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Super Cap Boost converter Suggestion

Velmurugan
Intellectual 2220 points
Other Parts Discussed in Thread: BQ24640, LM5122

One of our customer want us to suggest a device and solution that can charge a Super cap 12000F (2no’s in Parallel).

The input is 12V and they want charging voltage of 5.4V.

Battery team suggested to use bq24640.

Once the power goes they want a boost circuit that can take 5.4V and boost it to 12V / 300A for 20 to 30 Seconds output.

The end application is storage server. Please suggest a boost solution.

  • 0
    TI__Intellectual 1435 points

    Velmurugan,

    That is quite a boost!!  A  3.6KW 12V output from a 5.4V input.     Using conventional boost approaches, the inductor switch  current would be about 700A   [300/(5.4/12)].   Avery very aggressive multi-phase boost could manage 50A/phase so you would need 12 or 13 phases.   Parallel operation of sync boost controllers across that many phases is more than a challenge.   You might try posting this to the isolated power forum where there is more experience with  KW dc-dc converters.

  • 0
    TI__Mastermind 40060 points

     

    Hi,

     

    I think the problem gets even worse when you think of the fact that the Super Cap (SC) voltage will drop to lower and lower voltages.  I don’t think we have a practical solution. 

    Say we can get the boost (using the LM5122) to operate down to 2V from 5.4V (operate the IC from the output once its started) , at 2V it will require 1000A's instantaneous current.  You would need a bunch of multiphase boost to satisfy this requirement.  At a low Vin you could get away with 30A of input current per phase, seeing as this is not continuous, you may opt to push Iin AVE to 40A per phase.  Or perhaps even 50A???

     

    The total input current is ~Pout/Vin min = Iin AVE max

    Iin AVE max/40A = phases ( a load of them!!). 

    If this is slightly interesting we can discuss timing of the phases later...