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Application note
STEVAL-CCA025V1 demonstration board user guidelines for the
TS4621 high-performance stereo headphone amplifier
Introduction
This application note describes the STEVAL-CCA025V1 demonstration board, designed to
evaluate STMicroelectronics’ TS4621, a high-performance class G stereo headphone driver
with capacitorless outputs and I2C interface.
The document provides:
●
a brief description of the TS4621 device and its key features.
●
a description of the demonstration board and all of its components.
●
a description of the TS4621 control software provided.
●
schematics and layout of the demonstration board.
Figure 1.
TS4621 demonstration board
Description
The TS4621 is a class G stereo headphone driver dedicated to high audio performance and
space-constrained applications.
It is based on a low-power dissipation amplifier core technology combined with a highefficiency buck converter to supply this amplifier.
When powered by a battery, the buck converter generates the appropriate voltage to the
amplifier according to the amplitude of the audio signal to supply to the headsets.
An I²C interface offers volume control in 32 steps from -60 dB to +4 dB. A dedicated
common-mode sense pin is used to remove parasitic noise from the jack.
The device is packaged in a tiny 16-bump, flip-chip package with a pitch of 400 µm.
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www.st.com
Key features of the TS4621
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Key features of the TS4621
●
Power supply range: 2.3 V to 4.8 V.
●
0.6 mA/channel quiescent current
●
2.1 mA current consumption with 100 µW/channel (10 dB crest factor)
●
0.006% typical THD+N at 1 kHz
●
100 dB typical PSRR at 217 Hz
●
Zero pop and click
●
I²C interface for volume control.
●
Digital volume control range from -60 dB to +4 dB.
●
100 dB of SNR A-weighted at G = 0 dB.
●
Independent right and left channel enable control.
●
Integrated high-efficiency buck converter.
●
Low standby current: 5 µA max.
●
No output coupling capacitors (thanks to the internal negative supply).
●
Thermal shutdown and short-circuit protection.
●
Flip-chip package: 1.65 mm x 1.65 mm, 400 µm pitch, 16 bumps.
Refer to the TS4621 datasheet for complete information.
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Description of the demonstration board
Description of the demonstration board
The STEVAL-CCA025V1 demonstration board is designed to help you evaluate the TS4621
audio differential input stereo headphone amplifier. The TS4621 device is soldered on a
four-layer PCB. An on-board RS-232 to I2C interface makes this board easy to control from
a personal computer through its serial port.
The software provided controls all of the TS4621’s features (gain, mode, mute, standby and
register status). You can also use the connectors on the demonstration board to directly
control the features through another I²C interface.
Table 1.
●
By removing the jumpers on Cn6 and Cn7, you can disconnect the on-board I2C
interface to control the TS4621 through an external I2C bus interface.
●
The -3 dB cut-off input high-pass filter is set at about 6 Hz (C4 to C7) at G = 4 dB and
with Cin = 2.2 µF. If you want to change this frequency, you have to replace C4 to C7 at
the same time. More information on these component calculations is available in the
TS4621 datasheet.
●
The actual current consumption of the TS4621 can be measured directly by removing
the jumper on Cn3 and inserting a DC amperemeter in series. The overall current
consumption of the demonstration board is higher than the consumption of the TS4621
because the Cn1 power supply connector supplies the RS-232 to I2C adapter in
addition to the TS4621. The I2C can be supplied by a second power supply through
Cn8, in which case the I²C voltage (VI²C) must be 2.3 V< VI²C < Vcc.
Demonstration board connectors
Connector
Description
Cn1
Power connector (VCC and GND). Power supply voltage from 2.3 V to 4.8 V.
Cn2, Cn9
Fully differential positive and negative input signal connectors (active input signal and GND). By
shorting one active input to GND, you can use the demonstration board in single-ended input
mode (refer to the TS4621 datasheet for more information).
Cn3
Connector that allows direct measurement of the TS4621’s current consumption. Remove the
jumper and insert a DC amperemeter.
Cn4
Left output connector (GND and active signal).
Cn5
Right output connector (GND and active signal).
Cn6, Cn7
SCL and SDA connectors:
– pins shorted, the TS4621 is controlled by the on-board RS 232 to I2C interface.
– pins unshorted, the TS4621 can be controlled by an external I2C bus.
Cn8
Use this connector as an optional power connector (VCCI2C) thanks to a second power supply.
J1
3.5 mm stereo headphone plug.
J2
DB9 female connector enabling connection of the demonstration board to the RS-232 serial
port.
Note:
When you apply the power supply through Cn1, do not invert the polarity as this will
damage the demonstration board.
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Description of the demonstration board
Figure 2.
