Analysis of digital power supply circuit designed by foreigners using AVR!!

The above circuit is a digital power supply designed by a foreigner using an AVR microcontroller .

It uses key input and LCD display, and only uses a single chip microcomputer and a few peripheral components to form a power supply. The design idea is very good. It is worth learning from...

There is one very good point in his circuit design...

DA circuit... There is no DA circuit in the AVR microcontroller... It uses the IO port plus resistor voltage division method to complete the DA circuit... This can save a DA. So the circuit is more concise...

HE HE... Actually the whole circuit is not very complicated... I will now separate the various parts of the whole power supply circuit... Friends who like analysis can discuss it together. I hope we can learn from each other during the discussion. Haha. It would be even better if the circuit can be improved...

1. Power supply circuit

This power circuit inputs 30V and outputs 5V... Good design idea...

Use a high-power voltage regulator diode to reverse breakdown voltage to reduce the voltage . Then power the 7805 to provide the voltage of the entire system...

2. Output stage

Convert the DA output current signal into a voltage signal... Negative feedback is conducive to the stability of the output... The final stage uses a composite tube that can significantly increase the output current... And when outputting high-power transistors , the CE pole is connected to a protection diode...

3.DA circuit

The DA circuit uses a resistor plus an IO port... The output is in the form of a current signal... The greater the output current, the higher the output voltage...

4. Voltage sampling circuit

This is to sample the output voltage. Feedback to the microcontroller...control DA to achieve stable output voltage...Because the load becomes heavier or lighter, the output voltage will increase or decrease. It is necessary to add this sampling circuit...

5. Current sampling circuit

Current sampling uses negative terminal resistance sampling... In this way, the sampled voltage is relatively low and can be directly sent to the microcontroller for processing... The higher the sampled voltage... The greater the current. Overcurrent protection can be set in the microcontroller... Hehe, I personally feel that it would be better to detect the current at the positive end. But that would be very costly and difficult to implement.

6. Display circuit

HE HE There is nothing much to say about this. It is just an LCD... The LCD display and keyboard share the IO.

7.Keyboard circuit

It is also quite common. It shares the IO port with LCD...

8. In addition, there are some interfaces such as IC bus and others . They are also quite common. You can add a 24C08 or something. Power-off memory is also possible.

The entire power supply is composed of the above parts...