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250w DCDC 24v TO +- 75V to power Audio OpAmp

Antonio Faggio
Expert 7910 points
Other Parts Discussed in Thread: LM5155

Hi,

For a new project I need some recommendations in terms of products/Ref Designs/Eval Board for:

ACDC converter, 1kW, AC in 110-230Vac, DC out 27.6V@36A with no PFC.

Afterwards this ACDC supplies a DCDC, DCin 19-30V, DCout +- 75Vdc outP250W powering an audio OpAmp. I would need high switching f here so to reduce footprints of passives. Any comments?

This post can be only for the second stage, and the following E2E for the first stage: https://e2e.ti.com/support/power-management/f/196/t/870929

Many Thanks,

Antonio

  • 0
    TI__Guru* 78240 points

    Hi Antonio,

    It is not very clear about the requirement.  Is 250W the total power for the +/-75V rails, or it is for each rail?  

    Thanks,

    Youhao Xi, Applications Engineering

  • 0 in reply to Youhao Xi
    TI__Expert 7910 points

    Hi Youhao,

    You are right, I am sorry, it is a power supply of 125W on each rail, so 250W on the whole 150V range.

    Many Thanks,

    Antonio

  • 0 in reply to Antonio Faggio
    TI__Guru* 78240 points

    Hi Antonio,

    Thank you for the clarification.  I see two options.  the first one is using a single controller but a transformer with two secondary windings to generate the coupled but separate +/-75V rails.  This will be an "isolated" topology and the simplest is the flyback with the LM5155, and you may consider external driver. Flyback usually is the best choice for <75W but I saw 300W flyback in the past.  You may consider other topologies.   

    The other option is to use two separate controllers one for +75V and the other for -75V.  For +75V you can consider the LM5155 in conventional Boost.  For the -75V, you need buck controller in the inverting buck-boost topology.  Please contact the buck group for a proper selection. 

    Thanks,

    Youhao