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ISOW7841A-Q1: Typical/Maximum Current Available from V_ISO Supply

L Adachi
Prodigy 10 points
Part Number: ISOW7841A-Q1
Other Parts Discussed in Thread: ISOW7841

Tool/software:

For the ISOW784x 3.3V to 5V table below, I see the minimum current the VISO supply can provide an external load is about ~40mA. However, I am hoping to power a transceiver with current draws of: 30 mA minimum, 50mA typical, and 70mA maximum according to its datasheet. Are there typical and maximum current values that the VISO supply can provide? Can this isolator support power the transceiver assuming the current draws listed? 

  • 0
    Prodigy 10 points

    Also, would the total current drawn from the input supply (3v3 in this case) be the ICC listed in the table or would it be ICC + I_ISO_OUT? 

  • 0 in reply to L Adachi
    TI__Expert 7135 points

    Hi Adachi,

    Thanks for reaching out. Please find my inputs below:

    1. The correct way to read the table here is that for a particular VCC and VISO operation, the current (ILOAD) specified in the table under min column is what is definitely available and can at least be guaranteed.
      1. From the application perspective, this means that any ILOAD >40mA during VCC=3.3V/VISO=5V operation is not guaranteed to have stable VISO output although current can be drawn out from VISO..
      2. The VISO might go out of regulation if any current >40mA is demanded by external loads.
      3. In Summary - Any External Load >40mA in 3.3V to 5V operation can not be supported by ISOW7841
    2. For getting ICC values, you need to take efficiency and other current values of the device into consideration. Details of this calculation method is mentioned in datasheet under section 10.2.2. Attaching a snap below for your reference:

    Regards
    Varun