ST AN3959 APPLICATION NOTE

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

AN3959

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 STCompressor

TM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 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

2/65 Doc ID 022081 Rev 3

AN3959 Contents

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

7.3.1 Biquad CRC computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

7.3.2 Crossover CRC computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

7.3.3 STCompressor

TM

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

Doc ID 022081 Rev 3 3/65

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, V
Figure 10. Crosstalk, V
Figure 11. SNR, V

CC

= 18 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

CC

= 18 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 12. THD vs. frequency, V
Figure 13. FFT (0 dBFS), V
Figure 14. FFT (-60 dBFS), V

= 18 V, RL = 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . 18

CC

CC

Figure 15. THD vs. output power, V
Figure 16. THD vs. output power at different power supplies, R
Figure 17. Frequency response, V
Figure 18. Crosstalk, V
Figure 19. SNR, V

CC

= 24 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

CC

= 24 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 20. THD vs. frequency, V
Figure 21. FFT (0 dBFS), V
Figure 22. FFT (-60 dBFS), V

= 24 V, RL = 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . . 22

CC

CC

Figure 23. THD vs. output power, V
Figure 24. THD vs. output power at different power supplies, R

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 V
Figure 35. Path between V

and ground pin minimized in order to avoid inductive paths . . . . . . . . 32

CC

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. V

filter for high frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

CC

Figure 43. Thermal layout with large ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 44. Processing path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Figure 45. 2.1-channel with STCompressor

Figure 46. STCompressor - overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 47. STCompressor - mapper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 48. STCompressor - compression ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

= 18 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . 16

CC

= 18 V, RL = 8 ohm, Pout = 1 W . . . . . . . . . . . . . . . . . . . . . . . . . 17

CC

= 18 V, RL = 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . 18

= 18 V, RL = 8 ohm, f = 1 kHz . . . . . . . . . . . . . . . . . . . . . . . . 19

CC

= 24 V, RL = 8 ohm, 0 dB (Pout = 1 W) . . . . . . . . . . . . . . . . . . 20

CC

= 24 V, RL = 8 ohm, Pout = 1 W . . . . . . . . . . . . . . . . . . . . . . . . . 21

CC

= 8 ohm, f = 1 kHz . . . . . . . . . . . . . 19

L

= 24 V, RL = 8 ohm, 0 dBFS (Pout = 1 W) . . . . . . . . . . . . . . . . . . . . 22

= 24 V, RL = 8 ohm, f = 1 kHz . . . . . . . . . . . . . . . . . . . . . . . . 23

CC

TM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

= 8 ohm, f = 1 kHz . . . . . . . . . . . . . 23

L

branches . . . . . . . . . . . . . . . . . . . . . . 32

CC

4/65 Doc ID 022081 Rev 3

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

Doc ID 022081 Rev 3 5/65

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

1.1 Connections

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.

1.2 Output configuration

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

6/65 Doc ID 022081 Rev 3

1.3 Schematic and block diagrams, bill of material, PCB layout

Figure 2. Schematic-1

+3V3

R5

10K

C4
1nF

SDI1

49

48

47

36

46

35

45

34

33

32

31

30

29

28

27

26

25

32

C9

1uF/10V

0ohm

C3

2u2/10V

44

43

42

41

40

39

38

37

36

35

34

33

C8

1uF/10V

STA381BWS

LRCKI

BICKI

MCLK

FFX4B

FFX4A

FFX3B

FFX3A

C5

100nF

+3V3

Doc ID 022081 Rev 3 7/65

+3V3

R3

0 ohm

R1

0 ohm

C11

100nF

63

64

606162

47

OUT2B

+VS

C428

470U/35V

+

C35

100nF

C33NSC14

1uF/50V

C429

C426A

C34

NS

NS

NS

OUT2A

100nF

100nF

1uF/50V

OUT1B

C427B

C427A

C426B

OUT1A

NOTE:

