ST AN3959 APPLICATION NOTE

AN3959

Application note

2.0-channel demonstration board based on the STA381BW and STA381BWS

Introduction

The purpose of this application note is to describe:

■how to connect the STA381BW/STA381BWS 2.0-channel demonstration board

■how to evaluate the performance of the demonstration board with significant electrical curves

■how to avoid critical issues in the PCB schematic and layout of the STA381BW/STA381BWS

The STA381BW/STA381BWS demonstration board is configured for 2.0 BTL channels, releasing up to 2 x 20 W into 8 ohm of power output at 18 V of supply voltage in the VQFN48 package. It represents a total solution for the digital audio power amplifier.

Figure 1. STA381BW/STA381BWS 2.0-channel demonstration board

December 2011

Doc ID 022081 Rev 3

1/65

www.st.com

Contents	AN3959

Contents

1	Functional description of the demonstration board . . . . . . . . . . . . . .			. 6
	1.1	Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		6
	1.2	Output configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		6
	1.3	Schematic and block diagrams, bill of material, PCB layout . . . . . . . . . . . .		7
2	STA381BWS power section test results . . . . . . . . . . . . . . . . . . . . . . . .			16
3	STA381BW power section test results . . . . . . . . . . . . . . . . . . . . . . . . .			20
4	Analog section test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			24
5	Thermal performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			26
	5.1	Thermal results - test 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		26
	5.2	Thermal results - test 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		27
6	Design guidelines for schematic and PCB layout . . . . . . . . . . . . . . . .			28
	6.1	Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		28
		6.1.1 Criteria for selection of components . . . . . . . . . . . . . . . . . . . . . . . . . . .		28
		6.1.2	Decoupling capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	28
		6.1.3	Output filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	28
		6.1.4	Snubber filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	29
		6.1.5	Main filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	30
		6.1.6	Dumping network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	30
		6.1.7 Recommended power-up and power-down sequence . . . . . . . . . . . . .		31
	6.2	Layout .	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	31
7	Software setup to use the STA381BW/STA381BWS devices (ST Map)			38
	. . . . .	. . . . . . .	. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
	7.1	Processing configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		38
	7.2	STCompressorTM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		39

7.2.1 STCompressor settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 7.2.2 Configuring and enabling the STCompressor . . . . . . . . . . . . . . . . . . . . 41 7.2.3 Example settings of the STCompressor . . . . . . . . . . . . . . . . . . . . . . . . 42 7.2.4 Test results with APWorkbench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

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7.3 CRC computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

7.3.1 Biquad CRC computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.3.2 Crossover CRC computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 7.3.3 STCompressorTM CRC computation . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

	7.4	Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	47
	7.5	Short-circuit protection for the STA381BW/STA381BWS . . . . . . . . . . . . .	49
	7.6	Settings for bridge power-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	49
8	Examples of code (TV SoC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		50
	8.1	FFX381X_Sample.h . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	50
	8.2	FFX381X_Sample.C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	53
Appendix A Mono BTL schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .			63
9	Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		64

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List of figures	AN3959

List of figures

Figure 1. STA381BW/STA381BWS 2.0-channel demonstration board . . . . . . . . . . . . . . . . . . . . . . . . 1 Figure 2. Schematic-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Figure 3. Schematic-2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Figure 4. Top view of PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Figure 5. Inner layer2 view of PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Figure 6. Inner layer3 view of PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Figure 7. Bottom view of PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Figure 8. Block diagram of test connections with equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 9. Frequency response, VCC = 18 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . 16 Figure 10. Crosstalk, VCC = 18 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 11. SNR, VCC = 18 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Figure 12. THD vs. frequency, VCC = 18 V, RL = 8 ohm, Pout = 1 W . . . . . . . . . . . . . . . . . . . . . . . . . 17 Figure 13. FFT (0 dBFS), VCC = 18 V, RL = 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . 18 Figure 14. FFT (-60 dBFS), VCC = 18 V, RL = 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . 18 Figure 15. THD vs. output power, VCC = 18 V, RL = 8 ohm, f = 1 kHz . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 16. THD vs. output power at different power supplies, RL = 8 ohm, f = 1 kHz . . . . . . . . . . . . . 19

