General Description
The MAX9723D evaluation kit (EV kit) is a fully assem-
bled and tested PCB that evaluates the MAX9723
stereo DirectDriveTM headphone amplifier with
BassMax, volume control, and I2C. The MAX9723D EV
kit operates from a single 1.8V to 3.6V power supply,
and is capable of delivering 60mW into a 16Ωload.
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 I2C 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
Single 1.8V to 3.6V Power-Supply Operation
60mW Stereo DirectDrive Headphone Outputs
(16ΩΩ, VDD = 3V)
System Command Module: USB Interface
(CMODUSB+) or Serial Interface (CMOD232+)
Windows®98SE/2000/XP-Compatible Evaluation
Software
Evaluates the MAX9723A/MAX9723B/MAX9723C
(with IC replacement)
Fully Assembled and Tested
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
MAX9723D Evaluation Kit/Evaluation System
________________________________________________________________
Maxim Integrated Products
1
Ordering Information
PART
QTY
DESCRIPTION
M AX9723D E V KIT+
1 MAX9723D EV kit
CMODUSB+ 1 System command module
(USB serial interface)
PART
QTY
DESCRIPTION
M AX9723D E V KIT+
1 MAX9723D EV kit
CMOD232+ 1 System command module
(RS-232 serial interface)
PART TYPE INTERFACE
MAX9723DEVKIT+ EV kit User-supplied I2C
interface
MAX9723DEVCMODU+
EV system
CMODUSB+ USB
interface board
MAX9723DEVCMOD2+
EV system
CMOD232+ RS-232
serial-interface board
MAX9723DEVCMODU+
Component List
MAX9723DEVCMOD2+
19-0662; Rev 0; 11/06
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.
+
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.
DESIGNATION
QTY
DESCRIPTION
C1, C9, C10
3
0.1µF ±10%, 16V X7R ceramic
capacitors (0603)
TDK C1608X7R1C104K
Murata GRM188R71C104K
C2, C3, C6 3
1µF ±10%, 10V X7R ceramic
capacitors (0603)
TDK C1608X7R1A105K
TDK C1608X7R1C105K
Murata GRM188R61A105K
C4, C5 2
0.47µF ± 10%, X 7R cer am i c
cap aci tor s ( 0603)
TD K C 1608X 7R1A474K ( 10V )
M ur ata G RM 188R71E 474KA12D ( 25V )
M ur ata G RM 188R71C 747KA88 ( 16V )
Kem et C 0603C 474K9RAC 7867 ( 6.3V )
MAX9723DEVKIT+
________________________________________________________________________________________
Quick Start
Recommended Equipment
• DC power supply (3.3V @ 0.5A)
• Stereo audio source (e.g., CD player, MP3 player, etc.)
•32Ωor 16Ωheadphones
• MAX9723D EV system
MAX9723D EV kit
Maxim CMODUSB+ or CMOD232+ system
command module
• A user-supplied Windows 98SE/2000/XP PC
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) 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.
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
MAX9723D Evaluation Kit/Evaluation System
2 _______________________________________________________________________________________
Note: Indicate that you are using the MAX9723D when
contacting these component suppliers.
DESIGNATION
QTY
DESCRIPTION
J1 1 2 x 10 right-angle receptacle
JU1, JU2, JU3
3 3-pin headers
PJ1 1
3.5mm stereo jack
(SMT, lead free, and RoHS)
CUI Inc. SJ-3523-SMT
R1, R2 2 10kΩ ±1% resistors (0603)
lead free
R3, R6 2 22.1kΩ ±1% resistors (0603)
lead free
R4, R5 2 47.5kΩ ±1% resistors (0603)
lead free
U1 1
MAX9723DETE+ (16-pin TQFN)
Stereo DirectDrive headphone
amplifier
— 3 Shunts
— 1 MAX9723D EV kit PCB
Component List (continued)
MAX9723DEVKIT+
SUPPLIER PHONE WEBSITE
Keystone
800-221-5510
www.keyelco.com
Murata
770-436-1300
www.murata.com
TDK
847-703-6100
www.component.tdk.com
Component Suppliers
FILE DESCRIPTION
INSTALL.EXE Installs the EV kit files on your
computer
MAX9723V03.EXE Application program
PDF
USB driver installation help
file
FTD2XX.INF USB device driver file
UNINST.INI Uninstall the EV kit software
MAX9723D EV Kit Files
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
MAX9723D Evaluation Kit/Evaluation System
_______________________________________________________________________________________ 3
7) Connect a 3.3V power supply between the pads
labeled VDD 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 I2C-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.
MAX9723 SLAVE ADDRESS
VERSION A6 A5 A4 A3 A2 A1 A0 R/W
MAX9723A 1 0 0 1 1 0 0 X
MAX9723B 1 0 0 1 1 0 1 X
MAX9723C 1 0 0 1 1 0 0 X
MAX9723D* 1 0 0 1 1 0 1 X
*
EV kit IC version.