NS

C30

1uF/10V

C31

1uF/10V

C7

3.3nF/10V

CONFIGURATION

2.0CH & 2.1CH
MONO BT L

J15

1

2

J16

R6

11K
R7

11K

47K

47K

3.3nF/10V
R40

R39

F3XR

F3XL

1

HPJCKX3.5-06

Line in

J2

HPJCKX3.5-06

HEADER2X2

2

Line out

C56

100nF

J19

1

2

3

1

2

3

J7

1

34

C6

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

2

1

J14

R35

1K

C54

100nF

R46

470R

R37

1

J18

R44

1K

C55

100nF

R45

470R

R38

48

1

VDDDIG2

GNDDIG2

VCC_REG

TESTMODE

2

VSS_REG

3

OUT2B

4

GND2

5

VCC2

6

OUT2A

7

OUT1B

8

VCC1

9

GND1

10

OUT1A

11

VDD_REG

12

GND_REG

HALFVDD14F3XL15F3XR16HPIN_L17HPIN_R18LINEHPOUT_L19LINEHPOUT_R20GNDA21SOFTMUTE22VDD3V323CPVSS24CPM

13

171819202122232425262728293031

C1

1uF/10V

100nF

NS

C56

*

2

47R

2

47R

1

3

10uF/10V

C51

1

3

10uF/10V

C52

59

C53

2

SW2

2

SW3

58

44

45SA46

SCL

STA381BWS

STA381BWS_NEW

R8

27K

RESET

NS

NS

100nF

R4

R2

C2

SDA

SCL

INT_LINE

PWRDN

53

54

505152

555657

37

38

39

40

41

42

43

SDI

SDA

IC1

IC3

BICKI

LRCKI

PWDN

RESET

INTLINE

R9

27K

1uF/10V

SOFTMUTE

AGNDPLL

VREGFILT

GNDDIG1

VDDDIG1

VDD3V3CHP

GNDPSUB

C29
100nF

C10

MCLK

FFX4B

FFX4A

FFX3B

FFX3A

CPP

R36

OUT1A

R42

20(S)

C44

330P(S)

L1

SWPA6045S220MT

OUT1B

OUT2A

OUT2B

C45

330P(S)

R43

20(S)

SWPA6045S220MT

L2

SWPA6045S220MT

L4

C37

C32

NS

220nF

R10

0R

0R

R11

220nF

NS

C36

C38

NS

C41

C43

0R

220nF

R41

0R

R30

220nF

NS

C40

C42

C47

1N(S)

C46

220nF

220nF

4

C50

1N(S)

3

2

C48

1N(S)

1

C39

C49

1N(S)

SPEAKJA CK2X2

J9

L3

SWPA6045S220MT

OUTPUT FILTER

Note 1:
The output filter for the line/HP output
path is optional (not required for the STA381BW/S).
If the 2x 47 ohm resistors (R35 and R44) are
bypassed through J14 and J18, the 2x 100 nF
capacitors (C54 and C55) must also be removed.

Note 2:
C56 is not soldered when the STA 381BW/S
is configured in 2.0 or 2.1 channels; C56 is 100 nF
when the STA 381BW/S is configured in mono BTL.
Refer to the s
for an example of a mono BTL application.

