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LM5122ZA: Start up and driving into a super cap

Part Number: LM5122ZA
Other Parts Discussed in Thread: LM5122, , LM5155

Hi Support team

My customer is looking for a solution that can accept an input from 4~5.5 volts and output 12 volts into a super cap (2mF). The idea is that they want to power the device from a current limited source and charge up a cap. They will use the energy in the cap to flash a LED. I can provide more details in a separate email. Max input current is 1.5A. The LM5122Z is perfect except for the start up at 4volts. If I disconnect the load just to get the output started and then reconnect the cap load can I use the part in this application (4 v start up)? Or is there another part that you can recommend. Key feature being the ability to set an input current limit?

Thanks

Jeff Coletti

  • Hi Jeff,

    First, why LM5122ZA but not LM5122?  The ZA version has lager package.  Either one will require 4.5V min input to start up. 

    You may consider our new boost controller the LM5155, which can start up with 2.97Vin.  However, it is a non-sync boost.  But, do you really want sync boost for this applications?

    Thanks,

    Youhao Xi,  Applications Engineering 

  • May I assume the issue has been resolved so I can close this thread here?  You can always re-open it by adding a new post.

    Thanks,

    Youhao