DC-DC Converter Working Principle

The DC-DC converter is a voltage converter that effectively outputs a fixed voltage after converting the input voltage. DC to DC converters are divided into step up DC-DC converters, step down DC- DC converters, and buck-boost DC-DC converters. Three types of controls can be used according to requirements. At present, DC to DC converters are widely used in products such as mobile phones, MP3s, digital cameras, and portable media players. The circuit of DC converter belongs to the chopper circuit in the circuit type classification.

DC to DC converter working principle

DC to DC means DC to DC conversion. There are three types DC converter on ATO.com, including boost converter, buck converter and boost-buck converter. The output current of the step-down DC to DC converter is relatively large, mostly hundreds of milliamperes to several amperes, so it is suitable for occasions with relatively large output current. The basic working principle circuit of the step down converter is shown in the figure 1 below. VT₁ is a switch tube. When VT₁ is turned on, the input voltage V_i supplies power to the load R_L through the inductor L₁, and at the same time it also charges the capacitor C₂. In this process, energy is stored in the capacitor C₂ and the inductor L₁. When VT₁ is off, the energy stored in the inductor L₁ continues to supply power to R_L. When the output voltage is going to drop, the energy in the capacitor C₂ is also discharged to R_L, maintaining the output voltage unchanged. The diode VD₁ is a freewheeling diode to form a circuit loop. The output voltage Vo is divided by the voltage divider composed of R₁ and R₂, and the signal of the output voltage is fed back to the control circuit. The control circuit controls the on and off time of the switch tube to keep the output voltage unchanged.

Figure 1: Basic Working Principle Diagram of DC to DC Converter

To design DC-DC circuit should consider the following conditions:

1. The range of the external input power supply voltage and the size of the output current.
2. The maximum value of DC-DC output voltage, current, and system power.

In short, the DC to DC converter supplies power to each circuit in the entire system. Only by knowing the DC to DC converter circuit design and its working principle can the overall performance of the system be improved.