This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

SN6501-Q1: 5V to 5V isolated power

Part Number: SN6501-Q1
Other Parts Discussed in Thread: ISO1042-Q1, SN6501


I need to have a 5v to isolated 5V supply in my application, the datasheet recommends transformer both with and without LDO requirement based on the turns ratio.

I would like to know if there are any disadvantage of having without LDO on the sec of the transformer to  achieve 5V- 5Viso requirement (by using 1:1.1 transformer) as this is an unregulated output.

The load operating current will be 5mA to 75mA.

Looking forward to hear from you soon. Thanks in advance.


Anand M

  • Hi Anand,

    Thank you for reaching out and for your interest in SN6501-Q1.

    Yes, we have provided transformer recommendations for both with and without LDO. Since SN6501-Q1 is an open-loop push-pull transformer driver, the output voltage will have some variation with load. This is a good solution for those application where such output voltage variation is acceptable and there are cost and/or space constraints. If an application needs a well regulated output voltage then we recommend to use an LDO so that the output is well regulated across load.

    Apart from the output voltage variation with load and lower output ripple, there shouldn't be any other differences between the two solutions. SN6501-Q1 solutions should comfortably support 5V @ 75mA without any issues. Thanks.

    Koteshwar Rao

  • Hi Koteshwar,

    Thanks for the quick response. Yes you are rightly said about the voltage variation with load and ripple as I can see that in the characteristic graphs. I would like to also evaluate for other application such as for isolated CAN transceiver ISO1042-Q1.

    Would you recommend any special guidelines for such application when LDO is not used. What would be the output capacitor recommendation.


    Anand M

  • Hi Anand,

    I am Manuel, a colleague of Koteshwar's team supporting SN6501 and SN6505 devices. SN6501 does not have soft-start, internal current limit, or thermal shutdown features like SN6505 devices, so the maximum output capacitance recommended for SN6501-Q1 is 5uF: output capacitors of 4.7uF, 0.1uF, and other values within this limit can be used in different combinations to support the isolated load.

    We don't have special guidelines for applications where LDOs are not used since that is a typical application for SN650x devices, though we do recommend the input power supply is as stable as possible to help keep the output supply within a tight tolerance as well (since it is an open-loop topology).

    SN6501 can be used in a 5V-output configuration to power ISO1042-Q1 with additional loads within a combined ~1.75W.

    Thank you,
    Manuel Chavez

  • Dear Manuel Chavez,

    Thanks for the clarification and support.


    Anand M