chematic in Appendix A on page 63

AN3959 Functional description of the demonstration board

Figure 3. Schematic-2

Doc ID 022081 Rev 3 8/65

R12

FFX3B

FFX3A

FFX4B

FFX4A

4K7

C16
470PF

R13
4K7

R20

4K7

C19
470PF

R21
4K7

STEREO HEA DPHONE DRIVER

AN3959 Functional description of the demonstration board

C15

100uF
35V

10K

10K

C22

220PF

R29

R31

+VS

+VS

IC2

R27
4K7

LM833

1

2

3

4

OUTA

INA1

OUTB

INA2

VSS5INB2

VDD

INB1

+VS

R24

10K

220PF

C21

10K

R16

10K

R17

220PF

C28

47uF

8

7

6

10K

R25

C27
100nF

50V

C25

100uF

35V

10K

R34

220PF

C23

10K

10K

R33

R32

BD3

BEAD or 33R

C26

C24

100PF

100PF

BD4

BEAD o r 33R

10K

R28

1

2

3

HEADPHONE O/P

J13

C17

150PF

C20

150PF

R18
4K7

R19
4K7

C18

R26
4K7

R14
4K7

R15
4K7

R22

4K7

R23
4K7

+3V3

SDI1

BICKI

J17

MCLK

12

1

2

11 12

13 14

15 16

TO AP INTERFACE

AP INTERFACE CONNECTOR

J1

HEADER8X2

34

56

78

910

LRCKI

SDASCL

RESET

PWRDN

+VS

CN1

CN2

CN-5-02P

1

2

+

1

2

C12
10uF/10V

The r ange of +Vs is f rom +5V t o +24V

POWER SUPPLY INPUT

+3V3

C13
100nF

J3-1

J4-1

J3-2

J4-2

J6-1

J6-2

SDA

J5-1

SCL

J5-2

MCLK

LRCKI

BICKI

SDI1

INT_LINE

SDA

SCL

J8-1

J8-2

J10-1

J10-2

J11-1

J11-2

J12-1

J12-2

FFX3A

FFX3B

FFX4A

FFX4B

F3XL

F3XR

SOFTMUTE

TEST PINS

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

Headphone

2

3Switch

4 Terminal Through-hole

5 Header Through-hole 4P (2x2 row) 2.54 mm header 1 J7 Any source

6 Header Through-hole 2P (2x1 row) 2.54 mm header 14

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

15 CCAP CAP0603 50 Volt 100 nF +/-10% 12

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

jack

Phone jack

Deviator

switch

SONGCHEN CKX-3.5-06
3-pin

Deviator switch 2 SW2, SW3 Any source

2P pitch: 5mm connector
terminal

3 J2, J13, J19 Songchen

1 CN2

J3, J4, J5, J6, J8, J10,
J11, J12, J14, J15, J16,
J17, CN1, J18

C1, C2, C5, C11, C13,
C27, C29, C54, C55,
C429, C427A, C427B

Phoenix

Contact

Any source

Murata

18 CCAP CAP0805 10 Volt 1 µF +/-10% 5

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

26 ECAP Through-hole 100µF/35V 105 Centigrade 2 C15, C25

27 ECAP Through-hole

470µF/25V, pitch = 5 mm,
φ 10 mm

Doc ID 022081 Rev 3 9/65

C8, C9, C10, C30,
C31, C53

1C428

Murata

Rubycon/

Panasonic

Rubycon/

Panasonic

Rubycon/

Panasonic

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

35 RES R0603 11K +/-5% 1/16W 2 R6, R7 Murata

36 RES R0603 4.7K +/-5% 1/16W 12

37 RES R0603 47K +/-5% 1/16W 2 R39, R40 Murata

38 RES R0603 NS R2, R4 Murata

R28, R29, R31, R32,
R33, R34

R12, R13, R14, R15,
R18, R19, R20, R21,
R22, R23, R26, R27

Murata

Murata

39 RES R0805 27K +/-5% 1/16W 2 R8, R9 Murata

40 Bead L0805

41 Plastic rod

42 Plastic rod

43 IC

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

QFN48 or

QFP64

Bead 600 ohm at 100 MHz or
33R

Hexagonal rod 15 mm length,
male type

Hexagonal rod 8 mm length,
female type

STA381BWS (QFN48 or
QFP64)

2BD3, BD4 Murata

4 Four corners Any source

4 Four corners Any source

1 IC1 or IC3 ST

10/65 Doc ID 022081 Rev 3

AN3959 Functional description of the demonstration board

Figure 4. Top view of PCB layout

Doc ID 022081 Rev 3 11/65

Functional description of the demonstration board AN3959

Figure 5. Inner layer2 view of PCB layout

12/65 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 13/65

Functional description of the demonstration board AN3959

Figure 7. Bottom view of PCB layout

14/65 Doc ID 022081 Rev 3

AN3959 Functional description of the demonstration board

g

(

(

Figure 8. Block diagram of test connections with equipment

Output
to AP

STA380BWS

2.0CH

Demo

Board

From 4.5V to24V

Audio Precision Equipment

S/PDIF

nal

Si

I2S Input

DC3V3)

