Inductors (Coils)

Product Overview Power Inductor SPM Series

Power Inductor SPM SeriesThe SPM series power inductors are the metal composite type wire-wound inductors that have the coils integrally molded with metallic magnetic powder. Compared to ferrite-base wire-wound inductors, the SPM series inductors realize larger current, lower Rdc, smaller size and superior DC bias characteristic. In addition, they ensure low magnetic flux leakage and are effective as a means to suppress acoustic noise of the coil. This article introduces the structure, features, and application of these products, and other information that helps you in an easy-to-understand way.

Product summary

The SPM series are the inductors that have the coils integrally molded with metallic magnetic powder. TDK offers a large selection of the SPM series inductors, including the low-profile SPM-LR series, the SPM-HZ series for automotive applications, etc.

Figure 1: Product summary
Series
Product summary

Metal composite type inductor

The inductors that have the coils integrally molded with magnetic powder.
These inductors use Fe-base alloy powder to have high saturation characteristics, i.e. allowing for large current. The inductors of this series are offered in large selection of product sizes.

Metal composite type low-profile inductor

The inductors that have the coils integrally molded with magnetic powder.
These inductors use Fe-base alloy powder to have high saturation characteristics, i.e. allowing for large current. The low-profile (H = 1.0 to 2.0 mm) is achieved by employing the terminal of proprietary shape.

Metal composite type large inductor

The inductors that have the coils integrally molded with magnetic powder.
These inductors use Fe-base alloy powder to have high saturation characteristics, i.e. allowing for large current.
A simple structure without exterior terminals is achieved by employing the wire collinear electrode structure.

Metal composite type inductor for high frequency applications

The inductors that have the coils integrally molded with magnetic powder.
By using the proprietary alloy powder, low loss in the high frequency region is achieved, in addition to having high saturation characteristics.

Metal composite type inductor for automotive applications

The inductors that have the coils integrally molded with magnetic powder.
These inductors use Fe-base alloy powder to have high saturation characteristics, i.e. allowing for large current.
The inductors of this series are designed for automotive applications.

Metal composite type inductor for automotive applications

The inductors that have the coils integrally molded with magnetic powder.
These inductors use Fe-base alloy powder to have high saturation characteristics, i.e. allowing for large current.
Compared to the SPM-HZ series, this series inductors have wider operating temperature range in automotive environments.
Features
  • Large selection of products, ranging from 4 to 10 mm.
  • Low inductance variance in high-temperature environments.
  • With the use of a coil integrally molded with metallic magnetic material, hum noise and magnetic flux leakage are reduced.
  • High quality and high productivity, and therefore stable supply is possible.
  • The low-profile is achieved with the use of L-shaped terminals.
  • Low inductance variance in high-temperature environments.
  • With the use of a coil integrally molded with metallic magnetic material, hum noise and magnetic flux leakage are reduced.
  • Compatible with low inductance region.
  • Low inductance variance in high-temperature environments.
  • With the use of a coil integrally molded with metallic magnetic material, hum noise and magnetic flux leakage are reduced.
  • High quality and high productivity, and therefore stable supply is possible.
  • By employing proprietary alloy powder, low loss = high Q characteristics are achieved.
  • Low inductance variance in high-temperature environments.
  • With the use of a coil integrally molded with metallic magnetic material, hum noise and magnetic flux leakage are reduced.
  • AEC-Q200 complied.
  • Large selection of products, ranging from 4 to 10 mm.
  • Low inductance variance in high-temperature environments.
  • With the use of a coil integrally molded with metallic magnetic material, hum noise and magnetic flux leakage are reduced.
  • High quality and high productivity, and therefore stable supply is possible.
  • AEC-Q200 complied.
  • Large selection of products is offered, ranging from 1 to 100 uH.
  • Low inductance variance in high-temperature environments.
  • Vibration resistance to 30G is featured with vibration resistance structure.
  • With the use of a coil integrally molded with metallic magnetic material, hum noise and magnetic flux leakage are reduced.
Applications
  • LCD-TV,HDD
  • Amusement equipment
  • Other AV equipment
  • Notebook computers
  • Tablet terminals
  • Gaming equipment
  • Base stations, servers
  • Amusement equipment
  • Industrial equipment
  • Wireless chargers
  • IJP head drive
  • Car accessories
  • Electronic power steering
  • Headlights, etc.
  • LED
  • ADAS
  • Engine ECUs, etc.

Product structures

Figure 2 shows the structure of each SPM series. The integral mold structure and the welding method for connecting the wire and terminals achieves high reliability.

Figure 2: Product structures
Series SPM series SPM-LR series SPM-XT series SPM-CT series SPM-HZ series SPM-VT series
Product structures
SPM series
  • Wire
  • Terminal
SPM series
  • Metal core
  • Welded
SPM-LR series
  • Wire
  • Terminal
SPM-LR series
  • Metal core
  • Welded
SPM-XT series
  • Wire
  • Solder plating
SPM-XT series
  • Metal core
  • Wire collinear electrode
SPM-CT series
  • Wire
  • Terminal
SPM-CT series
  • Metal core
  • Welded
SPM-HZ series
  • Adhesive
  • Wire
  • Terminal
SPM-HZ series
  • Metal core
  • Welded
SPM-VT series
  • Adhesive
  • Wire
  • Terminal
SPM-VT series
  • Metal core
  • Welded

Product features

Figure 3 shows the features of each SPM series.

