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I am working on a circuit based on the LT1930 (DC634A) to boost input voltage between 30 and 90V.

I would like to take this boosted voltage and double it via a Dickson charge pump to the required ~160V.

This would allow for a variable voltage output between 60-180V. The current draw from this boosted supply is very low, ~1uA.

A logic level PWM signal will drive the Dickson charge pump.

I am having difficulty figuring out how to drive the boosted voltage through the C1 based on the PWM clock. I have setup a NPN driven by the PWM signal to switch a PNP MOSFET to high side switch the boosted HV.

When I run simulations, the output voltage does not double.

R1 and R2 are set to give a Vgs ~10V, but then this causes the drain on the FET to only vary between 80 and 70V.

I am open to suggestions, including completely wiping this circuit and using something else to generate a controllable ~100-180V.

CircuitLab Schematic rrtb78u26j6e

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    \$\begingroup\$ You need another FET to connect the drain of M1 to ground when it isn= not conducting. If you don't C1 will charge up to 80V then not do anything else. \$\endgroup\$ Commented Feb 28, 2021 at 19:39

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You already have nice high-frequency (2.2MHz) AC at the converter chip SW terminal.

Try adding 2 or 3 more stages to the converter and 2 stages to the feedback divider. Each converter stage is 2 diodes, one resistor and 2 capacitors. Each feedback stage is 35.7K in parallel with 150nF.

enter image description here

Obviously you'll have to increase the voltage rating on C7 as well.

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  • \$\begingroup\$ Oh, that does sound simpler to implement and keeps the BOM tidy. \$\endgroup\$
    – dtk
    Commented Mar 2, 2021 at 1:07
  • \$\begingroup\$ Just curious -- what do resistors R1 and R2 accomplish? Thanks. \$\endgroup\$ Commented Nov 25, 2023 at 18:28

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