Post Go back to editing

Supply LTC7803 with a different voltage than the mosfets

Category: Hardware
Product Number: LTC7803

Hi,

For a specific application, we would like to use the LTC7803 with a different voltage than the one supplying the switching mosfets.

The LTC7803 would be supplied through its VIN pin with 5V and the mosfets with 8V. 

We tested it with an evaluation board, it seems to be ok.  But we would like to make sure that the LTC7803 does not need to have the same supply as the switching mosfets.

Thank you

Parents
  • FormerMember
    0 FormerMember

Hello,

I'm assuming you are inputting the 8V through the EXTVCC, is that correct? In that case, this should be fine. When EXTVCC is enabled(>4.7V), the INTVCC gets its power from the EXTVCC, bypassing the LDO from VIN.

Regards,

Jhun

  • Hello Jhun,

    No, we would like to supply the LTC7803 through Vin pin with 5V. ExtVcc is not used and tied to GND. And the mosfet are supplied by 8V.

    Regards,

    Quentin 

  • FormerMember
    0 FormerMember in reply to quentinwa

    How did you do it exactly on an evaluation board? Since the BG and TG is integrated in the controller and INTVCC only regulates to 5.15V where it powers the TG and BG, can you share a schematic? Thank you!

  • I desoldered R3 resistors (in the DC2834 schematic found in https://www.analog.com/media/en/technical-documentation/eval-board-schematic/dc2834a-schematic.pdf), to connect a 5V power supply to the LTC7803 VIN pin.  RUN pin is also connected to the 5V supply with the pin-header.  All the rest of the board circuit is connected to a 8V power supply with Vin power plug.


    Because the LTC7803 generates its own IntVcc, it seemed ok for us to do it, but we want to make sure it would not cause any issue.

  • FormerMember
    0 FormerMember in reply to quentinwa

    This should be fine.

    Regards,

    Jhun

  • Reply
    • FormerMember
      0 FormerMember
    in reply to quentinwa

    This should be fine.

    Regards,

    Jhun

    Children
    No Data