ST AN3959 Installation and operating instructions

December 2011 Doc ID 022081 Rev 3 1/65
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
www.st.com

Contents AN3959
2/65 Doc ID 022081 Rev 3
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

AN3959 Contents
Doc ID 022081 Rev 3 3/65
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

List of figures AN3959
4/65 Doc ID 022081 Rev 3
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

AN3959 List of figures
Doc ID 022081 Rev 3 5/65
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

Functional description of the demonstration board AN3959
6/65 Doc ID 022081 Rev 3
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.

AN3959 Functional description of the demonstration board
Doc ID 022081 Rev 3 7/65
1.3 Schematic and block diagrams, bill of material, PCB layout
Figure 2. Schematic-1
Line in
Line out
OUTPUT FILTER
STA381BWS
C56
NS
100nF
2.0CH & 2.1CH
MONO BTL
CONFIGURATION
NOTE:
*
R4 NS
R1 0 ohm
R2 NS
R3 0 ohm
C11
100nF
C1
100nF
C426A 1uF/50V
C427A 100nF
C426B 1uF/50V
C427B 100nF
C2 100nF
C3 2u2/10V
C5
100nF
C6
3.3nF/10V
C7
3.3nF/10V
C30
1uF/10V
C31
1uF/10V
R6
11K
R7
11K
R8
27K R9
27K
C8 1uF/10V
C9 1uF/10V
C4
1nF
C10
1uF/10V
C29
100nF
C429 100nF
+
C428
470U/35V
R36 0ohm
R37 470R
R38 470R
1VCC_REG
2VSS_REG
3OUT2B
4GND2
5VCC2
6OUT2A
7OUT1B
8VCC1
9GND1
10 OUT1A
11 VDD_REG
12 GND_REG
13 HALFVDD 14 F3XL 15 F3XR 16 HPIN_L 17 HPIN_R 18 LINEHPOUT_L 19 LINEHPOUT_R 20 GNDA 21 SOFTMUTE 22 VDD3V3 23 CPVSS 24 CPM
25
GNDPSUB
26
CPP
27
VDD3V3CHP
28
VDDDIG1
29
GNDDIG1
30
FFX3A
31
FFX3B
32
FFX4A
33
FFX4B
34
VREGFILT
35
AGNDPLL
36
MCLK
37
BICKI
38
LRCKI
39
SDI
40
RESET
41
PWDN
42
INTLINE
43
SDA
44
SCL
45
SA
46
TESTMODE
47
GNDDIG2
48
VDDDIG2
IC1
STA381BWS
1 2
J15
1 2
J16
R5
10K
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17 18 19 20 21 22 23 24 25 26 27
28
29 30 31 32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50 51 52
53 54
55 56 57
58 59
60 61 62
63 64
IC3
STA381BWS_NEW
C33 NS C14 NS
C34 NS
C35 NS
1
2
3
J19
HPJCKX3.5-06
C32
220nF
C36
220nF
R10
0R
R11
0R
C37
NS
C38
NS
C39
220nF
C40
NS
C41
NS
R30
0R
R41
0R
C42
220nF
C43
220nF
C44
330P(S)
R42
20(S)
R43
20(S)
C45
330P(S)
L3
SWPA6045S220MT
L1
SWPA6045S220MT
L2
SWPA6045S220MT
L4
SWPA6045S220MT
C46
220nF
C47
1N(S)
C48
1N(S)
C49
1N(S)
C50
1N(S)
1
2
3
4
J9
SPEA KJA CK2X2
C51 10uF/10V
C52 10uF/10V
R39 47K
R40 47K
1
2
3
J2
HPJCKX3.5-06
C53
1uF/10V
1
2
3SW2
1
2
3SW3
R35 47R
R44 47R
R45 1K R46 1K
C54
100nF
C55
100nF
1
2
34
J7
HEADER2X2
C56
NS
1
2
J14
1 2
J18
MCLK
BICKI
LRCKI
SDI1
PWRDN
SCL
SDA
+3V3
OUT2B
OUT2A
OUT1B
OUT1A
+VS
INT_LINE
FFX4B
FFX4A
FFX3B
FFX3A
+3V3
F3XR
F3XL
+3V3
RESET
OUT1A
OUT1B
OUT2A
OUT2B
SOFTMUTE
Note 1:
The output filter for the line/HP output
path isoptional (not required for the STA 381BW/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 isnot soldered when the STA 381BW/S
isconfigured in 2.0 or 2.1 channels; C56 is100 nF
when the STA 381BW/Sisconfigured in mono BTL.
Refer to the schematic in Appendix A on page 63
for an example of amono BTL application.

