This project started as an incentive to gain a better understanding of power supplies and analogue design, whilst furnishing me with a reliable and hopefully accurate bench power supply. That and wanting to design it myself, rather than purchase an ebay special.
The design consists of;
- Switched mode section that converts 20V to 36V down to 3V above the required output. Makes use of a unity gain opamp with integral resistors to make a voltage follower that feeds back to the switch mode regulator.
- Linear section that converts the remaining 3V difference to the required output voltage and also provides programmable current limiting. [Ref. http://www.kerrywong.com/2013/11/24/a-digitally-controlled-dual-tracking-power-supply-i/]
- Control section of the linear regulator
- Analogue components for the ATMega MCU, namely precision voltage reference and ADC for setting the current limit and output voltage of the supply
- Digital section consisting of MCU with programming interface, LCD display and controller/switches for user interface.
- Power supply for the control circuitry, 5, +12, -12 volt output for three bench supply units.
This project is still under development and as of this time is entirely theoretical, I've not done any testing or implementation.