Figure 17. Frequency response, VCC = 24 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . 20 Figure 18. Crosstalk, VCC = 24 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Figure 19. SNR, VCC = 24 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Figure 20. THD vs. frequency, VCC = 24 V, RL = 8 ohm, Pout = 1 W . . . . . . . . . . . . . . . . . . . . . . . . . 21 Figure 21. FFT (0 dBFS), VCC = 24 V, RL = 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . 22 Figure 22. FFT (-60 dBFS), VCC = 24 V, RL = 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . 22 Figure 23. THD vs. output power, VCC = 24 V, RL = 8 ohm, f = 1 kHz . . . . . . . . . . . . . . . . . . . . . . . . 23 Figure 24. THD vs. output power at different power supplies, RL = 8 ohm, f = 1 kHz . . . . . . . . . . . . . 23

Figure 25. Temperature test 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Figure 26. Temperature test 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Figure 27. Output filter (BTL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Figure 28. Differential-mode snubber circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Figure 29. Common-mode snubber circuit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Figure 30. Main filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Figure 31. Dumping network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Figure 32. Recommended power-up and power-down sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Figure 33. Snubber network soldered as close as possible to the respective IC pin . . . . . . . . . . . . . . 31 Figure 34. Electrolytic capacitor used first to separate the VCC branches . . . . . . . . . . . . . . . . . . . . . . 32 Figure 35. Path between VCC and ground pin minimized in order to avoid inductive paths . . . . . . . . 32 Figure 36. Large ground plane on the top side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Figure 37. Large ground plane on inner layer2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Figure 38. Large ground plane on inner layer3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Figure 39. Large ground plane on bottom side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Figure 40. Symmetrical paths created for output stage, for differential applications . . . . . . . . . . . . . . 35 Figure 41. Coils separated in order to avoid crosstalk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 42. VCC filter for high frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Figure 43. Thermal layout with large ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 44. Processing path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Figure 45. 2.1-channel with STCompressorTM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Figure 46. STCompressor - overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Figure 47. STCompressor - mapper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Figure 48. STCompressor - compression ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

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AN3959	List of figures

Figure 49. STCompressor - limiter threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Figure 50. STCompressor - offset control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 Figure 51. APWorkbench results for STC example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Figure 52. F3X output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Figure 53. F3X for HPout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Figure 54. Mono BTL schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

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Functional description of the demonstration board	AN3959

1 Functional description of the demonstration board

The following terms used in this application note are defined as follows:

●THD+N vs. Freq: Total harmonic distortion (THD) plus noise versus frequency curve

●THD+N vs. Pout: Total harmonic distortion (THD) plus noise versus output power

●S/N ratio: Signal-to-noise ratio

●FFT: Fast Fourier Transform algorithm (method)

●CT: Channel separation L to R, or R to L channel crosstalk

The equipment used includes the following:

●Audio Precision (System 2700) by AP Co., USA

●DC power supply (4.5 V to 25.5 V operating range)

●Digital oscilloscope (TDS3034B by Tektronix)

●MS Windows-based PC with APWorkbench GUI control software installed. For the APWorkbench software setup, please refer to the APW UserManualR1.0.pdf

Reference documents include:

●STA381BW and STA381BWS datasheets

●Demonstration board schematic, PCB layout and test curves

1.1Connections

Power supply and interface connection

1.Connect the positive voltage of the 18 V DC power supply to the +VS pin and negative to GND (note that the operating voltage range of the DC power supply is from 4.5 V to 25.5 V).

2.Connect the APWLink board to the J1 connector of the STA380BWS demonstration board.

3.Connect the S/PDIF signal cable to the RCA jack on the APWLink board, the other side connects to the signal source such as Audio Precision or a DVD player.

1.2Output configuration

The STA381BW/STA381BWS demonstration board is specifically configured in 2 BTL channels.

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1.3

Schematic and block diagrams, bill of material, PCB layout

AN3959

Figure 2.

