I have an application that it appears the LTC7840 would work well for.
I have a supply of 5.5V to 32Vdc and need an output of 280V. Using the 7840 as a two stage with the first stage handling the wide input range and the second stage handing the large step-up seems like a solid plan. ADI has a demo board (DC2744) that demonstrates this.
The differences are:
1) The DC2744 does 9 to 36V input. I need to get down to at least 6V input.
2) The DC2744 output is 240V and I need 280V.
3) On the bright side I need only 200mA and the DC2744 provides 700mA.
What do I need to do to get the DC2744 to work down to 6V instead of 9V?