AN2542
Application note
Demo board BT-HTS-Rx_V1.0 for
audio receiver using Bluetooth
®
wireless technology
Features
!
!
!
Class 2 A2DP Bluetooth
®
technology receiver
1-Vpp line-out (stereo)
Single 3.3-V supply.
Overview
This board is designed for the evaluation of the BT-STA2416C2 receiver module in an A2DP
environment. It is based on the SOUNDabout
®
and BLUEmagic
®
software of Open Interface
North America and it guarantees a broad compatibility with boards from many other
manufacturers as given in
Section 5: Interoperability on page 12.
A full set of certifications is
given
on page 13.
The board also accommodates the STA529 device. This is a codec with an high efficiency
FFX™ class-D output stage. The line output pin is driven by the TS462 op-amp configured
to filter the PWM and to scale the output to 1 Vpp.
The output signal can be used to feed an amplification stage. Both ICs (codec and op-amp)
and the entire Bluetooth
®
technology module are designed and manufactured by
STMicroelectronics.
Figure 1
shows the BT-HTS-RX_V1.0 demo board. The BT-STA2416C2 Bluetooth
®
technology module and the RF antenna connection are positioned on the right-hand side of
the board, the STA529 codec is in the middle and the TS462 op-amp is on the left.
Figure 1.
BT-HTS-RX_V1.0 demonstration board
May 2007
Rev 2
1/16
www.st.com
Circuit description
AN2542
1
1.1
Circuit description
Block diagram
Figure 2
shows the block diagram of the BT-HTS-RX board. The Bluetooth
®
technology
stream received by the RF antenna is sent to the BT-STA2416C2, a highly integrated
module able to communicate wirelessly with BTA2DP sources such as cellular phones,
BT Dongles and Notebook PCs.
Whilst streaming audio the receiver manages the BT data in the BT-STA2416C2 module,
transferring them to the STA529, an IC comprising a digital stereo class-D audio amplifier, a
DSP and a CMOS power output stage based on the FFX technology. The STA529 is
dedicated to the decoding and the generation of the PWM analog output.
A low-pass filter stage cuts the high frequencies of the PWM signal before amplification to a
standard line-out signal of 1 Vpp.
Figure 2.
Circuit block diagram
3.3 V
BT-STA2416C2
Receiver module
BTA2DP
Stream
connection
indicator
STA529
Codec
XTAL
13 MHz
Low-pass
filter
TS462
Dual op-amp
Stereo
line out
1 Vpp
1.2
Schematic
Figure 3, Figure 4
and
Figure 5
make up the overall schematic. You can zoom in to see the
detail or you can download the original OrCAD
®
and PDF files from
http://www.st.com/stonline/products/applications/blocks/consumer/conb005.shtml.
2/16
AN2542
5
4
3
2
1
ALL Vdd (3.3V) must be connected only at the CON9 pin 5
3V3P_529
BLUE
AUDIO_R
AUDIO_L
3V3_OPAMP 3V3_1.8
BT_SIG
R1
3V3_529
1k
R2
1R1
D1
J1
Figure 3.
3V3 BT
3V3_529
R3
0
1
2
3
4
5
CON5
J2
D
D
3V3 BT
D2
R5
100
1SS335
+
C1
10uF 16V
R4
10k
TP1
TP2
1
2
CON2
J3
TP3
TP4
TP5
TP6
TP7
TP8
R6
100
RST
PWREN
BOOT
USB VCC
3.3V
UART_TXD
GND
UART RXD
J4
CON8
R7
0
100nF
3V3 BT
R8
3k3
C2
BT_SIG
1
2
3
4
5
6
7
8
UART2_TXD
TP9
TP10
C
C
1
2
3
4
5
6
7
8
9
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
UART2_RXD
CON9
GND
Schematic diagram, part 1
VDD33
DGND
AUDIO_L
AGND
AUDIO_R
BT_RESET
LED_CONT
TP11
TP12
TP13
TP14
TP15
1
Vss1
Vdd
GPIO15
GPIO14
GPIO13
GPIO12
N.C.
