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Generating 100V ,1mA from 3.3V-low power DC DC boost converter.

Stephen Thomas
Intellectual 710 points
Other Parts Discussed in Thread: TPS61040, TPS61170

Hi,

I need to generate 100V,1mA typical from a 3.3V input supply.The power requirement is very low.There should not be any transformer in the design.

I was looking to low power dc-dc converters that could do the job.I came across parts like  MAX15061,MAX15059,MAX15031which gives only upto 80V at output.

Is there any other similar solutions that can be help ful for me, ie something that provide 100V or above at boost output?

Or do you suggest using voltage multiplier configuration at the output from a lower voltage dc dc converter?

Thanks & Regards

Stephen Thomas

  • 0
    TI__Guru*** 144080 points

    One idea is a circuit like the last figure in the app note http://focus.ti.com/lit/an/slyt380/slyt380.pdf.  Using a 1:3 coupled inductor and a higher voltage IC like the TPS61170, instead of a 1:2 coupled inductor and the TPS61040, you can get the voltage you want.  Coilcraft makes a 1:3 coupled inductor.

     

  • 0
    TI__Guru*** 140346 points

    Hello Stephen,

    You could chain two boost regulators. For example boost 3.3V to 20V, then boost the 20V to 100V.
    The coupled inductors Jeff mentioned can protect the switcher IC from the high voltage output.

    As an alternative, you could make a single boost circuit but replace the output diode and filter cap with a Villard cascade voltage multiplier.

    Regards,
    Ron M.

     

  • 0
    TI__Mastermind 48270 points

    Stephen,

     

    Why don't you want to use a transformer?

    One of the issues you'll encounter is your 30:1 Output to Input ratio.  In a inductor-based boost converter, this is going to require:

    about 97% duty-cycle

    30x the output current in the inductor and switch

    Full 100V applied to the Switch

    Using a 15:1 or  20:1 transformer, you can keep the primary voltage under 10V, allowing the use of a 3.3V to 12V or 3.3V to 18V boost converter with lower voltage internal MOSFETs while keeping the diode currents and RMS output currents much lower.