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Isolated 12V supply for gate drivers

Céline Mathis
Prodigy 80 points
Other Parts Discussed in Thread: SN6501, SN6505B, LM25180

Hello 

I am need for two outputs of a gate driver two isolated 12V power supply to load the Cboot. How is it the easiest way to generate this two 12V power supplies? 

I found the SN6501 and SN6505 but I haven't found a transformer with two 12V outputs.

Regards

Céline

  • 0
    TI__Guru 55795 points

    Hi Celine,

    Thanks for reaching out.

    Please refer to the below application note that lists various transformers that can be used for generating 12V and 15V. Most of these transformers generate bipolar supply outputs and it seems like you are looking for two positive output voltage isolated supplies. We currently do not have a transformer to recommend for SN650x to generate two 12V isolated outputs. I would recommend reaching out one of the transformer vendors for recommendations and they should be able to suggest a suitable transformer to go with SN650x.

    Signal and Power Isolation with 3.3 V / 5 V Input and 12 V / 15 V Output

    If I do find a transformer for your requirement (assuming current of <100mA on each rail), I will come back and list it out here. Thanks.


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Prodigy 80 points

    Hi Koteshwar

    Thanks for your answer. I look again for a suitable transformer. I don’t want to use a customized transformer.

    Is there another easy solution to build two isolated 12V supplies? 

    Regards

    Céline

  • 0 in reply to Céline Mathis
    TI__Genius 17100 points

    Hi Céline,

    I am Manuel, a colleague of Koteshwar's supporting TI's SN6501 and SN6505 devices. Are you looking to build two isolated 12V output supplies with separate 12V inputs, or would the 12V outputs share a common 12V-input supply?


    Thank you,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    Prodigy 80 points

    Hello Manuel

    I would like to have one input with 12V or 5V and two isolated 12V outputs.

    Regards

    Céline

  • 0 in reply to Céline Mathis
    TI__Genius 17100 points

    Hi Céline,

    If the two 12V outputs should be isolated from each other, the configuration below can be used:




    The transformer outputs do not need to be isolated from each other and can share GND potentials on the output side in this topology too. This configuration is optimal for 5V inputs since the input power supply can be connected to SN6505's Vcc directly. SN6505B can be used, and the transformers will need turns ratios ~3.1 to step the voltage up to 12V, like Pulse's PH9185.013NL or Coilcraft's JA4650-BL. Turns ratios would need to be slightly higher if an LDO is used to regulate the outputs.

    The downside of using this topology with 5V connected is that less current will be available on the output sides combined -- limited by a factor of 1/N, the turns ratio of the transformer used. If support for load currents >300mA is needed or if a 12V input power supply is preferred, please let me know and I can share additional options.


    Respectfully,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    Prodigy 80 points

    Hello Manuel

    Is this solution with two transformer? I have to do a redesign and there is not alot of space. It would be better if I have to place only one tranformer for the two outputs. I dont have a preference for the power supply, I have a 12V and a 5V power supply on the PCB. The most importent part is, that the circuit is small, available and not too expensive.

    Regards

    Céline

  • 0 in reply to Céline Mathis
    TI__Genius 17100 points

    Hi Céline,

    The solution I shared above shows two transformers in separate packages, but two transformers integrated into a single package can be configured in the same way. I am not aware of a commercially-available part that would support two 12V outputs like this, but you can check with your preferred magnetics vendor since many are willing to make custom devices meeting your electrical and layout requirements.


    Thank you,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    Prodigy 80 points

    Hi Manuel

    This is my problem that I cannot find the right transformer. So is there another solution than with the SN6505?

    Regards

    Céline

  • +1 in reply to Céline Mathis
    TI__Genius 17100 points

    Hi Céline,

    If custom transformers are not an option, different power supply topologies can have more transformer options with two 12V outputs, like 750313443, which is a flyback converter transformer and can be used with a flyback converter like TI's LM25180.

    Are you interested in using a different power supply topology, like flyback or buck?


    Thank you,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    TI__Genius 17100 points

    Hi Céline,

    I hope you have found a solution to this question. Since no response has been posted, this thread will be closed.

    Please feel free to follow up by replying or creating a new thread using the red and yellow buttons in the upper right corner of this window.


    Thank you,
    Manuel Chavez