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Schematic diagram
Vcc
Cn1
VccI2C
C1
2.2 μF
3.3 μH
Gnd
Power
A2
Cn3
Gnd
A1
U1
Sw
Positive HpVdd B3
supply
AVdd
Cn2
Gnd
C4
2.2 μF
A4
InL-
C5
2.2 μF
B4
InL+
HPVdd
L1
Gnd
Gnd
-
C9
2.2 nF
Left output
R1
VoutL A3
Level
detector
+
12
Left input
3
2
CMS C3
Cn9
C6
2.2 μF
Gnd
Right input
C7
2.2 μF
SDA
SCL
Gnd
C4 InR+
D4
D2
SCL
I2C
Cn5
C10
2.2 nF
Negative
supply
PVss
1
12
-
D1 SDA
J1
R2
VoutR D3
Level
detector
+
InR-
Cn4
Gnd
C8
10 μF
Right output
Gnd
PVss
C1
C2
C2
B2
C1
Gnd
AGnd
B1
TS4621_FC
Gnd
C2
2.2 μF
Gnd
C3
2.2 μF
TS4621 main application
Cn6 SCL
Cn7 SDA
SCL
SDA
Vcc
VccI2C
Cn8
R6
10K
R7
10K
VccI2C
R4
180
16
U2A
1
15
Q1
Q2
Q3
2
R5
100
KP1040
J2
5GND
9
4DTR
8
3TXD
7RTS
2
6DSR
1
Gnd Gnd Gnd
Gnd
GND2
R3
1K
D1
3
1N4148
U2B
4
14
13
KP1040
DB9
R8
2k2
GND2
R9
1K
D2
5
1N4148
Gnd
U2C
6
12
11
KP1040
GND2
Gnd
RS232 to I2C converter
AM06121
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Description of the demonstration board
Table 2.
Component list for the demonstration board
Name
Quantity
Description
L1
1
3.3 µH LQM2MPN3R3 Murata
C2, C3
2
2.2 µF/6.3V X5R, SMD ceramic capacitors 0603
C1, C4, C5,C6, C7 5
2.2 µF/10V X5R, SMD ceramic capacitors 0603
C9, C10
2
2.2 nF/50V X7R, SMD ceramic capacitors, 0603
C8,
1
10 µF/6.3V X5R, SMD ceramic capacitors, 0603
Cn1, Cn3, Cn4,
Cn5, Cn6,
Cn7,Cn8
7
2-pin header 2.54 mm pitch
Cn2, Cn9
2
4-pin header 2.54 mm pitch
D1, D2
2
1N4148,
J1
1
3.5 mm stereo PCB headphone jack connector
J2
1
PCB 90° female DB9 connector
R1, R2
2
12 Ω/1% SMD resistor, 0603
R3, R9
2
1 kΩ/1% SMD resistor, 0603
R4
1
180 Ω/1% SMD resistor, 0603
R5
1
100 Ω/1% SMD resistor, 0603
R6, R7
2
10 kΩ/1% SMD resistor, 0603
R8
1
2.2 kΩ/1% SMD resistor, 0603
Q1,Q2,Q3
3
2N7002 SOT23 MOSN
U1
1
TS4621EIJT
U2
1
KP1040, TLP521-4(GB)
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Demonstration board layout
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Demonstration board layout
The following figures show the layers and top and bottom views of the demonstration board.
Figure 3.
PCB top layer
Figure 4.
PCB mid layer 1
Figure 5.
PCB mid layer 2
Figure 6.
PCB bottom layer
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Figure 7.
Demonstration board layout
Top view of the demonstration
board
Figure 8.
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Bottom view of the demonstration
board
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TS4621 demonstration software
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TS4621 demonstration software
The TS4621 demonstration software provides a quick and easy way of driving the TS4621
audio system from a PC, and in particular, of configuring the output mode and the volume.
The software is located on the CDROM provided with the demonstration board. The latest
revision of this software is available on STmicroelectronics’ web site at www.st.com. It runs
under Microsoft® Windows XP.
The PC must have a free serial port. If not, a USB-to-serial adapter can be used but note
that compatibility with all adapters available on the market has not been tested.
4.1
Connecting the demonstration board and starting the
software
Follow these steps to drive the TS4621 from a PC.
1.
Use a DB9 female to DB9 male RS-232 cable to connect the PC to the TS4621
demonstration board on J2.
2.
Connect the power supply VCC to Cn1 and place the jumper on Cn8.
3.
Verify that Cn3, Cn6 and Cn7 are shorted.
4.
Connect the modulation source to Cn2 and Cn9 and plug a headphone into J1.
