I am working on a project where the aim is to charge two energy storage capacitors to +/- 200 V to give 400 volts between them for use in a constant-current stimulator. The input I'm hoping to use is equivalent to a USB power connection (5 V, up to 500 mA) and I'm looking at a flyback topography with two windings on the secondary side to give me the positive and negative voltages.
Browsing through the list of analog products under flyback controllers, step-up controllers, and even photoflash capacitor chargers yields a long list of parts that I am unfamiliar with. What are the recommended chips that I should start looking into that would be best/most efficient for 5V to 200V capacitor charging? My main focus is on efficiency rather than speed of charging.