Schematic-1

+3V3

L3

R5

10K

SWPA6045S220MT

OUT1A

+3V3

RESET

C32

C37

100nF

NS

NS

C4

20(S)

R42

220nF

NS

1N(S)

C47

R10

1nF

C2

R2

R4

330P(S)

0R

220nF

C46

R3

0 ohm

INT LINE

PWRDN

C44

0R

R1

0 ohm

SCL

SDA

SDI1

R11

1N(S)

C50

4

220nF

NS

L1

SWPA6045S220MT

OUT1B

C36

C38

C11

3

100nF

64

63

62

61

60

59

58

57

56

55

54

53

52

51

50

49

2

OUT2A

NS

L2

330P(S)

SWPA6045S220MT

C43

C41

1N(S)

C45

C48

220nF

0R

220nF

1

OUT2B

1

48

47

46

45

44

43

42

41

40

39

38

37

48

LRCKI

R41

C39

VDDDIG2

GNDDIG2

TESTMODE

SA

SCL

SDA

INTLINE

PWDN

RESET

SDI

LRCKI

BICKI

0R

2

47

20(S)

R43

BICKI

1N(S)

C49

R30

3

1

36

46

220nF

MCLK

MCLK

NS

VCC_REG

SPEAKJACK2X2

4

2

VSS_REG

AGNDPLL

35

45

C42

C40

Doc

OUT2B

J9

+VS

5

3

34

44

C3 2u2/10V

L4

OUT2B

VREGFILT

6

4

33

43

FFX4B

SWPA6045S220MT

GND2

IC1

FFX4B

OUT2A

7

5

32

42

FFX4A

1uF/50V

1uF/50V

VCC2

STA381BWS

FFX4A

OUTPUT FILTER

C428

NS

100nF

100nF

100nF

8

6

OUT2A

FFX3B

31

41

FFX3B

IC3

3Rev 022081ID

470U/35V

C35NS

C34NS

C33NS

OUT1B

9

7

OUT1B

STA381BWS_NEW

FFX3A

30

40

FFX3A

+

C14

C429

C426A

C427A

C426B

C427B

10

8

VCC1

GNDDIG1

29

39

C5

Functional

11

9

28

38

GND1

VDDDIG1

100nF

12

10

OUT1A

VDD3V3CHP

27

37

13

11

VDD_REG

LINEHPOUT L

LINEHPOUT R

CPP

26

36

14

12

GND_REG

SOFTMUTE

GNDPSUB

25

35

+3V3

OUT1A

15

HALFVDD

HPIN L

HPIN R

VDD3V3

CPVSS

34

F3XL

F3XR

GNDA

CPM

NOTE:

16

33

13

14

15

16

17

18

19

20

21

22

23

24

C56

CONFIGURATION

Note 1:

NS

2.0CH & 2.1CH

17

18

19

21

22

28

29

30

31

32

description

100nF

MONO BTL

C1

20 1uF/10V

C53

23

24

25

26

27

SOFTMUTE

C8

1uF/10V

The output filter for the line/HP output

100nF

C9

1uF/10V

path is optional (not required for the STA381BW/S).

J15

F3XR

*

C56

NS

R36

0ohm

1

2

F3XL

If the 2x 47 ohm resistors (R35 and R44) are

C29

100nF

J19

J16

1 2

1uF/10V

C10

bypassed through J14 and J18, the 2x 100 nF

HPJCKX3.5-06

capacitors (C54 and C55) must also be removed.

Line in

1

of

2

C30

R6

the

1uF/10V

11K

3

C31

R7

Note 2:

1uF/10V

11K

J2

J14

1

2

demonstration

HPJCKX3.5-06

C56 is not soldered when the STA381BW/S

1

R8

R9

2

R35

47R

1

27K

27K

100nF 100nF

C55 C54

1K

2

is configured in 2.0 or 2.1 channels; C56 is 100 nF

3

3

SW2

R46

J7

when the STA381BW/S is configured in mono BTL.

HEADER2X2

2

1

R37

470R

C51

10uF/10V

4

3

J18

1

2

Refer to the schematic in Appendix A on page 63

Line out

3.3nF/10V

47K

C6

C7

3.3nF/10V

R40 R39 47K

R44

47R

1

for an example of a mono BTL application.

1K

2

3

SW3

STA381BWS

R45

R38

470R

C52

10uF/10V

board

7/65

Figure 3.

