19-0662; Rev 0; 11/06
MAX9723D Evaluation Kit/Evaluation System
General Description
The MAX9723D evaluation kit (EV kit) is a fully assem-
bled and tested PCB that evaluates the MAX9723
stereo DirectDrive
TM
headphone amplifier with
BassMax, volume control, and I
2
C. The MAX9723D EV
kit operates from a single 1.8V to 3.6V power supply,
and is capable of delivering 60mW into a 16Ω load.
The MAX9723D evaluation system (EV system) includes
a MAX9723D EV kit, Windows 98SE/2000/XP-compati-
ble software, and a Maxim system command module.
The software’s graphical user interface (GUI) allows
easy control of the MAX9723D’s I
2
C interface, adjusting
settings such as BassMax and volume.
Order the complete EV system (MAX9723DEVC-
MODU+ or MAX9723DEVCMOD2+) for a comprehen-
sive evaluation of the MAX9723A/MAX9723B/
MAX9723C/MAX9723D using a PC. Order the EV kit
(MAX9723DEVKIT+) if the CMODUSB+ or CMOD232+
system command module has already been purchased
with a previous Maxim EV system, or for custom use in
other microcontroller-based (µC) systems.
The EV kit comes with the MAX9723DETE+ installed.
Contact the factory for free samples of the pin-compati-
ble MAX9723A/MAX9723B/MAX9723C to evaluate
these parts.
Windows is a registered trademark of Microsoft Corp.
Features
o
Single 1.8V to 3.6V Power-Supply Operation
o
60mW Stereo DirectDrive Headphone Outputs
Ω
(16Ω, V
DD
= 3V)
o
System Command Module: USB Interface
(CMODUSB+) or Serial Interface (CMOD232+)
o
Windows
®
98SE/2000/XP-Compatible Evaluation
Software
o
Evaluates the MAX9723A/MAX9723B/MAX9723C
(with IC replacement)
o
Fully Assembled and Tested
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
Ordering Information
PART
MAX9723DEVKIT+
MAX9723DEVCMODU+
MAX9723DEVCMOD2+
TYPE
EV kit
EV system
EV system
INTERFACE
User-supplied I
2
C
interface
CMODUSB+ USB
interface board
CMOD232+ RS-232
serial-interface board
+Denotes
a lead-free and RoHS-compliant EV kit.
Note:
The MAX9723D EV kit software is included with the
MAX9723D EV kit, but is designed for use with the complete EV
system. The EV system includes a Maxim system command
module (CMODUSB+ or CMOD232+) and the EV kit. If the
Windows software will not be used, the EV kit board can be pur-
chased without the Maxim system command module.
Component List
MAX9723DEVCMODU+
PART
MAX9723DEVKIT+
CMODUSB+
QTY
1
1
DESCRIPTION
MAX9723D EV kit
System command module
(USB serial interface)
C1, C9, C10
3
DESIGNATION
QTY
MAX9723DEVKIT+
DESCRIPTION
0.1µF ±10%, 16V X7R ceramic
capacitors (0603)
TDK C1608X7R1C104K
Murata GRM188R71C104K
1µF ±10%, 10V X7R ceramic
capacitors (0603)
TDK C1608X7R1A105K
TDK C1608X7R1C105K
Murata GRM188R61A105K
0.47µF ±10%, X7R ceramic
capacitors (0603)
TDK C1608X7R1A474K (10V)
Murata GRM188R71E474KA12D (25V)
Murata GRM188R71C747KA88 (16V)
Kemet C0603C474K9RAC7867 (6.3V)
MAX9723DEVCMOD2+
PART
MAX9723DEVKIT+
CMOD232+
QTY
1
1
DESCRIPTION
MAX9723D EV kit
System command module
(RS-232 serial interface)
C4, C5
2
C2, C3, C6
3
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX9723D Evaluation Kit/Evaluation System
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
Component List (continued)
MAX9723DEVKIT+
DESIGNATION
J1
JU1, JU2, JU3
PJ1
QTY
1
3
1
DESCRIPTION
2 x 10 right-angle receptacle
3-pin headers
3.5mm stereo jack
(SMT, lead free, and RoHS)
CUI Inc. SJ-3523-SMT
10kΩ ±1% resistors (0603)
lead free
22.1kΩ ±1% resistors (0603)
lead free
47.5kΩ ±1% resistors (0603)
lead free
MAX9723DETE+ (16-pin TQFN)
Stereo DirectDrive headphone
amplifier
Shunts
MAX9723D EV kit PCB
SUPPLIER
Keystone
Murata
TDK
Component Suppliers
PHONE
800-221-5510
770-436-1300
847-703-6100
WEBSITE
www.keyelco.com
www.murata.com
www.component.tdk.com
Note:
Indicate that you are using the MAX9723D when
contacting these component suppliers.