AN3959 Functional description of the demonstration board
Doc ID 022081 Rev 3 8/65
Figure 3. Schematic-2
AP INTERFACE CONNECTOR
TO AP INTERFACE
POWER SUPPLY INPUT
The range of +Vs is from +5V to +24V
TEST PINS
HEADPHONE O/P
STEREO HEADPHONE DRIVER
12
34
56
78
910
11 12
13 14
15 16
J1
HEADER8X2
+C12
10uF/10V C13
100nF
1
2
CN2
CN-5-02P 1
2
CN1
J5-1
J5-2
J3-1
J3-2
J4-1
J4-2
J6-1
J6-2
J8-1
J8-2
J10-1
J10-2
J11-1
J11-2
J12-1
J12-2
C15
100uF
35V
R12
4K7
C16
470PF
R13
4K7
R14
4K7
C17
150PF
R15
4K7
R16
10K
R17
10K
R18
4K7
R19
4K7
C18
220PF
R20
4K7
C19
470PF
R21
4K7
R22
4K7
C20
150PF
R23
4K7
R24
10K
R25
10K
R26
4K7
R27
4K7
C21
220PF
R28 10K
R29 10K
R31 10K
C22
220PF
R32 10K
R33 10K
C23
220PF
BD3
BEAD or 33R
C24
100PF
C25
100uF
35V
R34 10K
BD4
BEA D or 33R
C26
100PF
1
2
3
J13
C27
100nF
C28
47uF
50V
1
OUTA
2
INA1
3
INA2
4
VSS
5
INB2
6
INB1
7
OUTB
8
VDD
IC2
LM833
1
2
J17
PWRDN
MCLK
RESET
SDASCL
BICKI
LRCKI
SDI1
+3V3
+VS
SDA
SCL
SDA
SCL
MCLK
BICKI
LRCKI
SDI1
INT_LINE
FFX3A
FFX3B
FFX4A
FFX4B
F3XL
F3XR
SOFTMUTE
FFX3B
FFX3A
FFX4B
FFX4A
+VS
+VS
+VS
+3V3

AN3959 Functional description of the demonstration board
Doc ID 022081 Rev 3 9/65
Table 1. Bill of material
No. Type Footprint Description Qty Reference Manufacturer
1 Jack Speaker jack MP4-16 1 J9 Songchen
2Headphone
jack Phone jack SONGCHEN CKX-3.5-06 3-pin 3 J2, J13, J19 Songchen
3Switch Deviator
switch Deviator switch 2 SW2, SW3 Any source
4 Terminal Through-hole 2P pitch: 5mm connector
terminal 1 CN2 Phoenix Contact
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
J3, J4, J5, J6, J8, J10,
J11, J12, J14, J15, J16,
J17, CN1, J18
Any source
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
C1, C2, C5, C11, C13,
C27, C29, C54, C55,
C429, C427A, C427B
Murata
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,
C31, C53 Murata
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,
φ10 mm 1C428 Rubycon/ Panasonic

Functional description of the demonstration board AN3959
10/65 Doc ID 022081 Rev 3
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
34 RES R0603 10K +/-5% 1/16W 11
R5, R16, R17, R24, R25,
R28, R29, R31, R32,
R33, R34
Murata
35 RES R0603 11K +/-5% 1/16W 2 R6, R7 Murata
36 RES R0603 4.7K +/-5% 1/16W 12
R12, R13, R14, R15,
R18, R19, R20, R21,
R22, R23, R26, R27
Murata
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
33R 2BD3,BD4 Murata
41 Plastic rod Hexagonal rod 15 mm length,
male type 4 Four corners Any source
42 Plastic rod Hexagonal rod 8 mm length,
female type 4 Four corners Any source
43 IC QFN48 or
QFP64
STA381BWS (QFN48 or
QFP64) 1 IC1 or IC3 ST
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
Table 1. Bill of material (continued)
No. Type Footprint Description Qty Reference Manufacturer

AN3959 Functional description of the demonstration board
Doc ID 022081 Rev 3 11/65
Figure 4. Top view of PCB layout

Functional description of the demonstration board AN3959
12/65 Doc ID 022081 Rev 3
Figure 5. Inner layer2 view of PCB layout

AN3959 Functional description of the demonstration board
Doc ID 022081 Rev 3 13/65
Figure 6. Inner layer3 view of PCB layout

Functional description of the demonstration board AN3959
14/65 Doc ID 022081 Rev 3
Figure 7. Bottom view of PCB layout

