A lot of power supply designs are here and there on the Internet, but not all of them have constant current and voltage modes. You can read the following Q&A in electronics.stackexchange to learn what constant current and voltage modes mean.
Elia over Hackaday.io built a linear bench power supply with the following features:
- Output voltage range: 0 – 15V.
- Output current range: 0 – 3A.
- Constant voltage with current limiting and constant current modes.
- LCD interface.
LT3083 the adjustable 3A low dropout regulator from Linear technology is used to provide the output voltage.
To reduce the power dissipation in the linear regulator, supply voltage is not connected directly with the adjustable LDO regulator input. Elia added a stage to reduce the input voltage of LT3083 to (Vout+2) using a buck converter. This Buck converter, TI TPS54331, is configured to follow the output voltage of the adjustable regulator plus 2 volts as an output voltage of the buck converter.
ATmega8 MCU is used to drive the 16*2 LCD, read values from the rotary switch STEC12E08, read user buttons and to produce the reference PWM signals for voltage and current.
These PWM signals are converted to analog value, the way used to convert the PWM signal to an analog value proportional with PWM is by using “resistor, a capacitor and an opamp”.
LM334, an adjustable current source, used in the output voltage of LT3083. Elia said in a log, it is needed for stable operation, the LT3083 needs a minimum load current of 1mA.
Design Files and Source Code
ElbSupply is an Open-source hardware project. You can download the source files from the GitHub repository.