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ISOW7840: ISOW7840DWE - About VISO pin

Hide
Guru 21045 points
Part Number: ISOW7840
Other Parts Discussed in Thread: ISOW7721

Hi Team,

 

I have two questions.

 

-------

[Q1]

Our customer would like to use ISOW7840DWE more than 3pcs.

Then, can I connect each VISO(setting voltage is 3.3V) pins?

(Image is following.)

Could you please let us know if you have any concern?

 

<Image>

-------

 

[Q2]

When VISO pin output 3.3V, is it possible to apply around 3.3V(3.2V to 3.4V) to VISO(setting voltage is 3.3V) externally?

(Image is following.)

Could you please let us know if you have any concern?

 

<Image>

-------

 

Regards,

Hide

  • +1
    TI__Guru 55885 points

    Hi Hide,

    Thank you for reaching out, please find my inputs below.

    1. In generally, power supply outputs cannot be connected together directly. To do this, the power supply needs to have a specific features called "Load Sharing". ISOW7840 doesn't have this feature, hence, the outputs cannot be connected together directly.

    ISOW7721, specifically this part number alone, supports load sharing. You can connect multiple outputs of ISOW7721 together by following the datasheet recommendations in section 9.3.4 on LF/CC pin connections.

    2. No, external voltage shouldn't be connected to VISO pin. 

    Let me know if you have any questions, thanks.

    Regards,

    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Guru 21045 points

    Hi Koteshwar-san,

    Thank you for the information.

    Regards,

    Hide

  • 0 in reply to Hide
    Guru 21045 points

    Hi Koteshwar-san,

     

    I have additional question.

     

    [Q3]

    Even if no Load, does VISO pin need output capacitors(10uF and 0.1uF)?

    Our customer would like to remove output capacitors.

     

    Regards,

    Hide

  • +1 in reply to Hide
    TI__Guru 55885 points

    Hi Hide-san,

    Yes, the output decoupling capacitors are needed to filter switching supply voltage and provide a regulated DC output voltage. Without these capacitors, the output voltage wouldn't be able to hold-up and we don't expect the device to meet any of the datasheet specifications. Thanks.


    Regards,
    Koteshwar Rao