Teach you to simply distinguish between analog power supply, switching power supply and digital power supply

How do we choose a power module in power supply design? The premise of the selection is that we must understand various power supplies and the differences between them, so that we can choose the power module correctly.

Analog Power Supply Introduction

Analog power supply: that is, transformer power supply, which is realized by iron core and coil. The number of turns of the coil determines the voltage ratio at both ends. The function of the iron core is to transmit the changing magnetic field. (In my country) The main coil generates a changing magnetic field at a frequency of 50HZ. This changing magnetic field is transmitted to the secondary coil through the iron core, and an induced voltage is generated in the secondary coil, so the transformer realizes the voltage conversion.

Disadvantages of analog power supply: The coil and iron core are conductors themselves, so they will generate heat (loss) due to self-inductance current in the process of converting voltage, so the efficiency of the transformer is very low, generally not more than 35%.

Application of transformers in audio equipment amplifiers: High-power amplifiers require transformers to provide more power output, so this can only be achieved by increasing the number of coil turns and the size of the core. The increase in the number of turns and the size of the core will increase the loss. Therefore, the transformer of a high-power amplifier must be made very large, which will result in: bulky and high heat generation.

Switching Power Supply Introduction

Switching power supply: Before the current enters the transformer, the switching function of the transistor is used to increase the current frequency of our usual 50HZ to tens of thousands of HZ. At such a high frequency, the frequency of magnetic field change also reaches tens of thousands of HZ. Then, the number of coil turns and the volume of the core can be reduced to obtain the same voltage conversion ratio. Due to the reduction in the number of coil turns and the volume of the core, the loss is greatly reduced. Generally, the efficiency of the switching power supply reaches 90%, and the volume can be made very small, and the output is stable, so the switching power supply has advantages that are difficult to achieve with analog power supplies.

(Switching power supplies also have their own shortcomings, such as output voltage ripple and switching noise, which linear power supplies do not have)

Audio equipment - Application of switching power supply in power amplifier: The advantages of switching power supply have been shown in the description process, so even for high-power amplifier, the switching power supply can be made very delicate and compact. At present, the digital power amplifier of Shenzhen Cuipas Digital Audio Equipment Co., Ltd. is the most advanced in China. They have developed to T-class pure digital power amplifier, and the next generation of S-class power amplifier is also under development. For details, please refer to the following information:

Introduction to Digital Power Supply

In applications that are easy to use and require few parameter changes, analog power products have more advantages because their application targeting can be achieved through hardware solidification, while digital power has advantages in complex high-performance system applications with more controllable factors, faster real-time response, and the need for multiple analog system power management . In addition, in complex multi-system businesses, compared with analog power, digital power is implemented in many aspects through software programming. Its scalability and reusability allow users to easily change operating parameters and optimize the power system. Through real-time overcurrent protection and management, it can also reduce the number of peripheral devices.

In complex multi-system business, compared with analog power supply, digital power supply can realize various applications through software programming. Its scalability and reusability enable users to easily change working parameters and optimize power supply system. Through real-time over-current protection and management, it can also reduce the number of peripheral devices.

Digital power supplies can be controlled by DSP or MCU. Relatively speaking, DSP-controlled power supplies use digital filtering, which can better meet complex power supply requirements, have faster real-time response speed, and better power supply voltage regulation performance than MCU-controlled power supplies.

What are the advantages of digital power supply? First of all, it is programmable. For example, all functions such as communication, detection, and telemetry can be realized by software programming. In addition, digital power supply has high performance and high reliability and is very flexible.

Interference: Between digital and analog in a single-chip microcomputer, because digital signals are pulse signals with a wide spectrum, it is mainly the digital part that interferes strongly with the analog part; not only are digital power supplies and analog power supplies generally separated and connected with filters, but in some occasions with higher requirements, such as when the AD converter inside some single-chip microcomputers performs AD conversion, the digital part is often put into a dormant state, and most digital logic stops working to prevent them from interfering with the analog part. If the interference is serious, you can even use two power supplies separately, generally using inductors and capacitors to isolate them. You can also connect the power supplies of the digital and analog parts of the entire board together, and use separate paths to directly connect them to the solder joints of the power filter capacitors. If the requirements for anti-interference are not high, you can just connect them together.

Kind tips

(1) If the A/D or D/A function of the chip is not used, it is not necessary to distinguish between digital power supply and analog power supply.

(2) If A/D or D/A is used, the reference power supply design must also be considered.

The above is just a brief introduction to the differences between analog power supply, digital power supply and switching power supply. If you want to become an engineer, you must learn more.