PMP2796: Solution that can generate -3000V

Hello Dice,

basically you could generate any HV out of an inverting flyback converter,
just a matter of number of multipliers or stacking secondary windings to xfmr.
Main topic here is the limited amount of input power 240mW:
- housekeeping currents of controller
- driver losses of controller
- switching losses/conducted losses FET
- bias currents of HV capacitors
- losses at feedback network
- bias currents at opto isolator (isolation might be needed at 3kV)

Each uA at your 3kV output results into 3mW; If I assume half, so only 120mW at the converter
just 120mW remaining for the load, 40uA output current left.

So to answer your question - with any boost device you could build a flyback converter;
for HV and low power run the flyback in DCM. A controller that offers low power consumption
is LM5155. An integrated FET and especially primary side feedback lowers consumption at
feedback itself, no opto bias current - so LM5180 could be a valid choice.
Watch for flyback voltage from secondary, the internal FET is limited to 100Vmax.

Best regards, Bernd

Hello Dice,

we got no reference design online that generates several kV output voltage;
starting point is a DCM flyback topology;
keep multiplier or windings stack voltage below 1kV at rectifier;
decide for PSR or opto feedback - attached two schematics on this.
be careful - you're dealing w/ HIGH VOLTAGE.

Best regards, Bernd

PMP9198opto.pdfPMP9198primary.pdf