Summary of 3A Variable Bench PSU with Color Display
This article details the design of a 3A variable bench power supply unit. The core analog section utilizes an LM350 linear regulator, while digital features like voltage/current readouts, temperature monitoring, and smart fan control are managed by an ATMEGA8 microcontroller. The system incorporates an ADS1115 ADC for precision, an ACS714 breakout board for current sensing, and an LM35 sensor for thermal management. A standout feature is the use of a low-cost 128x64 SPI color display driven by an ILI9341 controller, requiring a level shifter for operation. The firmware was developed in C using WinAVR with modular code structures for easy debugging.
Parts used in the 3A Variable Bench PSU:
- LM350 linear regulator chip
- ATMEGA8 microcontroller
- ADS1115 16-bit ADC
- ACS714/5A current measuring breakout board
- LM35 temperature sensor
- SPI controlled cooling fan
- 128x64 SPI colour display
- ILI9341 display driver/controller
- 5V to 3.3V level shifter
I am playing with electronics since i was a child and made numerous circuits.But still now,i didn’t made any power supply unit for general purpose use.So tired of making PSU for each circuit,I decided to make a stable Bench PSU for general purpose use with some enhanced features.I decided to made the core power supply analog controlled and extra features digitally controlled.
So that’s why i choose LM350 linear regulator chip as the heart because 3A is sufficient for day to day use.
For the digital part,the functionalities i choose are listed below:
1.Digital readout of Voltage.
2.Digital readout of current.
3.Digital readout of LM350 temperature.
4.Smart Fan controlled cooling for LM350.
All the mentioned criterias were fullfilled by ATMEGA8 so it was finalized for this circuit.
The ADC i choose is ADS1115 which is 16 bit ADC.I will discuss about it later.
Now for current measuring,i used ACS714/5A breakout board which does it job pretty good.
LM35 is used as the conventional temperature sensor and it also does it job perfectly.Atmega8 senses temp and controls the fan according to it.
Now last but not the lease…the Display!!!Generally we see 16×2/20×4/128×64 monochrome type of display in this type of power supply.But i thought something different and used really cheap 128×64 SPI colour display.It generally uses ili9341 as it’s controller and is pretty popular as display driver.It is SPI controlled.But you need 5v to 3.3v level shifter to run this type of display which are available at the market and are pretty cheap.
Now comes the software part.Coding the software took me a lot of time.I put enough comments at the end of each line by which anyone cans easily understand the functions.I modularized the code so debugging is very easy.I used winavr and C to write the code.
For more detail: 3A Variable Bench PSU with Color Display
So that’s why i choose LM350 linear regulator chip as the heart because 3A is sufficient for day to day use.
For the digital part,the functionalities i choose are listed below:
1.Digital readout of Voltage.
2.Digital readout of current.
3.Digital readout of LM350 temperature.
4.Smart Fan controlled cooling for LM350.
All the mentioned criterias were fullfilled by ATMEGA8 so it was finalized for this circuit.
The ADC i choose is ADS1115 which is 16 bit ADC.I will discuss about it later.
Now for current measuring,i used ACS714/5A breakout board which does it job pretty good.
LM35 is used as the conventional temperature sensor and it also does it job perfectly.Atmega8 senses temp and controls the fan according to it.
Now last but not the lease…the Display!!!Generally we see 16×2/20×4/128×64 monochrome type of display in this type of power supply.But i thought something different and used really cheap 128×64 SPI colour display.It generally uses ili9341 as it’s controller and is pretty popular as display driver.It is SPI controlled.But you need 5v to 3.3v level shifter to run this type of display which are available at the market and are pretty cheap.
Now comes the software part.Coding the software took me a lot of time.I put enough comments at the end of each line by which anyone cans easily understand the functions.I modularized the code so debugging is very easy.I used winavr and C to write the code.
For more detail: 3A Variable Bench PSU with Color Display
- Why did the author choose the LM350 linear regulator?
The author selected the LM350 because its 3A capacity is sufficient for day-to-day use. - Which microcontroller handles the digital functionalities?
The ATMEGA8 microcontroller was finalized to handle digital readouts and smart fan control. - What type of ADC was chosen for this project?
An ADS1115 16-bit ADC was chosen for the circuit. - How is current measured in this power supply?
Current is measured using an ACS714/5A breakout board. - What sensor is used to monitor the LM350 temperature?
An LM35 conventional temperature sensor is used to sense temperature and control the fan. - What kind of display was used instead of standard monochrome types?
A cheap 128x64 SPI colour display was used for the project. - What controller does the colour display use?
The display generally uses the ili9341 as its controller. - What is required to run the 128x64 SPI colour display?
A 5v to 3.3v level shifter is needed to run this type of display. - What software tools were used to write the code?
The code was written using WinAVR and C.
