ECRI Microelectronics

How does the DC DC converter work?

    In the design process of power products, if engineers can make rational use of the working principle knowledge and performance characteristics of DC-DC converters for product development, not only can improve efficiency, but also can effectively save test time and speed up the launch of new products. In today's article, we will briefly analyze and introduce the principle of DC-DC converter, hoping to help the research and development of newcomers.
    In fact, the DC-DC converters we are familiar with are often referred to as switching regulators in practical applications. This important component has the advantages of high working efficiency and small quiescent current, so it can be seen in different fields. To its figure. Generally speaking, a basic DC-DC converter is composed of a control chip, an inductor coil, a thyristor, a triode, and different types of capacitors.
    After understanding the basics of the DC-DC converter, let's take a look at how it works. As a kind of conversion device, in the normal work, the main work of the DC-DC converter in the circuit system is to invert the DC power transmitted in the circuit first (to perform step-up or step-down operation), so that it becomes AC power. It is then rectified and converted to another DC voltage. Commonly used DC-DC converters are generally composed of a DC-DC converter module, a monitoring module, and a user interface board and a DC power distribution unit. In this working system, multiple DC-DC converter modules are operated in parallel and load-sharing. The −48V DC voltage is converted into −24V (or +12V, +5V) DC voltage, and then output to the load through the output shunt. The monitoring module is responsible for monitoring the working status and performance of the converter module and the entire system, and incorporating the monitoring system into the upper level through the RS232 communication port. During the DC voltage conversion process, the converter module of the DC-DC converter will convert the −48V DC voltage to −24V DC voltage. This conversion is done by two parts of the power circuit and the control circuit. The power circuit provides a switching operation from the DC input to the DC output, while the control circuit provides all the control signals required for power conversion, including feedback loops, DC signal processing, analog and digital processing circuits.
    Through the above introduction, we can summarize the complete working process of voltage conversion by a DC-DC converter as follows: First, the output voltage is connected to the FBpin sampling amplifier through the FB feedback circuit. At this time, the feedback voltage VFB is compared with the set comparison voltage Vcomp, and an error voltage signal is simultaneously generated. The error voltage signal will be input to the PWM module through the internal circuit of the converter, and then the PWM adjusts the duty ratio according to the magnitude of the error voltage, thereby achieving the purpose of adjusting the output voltage.

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