Schematic-2

AN3959

C15

100uF

35V

C22

10K

10K

R31

R29

220PF

R12

R14

R18

4K7

4K7

4K7

FFX3B

+VS

1

2

+VS

BD3

BEAD or 33R

3

C28

IC2

C27

C16

C17

47uF

J13

100nF

470PF

150PF

LM833

50V

C26

C24

HEADPHONE O/P

100PF

100PF

R16

10K

C25

1

OUTA

VDD

8

100uF

R13

R15

R19

2

INA1

OUTB

7

FFX3A

4K7

4K7

4K7

3

INA2

INB1

35V

BD4

6

BEAD or 33R

4

VSS

INB2

5

10K

10K

C18

220PF

R17

10K

+VS

R34

R28

Doc

R20

R22

R26

R24

10K

ID

4K7

4K7

4K7

FFX4B

3 Rev 022081

220PF

R25

10K

C23

10K

10K

Functional

220PF

R33

C21

R32

C19

470PF

C20

150PF

R21

R23

R27

4K7

4K7

4K7

FFX4A

STEREO HEADPHONE DRIVER

description

+3V3

J3-1

MCLK

J8-1

FFX3A

of

J1

the

HEADER8X2

+VS

J4-1

LRCKI

J8-2

FFX3B

1

2

SDI1

CN1

3

4

LRCKI

J3-2

BICKI

J10-1

FFX4A

CN2

demonstration

BICKI

5

6

CN-5-02P

1

+

C12

C13

1

J4-2

SDI1

J10-2

FFX4B

7

8

10uF/10V

SCL

SDA

2

2

100nF

9

10

J17

1

2

J6-1

INT_LINE

J11-1

F3XL

+3V3

11

12

RESET

J6-2

J11-2

F3XR

13

14

PWRDN

SDA

15

16

SDA

SOFTMUTE

MCLK

J5-1

J12-1

TO AP INTERFACE

The range of +Vs is from +5V to +24V

SCL

SCL

J12-2

J5-2

POWER SUPPLY INPUT

AP INTERFACE CONNECTOR

TEST PINS

board

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	AN3959				Functional description of the demonstration board
	Table 1.		Bill of material
	No.		Type	Footprint	Description	Qty	Reference	Manufacturer
	1		Jack	Speaker jack	MP4-16	1	J9	Songchen
	2	Headphone		Phone jack	SONGCHEN CKX-3.5-06	3	J2, J13, J19	Songchen
			jack		3-pin
	3	Switch		Deviator	Deviator switch	2	SW2, SW3	Any source
				switch
	4	Terminal		Through-hole	2P pitch: 5mm connector	1	CN2	Phoenix
					terminal			Contact
	5	Header		Through-hole	4P (2x2 row) 2.54 mm header	1	J7	Any source
							J3, J4, J5, J6, J8, J10,
	6	Header		Through-hole	2P (2x1 row) 2.54 mm header	14	J11, J12, J14, J15, J16,	Any source
							J17, CN1, J18
	7	Header		Through-hole	16P (8x2 row) 2.54 mm header	1	J1	Any source
	8	CCAP		CAP0603	50 Volt NPO 100 pF +/-10%	2	C24, C26	Murata
	9	CCAP		CAP0603	50 Volt NPO 150 pF +/-10%	2	C17, C20	Murata
	10	CCAP		CAP0603	50 Volt NPO 220 pF +/-10%	4	C18, C21, C22, C23	Murata
	11	CCAP		CAP0603	50 Volt NPO 330 pF +/-10%	2	C44, C45	Murata
	12	CCAP		CAP0603	50 Volt NPO 470 pF +/-10%	2	C16, C19	Murata
	13	CCAP		CAP0603	50 Volt 1 nF +/-10%	5	C4, C47, C48, C49, C50	Murata
	14	CCAP		CAP0603	50 Volt 3.3 nF +/-10%	2	C6, C7	Murata
							C1, C2, C5, C11, C13,
	15	CCAP		CAP0603	50 Volt 100 nF +/-10%	12	C27, C29, C54, C55,	Murata
							C429, C427A, C427B
	16	CCAP		CAP0603	50 Volt 220 nF +/-10%	4	C32, C36, C42, C43	Murata
	17	CCAP		CAP0603	NS	5	C37, C38, C40, C41, C56	Murata
	18	CCAP		CAP0805	10 Volt 1 µF +/-10%	5	C8, C9, C10, C30,	Murata
							C31, C53
	19	CCAP		CAP0805	10 Volt 2.2U +/-10%	1	C3	Murata
	20	CCAP		CAP1206	50 Volt 220 nF +/-10%	2	C39, C46	Murata
	21	CCAP		CAP1206	50 Volt 1U +/-10%	2	C426A, C426B	Murata
	22	CCAP		CAP1206	10 Volt 10 µF +/-10%	2	C51, C52	Murata
	23	CCAP		CAP1206	NS	4	C14, C33, C34, C35	Murata
	24		ECAP	CAP1206	10µF/10V	1	C12	Samsung
	25		ECAP	Through-hole	47µF/35V 105 Centigrade	1	C28	Rubycon/
								Panasonic
	26		ECAP	Through-hole	100µF/35V 105 Centigrade	2	C15, C25	Rubycon/
								Panasonic
	27		ECAP	Through-hole	470µF/25V, pitch = 5 mm,	1	C428	Rubycon/
					φ 10 mm			Panasonic

