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Negative to Positive DC/DC

Matthew Webster
Prodigy 50 points

Hello, I am looking for some information regarding a DC/DC design that can take me from a -V to a +V.  Due to the details of the project I am unable to provide much detail on a public forum, is there someone i can talk to directly?

Regards,

Matthew

  • 0
    TI__Mastermind 46905 points

    Hi Matthew

    maybe you could use a boost converter as following. could you just share the input voltage range, output voltage and output current? other engineers may have better suggestion.

  • 0 in reply to Jasper Li
    Prodigy 90 points
    Jasper,

    Thank you for your response. The input voltage range will be between -30V and -20V, with a -24V nom. Output would be +5V @500mA max.

    I found a Tina file slvm755.tsc, is there a way I can modify it to show the system? Also, What would the level shifter look like?

    Lastly, I would consider other topologies like a flyback if you think it could be a better option.

    Regards,
    Matthew
  • 0 in reply to matthew webster
    TI__Mastermind 46905 points
    Hi Matthew
    Please refer this application note i just found "Negative Input to Positive Output made SIMPLE"
    www.ti.com/.../snva740.pdf

    as i know, the circuit can's simulate in TINA, because the internal circuit of the model is connected to zero volt. but we need to connect the GND pin of the IC to -24V in this circuit. i would suggest you post a new question in the forum about the simulation tool. maybe engineer there have a solution. should be this link "e2e.ti.com/.../"

    flyback is also a solution, efficiency should be higher. but you need a transformer and the output voltage feedback is still a challenge.
  • 0 in reply to Jasper Li
    Prodigy 50 points
    Jasper,

    Reviewing the datasheet I discovered a few discrepancies between the schematic (figure 2) on P.2 and the BOM (table 1) on P.8. Can you please advise which are correct?


    Item DESIGNATOR Schematic Value BOM Value
    ---- ---------- --------------- ----------
    1 Cc 0.22uF 0.1uF
    2 Cin1 56uF 10uF
    3 Cin2 10uF 1uF
    5 Cout3 10uF 1uF
    12 Rfbt 4.07k Not standard Value
    13 Cc2 1nf Not in BOM
  • 0 in reply to Matthew Webster
    TI__Mastermind 46905 points
    Hi Matthew
    i had replied you through email