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WEBENCH-POWER-DESIGNER: Design power supply with dual outputs

Mark Thompson2
Intellectual 620 points
Part Number: WEBENCH-POWER-DESIGNER
Other Parts Discussed in Thread: UCC256402, UCC28180

Hi there,

I managed to design a power supply that meets my PVDD requirements (for driving multiple Class-D amplifiers) using WEBENCH, but I'd like to include a second Vdc output to drive the logic on my PCB's too.  Is it possible to setup WEBENCH to design a power supply with dual (or even 3) different output supplies?

My design requirements:

240 Vac (10 A 50 Hz supply here in Australia) as input voltage source

Output 1:  24 Vdc, max 30 A (isolated so no/very low switching noise in the outputs)

Output 2: 5.0 Vdc, max 3 A (again isolated)

Are you able to assist me with this please?

Many thanks.

Mark

  • 0
    TI__Guru* 78126 points

    Hello,

    At this power range you are going to need a PFC front end.  I would recommend using the UCC38180 for 240 AC off line to 390 V regulated boost voltage.  

    There is a Webench design tool you can use at the following link for this design.  https://www.ti.com/product/UCC28180?keyMatch=UCC28180&tisearch=search-everything&usecase=GPN#design-development

    For the 390 V to 24 V 30 A output you might consider doing an LLC design using the UCC256402.  This device has zero voltage switching and is quite efficient.   You can find a Webench design tool at the following link.  https://www.ti.com/product/UCC256402?keyMatch=UCC256402#design-development

    When it comes to dual output supplies even though Webench may not be setup for it you can do it with a little bit of thought.  For example if you were designing using the LLC.

    1. You would do one design based on the total output power 24V*30A + 5V*3A = 735 W with a Vout of 24 V.

        a. This will give the correct transformer turns ratio for the 24 V output and the correct primary magnetizing inductance and power stage before the transformer.

     

    2.  Next, you would do a design for the 24V 30A output and this will give you the components for the 24 V secondary.

    3.  Last you need to a design for the 5 V 3 A output and this  will give you the components for the 5 V 3A output.

    If you decide to use the UCC28180 and the UCC256402 in your design and have questions.  You will need to repost in e2e with UCC28180 and UCC256402 in the thread title so the appropriate applications engineer can help you.

    Regards,

  • 0 in reply to Mike O'
    Intellectual 620 points

    Thanks, Mike!

    I don't currently have access to a power supply designer internally, so I was using WEBENCH to first validate the concept can be achieved.

    You suggested the UCC38180 for the 240 AC to 390 V regulated boost voltage.  The Webench tool you linked to was the UCC28180.  I'm assuming they are equivalent.  My first question here is what would the output current need to be for the 390 V in the simulation to ensure its use for the later stages?

    The LLC topology may be better for our audio application.  I will look further into that.

    Thanks for your advice regarding designing the dual output supplies within Webench, that makes complete sense now.

    Kind regards,

    Mark

  • 0 in reply to Mark Thompson2
    TI__Guru* 78126 points

    Hello,

    Sorry about the typo the UCC28180 is the correct device.

    Regards,

  • 0 in reply to Mike O'
    Intellectual 620 points

    Thanks, Mike.  Do you suggest setting the output current to 2A for the UCC28180 designer?

  • +1 in reply to Mark Thompson2
    TI__Guru* 78126 points

    Hello Mark,

    I am going to assign this to another application engineer to help you in the future.

    The PFC does need to be designed to be designed to handle more power than the LLC step down converter.  2A is roughly 108% of the output power.

    The LLC will be roughly 94% efficient so to be safe. I would design the PFC for 115 to 120% of the total output power.

    Regards,

    Mike

  • 0 in reply to Mike O'
    Intellectual 620 points

    That's fine Mike.  Your answer was all I need for now.  I really appreciate your assistance!

    Cheers,

    Mark

  • 0 in reply to Mark Thompson2
    TI__Guru* 78126 points

    Hello,

    I was glad that I could help.

    Regards,