MAX9723D EV Kit Files
FILE
INSTALL.EXE
MAX9723V03.EXE
TROUBLESHOOTING_USB.
PDF
FTD2XX.INF
UNINST.INI
DESCRIPTION
Installs the EV kit files on your
computer
Application program
USB driver installation help
file
USB device driver file
Uninstall the EV kit software
R1, R2
R3, R6
R4, R5
2
2
2
U1
—
—
1
3
1
Quick Start
Recommended Equipment
•
•
•
•
DC power supply (3.3V @ 0.5A)
Stereo audio source (e.g., CD player, MP3 player, etc.)
32Ω or 16Ω headphones
MAX9723D EV system
MAX9723D EV kit
Maxim CMODUSB+ or CMOD232+ system
command module
A user-supplied Windows 98SE/2000/XP PC
2) Install the MAX9723D EV kit software on your com-
puter by running the INSTALL.EXE program inside
the temporary folder. The program files are copied
and icons are created in the Windows
Start |
Programs
menu.
3) Carefully connect the system command module to
the EV kit by aligning the 20-pin connector of the
MAX9723D EV kit with the 20-pin header of the
Maxim system command module interface board.
4) Enable the pullup resistors on the system command
module by making sure the SDA switch and SCL
switch (both on SW1) are thrown on.
5) If using Maxim’s serial-interface board (CMOD232+),
connect a 9-pin male-to-female cable from the com-
puter’s serial port to CMOD232+. CMOD232+
requires a 9V power supply to P1 (DC IN). For regu-
lated 3.3V output voltage, install a shunt across pins
1-2 of J1 on the CMOD232+. If using Maxim’s USB
interface board (CMODUSB+), connect the A-to-B
USB cable from the computer’s USB port to
CMODUSB+. CMODUSB+ requires no external
power as it is powered from the PC USB port. For reg-
ulated 3.3V output, install a shunt across pins 2-3 of
J1 on the CMODUSB+.
6) Ensure that a shunt is placed across pins 1-2 of
JU3 on the MAX9723D EV kit board.
•
Note:
In the following sections, software-related items
are identified by bolding. Text in bold refers to items
directly from the EV kit software. Text in
bold and
underlined
refers to items from the Windows 98SE/
2000/XP operating system.
Procedure
Follow the steps below to verify board operation.
Caution:
Do not turn on the power supply until all con-
nections are complete.
1) Visit the Maxim website (www.maxim-ic.com/evkit-
software) to download the most recent version of
the EV kit software, 9723RXX.ZIP. Save the EV kit
software to a temporary folder and uncompress the
ZIP file.
2 ________________________________________________________________________________________
_______________________________________________________________________________________
MAX9723D Evaluation Kit/Evaluation System
7) Connect a 3.3V power supply between the pads
labeled V
DD
and GND on the MAX9723D EV kit
board.
8) Ensure that the input audio source is turned off.
9) Connect the stereo audio source to the pads
labeled RIN, LIN, and GND on the MAX9723D EV
kit board.
10) Plug the headphones into the 3.5mm headphone
jack on the MAX9723D EV kit board.
11) Turn on the DC power supply.
12) Enable the audio source.
13) Start the MAX9723 program by opening its icon in the
Windows
Start
menu. Select the device slave
address from the device pulldown menu. See Table 1.
Detailed Description of Software
Device Selection and Slave Address
The MAX9723 has an I
2
C-compatible interface that
allows serial communication between the MAX9723
and a microcontroller. The MAX9723 is available with
one of two preset slave addresses (see Table 1). The
MAX9723D EV kit ships with the MAX9723D. Change
IC U1 to evaluate other devices. Samples of other
MAX9723 devices are available through Maxim’s web-
site at www.maxim-ic.com.
The
Device
pulldown menu allows the user to select
the device slave address. Select the slave address of
the device being evaluated at startup. See Figure 2 for
details.
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
Table 1. MAX9723 Slave Address
VERSION
MAX9723A
MAX9723B
MAX9723C
MAX9723D*
MAX9723 SLAVE ADDRESS
A6
1
1
1
1
A5
0
0
0
0
A4
0
0
0
0
A3
1
1
1
1
A2
1
1
1
1
A1
0
0
0
0
A0
0
1
0
1
R/W
X
X
X
X
*EV
kit IC version.
Figure 1. MAX9723D EV Kit Software GUI Window
Figure 2. Device Selection and Slave Address
_______________________________________________________________________________________
3
MAX9723D Evaluation Kit/Evaluation System
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
Gain Range and Gain Settings
The MAX9723 offers two options for the maximum vol-
ume setting (A
V_VOL
)
.
The MAX9723A/MAX9723B have
selectable maximum gains of -5dB or 0dB, while the
MAX9723C and MAX9723D have selectable maximum
gains of +1dB or +6dB.
