High voltage conversion (1000V to 25V) for low power application - Are there some application circuit close to those values?

[MLoua.1]

Hi,

For a project I'm working on, I need to design a 3.3V power source (to power a microcontroller and measure circuit), the max load should be about 100mW. I only have a voltage source around 1000V next to it and I have to use it to make the 3.3V voltage source and since I need this circuit to be as small as possible I want to avoid using a transformer so flyback converter isn't an option. I know converting 1000V to 3.3V in one stage isn't possible since the conversion ratio is enormous so I'm planning to make it in at least 2 steps, I would like my first step to be at around 25V (1/40 reduction ratio).

I tried to look at reference design from ST and found the STEVAL-VP26K01B which features Viper26K which seems interesting. But its max voltage input is 870VDC which is a bit too low. Does anyone know about an application circuit closer to the 1000V entry or has any idea of a way to tweak STEVAL-VP26K01B design to make it widthstand 1000V entry?

Thanks a lot.

[Peter BENSCH]

Welcome. @Mathis Louazé​, to the community!

1000V is definitely not an easy thing to do, even if it is "only" 100mW power on 3.3V.

The integrated switching regulator with the highest voltage is currently the VIPER26K with 1050V, which is probably too tight for possible overvoltage peaks. The STEVAL-VP26K01B is an evaluation board for 15V, 100mA, but it is only designed for up to 870VDC. Perhaps this could be used as a basis for your own development?

Hope that helps?

Regards

/Peter