Inductors for Class-D
Audio Amplifiers
Based on their miniaturized package size andhigh efficiency, Class-D power amplifiers havebecome increasingly popular replacements
for linear amplifiers in many high-end audio
system applications.

For high-power Class-D amplifiers (>50 Watts),
selecting the right inductor for the output LC
filter plays a critical role in improving the efficiency and overall sound quality of the system.

Dual Inductors for Ultra-low Distortion Class-D Amplifiers
Design Features

Product Overview:UA8013-AL / UA8014-AL / RA7231-AL
Coilcraft offers a unique selection of dual inductors thatsignificantly improve the performance of the output LC
filter and reduce the board area with a compact single shielded package. Good linearity of the inductors’saturation current and ultra low total losses minimize theimpact of total harmonic distortion plus noise (THD+N),
greatly improving audio quality.

• Designed into Texas Instruments’ TPA3220(50 W Stereo), TPA3244 (60 W Stereo) andTPA3245 (115 W Stereo) Class-D Amplifier
evaluation modules• Also suitable for TI’s TPA3251 (175 W Stereo)
Class-D Amplifier• Dual inductors in a single shielded package to save
circuit board spaceApplications• Very low coupling coefficient (k<0.001), minimal
crosstalk between the two inductors• Handheld audio devices & portable docking stations• Excellent inductance vs. current linearity up to 10 A

• High-end TV soundbars• Economical solutions for a wide variety of audio
amplifier applications• Active speakers and subwoofers• RA7231-AL: AEC-Q200 Grade 1 qualified(-40°C to +125°C ambient)• Automotive stereo audio systems

UA8013-AL_
UA8014-AL_
RA7231-AL_

Isat (A)Irms (A)Inductance±10% (µH)

DCR Max(mOhms)

SRF typ(MHz)

10% drop

20% drop

30% drop

L1

7.0

6.6

40

12.0

12.5

13.2

L2

7.0

6.6

40

12.0

12.5

13.2

L1

10.0

6.6

28

8.7

9.1

9.4

L2

10.0

6.6

28

8.7

9.1

9.4

L1

5.0

6.0

34

15.5

16.6

17.6

L2

5.0

6.0

34

15.5

16.6

17.6

Part Number

20°C rise

40°C rise

6.5

9.0

6.5

9.0

7.6

10.6

Inductors for Class-D
Audio Amplifiers
Dual Inductors for Ultra-low Distortion Class-D Amplifiers (continued)
L vs. Current

TI’s TPA3244/3245 60W/115W Stereo PurePath™ Ultra-HD, Analog-In Class-D Amplifier100

UA8013-AL
UA8014-AL
RA7231-AL
L1

Inductance (µH)

Vout A

L2
Vout B

UA8014-AL

10

TPA3244
TPA3245

UA8013-AL

L1

RA7231-AL

Vout A

L2
Vout B

10.1

10

1

UA8013-AL
UA8014-AL
RA7231-AL

100

Current (A)inchesmm

Dimensions

Dotindicatespin 1
Dot indicatespin
1

XXXX Y

UA801X-AL

XXXX Y

UA801X-AL

10.551
max
14,00

0.551
max
14,00

0.630
max
16,00
0.630

16,00

max

L1
20.004 /0,100.610max
15,50

1L14L234L22

30.004 /0,100.610
max
15,50Single Power Inductors for TI Automotive Class-D Audio Amplifier
0.224
5,7CL

0.094
2,40.122
3,10.047
1,2Coilcraft provides a complete solution for the PMP11769
CL
0.094
0.224
0.047
700 Watt
automotive
Class-D audio amplifier reference
2,4
5,7
1,20.122
3,1
design from Texas Instruments. Our SER2918H-103
Cpower inductor is used for the output LC filter whichLRecommended
PatternconvertsLandthePWM
output into a continuous low noise
0.122
3,1analog
signalto achieve great performance. It is also
0.248
0.071
6,3
1,8
used with other Coilcraft parts in the Buck and Boost
Recommended
Land Patternpowerstages (see table).

L5_1, L5_2

10 µH

SER2918H-103KLClass-D Amplifier Output LC Filter L6_1, L6_2
(Left and right channel)
L7_1, L7_2

10 µH

SER2918H-103KL

10 µH

SER2918H-103KL

32CL

4120.248 36,31

40.303
7,70.122
3,10.071
1,80.126
3,214230.134
3,4 0.102
2,6Buck Power StageCL

0.303
7,71CL
20.2095,30.102
2,60.031
0.126
3,20,8 0.134

3,4 0.102
Design Features
2,6CL

Boost Power Stage

L8_1, L8_2

10 µH

SER2918H-103KL

L1330 µH

LPS6235-334MLB

L2, L4500 nH

XPL2010-501MLB

L31 mH

LPS4012-105MLB

L910 µH

SER2918H-103KL

L1110 µH

SER2918H-103KL

4• Easily integrated into automotive systems with 50V
load dump0.102
and integrated protection system
32,6• Ultra-HD audio for best quality sound for anyCLintegrated
Class-D amplifier

0.2095,30.031
0,8• 100kHz bandwidth, which enables support for highresolution audio files and formats• Low noise eliminates “hiss” or “buzz” sounds

www.coilcraft.com

Photo courtesy of Texas Instruments, Inc.
Document 1404

Revised 3/1/18