AN3959 Functional description of the demonstration board
Doc ID 022081 Rev 3 15/65
Figure 8. Block diagram of test connections with equipment
Audio Precision Equipment
STA380BWS
2.0CH Demo
Board
DC Power Supply
Digital Oscilloscope
TDS3034B Tektronix
Output
to AP
S/PDIF
Si
g
nal
Monitor
APWLink Board
I2S Input
PC with GUI to control the
chipset
(
DC3V3
)
From 4.5V to24V
(
DC7V
)

STA381BWS power section test results AN3959
16/65 Doc ID 022081 Rev 3
2 STA381BWS power section test results
Figure 9. Frequency response, VCC = 18 V, RL= 8 ohm, 0 dB (Pout = 1 W)
Figure 10. Crosstalk, VCC = 18 V, RL= 8 ohm, 0 dB (Pout = 1 W)
Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Input Signal=-14dBFS, Pout=1W, Volume: +3dB
-3
+3
-2.5
-2
-1.5
-1
-0.5
+0
+0.5
+1
+1.5
+2
+2.5
d
B
r
A
20 20k50 100 200 500 1k 2k 5k 10k
Hz
Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Pout=1W, Volume: +3dB
-100
+0
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
r
A
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Hz

AN3959 STA381BWS power section test results
Doc ID 022081 Rev 3 17/65
Figure 11. SNR, VCC = 18 V, RL= 8 ohm, 0 dB (Pout = 1 W)
Figure 12. THD vs. frequency, VCC = 18 V, RL= 8 ohm, Pout = 1 W
Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Pout=1W, Volume: +3dB
-100
+0
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
r
A
20 20k50 100 200 500 1k 2k 5k 10k
Hz
Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Pout=1W, Volume: +3dB
0.01
5
0.02
0.05
0.1
0.2
0.5
1
2
%
20 20k50 100 200 500 1k 2k 5k 10k
Hz

STA381BWS power section test results AN3959
18/65 Doc ID 022081 Rev 3
Figure 13. FFT (0 dBFS), VCC = 18 V, RL= 8 ohm, 0 dBFS (Pout = 1 W)
Figure 14. FFT (-60 dBFS), VCC = 18 V, RL= 8 ohm, 0 dBFS (Pout = 1 W)
Test Conditions: VCC=18V, Rl=8ohm, f=1KHz, Dual BTL, Input Signal=0dBFS, Pout=1W, Volume: -11.5dB
-140
+10
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
+0
d
B
r
A
20 20k50 100 200 500 1k 2k 5k 10k
Hz
Test Conditions: VCC=18V, Rl=8ohm, f=1KHz, Dual BTL, Input Signal=-60dBFS, Volume: -11.5dB
-140
+10
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
+0
d
B
r
A
20 20k50 100 200 500 1k 2k 5k 10k
Hz

AN3959 STA381BWS power section test results
Doc ID 022081 Rev 3 19/65
Figure 15. THD vs. output power, VCC = 18 V, RL= 8 ohm, f = 1 kHz
Figure 16. THD vs. output power at different power supplies, RL= 8 ohm, f = 1 kHz
Test Conditions: VCC=18V, Rl=8ohm, Dual BTL, Volume: +3dB
0.01
10
0.02
0.05
0.1
0.2
0.5
1
2
5
%
10m 2020m 50m 100m 200m 500m 1 2 5 10
W
Test Conditions: Rl=8ohm, Dual BTL, Volume: +3dB
0.01
10
0.02
0.05
0.1
0.2
0.5
1
2
5
%
10m 4020m 50m 100m 200m 500m 1 2 5 10 20
W
VCC=24V
VCC=21V
VCC=18V
VCC=15V
VCC=12V
VCC=9V
VCC=6V

STA381BW power section test results AN3959
20/65 Doc ID 022081 Rev 3
3 STA381BW power section test results
Figure 17. Frequency response, VCC = 24 V, RL= 8 ohm, 0 dB (Pout = 1 W)
Figure 18. Crosstalk, VCC = 24 V, RL= 8 ohm, 0 dB (Pout = 1 W)
Test Conditions: VCC=24V, Rl=8ohm, Dual BTL, Input Signal=-17dBFS, Pout=1W, Volume: +3dB
-3
+3
-2.5
-2
-1.5
-1
-0.5
+0
+0.5
+1
+1.5
+2
+2.5
d
B
r
A
20 20k50 100 200 500 1k 2k 5k 10k
Hz
Test Conditions: VCC=24V, Rl=8ohm, Dual BTL, Pout=1W, Volume: +3dB
-100
+0
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
r
A
20 20k50 100 200 500 1k 2k 5k 10k
Hz