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LM5119, High Current O/p and Webench

aamir sheikh
Prodigy 30 points
Other Parts Discussed in Thread: LM5119

i am trying to design a dc-dc converter, and i was going to use lm5119 with its high output current and dual channels,

however if i increase my ambient temperature in webench designing tool to 50, it uses both channels for an interleaved operation,

my question is that there a relationship between output current and ambient temperature? and can i design a 12 volt 8 ampere output using a single channel only?

Also when i try to use a single channel by specifying a Vout2, it gives the following error message for Lm5119

'Can't find suitable FET for  the design, try reducing load current.'

What should i do?

also is it possible to use two lm5119 for a multiphase operation of 3-4 phases?

  • TI__Guru 58881 points

    Hi

    There is no direct relationship between output current and ambient temperature, but WEBENCH recommends 2-phase operation if the loss is too much for 1-phase convereter to handle easily at the specific ambient temperature.

    You can design 12V at 8A using 1-phase, but you may have to take care about the thermal design seriously.

    'Can't find suitable FET for  the design, try reducing load current.' means 'WEBENCH cannot find suitable FET in WEBENCH database. try reducing load current if you want to find FETs in WEBENCH database' . That does not mean impossible.

    Assuming 95% efficiency, there will be about about 5W loss which you should take care of.

    LM5119 is not designed for 3 or 4-phase operation originally, but can be configured as 4-ph. Please contact your local FAE.

    Regards,

     

     

    Regards,