Table 1. MAX9723 Slave Address
Figure 1. MAX9723D EV Kit Software GUI Window Figure 2. Device Selection and Slave Address
Gain Range and Gain Settings
The MAX9723 offers two options for the maximum vol-
ume setting (AV_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.
The MAX9723 also includes a 32-level volume control
that adjusts the overall gain (AV_VOL) of the output
amplifiers.
Use the Gain Setting slide bar to adjust AV_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
(AV_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.
Checking the Bass Boost Select checkbox (Figure 4)
enables bass boost. The output has additional gain
(AV_BOOST) on top of the overall gain (AV_VOL). The
default AV_BOOST is +8.8dB for bass frequencies. The
absolute gain at low frequencies is equal to:
AV_TOTAL = AV_VOL + AV_BOOST
Powered Up Checkbox and Close Button
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.
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
MAX9723D Evaluation Kit/Evaluation System
4 _______________________________________________________________________________________
Figure 3. Gain Range Checkbox and Gain Setting Slide Bar for
MAX9723 Gain Adjustments
Figure 5. Powered Up Checkbox and Close Button
VERSION GAIN RANGE (dB)
MAX9723A -5 or 0
MAX9723B -5 or 0
MAX9723C +1 or +6
MAX9723D* +1 or +6
*
EV kit IC version.
Table 2. MAX9723 Gain Range
Figure 4. MAX9723 Bass-Boost Feature
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
_______________________________________________________________________________________ 5
MAX9723D Evaluation Kit/Evaluation System
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
(AV_BOOST_) that is calculated using the following equa-
tion. Adjust resistors R4 and R3 to set the right-channel
bass boost.
To maintain circuit stability, the ratio:
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 40kΩto ensure
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.
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).
R
RR
6
56+
ARR
RR
V BOOSTL_log=× +
⎛
⎝
⎜
⎞
⎠
⎟
−
20 56
56
MAX9723D
R
R
OUT_
BB_
R5
(R4)
*REFERENCE DESIGNATORS IN PARENTHESIS INDICATE RIGHT-CHANNEL COMPONENTS.
R6
(R3)
AUDIO INPUT
BASSMAX
ENABLE C9
(C10)
Figure 6. Bass Boost External Components for Left Channel
R6 (R3) (kΩ) AV GAIN (dB)
39 20.6
33 15.1
27 11.3
22 8.8
15 5.7
10 3.7
Note: Reference designators in parenthesis indicate right-
channel components.
Table 3. BassMax Gain Examples—R5
(R4) = 47kΩ
GAIN PROFILE WITH AND
WITHOUT BASSMAX
FREQUENCY (Hz)
AV_TOTAL (dB)
10,0001000100
-2
0
2
4
6
8
10
12
14
16
fPOLE
fZERO
WITH BASSMAX
MAX9723D
R5(R3) = 47kΩ
R6 (R4) = 22.1kΩ
C9 (C10) = 0.1µF
AV_VOL = +6dB
WITHOUT BASSMAX
-4
10 100,000
Figure 7. BassMax, Gain Profile Example for AV_VOL = +6dB
For the left channel, capacitor C9 creates a pole and a
zero according to the following equations:
fPOLE is the frequency that the gain boost begins to roll
off. fZERO is the frequency that the bass-boost gain no
longer affects the transfer function and the volume-control
gain dominates. Table 4 lists capacitor values and the
corresponding poles and zeros for a given DC gain.
See Figure 7 for an example of a gain profile using
BassMax. Set the right-channel frequency response by
adjusting R4, R3, and C10.
MAX9723D EV System
The MAX9723D EV system (MAX9723DEVCMODU+ or
MAX9723DEVCMOD2+) is a complete stereo
DirectDrive headphone amplifier system consisting of
the MAX9723D EV kit and Maxim’s system command
module (CMODUSB+ or CMOD232+).
The MAX9723D EV kit provides a proven layout for
evaluating the MAX9723 and comes with the
MAX9723DETE+ installed.
CMODUSB+ and CMOD232+
Command Module
The CMODUSB+ and CMOD232+ use a proprietary
design to provide SPI- and I2C-compatible interfaces to
demonstrate various Maxim devices. Maxim reserves
the right to change the implementation of this module at
any time with no advance notice.
CMODUSB+ Power Supply
The CMODUSB+ board uses a MAX1658 linear regula-
tor. Jumper J1 selects between the 5VDC voltage that
comes from the USB connector and the MAX1658’s
regulated 3.3V output voltage. Set the CMODUSB+
jumper J1 at position 2-3 to have 3.3V output voltage to
evaluate the MAX9723D EV kit.