Figure 3: List of product features
Series SPM series SPM-LR series SPM-XT series SPM-CT series SPM-HZ series SPM-VT series
Appearance SPM series SPM-LR series SPM-XT series SPM-CT series SPM-HZ series SPM-VT series
Operating temperature range -40 to 125°C
(including self-temperature rise)
-55 to 125°C
(including self-temperature rise)
Magnetic material Metallic magnetic material
Terminal electrode specifications Metal terminal + plating Wire collinear electrode + plating Metal terminal + plating
Features Standard specifications Low-profile specifications Large current specifications High frequency & High Q specifications Automotive application specificationsAutomotive application specifications

One of the remarkable features of the SPM series is that they are made with metallic magnetic core. Compared to ferrite cores, metallic magnetic cores have higher magnetic saturation density and better DC bias characteristic. In addition, since their Curie temperature is high, they show only a small change in characteristics with ambient temperature.

Figure 4: Comparison of DC bias characteristic (Metallic magnetic core vs. ferrite core)

Core material characteristics of high magnetic saturation
Superior DC bias characteristic

DC bias characteristic of each core material
DC bias characteristic of each core material
Saturation magnetic flux density
Saturation magnetic flux density
Figure 5: Change in DC bias characteristic with ambient temperature

Core material characteristics of high Curie temperature
Change in characteristics with ambient temperature is small.

Change in characteristics with ambient temperature is small.
DC bias characteristic under different temperatures

Since the SPM series inductors are made with wire-wound cores integrally molded with metallic magnetic powder, they do not have a core gap and the acoustic noise is reduced. Also, they have good shielding qualities and the magnetic flux leakage is small.

Figure 6: Integral molding for suppressing acoustic noise

Core gapless (integral molding) for suppressing acoustic noise
Contributes to improve the set quality

Acoustic noise generates from the gap
Combination core type
Combination core type

With the gapless structure, acoustic noise is suppressed
Integral molding type (SPM)
Integral molding type (SPM)
Figure 7: Comparison of magnetic flux leakage

Shielding structure for low magnetic flux leakage
Effective for reducing EMI

Vertical near magnetic field measurement result

Resin shield type
Resin shield type
Integral molding type (SPM)
Integral molding type (SPM)

List of products

Figure 8 shows the list of products by series and by shape. You can view the detailed information of the product or purchase a sample by clicking the type name.

Figure 8: List of products
  • Commercial gradeCommercial grade
  • Automotive gradeAutomotive grade
Size
(mm)
SPM series SPM-LR series SPM-XT series SPM-CT series SPM-HZ series SPM-VT series
3mm sqr.   3.2x3.0mm
SPM3010-LR
SPM3012-LR
SPM3015-LR
SPM3020-LR
       
4mm sqr. 4.2x4.0mm
SPM4030
4.4x4.1mm
SPM4010-LR
SPM4012-LR
SPM4015-LR
SPM4020-LR
    4.2x4.0mm
SPM4030-HZ
 
5mm sqr. 5.2x5.0mm
SPM5030
5.4x5.1mm
SPM5010-LR
SPM5012-LR
SPM5015-LR
SPM5020-LR
    5.2x5.0mm
SPM5030-HZ
 
6mm sqr. 7.1x6.5mm
SPM6530
SPM6550
    7.1x6.5mm
SPM6550-CT
7.1x6.5mm
SPM6530-HZ
SPM6550-HZ
 
7mm sqr.           7.5x7.0mm
SPM7054-VT
10mm sqr. 10.7x10.0mm
SPM10040
  11.5x10.0mm
SPM10040XT
  10.7x10.0mm
SPM10040-HZ
SPM10054-HZ
 
12mm sqr.     12.6x13.0mm
SPM12565XT
     

What are power inductors?

Power inductors are inductors used for power supply circuit such as DC-DC converters. They are also called power coils or power chalks. One of the inductors' characteristics is that they store energy by self-induction function. Chopper type DC-DC converters use inductors having such characteristics with switching devices for voltage conversion (see Figure 9).
Depending on the processing method, inductors can be classified into multilayer type, thin-film type, and wire-wound type. Since wire-wound type permits large current to flow, most of the power inductors are wire-wound type. Various wound-type power inductor products with ferrite or soft magnetic metal core are offered. Recently, the multilayer type and thin-film type, with which reduction of size and thickness can be achieved, are being improved to allow for larger current.

Figure 9: DC-DC converter (chopper type / step-down type) and inductor

The voltage is dropped to a desired level in accordance with the duty ratio (the ratio that indicates how long the switch is ON during the switching cycle) setting.

Switching
repeated