ISOW7741: The input voltage and isolated output voltage of ISOW7741

Part Number: ISOW7741

My customer has a question regarding the input voltage and isolated output voltage of ISOW7741. That is whether the integrated isolated dc/dc converter can boost the voltage (It is shown in the datasheet that the input voltage range is 3V to 5V).

For example, when the input voltage is 4.5V, the isolated voltage can also be 5V, is that correct?

Regards,

Xiaoying

  • Hi Xiaoying,

    Thanks for reaching out.
    ISOW7741 does support an input supply range of 3V to 5.5V but it doesn't support 3.3V input to 5V output boost operation. Regulating output to 5V when input is 4.5V to 5.5V still falls in the same buck operation. This is possible due to slightly higher transformer turns ratio than 1:1. This is was specifically done to support ±10% variation in input supply voltage. Thanks.


    Regards,
    Koteshwar Rao

  • Hi Koteshwar,

    So you mean when the desired output is 5V, the input must be ±10% variation of that, that is 4.5V to 5.5V, right? But how much margin is needed exactly? If the input voltage is exactly 4.5V or even a little bit lower, is there any risk for the output? Or what will happen to the regulated 5V output? Thanks.

  • Hi Xiaoying,

    I won't be able to comment on the margins we have to the specifications provided in datasheet but the regulated output voltage that we guarantee in datasheet is for an input voltage of 5V ± 10% as stated in the datasheet.

    If the input voltage is exactly 4.5V, this is covered in datasheet guarantee. If it is slightly lower, it shouldn't cause any issues but this is not in the range of what is guaranteed by TI. If input voltage goes further down, then we don't expect the device to get damaged but you might see higher output ripple or under worst-case the output might go below the guaranteed voltage. Thanks.

    Regards,
    Koteshwar Rao