# Fifth Lichuang Electronic Design Competition# Simple and low-cost all-digital adjustable DC power supply

1. Self/Team Introduction

An ordinary electronics enthusiast.

2. Briefly introduce the project

When debugging hardware equipment, we may need a 5V, 9V or 12V power supply, but it is impossible to have all of them on hand. Such a simple adjustable power supply that can step up and step down is very convenient. Add an ordinary power supply when going out. The power bank can be turned into a mobile adjustable power supply. It is greatly convenient for our daily or outing use.

3. Project introduction:

1.DC input or USB input, wide voltage input and output.

2.LCD displays current voltage, current and other parameters

3. Convenient human-machine operation, use 1 encoder to quickly and easily adjust the required voltage

4. Describe project details

Based on the SC8721 digital adjustable power supply, the main control uses Cortex-M0's STM32F030 or GD32F330, the display uses a 0.96 LCD, and the parameter adjustment uses a rotary encoder.

The display interface is as follows:

In the first line, set _0.02V or _0.1V behind the voltage display as the step value of the rotary encoder. Press the encoder once and the voltage step will be 0.02V. Press it once and the voltage step will be 0.1V. Press it again. Current limit setting, if pressed again, returns to voltage setting.

The second line sets the current limit display and current limit. The default is 0, which does not limit the subsequent status flags CV or CC.

The third line is the actual measured value of the output voltage AD, followed by the status flag indicating whether it is a boost or a step-down.

The fourth line, the actual measured value of the output current AD, and the power value

5. Describe the challenges faced by the project and the problems solved

Since the chip used this time is similar to PD fast charging, it is convenient but also has limitations. The test has the following questions:

        1. According to the chip manual, the output range is 2.7V~22V, so it cannot be used in the range lower than 2.7V. The same is true in actual tests. When lower than 2.7V, the power output hiccups under load and cannot be used normally. Can this be used? Solved by internal hidden register?

        2. This chip can set the output current limit to prevent overload or short circuit. The actual measured current limit is about 260mA. If set lower than this value, the current limit will not work.

6. Describe the key points involved in the hardware and software parts of the project

The hardware of this power supply is very simple. There is no need to use analog devices. The PCB has a good high-current layout and just adjusts the IIC.

7. Project material list display

1.         MCU: STM32F030F4 or GD32F330F4 are acceptable.
2.         Power chip: SC8721 is the protagonist of this adjustable power supply. Powerful function, IIC communication.
3.         0.96 LCD.
4.         Rotary encoder.
5.         A certain amount of resistance and capacity.

8. Upload project pictures

8.1. Print the competition logo picture on the PCB. Failure to do so will be deemed as giving up the competition < br > PCB:   Welded pictures  5.2. Other pictures of the project. Several sets of common voltage test pictures.      I didn’t have an electronic load on hand, so I simply tested the current with a power resistor. Procedure No calibration Output short circuit protection

* 6. Demonstrate your project and record it as a video for uploading

6.1. Video upload contest official website

uploaded

6.2. Video title and link at Station B

The 5th Lichuang Electronic Design Competition: Simple and low-cost fully digital adjustable DC power supply--Function Demonstration & Performance Test

https://www.bilibili.com/video/BV1uA411J79B/ * 7. Is it the first public release?

7.1. Please indicate whether the project has been published or won awards before.

no

7.2. If the project is optimized on the original basis, please explain the optimization part

no

* 8. Open source documents

none

* 9. References

none

Click the link for more details: https://www.szlcsc.com/go/dsxq