DC/DC Converter and Coil Integrated Type—XCL205/XCL206/XCL207 Series

As portable electronic devices such as mobile phones are developing towards high functionality and miniaturization with each passing day, the requirements for high integration, miniaturization, and ultra-thinness of electronic components are also increasing. Power ICs are no exception and are required to continue to be miniaturized.

Especially when powered by batteries, how to use the batteries efficiently becomes an extremely important issue, and portable electronic devices must have the characteristics of both miniaturization and high efficiency.

Among them, DC/DC converters are effective power sources in terms of high-efficiency energy conversion, but because the coil must have magnetic saturation characteristics and characteristics to prevent burnout, it is difficult to achieve ultra-thinness. Generally, ICs, coils, and capacitors can only be mounted on a flat circuit board, which is not conducive to product miniaturization.

In order to solve the above problems, the following considerations and designs were carried out. The first is the method of forming a coil on a silicon wafer. In order to ensure sufficient inductance when used as a DC/DC converter, the semiconductor process becomes extremely complicated, which increases the cost. In fact, it is only used in high-frequency filters.

The second method is to enclose the coil and DC/DC converter IC in a plastic molded package component, because simply installing components cannot reduce the mounting area too much and cannot bring about a significant improvement.

Then, a design scheme that stacks components including ICs instead of placing various components on a flat surface appeared, and several such products actually appeared. However, this scheme either requires printing wiring patterns on the coil, or requires CSP (chip size package) type ICs, or requires molding when packaging ICs, which makes the production process complicated and brings about the issue of rising costs.

micro DC/DC XCL205/XCL206/XCL207 Series

The newly developed "micro DC/DC" XCL series is a step-down DC/DC converter and coil integrated IC with a simple structure in which the coil is mounted on top of the final product DC/DC converter IC, which can reduce the mounting area while ensuring various characteristics.

The components required to provide the output current (maximum 600mA) are only two capacitors, making it possible to miniaturize the mounting circuit board (Figure 1).

Because of its simple structure, it has the advantage of not losing IC characteristics and can be produced using existing molded products.

Extremely simple structure To simplify the production process, the XCL series adopts a simple structure in which a concave portion is formed in the center of the coil when the DC/DC converter and the coil are made into one piece, the XC9235/XC9236/XC9237 series products are buried in the concave portion, and then fixed with adhesive, thus solving the problem of cost increase caused by complex processes (Figure 2).

In addition, with this structure, the electrodes above the coil and the IC pins can be mounted directly on the PCB, respectively, and the wiring of the DC/DC converter can be implemented on the PCB layout.

Achieved ultra-thinness of 1mm in height In order to keep the total height of the coil and DC/DC converter within 1mm, the DC/DC converter adopts a newly developed ultra-thin package component (USP-6EL) with a height of only 0.4mm after packaging