5.
Copy the TS4621 demonstration board program board.exe provided on the CDROM to
the hard drive of your PC and launch it by double-clicking on it (no installation required,
copying the program is sufficient).
The dialog box shown in Figure 9 is displayed.
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Figure 9.
TS4621 demonstration software
TS4621 demonstration software main window
Read internal
registers menu
Internal TS4621
diagram: changes
when output mode
changes
Output mode
buttons
Actual volume
indicator
Mute buttons
Volume control cursor
Automatically read the
current register settings
Software exit button
Serial port selection
6.
Choose the appropriate COM port from the Port frame or click Auto Detect for the
program to select the COM port automatically.
When the Port Status indicator turns to green, the program is ready to send
commands to the TS4621.
In some rare cases, when auto detect is used, a COM port may be selected (Port
Status is green) which is not the correct one. If this happens, manually force the proper
COM port by clicking directly in the Port box.
Note:
The COM port to which the device is connected must be in the range of COM1 to COM8. If
this is not the case, change the COM port number in Windows by selecting Start>Control
Panel>System>Hardware>Device Manager.
4.2
Using the TS4621 software
The following features are available in the main window of the TS4621 demonstration
software shown in Figure 9.
●
Mode select buttons
Allow you to select the TS4621 output mode. The diagram located in the middle of the
window summarizes the mode currently selected and shows which inputs and outputs
are active. The indicator located to the right of each output mode lights up when the
mode is active. Figure 10 shows an example of this window when the software is in
operation.
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TS4621 demonstration software
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Figure 10. TS4621 main window in operating mode
●
Mute buttons
Allow you to set the TS4621 output to mute or operating mode. When the indicator
located to the right lights up in green, the channel mute is active.
●
Auto Read I²C
Allow you to update the graphical user interface according to the register value
automatically (after pressing a button).
●
Read internal register menu
When you click on this menu, the TS4621 Internal Registers pop-up window is
displayed (see Figure 11). By clicking on the Read Internal Registers button, you can
display the actual state of the TS4621. The hexadecimal values of the CR1 to CR4
registers are also displayed. By pressing the Clear Results button, all results
disappear and you need to press the Read Internal Registers button again for a new
display.
Note that this window remains open until you close it by clicking on the cross in the
upper right corner.
Note also that this window is not automatically refreshed. If you change the output
mode or something else in the main window, you have to press the Read Internal
Registers button again to display the new TS4621 settings.
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TS4621 demonstration software
Figure 11. TS4621 main window + register status window
The following feature is available in the main window of the TS4621 demonstration software
shown in Figure 9.
●
Volume control cursor
By dragging this cursor up and down, you can control the TS4621’s output volume. The
actual gain set is displayed in the Gain box.
To exit the program, just click the Exit button on the bottom right or click the cross in the
upper right corner of the window.
Note:
Occasional problems may arise when trying to drive the demonstration board using certain
notebook or laptop PCs and the RS-232 output.
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TS4621 demonstration software
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Common error messages
No acknowledge for address
You pressed an output mode button and the software displays an information pop-up
window that indicates “Error: No acknowledge for address!” (see example in Figure 12).
This error message can have several causes.
●
The power supply is down or disconnected from Cn1.
●
One or several jumpers are missing on Cn6 or Cn7 or Cn8.
●
The serial cable is disconnected from J2.
●
The jumper on Cn3 is missing and there is no amperemeter in series.
●
The power supply for the I²C is down or disconnected from Cn8 if a second power
supply is optionally used for the I²C.
Figure 12. TS4621 acknowledge pop-up message
Results displayed in the Internal Registers window are different from main
window
The Auto Read I²C checkbox allows you to update the graphical user interface according to
the register value automatically (after pressing a button).
If the Auto Read I²C box is unchecked, the main window is not automatically refreshed and
if you press the read internal registers button in the TS4621 internal registers window, the
results displayed might be different from what the main window indicates (see Figure 13).
This can happen if, while the software is running, you switch the TS4621 power supply OFF
and ON. When you do this, the TS4621 is reset and all internal registers are set to their
initial value. This is why, when you press the Read Internal Registers button, the result
displayed is quite different from the display in the main window.
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TS4621 demonstration software
To avoid this issue, check the Auto Read I²C box.
Figure 13. Uncorrelated windows in TS4621 demonstration software
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Conclusion
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Conclusion
To order the board online, go to http://www.st.com/stonline/domains/buy/buy_dev.htm and
use the order code STEVAL-CCA025V1.
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Revision history
Revision history
Table 3.
Document revision history
Date
Revision
09-Apr-2010
1
Changes
Initial release.
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