CMOD232+ Power Supply
The CMOD232+ board uses a MAX1659 linear regula-
tor. Jumper J1 selects either the MAX1659’s 5V default
output voltage or 3.3V output voltage. Set the
CMOD232+ jumper J1 at position 1-2 to have 3.3V out-
put voltage to evaluate the MAX9723D EV kit.
MAX9723D EV Kit Stand-Alone Operation
The MAX9723D EV kit operates without the system
command module, but the functions are limited to
power-on reset-default settings listed below:
• BassMax enabled
• Maximum gain range:
0dB for MAX9723A/MAX9723B or +6dB for
MAX9723C/MAX9723D
• Maximum gain setting
• Device enabled
Input Mode
The audio input terminals on the MAX9723D EV kit
accept stereo single-ended inputs (INR and INL).
MAX9723 I2C Address
The MAX9723 device is an I2C/SMBus™ slave and is
write only. Versions A and C have a fixed slave address
of 1001100X, and versions B and D have a fixed slave
address of 1001101X. See Table 1 for details.
fRR
CRR
fRR
CRR
POLE
ZERO
=×××
=+
×××
−56
2 956
56
2 956
π
π
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
MAX9723D Evaluation Kit/Evaluation System
6 _______________________________________________________________________________________
C9 (C10) (nF) fPOLE (Hz) fZERO (Hz)
100 38 106
82 47 130
68 56 156
56 68 190
47 81 230
22 174 490
10 384 1060
Note: Reference designators in parenthesis indicate right-
channel components. Simply substitute R4 for R5, R3 for R6,
and C10 for C9 for right-channel equations.
Table 4. BassMax Pole and Zero
Examples for a Gain Boost of 8.8dB—R5
(R4) = 47kΩand R6 (R3) = 22kΩ
SMBus is a trademark of Intel Corp.
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
MAX9723D Evaluation Kit/Evaluation System
_______________________________________________________________________________________ 7
Power Supply
The MAX9723D EV kit board is powered from a user-
supplied +1.8V to +3.6VDC power supply between the
VDD and GND pads.
Hardware- or Software-Shutdown Control
The MAX9723 features a shutdown mode to reduce
power consumption and extend battery life. Shutdown
can be either hardware- or software-controlled. The soft-
ware-controlled shutdown maintains the configuration
set by the user (see the
Powered Up Checkbox and
Close Button
section). Jumper JU3 controls the hard-
ware-shutdown function of the MAX9723D EV kit. Move
jumper JU3 to position 2-3 to shut down the entire
MAX9723 and reset all the registers to their power-on
defaults. See Table 5 for shutdown shunt positions.
User-Supplied I
2
C Interface
Connect SDA, SCL, and GND lines from the user-sup-
plied I2C interface to the corresponding pads on the
MAX9723D EV kit board. Install shunts across pins 1-2
of JU1 and JU2 to pull up the SDA and SCL lines.
Remove the jumpers if the bus is already pulled up.
JU3 FUNCTION
1-2* Normal operation
2-3 Power-down mode
*
Default position.
Table 5. Hardware Shutdown Selection
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
MAX9723D Evaluation Kit/Evaluation System
8 _______________________________________________________________________________________
MAX9723D
U1
J1
20-PIN HEADER
VDD
VDD
SHDN
C2
1µF
C3
1µF
R6
22.1kΩ
1%
1
C1N
4
5
C1P
2
PGND
3
SVSS
12
SGND 9
INR 11
INL 10
C6
1µF
VDD
1
2JU1
3
J1-2
R1
10kΩ
1%
J1-4
J1-6
J1-8
J1-10
J1-1
J1-3
J1-5
J1-7
J1-9
J1-12
J1-14
J1-16
J1-18
J1-20
J1-11
J1-13
J1-15
J1-17
J1-19
SCL
SDA
SCL
6
PVSS
7
VDD
1
2JU2
3
R2
10kΩ
1%
SDA
VDD
1
2JU3
3
8
SHDN
INL
C4
0.47µF
C5
0.47µF
R5
47.5kΩ
1%
INR
RIGHT
LEFT
GND
16
BBL
13
BBR
15
OUTL
R4
47.5kΩ
1%
14
OUTR
PJ1
C1
0.1µF
C9
0.1µF
C10
0.1µF
R3
22.1kΩ
1%
Figure 8. MAX9723D EV Kit Schematic
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
MAX9723D Evaluation Kit/Evaluation System
_______________________________________________________________________________________ 9
Figure 9. MAX9723D EV Kit Component Placement Guide—
Component Side
Figure 10. MAX9723D EV Kit PCB Layout—Component Side
MAX9723D Evaluation Kit/Evaluation System
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
10
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Evaluate: MAX9723A/MAX9723B/MAX9723C/MAX9723D
Figure 11. MAX9723D EV Kit Component Placement Guide—
Solder Side
Figure 12. MAX9723D EV Kit PCB Layout—Solder Side