GPIO11
GPIO9
GPIO8
GPIO7
GPIO6
GPIO5
GPIO4
GPIO3
GPIO2
GPIO1
GPIO0
SW1
2
R9
R10
R11
R12
R13
0
0
0
0
0
POW_FAULT
STA529_RESET
SEL_CLK33
STA529_STBY
STA529_MUTE
CON5
IC1
1
2
3
4
5
43
44
45
Vss2 (RF GND)
+ANTENNA
Vss2 (RF GND)
BT-STA2416C2
J5
R14
R15
0
0
B
BOOT
RESET
USB_DP
USB_DN
SPI_RXD
SPI_TXD
SPI_CLK
SPI_FRM
17
24
23
22
21
20
19
18
STA529_SPI_RXD
STA529_SPI_TXD
R16
R17
R18
R19
0
0
0
0
STA529_SPI_CLK
STA529_SPI_FRM
STA529_SCL
STA529_SDA
B
A
1
2
3
4
5
6
7
8
9
10
11
12
UART2_RXD
13
UART2_TXD
14
15
16
ALL GNDs must be connected only at the CON9 pin 7
TDI
TMS
NTRST
TDO
TCK
INT1
I2C_DAT
I2C_CLK
PCM_CLK
PCM_SYNC
PCM_B
PCM_A
UART2_RXD
UART2_TXD
UART2_I1
UART2_O2
R20
1k
3V3 BT
R21
1k
A
GND
Title
STMICROELECTRONICS BT-STA2416C2-STA529Q-OPAMP
Size
B
Date:
4
3
2
Document Number
BT-STA2416C2
Tuesday, February 20, 2007
Sheet
1
Rev
<RevCod
1
of
3
Circuit description
3/16
5
1
52
51
50
49
48
47
46
45
44
43
42
41
40
3V3_529
C8
XTO
XTI
R24
0
100nF
12K
C13
+
C12
C14
+
IC2
STA529QFN
10nF
33uF 10V
STA529_RESET
C19
C16
+
10nF
1V8
100nF
C17
10nF
C15
R25
470
10uF 16V
STBY
BICKO
BICKI
Vdd_IO1
GND_IO1
LRCKO
LRCKI
SDATAO
SDATAI
Vdd1
GND1
Vdd_PLL
GND_PLL
FILT
15
16
17
18
19
20
21
22
23
24
25
26
3V3_1.8
STA529_MUTE
Vcc1A
OUT1A
GND1A
GND1B
OUT1B
Vcc1B
Vcc2B
OUT2B
GND2B
GND2A
OUT2A
Vcc2A
4/16
4
3
2
1
5
Circuit description
C3
STA529_SPI_TXD
100nF
XTI
C5
C4
3V3_529
STA529_SPI_CLK
STA529_STBY
C6
100nF
STA529_SPI_FRM
100nF
XTO
R22
1M
1A8
STA529_SPI_RXD
Figure 4.
1V8
D
D
13MHz
Y1
C7
22pF
C9
22pF
close to the IC
R23
C11
220pF
82pF
C10
100nF
SEL_CLK33
STA529_SDA
STA529_SCL
POW_FAULT
3V3P_529
C20
100nF
100nF
3V3_529
C18
C
C
2
3
4
5
6
7
8
9
10
11
12
13
14
INL
INR
VBIAS
AVDD
Vhi
Vlo
AGND
VCM
RESET
CLKOUT
GND2
VDD2
MUTE
XTO
XTI
MCLK_33
SEL_CLK33
SDA
SCL
I2C DIS
TM
PWR_FAULT
Vcc33
Vdd_IO2
GND_IO2
GND33
39
38
37
36
35
34
33
32
31
30
29
28
27
Schematic diagram, part 2
33uF 10V
OUT1A
OUT1B
C22
10nF
33uF 10V
C23
1uF
C24
100nF
3V3P_529
C25
1uF
OUT2A
OUT2B
1V8
1A8
C21
+
3V3P_529
C26
100nF
+
IC3
C27
220uF/16V
B
B
1
IN
OUT
5
R26
1R1
2
4
+
C29
C32
100nF
100nF
R27
1R1
33uF 10V
C28
GND
3
INH
BYP
+
C30
33uF 10V
C31
LD2985AM18
100nF
R28
0
A
A
Title
STMICROELECTRONICS BT-STA2416-STA529Q-OPAMP
Size
B
Date:
4
3
2
Document Number
STA529Q
Tuesday, February 20, 2007
Sheet
1
Rev
2
of
3
AN2542
5
AN2542
5
4
3
2
1
close to the IC
C33
0.1u
+
C34
100u / 16V
R29
30k
Figure 5.
3V3_OPAMP
D
D
OUT2B
C35
2.2nF
R34
1500
C38
150pF
+
15k
OUT2A
R38
47u/16V
R35
4k7
R36
4k7
R37
4k7
C39
L1
FERRITE
R39
10k
C36
150pF
R33
30k
C37
150pF
R30
4k7
R31
4k7
R32
4k7
C40
100p
AUDIO_R
Schematic diagram, part 3
C
C
4
3
2
2
1
4
Title
Rev
5
6
OPAMP
5
Sheet
3
of
3
6
3
1
IC4
ADA4841-2
8
8
STMICROELECTRONICS BT-STA2416-STA529Q-OPAMP
7
7
Size
A
Document Number
Date:
Friday, February 23, 2007
B
B
C41
OUT1A
R40
4k7
R41
4k7
R42
4k7
R43
R45
1500
R46
4k7
R47
4k7
R48
4k7
R50
30k
C46
150pF
R49
C44
2.2nF
C45
150pF
150pF
15k
C42
+
L2
FERRITE
47u/16V
R44
10k
C43
100p
AUDIO_L
OUT1B
30k
3V3_OPAMP
A
Circuit description
A
5/16
5
4
3
2
1
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