Power supply designers often face conflicting requirements. On the one hand, it should reduce the size and cost, on the other hand, it should provide more functions and improve the output power. Limited by the principle, the function of analog power supply controller itself is limited, and the design of analog power supply controller is more and more complex. For this reason, some designers have turned to pure digital power designs. However, it is not easy for many designers to switch to unfamiliar territory so quickly. A good compromise is to use a traditional analog power supply, but add a digital microprocessor as the front end.

The advantage of this design is that the control of the power supply itself is still implemented using analog technology. So the power supply designer can add new functionality to an existing design without having to reinvent the digital design from the ground up. Using this method, familiar error amplifiers, current detection, and voltage detection circuits are still used in the design. Of course, while some design units (such as compensating networks) still use discrete components, the rest is controlled by microprocessors. Control and monitoring

The functions of a microprocessor can be divided into four categories: control, monitoring, judgment and communication. We will discuss these types of functionality in more detail below.

The first type of control function relates to the hardware interface between the microprocessor and the power supply. In analog design, it is important to preserve the interface for the connected microprocessor. Some power controllers generate control signals internally (such as reference voltages), and such controllers provide few external connections to the microprocessor. However, Microchip's MCP1630 power controller is designed to provide ample connectivity for microprocessors. For the purposes of this article, we assume that the power controller provides two control points -- the ability to turn off the input and set the reference voltage, as shown in figure 1. Although these two join points may not seem like much, they already provide very powerful control and complexity.

At present, the main function of microprocessor in many power supply designs is monitoring. Many microprocessors are equipped with analog to digital converter (ADC) and analog comparator. Therefore, microprocessors are ideal for monitoring input voltage, input current, output voltage, output voltage, temperature and other signals.

By being able to monitor such a wide range of signals, microprocessors can perform more functions, such as intelligent fault detection. The multifunction of microprocessor derives from its programmable ability, which can be conveniently designed to meet the design requirements. In this way, the fault situation can be classified for processing. Transient overloads and other non-critical failures may require only a flag. In the case of overheating, the power may need to be turned off until the problem is resolved. Faults that require restarting the power supply can also be more tightly controlled. If there are too many failures over a certain period of time, the microprocessor can shut off the power permanently.

The processing power of a microprocessor can also enable complex computational measurements, such as real-time calculations of power. Determining the power value in a simulation system requires complex simulation calculations. But for microprocessors, it's a small thing. Parameters such as input power, output power, efficiency and power loss can be calculated.