Need a multi-out supply with up to 50V

So you have two requirements:

Supply 1, Vin = 30 V, Vout = 2 V, Iout = 2 A

Supply 2, Vin = 50 V, Vout = 10 V, Iout = 500 mA

Or are you trying to do something else?

No. Sorry for the ambiguity. 

I will try to describe more clearly. 

1. If you look at the load on the right side of the figure 1 below, the main load is between 32V and 30V and the second load is between 50V and 10V.
    
2. Parasitic loads are mainly from 50V to GND and 32V to GND.
3. The most difficult part for me is that: we need to control the start sequence of each rail. The intended sequence is as below (also shown in figure 2):
   1. power the main load with 2V
   2. lift up the reference of this 2V to 10V, that implies 12V and 10V.
   3. keep the 10Vdc output and continuously lift up the reference of 2V to 30V, that is 32V and 30V.
   4. power up the 50V rail.
       

I think one way of generate these rails can be done as in the figure 1. But I don’t know if the way to stack one DC/DC converter on top of another is suitable or not.

The problem with this one is the sequence control and synchronization.

If my proposal of the supply is not good. Do you have some other more efficient architecture? If it is usable, how can I choose a good power management chip to control them?

Thanks a lot.

Sincerely

Kangqiao

That is rather complicated. In general nonisolated buck converters will require that the input and output voltages be referenced to ground.  i think this may require an isolated solution.  I will move this thread to that forum.