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The 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 and SPM-V series for automotive applications, and others.

Figure 1: Product summary
Commercial Grade Automotive Grade
Series
SPM
series
SPM Series
Standard specifications
SPM-CT
series
SPM-CT Series
For high frequency use
SPM-LR
series
SPM-LR Series
Low-profile model
SPM-XT
series
SPM-XT Series
Large model
Product summary 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 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 wider operating temperature range than commercial grade products (DZ,V Series)
Features
  • Their Curie temperature is high, and they show only small changes in characteristics with changes in ambient environment temperature.
  • With the use of a coil integrally molded with metallic magnetic material, hum noise and magnetic flux leakage are reduced.
  • Their Curie temperature is high, and they show only small changes in characteristics with changes in ambient environment temperature.
  • 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 square.
  • High productivity
  • By using a proprietary alloy powder, low loss in the high-frequency range is achieved.
  • The low-profile is achieved with the use of L-shaped terminals.
  • Compact forms ranging from 3 to 5 mm square.
  • Low resistance with no joint terminal (terminal integrated to wire)
  • Compatible with low inductance range.
  • High productivity
  • Large selection of products, ranging from 4 to 10 mm square.
  • High productivity
  • Compact, low profile
  • 30 G vibration resistance
  • High productivity
  • High inductance
  • High DC superimposition characteristics
  • Large selection of products is offered, ranging from 0.1 to 100 μH.
  • 30 G vibration resistance
Applications
  • LCD-TV,HDD
  • Amusement equipment
  • Other AV equipment
  • Wireless chargers
  • IJP head drive
  • Notebook computers
  • Tablet terminals
  • Gaming equipment
  • Base stations, servers
  • Amusement equipment
  • Industrial equipment
  • Car
    accessories
  • Car navigation
  • Car audio
  • ADAS
  • Start/Stop
  • Engine ECUs
  • 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
Commercial Grade Automotive Grade
Series SPM SPM-CT SPM-LR SPM-XT SPM-HZ SPM-DZ SPM-V
Product structures
SPM-LR series
SPM-LR series

Product features

Figure 3 shows the features of each SPM series.

Figure 3: List of product features
Series SPM SPM-CT SPM-LR SPM-XT SPM-HZ SPM-DZ SPM-V
Appearance
SPM series
SPM-CT series
SPM-LR series
SPM-XT series
SPM-HZ series
SPM-V series
Operating temperature range -40 to 125°C
(including self-temperature rise)
-55 to 155°C
(including self-temperature rise)
Magnetic material Metallic magnetic material
Terminal electrode specifications Metal terminal + plating No joint terminal + plating Metal terminal + plating
Features Commercial Grade Automotive Grade
Standard specifications High frequency & High Q specifications Low-profile specifications Large current specifications Supports use up to 125°C Compact, low profile High inductance
High DC superimposition characteristics

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
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.

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 grade
    Commercial grade
  • Automotive grade
    Automotive grade
Size
(mm)
SPM SPM-CT SPM-LR SPM-XT SPM-HZ SPM-DZ SPM-V
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
4.3x4.0mm
SPM4020-DZ
 
5mm sqr.
5.2x5.0mm
SPM5030
 
5.4x5.1mm
SPM5010-LR
SPM5012-LR
SPM5015-LR
SPM5020-LR
 
5.2x5.0mm
SPM5030-HZ
 
Induktivitäten,Spulen:SPM5030VT-D
5.3x5.1mm
SPM5030VT
6mm sqr.
7.1x6.5mm
SPM6530
SPM6550
7.1x6.5mm
SPM6550CT
   
7.1x6.5mm
SPM6530-HZ
SPM6550-HZ
 
7.0x6.5mm
SPM6545VT
7mm sqr.            
7.5x7.0mm
SPM7054VT
SPM7054VC
10mm sqr.
10.7x10.0mm
SPM10040
   
11.5x10.0mm
SPM10040XT
10.7x10.0mm
SPM10040-HZ
SPM10054-HZ
10.5x10.0mm
SPM10065VT
12mm sqr.      
12.6x13.0mm
SPM12565XT
   
13.0x12.5mm
SPM12565VT

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