DC7V)

DC Power Supply

Monitor

Digital Oscilloscope

TDS3034B Tektronix

APWLink Board

PC with GUI to control the
chipset

Doc ID 022081 Rev 3 15/65

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

+0.5

d
B

+0

r

A

-0.5

-1

-1.5

-2

-2.5

-3
20 20k50 100 200 500 1k 2k 5k 10k

Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Input Signal=-14dBFS, Pout=1W, Volum e: +3dB

Figure 10. Crosstalk, V

+0

-10

-20

-30

-40

d
B

r

-50

A

-60

-70

-80

-90

Hz

= 18 V, RL = 8 ohm, 0 dB (Pout = 1 W)

CC

-100
20 20k50 100 200 500 1k 2k 5k 10k

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

16/65 Doc ID 022081 Rev 3

Hz

AN3959 STA381BWS power section test results

Figure 11. SNR, VCC = 18 V, RL = 8 ohm, 0 dB (Pout = 1 W)

+0

-10

-20

-30

-40

d
B

r

-50

A

-60

-70

-80

-90

-100
20 20k50 100 200 500 1k 2k 5k 10k

Hz

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

Figure 12. THD vs. frequency, V

5

2

1

0.5

%

0.2

0.1

0.05

0.02

0.01
20 20k50 100 200 500 1k 2k 5k 10k

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

= 18 V, RL = 8 ohm, Pout = 1 W

CC

Hz

Doc ID 022081 Rev 3 17/65

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

-50

d

B

-60

r

-70

A

-80

-90

-100

-110

-120

-130

-140
20 20k50 100 200 500 1k 2k 5k 10k

Hz

Test Conditions: VCC=18V, Rl=8ohm, f=1KHz, Dual BTL, Input Signal=0dBFS, Pout=1W, Volum e: -11.5dB

Figure 14. FFT (-60 dBFS), V

+10

+0

-10

-20

-30

-40

-50

d

B

-60

r

-70

A

-80

-90

-100

-110

-120

-130

-140
20 20k50 100 200 500 1k 2k 5k 10k

Test Conditions: VCC=18V, Rl=8ohm, f=1KHz, Dual BTL, Input Signal=-60dBFS, Volume: -11.5dB

= 18 V, RL = 8 ohm, 0 dBFS (Pout = 1 W)

CC

Hz

18/65 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

10m 2020m 50m 100m 200m 500m 1 2 5 10

W

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

Figure 16. THD vs. output power at different power supplies, R

10

5

2

1

0.5

%

0.2

0.1

0.05

0.02

0.01
10m 4020m 50m 100m 200m 500m 1 2 5 10 20

Test Conditions: Rl=8ohm, Dual BTL, Volum e: +3dB

VCC=6V

VCC=9V

VCC=12V

VCC=15V

W

= 8 ohm, f = 1 kHz

L

VCC=24V

VCC=21V

VCC=18V

Doc ID 022081 Rev 3 19/65

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

+0.5

d
B

+0

r

A

-0.5

-1

-1.5

-2

-2.5

-3
20 20k50 100 200 500 1k 2k 5k 10k

Test Conditions: VCC=24V, Rl=8ohm, Dual BTL, Input Signal=-17dBFS, Pout=1W, Volume: +3dB

Figure 18. Crosstalk, V

+0

-10

-20

-30

-40

d

B

r

-50

A

-60

-70

-80

Hz

= 24 V, RL = 8 ohm, 0 dB (Pout = 1 W)

CC

-90

-100
20 20k50 100 200 500 1k 2k 5k 10k

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

20/65 Doc ID 022081 Rev 3

Hz