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Functional description of the demonstration board							AN3959
Table 1.		Bill of material (continued)
No.		Type	Footprint	Description	Qty	Reference	Manufacturer
28		RES	R1206	0R	4	R10, R11, R30, R41	Murata
29		RES	R1206	20 +/-5% 1/8W	2	R42, R43	Murata
30		RES	R0603	0 ohm 1/16W		R1, R3, R36	Murata
31		RES	R0603	47R +/-5% 1/16W	2	R35, R44	Murata
32		RES	R0603	470R +/-5% 1/16W	2	R37, R38	Murata
33		RES	R0603	1K +/-5% 1/16W	2	R45, R46	Murata
						R5, R16, R17, R24, R25,
34		RES	R0603	10K +/-5% 1/16W	11	R28, R29, R31, R32,	Murata
						R33, R34
35		RES	R0603	11K +/-5% 1/16W	2	R6, R7	Murata
						R12, R13, R14, R15,
36		RES	R0603	4.7K +/-5% 1/16W	12	R18, R19, R20, R21,	Murata
						R22, R23, R26, R27
37		RES	R0603	47K +/-5% 1/16W	2	R39, R40	Murata
38		RES	R0603	NS		R2, R4	Murata
39		RES	R0805	27K +/-5% 1/16W	2	R8, R9	Murata
40		Bead	L0805	Bead 600 ohm at 100 MHz or	2	BD3, BD4	Murata
				33R
41	Plastic rod			Hexagonal rod 15 mm length,	4	Four corners	Any source
				male type
42	Plastic rod			Hexagonal rod 8 mm length,	4	Four corners	Any source
				female type
43		IC	QFN48 or	STA381BWS (QFN48 or	1	IC1 or IC3	ST
			QFP64	QFP64)
44		IC	SOP8	LM833D (SOP8)	1	IC2	ST
45		Coil	SMD	SWPA6045S220MT, 22 µH	4	L1, L2, L3, L4	Sunlord
46		PCB		STA381BWS 2.0CH REV2.2	1		Fastprint

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Doc ID 022081 Rev 3

AN3959	Functional description of the demonstration board

Figure 4. Top view of PCB layout

Doc ID 022081 Rev 3

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Functional description of the demonstration board	AN3959

Figure 5. Inner layer2 view of PCB layout

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Doc ID 022081 Rev 3

AN3959	Functional description of the demonstration board

Figure 6. Inner layer3 view of PCB layout

Doc ID 022081 Rev 3

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Functional description of the demonstration board	AN3959

Figure 7. Bottom view of PCB layout

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Doc ID 022081 Rev 3

AN3959	Functional description of the demonstration board

Figure 8. Block diagram of test connections with equipment

Audio Precision Equipment

		Monitor
Output	S/PDIF
to AP	Signal	Digital Oscilloscope
		TDS3034B Tektronix

					I2S Input			APWLink Board
	STA380BWS
					(DC3V3)
	2.0CH	Demo
	Board
						(DC7V)
								PC with GUI to control the
					DC Power Supply			chipset

From 4.5V to24V

Doc ID 022081 Rev 3

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STA381BWS power section test results	AN3959

2 STA381BWS power section test results

Figure 9. Frequency response, VCC = 18 V, RL = 8 ohm, 0 dB (Pout = 1 W)
	+3
	+2.5
	+2
	+1.5
	+1
d	+0.5
B	+0
r
A	-0.5
	-1
	-1.5
	-2
	-2.5
	-3	50	100	200	500	1k	2k	5k	10k	20k
	20
						Hz
	Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Input Signal=-14dBFS, Pout=1W, Volume: +3dB

