Introduction of Wirewound Power Inductors for DC-DC Converters Developed for Mobile Phones

Foreword

Mobile phones, portable music players, portable game consoles, laptops and other portable electronic products exist in our daily lives. These portable electronic products are powered by batteries, and each machine is equipped with multiple power supply voltage conversion circuits (DC-DC converters) that convert the battery voltage into the voltage required by the functional modules.

There are many types of DC-DC converters, and those used for portable electronic devices are mainly non-isolated conversion power supplies. This non-insulated switching power supply has a circuit breaker type using a coil and a supply pump type mainly using a capacitor. For example, a lithium battery mainly used for portable devices may have a change in battery voltage, and a supply pump type DC-DC converter is widely used because it can maintain a high power conversion efficiency when the battery voltage changes.

The types of power supplies required for portable electronic devices vary greatly depending on the type and function of the machine. Therefore, the input and output voltage and current specifications and volume of the DC-DC converter are also very different. The size and performance of coil components (power inductors) used in these DC-DC converters are also diverse.

Murata has two types of power inductors, laminated and wound, which can be applied to various DC-DC converters for portable electronic devices.

This time, it is applicable to a wide range of winding power inductors (LQH series) from small portable devices such as portable music players to large portable electronic devices such as notebook computers.

Summary of the LQH series

The product line of the wound-type power inductor LQH series is shown in Table 1. The LQH series is available in a variety of different sizes of winding inductance. The LQH2MC_52 series is the smallest size for small LCD modules such as mobile phones; the AQH55P_R0 series is the largest size for notebook hard drives and digital cameras. The most suitable sense value can be selected according to the performance requirements and size requirements of various DC-DC converters.

Table 1: List of power inductor LQH series product lines

Mobile phone DC-DC

LQH2MC_52 series

Introducing the smallest and thinnest LQH2MC_52 series in the LQH series.

Mobile phone DC-DC

Figure 1 shows the outline drawing of the LQH2MC_52 series.

Portable devices such as portable music players and mobile phones are becoming more and more high-performance, multi-functional, and power-saving. More and more DC-DC conversion circuits are used, and DC-DC conversion circuits are miniaturized and thin. It has become indispensable. The power inductor used under such a trend also requires miniaturization and thinning. The LQH2MC_52 series is based on a unique material and molding technology. The ultra-thin ferrite core and the highly coiled wire and terminal processing technology realize the largest 2.0 & TImes; 1.6 & TImes; 0.70m small ultra-thin power inductors, especially suitable for LCD screen for portable music players and mobile phones. In addition, according to the above technique and the magnetic circuit design technique, it is possible to obtain a maximum value of 10 μH which satisfies the actual demand (Table 2), and at the same time achieve excellent DC overlap characteristics (Fig. 2).

Mobile phone DC-DC

Mobile phone DC-DC

Fig. 3 shows the evaluation results of the power supply voltage conversion efficiency when the LQH2MCN2R2M02 and LQH2MCN2R2M52 are used in the step-down DC-DC converter. Although the LQH2MC_52 series is a miniaturized product with a maximum thickness of only 0.7 mm, it has the same high power supply voltage conversion efficiency as the LQH2MC_02 series with a maximum thickness of 0.95 mm.

Table 2: LQH2MC_52 Series Rating Table

Mobile phone DC-DC

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