I want to build a bench power supply. My basic reqirements are:
- 0 - ~30V adjustable output voltage
- 0 - ~2A adjustable output current limit
- input from mains
I found this design by EEVblog guy loosely fitting my requirements, except for point 3. So my idea was to insert isolated switchmode converter beetwen the mains and said circuit like this: Swithing converter would output voltage needed at the output + linear regulator's dropout voltage. The converter would: convert 230V to lower voltage without the need of bulky transformer, isolate output from mains and reduce power dissipated on linear regulator - without converter in the worst case scenario power on the regulator could be as high as 60W in my case, while with converter outputing voltage 2V higher then output voltage maximal power on regulator equals 4W.
So I started looking for the switching converter IC that satisfies these conditions:
- Mains input voltage
- 0-30V adjustable output voltage
- 2A output current
I searched mouser, digikey and tme and didnt find single IC that satisfies both 2 and 3. Am i expecting too much from a single IC, or am i just bad at searching?
If such ICs really aren't available, would you advise me to achieve my goals in 2 separate converters (one isolated non-adjustable converter lowering voltage to <50V and second adjusting the voltage to the needed value), or rather to design my own DC-DC converter control circuit(my knowledge about switchmode power supplies is very limitted)? Or maybe the whole idea is ill-formed and the best way is to use a 50Hz transformer, large heatsink and fans?