavez:

    Hi Liang,

    This thread has been idle for the past couple weeks and it will be closed. Please feel free to post a new or follow up question using the red and yellow buttons on the top right corner of this window.


    Thank you for posting to E2E!

    Best,
    Manuel Chavez

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