Figure 10. Crosstalk, VCC = 18 V, RL = 8 ohm, 0 dB (Pout = 1 W)
	+0
	-10
	-20
	-30
d	-40
B
r	-50
A	-60
	-70
	-80
	-90
	-100	50	100	200	500	1k	2k	5k	10k	20k
	20
						Hz

Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Pout=1W, Volume: +3dB

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Doc ID 022081 Rev 3

AN3959	STA381BWS power section test results

Figure 11.		SNR, VCC = 18 V, RL = 8 ohm, 0 dB (Pout = 1 W)
		+0
		-10
		-20
		-30
d		-40
B
r		-50
A		-60
		-70
		-80
		-90
	-100		50	100	200	500	1k	2k	5k	10k	20k
		20
							Hz

Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Pout=1W, Volume: +3dB

Figure 12.		THD vs. frequency, VCC = 18 V, RL = 8 ohm, Pout = 1 W
		5
		2
		1
		0.5
%		0.2
		0.1
	0.05
	0.02
	0.01		50	100	200	500	1k	2k	5k	10k	20k
		20
							Hz

Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Pout=1W, Volume: +3dB

Doc ID 022081 Rev 3

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STA381BWS power section test results	AN3959

Figure 13.		FFT (0 dBFS), VCC = 18 V, RL = 8 ohm, 0 dBFS (Pout = 1 W)
	+10
		+0
		-10
		-20
		-30
		-40
d		-50
B		-60
r		-70
A		-80
		-90
	-100
	-110
	-120
	-130
	-140		50	100	200	500	1k	2k	5k	10k	20k
		20
							Hz
		Test Conditions: VCC=18V, Rl=8ohm, f=1KHz, Dual BTL, Input Signal=0dBFS, Pout=1W, Volume: -11.5dB

Figure 14.		FFT (-60 dBFS), VCC = 18 V, RL = 8 ohm, 0 dBFS (Pout = 1 W)
	+10
		+0
		-10
		-20
		-30
		-40
d		-50
B		-60
r		-70
A		-80
		-90
	-100
	-110
	-120
	-130
	-140		50	100	200	500	1k	2k	5k	10k	20k
		20
							Hz
		Test Conditions: VCC=18V, Rl=8ohm, f=1KHz, Dual BTL, Input Signal=-60dBFS, Volume: -11.5dB

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Doc ID 022081 Rev 3

AN3959	STA381BWS power section test results
Figure 15.	THD vs. output power, VCC = 18 V, RL = 8 ohm, f = 1 kHz

10
5
2
1
0.5
%
0.2
0.1
0.05
0.02
0.01	20m	50m	100m	200m	500m	1	2	5	10	20
10m
					W

Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Volume: +3dB

Figure 16. THD vs. output power at different power supplies, RL = 8 ohm, f = 1 kHz

10
5				VCC=6V
											VCC=24V
2				VCC=9V							VCC=21V
1				VCC=12V							VCC=18V
0.5				VCC=15V
%
0.2
0.1
0.05
0.02
0.01	20m	50m	100m	200m	500m	1	2	5	10	20	40
10m
					W
Test Conditions: Rl=8ohm, Dual BTL, Volume: +3dB

Doc ID 022081 Rev 3

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STA381BW power section test results	AN3959

3 STA381BW power section test results

Figure 17. Frequency response, VCC = 24 V, RL = 8 ohm, 0 dB (Pout = 1 W)
	+3
	+2.5
	+2
	+1.5
	+1
d	+0.5
B	+0
r
A	-0.5
	-1
	-1.5
	-2
	-2.5
	-3	50	100	200	500	1k	2k	5k	10k	20k
	20
						Hz
	Test Conditions: VCC=24V, Rl=8ohm, Dual BTL, Input Signal=-17dBFS, Pout=1W, Volume: +3dB

Figure 18. Crosstalk, VCC = 24 V, RL = 8 ohm, 0 dB (Pout = 1 W)
	+0
	-10
	-20
	-30
d	-40
B
r	-50
A	-60
	-70
	-80
	-90
	-100	50	100	200	500	1k	2k	5k	10k	20k
	20
						Hz

Test Conditions: VCC=24V, Rl=8ohm, Dual BTL, Pout=1W, Volume: +3dB

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Doc ID 022081 Rev 3