The
Gain Range
checkbox (Figure 3) allows the user to
select between the two maximum gain ranges. See Table
2 for the corresponding gain range of each IC version.
Figure 4. MAX9723 Bass-Boost Feature
Checking the
Bass Boost Select
checkbox (Figure 4)
enables bass boost. The output has additional gain
(A
V_BOOST
) on top of the overall gain (A
V_VOL
). The
default A
V_BOOST
is +8.8dB for bass frequencies. The
absolute gain at low frequencies is equal to:
A
V_TOTAL
= A
V_VOL
+ A
V_BOOST
Powered Up Checkbox and Close Button
Figure 3. Gain Range Checkbox and Gain Setting Slide Bar for
MAX9723 Gain Adjustments
Table 2. MAX9723 Gain Range
VERSION
MAX9723A
MAX9723B
MAX9723C
MAX9723D*
*EV
kit IC version.
GAIN RANGE (dB)
-5 or 0
-5 or 0
+1 or +6
+1 or +6
Uncheck the
Powered Up
checkbox (Figure 5), while
SHDN
is pulled high, to shut down the MAX9723. The
EV kit software powers up in the state shown in Figure
5. Clearing the
Powered Up
checkbox does not reset
the internal registers.
Press the
Close
button (Figure 5) to quit the
MAX9723D EV kit software.
The MAX9723 also includes a 32-level volume control
that adjusts the overall gain (A
V_VOL
) of the output
amplifiers.
Use the
Gain Setting
slide bar to adjust A
V_VOL
.
Bass Boost Select
The MAX9723 includes a bass-boost feature that com-
pensates for the headphone’s poor bass response by
increasing the amplifier gain at low frequencies
(A
V_BOOST
). The bass-boost setting is customized by
adjusting R5, R6, and C9 for the left channel and R4,
R6, and C10 for the right channel. See the
Detailed
Description of Hardware
section.
4
Figure 5. Powered Up Checkbox and Close Button
_______________________________________________________________________________________
MAX9723D Evaluation Kit/Evaluation System
that positive feedback is negligible when BassMax is
disabled. Table 3 contains a list of R6 (R3) values, with
R5 (R4) = 47kΩ, and the corresponding low-frequency
gain.
OUT_
R5
(R4)
BB_
BASSMAX
ENABLE
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
MAX9723D
R
AUDIO INPUT
R
Table 3. BassMax Gain Examples—R5
(R4) = 47kΩ
R6 (R3) (kΩ)
39
33
R6
(R3)
C9
(C10)
AV GAIN (dB)
20.6
15.1
11.3
8.8
5.7
3.7
27
22
15
10
*REFERENCE DESIGNATORS IN PARENTHESIS INDICATE RIGHT-CHANNEL COMPONENTS.
Figure 6. Bass Boost External Components for Left Channel
Note:
Reference designators in parenthesis indicate right-
channel components.
Detailed Description of Hardware
BassMax Component Selection
PCB components R5, R6, and C9 set the bass boost for
the left channel, while components R4, R3, and C10 set
the bass boost for the right channel (see Figure 6). The
default bass boost is +8.8dB. Changing the components
listed above modifies the bass-boost gain and frequency
response. For example, when bass boost is enabled, the
ratio of R5 and R6 sets the left-channel bass boost gain
(A
V_BOOST_
) that is calculated using the following equa-
tion. Adjust resistors R4 and R3 to set the right-channel
bass boost.
⎛
R5
+
R6
⎞
A
V _ BOOSTL
=
20
×
log
⎜
⎟
⎝
R5
−
R6
⎠
The low-frequency boost attained by the BassMax cir-
cuit is added to the gain realized by the volume setting.
Select the BassMax gain so that the output signal
remains within the dynamic range of the MAX9723.
Output signal clipping occurs at low frequencies if the
BassMax gain boost is excessively large (refer to the
Output Dynamic Range
section in the MAX9723 data
sheet).
GAIN PROFILE WITH AND
WITHOUT B
ASS
M
AX
16
14
12
10
A
V_TOTAL
(dB)
8
6
4
2
0
-2
-4
10
100
1000
FREQUENCY (Hz)
10,000
100,000
WITHOUT B
ASS
M
AX
MAX9723D
R5(R3) = 47kΩ
R6 (R4) = 22.1kΩ
C9 (C10) = 0.1µF
A
V_VOL
= +6dB
f
ZERO
WITH B
ASS
M
AX
f
POLE
To maintain circuit stability, the ratio:
R6
R5
+
R6
must not exceed 1/2 (a ratio of 1/3 is recommended).
The switch that shorts BB_ to SGND, when BassMax is
disabled, can have an on-resistance as high as 300Ω.
Choose a value for R5 (R3) greater than 40kΩ to ensure
Figure 7. BassMax, Gain Profile Example for AV_VOL = +6dB
_______________________________________________________________________________________
5
