PMI - Power Multilayer Inductors: Introduction of the compact WE-PMI Type size 1008
The award winning WE-PMI range is now available exclusively from Farnell - Click here to view
The widespread trend of portable electronic devices is to become more compact: smaller and thinner. That means that the power supply unit has to become smaller, too. The main focus herein lies on the Power Inductor which normally needs the most capacity.
In general we differentiate between two power supply and operating modes: the Linear regulator which doesn’t have a storage choke, and the DC/DC switching regulator which are often used because of their low losses. (see Fig. 2). Based on the higher efficiency, the DC/DC regulator is preferred in all mobile or handheld applications for increasing the maximum usage of a battery.
Fig.2: Circuit diagram of a switch regulator and a Linear regulator
A reduction in the size of the choke is possible because the latest generation of controller-ICs use switching frequencies up to 8MHz. Furthermore with new core materials being developed for these components switching frequencies up 40MHz are possible for the 1µH type. (see Fig. 3)
Fig.3: Inductance vs. Frequency Chart
The dimensions of the requested storage choke can therefore be reduced by up to 90 percent compared to 500 kHz DC/DC regulator. The small package of the new Power Multilayer Inductor Type in EIA size 1008 (2.5 mm x 2.0 mm ) typically has a height of only 1.0mm.
The Power Multilayer Inductors are completely magnetically shielded. A cross-talk to other signal lines affected by the high switching frequency is reduced, and therefore the DC/DC converter has a better noise resistance stability.
The internal structure Design of the new WE-PMI allows DC/DC supply currents up to 1.0A while still generating a higher efficiency for the mobile device than a wire-wound choke. The rated current is referenced to 40K self-heating based on 25°C room temperature.
Saturation current is typically measured to a 30% inductance drop-off. (see Fig. 4)
Fig.4: Inductance vs. DC-Bias
Individual Specifications of the WE-PMI are shown in the below table.
Specifications:
p/n | Inductance Tol. ±20% | Test Condition | DC Resistance Tol. ±25% | Rated current | Saturation Current |
74479887210 | 1,00 | 1 MHz | 290 | 1000 | 1200 |
74479887222 | 2,20 | 1 MHz | 400 | 850 | 1100 |
74479887247 | 4,70 | 1 MHz | 530 | 750 | 850 |
74479887268 | 6,80 | 1 MHz | 650 | 650 | 600 |
74479887310 | 10,00 | 1 MHz | 700 | 500 | 350 |
The award winning WE-PMI range is now available exclusively from Farnell - Click here to view