Products & Markets

Monolithic Type Power Inductor

As the function of mobile devices has become more sophisticated and multifunctional, compact power inductors for large current lines have become highly sought-after products. To cater for these market needs, Murata has commercialized the LQM2HP-GH series, using the performance enhancement technologies that Murata had established during the development of monolithic type power inductors.

The power supply circuits of mobile devices, such as feature phones and smartphones, use switching type DC-DC converter circuits that have excellent voltage conversion efficiency (low power loss). In DC-DC converter^*1circuits, compatibility with large current is progressing. For power inductors^*2 used in such circuits, people seek inductors that are low in power loss and able to accommodate large currents. Murata has already developed and started mass-production of the sub-1 mm high monolithic type power inductors LQM2HP-GH series (L2.5 x W2.0 x t1.0mm), which can be fit into mobile devices such as feature phones and smartphones. Compared with our existing products, we have achieved a 10% reduction in resistance and a 2.3-fold increase in current flow (DC superposition characteristics) (Table 1, Fig. 1) . We have succeeded in reducing the power loss in the DC-DC converter circuits, thereby improving the conversion efficiency by 5% compared with our existing products (Fig. 2) .

Fig. 1 Comparison of DC Superposition Characteristics

Fig. 2 Comparison of the Energy Conversion Efficiency of the DC-DC Converter

Table 1 Comparison of Electrical Characteristics

Part Number	Inductance	DC resistance	Allowable current I*	Allowable current II**
LQM2HPN1R0MGH (Product under development)	1.0µH	0.50Ω	2.3A	2.3A
LQM2HPN1R0MG0 (Existing product)	1.0µH	0.55Ω	1.0A	1.6A

*Allowable current I: The electric current value at which the falling rate of L becomes -30% when applied. (DC superposition characteristics)
*Allowable current II: The electric current value at which the temperature increase becomes less than 40℃ when applied.

To accomplish this product, Murata tried to reduce DC resistance and core loss to minimize electric power loss, and tried further to prevent the magnetic saturation of ferrite to ensure large current flow. To reduce the DC resistance of inductors, you need to make internal conductors thicker and maintain their shape, but it was difficult to achieve that with the conventional sheet layering technique because this technique crushes the conductors inside when you try to form layers. To overcome this problem, Murata developed a new method to thicken internal conductors or make them with the higher aspect ratio and maintaining their shape (Fig. 3). Murata has successfully prevented core loss by introducing its unique ferrite material technology and optimizing magnetic circuit design. Murata has also successfully prevented the magnetic saturation of ferrite through the use of a manufacturing technology that creates gaps between the magnetic paths and optimal structure design using electromagnetic field simulations. With these new products, Murata will reduce the electric power loss in the DC-DC converter circuits, and contribute to extended battery life of mobile devices, including mobile phones and smartphones.

Fig. 3 Thickening and High Aspect Ratio Construction of Internal Electrodes

Glossary

*1 DC-DC Converter:

Electronic circuits which convert DC voltage. They also serve as switching regulators. Their use in mobiles devices has been increasing, following the decentralization of power supplies.

*2 Power Inductor:

They are used in circuits where an electric current from a power supply flows. The current is larger there than in signal circuits.

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