How does a board-level power supply strike a balance between performance and size?

　　In the power supply scheme of actual engineering applications, AC-DC centralized power supply plus DC-DC is often used to power each discrete circuit board, as shown in Figure 1.

　　Figure 1 Common power supply solutions for engineering applications

　　In the power supply scheme shown in Figure 1, the AC-DC not only provides AC-DC power conversion, but also plays the role of safe isolation of the power grid, anti-interference and anti-fluctuation of the power grid, and provides a stable and reliable DC power source for the subsequent stage. For the internal DC-DC of the circuit functional unit, its main function is to provide secondary voltage regulation and power other circuits on the circuit board.

　　Therefore, the DC-DC for such applications generally does not need to assume the function of isolation and anti-interference, but has higher requirements on other parameters such as volume, conversion efficiency, dynamic response, static power consumption, etc.

　　Small size board-level power supply solution

　　There are many non-isolated board-level power supply solutions, such as the LM78xx series of linear regulators, the LM2576 switching regulator, etc. Generally speaking, it is difficult to achieve a balance between performance and size, that is, either the performance is good but the size is large; or the size is well controlled but the electrical parameters do not meet the standards.

　　The ZY78xxS series of Zhiyuan Electronics perfectly integrates the two, achieving high performance and small size. Taking ZY7805S-500 as an example, the pins are fully compatible with LM7805, and the output current can reach 500mA without any external circuit, and the efficiency is as high as 95%. The comparison of the device configuration required by LM7805 when using it is shown in Figure 2.

　　Figure 2 Comparison of external device requirements between ZY7805S-500 and LM7805

　　It can be seen that the solution using ZY7805S-500 is simple to use, small in size and high in efficiency. More parameters of ZY7805S-500 are shown in the following figure.

　　Figure 3 Fast startup: 580uS startup time

　　Figure 4 Smooth startup waveform

　　Figure 5 High conversion efficiency: up to 96%

　　Models with larger output current include: ZY78xxS-1000, ZY78xxS-1500 series, with output currents of 1A and 1.5A respectively, which can meet most board-level power supply requirements.

　　Figure 6 Ripple comparable to that of a linear regulator