I'm trying to design a variable dual rail power supply, which has an unregulated input voltage of ~11V and a maximum output current of 1A.
I want to have a 5V/12V/20V positive and negative output. The different voltages will be controlled via switches which alter the feedback resistor.
Here's a block diagram of my design:
I chose to boost the voltage to above the maximum and then step it down as it made choosing the voltage via a switch easier.
I have had a look at many DC-DC Converters (the ones with the inbuilt mosfet), however most of them only have a very limited current capability, especially at high voltages. DC-DC Controllers however, only have a maximum voltage restriction.
So my questions are:
Is a DC-DC controller a suitable option for me to step-up/step-down the current?
Is the only different between the two the inbuilt MOSFET?
I'm not working with very much current here. Will stepping up then stepping down cause too much power loss?