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LM5017 Questions

Andrew Meikle
Prodigy 90 points
Other Parts Discussed in Thread: LM5017

I have a requirement to regulate from 100v (max) to 5v, to power a micro and a USB (charge port 500ma) 

I have not used  or tested the LM5017 before, and I am concerned about ripple from the regulator affecting the micro.

The 100v battery input supply will dip around 4 volts when loaded elsewhere.

Questions

1. Should I regulate directly to 5 volts using the LM5017    (which Type 1,2 or 3 should I use in the design) ?

2. Should I regulate to 12 volts using the LM5017 and then re regulate to 5 volts with a conventional regulator?   

3. If the input voltage is 100.3v, will this damage the LM5017? (When fully charged the battery is 100.8v) I can add second diode to drop the voltage by 0.5v when loaded.

Thanks

Andrew

 

 

 

  • 0
    TI__Genius 11490 points

    Hi Andrew,

    1. If you use the type III there should not be any extra ripple at the output.

    2. The regulation is somewhat dependent on input voltage range. If you really need very precise regulation (say 1%) over the whole input voltage range, you may have to use an ldo or a two stage solution. In most applications however one stage solution with LM5017 will do fine.

    2. The abs max is 100V so I would keep it below that under all conditions. Diodes may help.

    The easiest way to check the solution is to get an evaluation board from LM5017 website

    Thanks and regards,

    Vijay 

  • 0
    Prodigy 35 points

    I have not used that particular Reg. But I have needed to solve a similar problem and would definitely drop in 3 or 4 stages depending on the final stage quality you need

    I dropped from 50 volts to 3  and ended up bread boarding the circuit soldered leads to the final SMD component. I work with SMD components only now and have drawn up small PCBs to attach to Veroboard or Bread Boards. Has saved a lot of problems. Try running the circuit through LTSPICE or TINA they work well for your type of project.

    ALL THE BEST

    Rachael