19-3311; Rev 0; 6/04
MAX9722A Evaluation Kit
General Description
The MAX9722A evaluation kit (EV kit) is a fully assembled
and tested circuit board that uses the MAX9722A to drive
a stereo headphone in portable audio applications. The
MAX9722A is a differential stereo headphone driver with
DirectDrive. MAXIM’s DirectDrive technology eliminates
the need for DC-blocking capacitors on the output of the
amplifier. Designed to operate from a 2.4V to 5.5V DC
power supply, the EV kit is capable of delivering up to
70mW per channel into a 16Ω load or 130mW per chan-
nel into a 32Ω load and 0.009% THD+N at 1kHz.
The EV kit can also be used as a line driver that pro-
vides 2V
RMS
into a 1kΩ load from a single 5V supply.
The MAX9722A EV kit also evaluates the MAX9722B.
Features
♦
2.4V to 5.5V Single-Supply Operation
♦
Drives Two Channels at 70mW per Channel into a
16Ω load, 130mW per Channel into a 32Ω load
♦
≤2µA
Shutdown Current
♦
Evaluates the MAX9722A or MAX9722B
(IC and Component Replacement Required)
♦
Small 16-Pin TQFN (3mm x 3mm) Package
♦
Available in 16-Pin TSSOP Package
♦
Fully Assembled and Tested
Evaluates: MAX9722A/MAX9722B
Ordering Information
PART
MAX9722AEVKIT
TEMP RANGE
0°C to +70°C
IC PACKAGE
16 TQFN-EP*
*EP
= Exposed paddle.
Component List
DESIGNATION QTY
A1
C1–C4
1
4
DESCRIPTION
MAX9722AEUE (16-pin TSSOP)
1µF ±20%, 16V plastic film
capacitors (1210)
Panasonic ECPU1C105MA5
10µF ±20%, 6.3V X5R ceramic
capacitor (0805)
TDK C2012X5R0J106M
1µF ±10%, 10V X5R ceramic
capacitors (0603)
TDK C1608X5R1A105K
3.5mm stereo headphone jack
3-pin header
2-pin header
10kΩ
±1%
resistors (0603)
Not installed, resistors (0603)
0Ω ±5% resistor (1206)
MAX9722AETE
(16-pin TQFN, 3mm x 3mm)
Shunts
MAX9722A PC board
SUPPLIER
Panasonic
TDK
PHONE
Component Suppliers
FAX
714-
737-7323
847-
390-4405
WEBSITE
www.panasonic.com
www.component.tdk.com
714-
373-7366
847-
803-6100
C5
1
Note:
Indicate that you are using the MAX9722A when contact-
ing these component suppliers.
Quick Start
The MAX9722A EV kit is fully assembled and tested.
Follow the steps listed below to verify board operation.
Do not turn on the power supply until all connec-
tions are completed.
C6–C11
J1
JU1
JU2
R1–R8
R9, R10
R11
U1
None
None
6
1
1
1
8
0
1
1
2
1
Recommended Equipment
• 2.4V to 5.5V, 500mA power supply
• Audio signal source (i.e., CD or MP3 player)
• 16Ω or 32Ω headphone
Procedure
1) Verify that a shunt is installed across pins 1 and 2
of jumper JU1 (EV kit ON).
2) Verify that no shunt is installed across jumper JU2
(remote GND sensing OFF).
3) Plug the headphone into headphone jack J1.
4) Connect the positive terminal of the power supply to
the PVDD pad and ground terminal to the PGND pad.
________________________________________________________________
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.
MAX9722A Evaluation Kit
Evaluates: MAX9722A/MAX9722B
5) Connect the left output of the audio source to the
INPUTL- pad.
6) Connect the ground of the audio source to the
INPUTL+ pad.
7) Connect the right output of the audio source to the
INPUTR- pad.
8) Connect the ground of the audio source to the
INPUTR+ pad.
9) Turn on the power supply.
10) Turn on the audio source.
Refer to the MAX9722A/MAX9722B data sheet for addi-
tional information on using the MAX9722B as a head-
phone amplifier or as an audio line driver.
Table 1. JU1 Jumper Selection
SHUNT POSITION
1-2 (SHDN = high)
2-3 (SHDN = low)
None.
External controller
connected to
SHDN
pad
(logic level).
EV KIT FUNCTION
EV kit enabled
Shutdown mode
SHDN
driven by external
controller. Shutdown is active
low.
Detailed Description
The MAX9722A EV kit features the MAX9722A differential
stereo headphone amplifier with DirectDrive, which is
designed to directly drive a 16Ω or 32Ω stereo head-
phone in portable audio applications. The EV kit oper-
ates from a DC power supply that can provide 2.4V to
5.5V and 500mA of current. The EV kit accepts two sets
of differential or single-ended audio inputs. The amplifier
is able to deliver 70mW per channel into a 16Ω load or
130mW per channel into a 32Ω load.
The EV kit can also be used as an audio line driver to
provide 2V
RMS
into a 1kΩ load from a single 5V supply.
When used in this way, the EV kit features a remote
ground-sensing network to reduce any ground loop
noise at the receiving device (see the
Remote Ground
Sensing
section).
Table 2. JU2 Jumper Selection
SHUNT
POSITION
R9,
R10
R3, R4, R11
R7, R8 (Ω)
REMOTE
GND
SENSING
EV KIT
FUNCTION
Not
installed
(default)
Open
10kΩ
0
Differential
inputs,
Not
output
configured
referenced to
local ground
Single-ended
inputs,
Configured
output senses
remote ground
Jumper Selection
Shutdown Mode
(SHDN)
Jumper JU1 controls the shutdown pin (SHDN) of the
MAX9722A. See Table 1 for jumper positions.
Remote Ground Sensing
Jumper JU2, resistors R9 and R10 configure the remote
ground-sensing feature for the MAX9722A EV kit. See
Table 2 for jumper shunt positions and approximate
resistor values.
Note:
When using the remote ground-sensing feature,
remove resistors R3, R4, R7, and R8. Install a 10kΩ
resistor at the R9 and R10 PC board pads. Replace R11
with a 10Ω resistor. In this mode of operation, the input
signals on the INPUTL- and INPUTR- pads are refer-
enced to the EV kit PGND pad and are single ended. If
headphones are used in this configuration, channel-to-
channel isolation may be degraded.
Evaluating the MAX9722B
The MAX9722A EV kit can evaluate the MAX9722B. To
evaluate the MAX9722B, replace U1 with a MAX9722B
and replace the components as outlined in Table 3.
2
Installed
10kΩ
Open
10
Table 3. Component Values for
Evaluating the MAX9722B
EV KIT USES
DIFFERENTIAL
INPUTS; OUTPUT
REFERRED TO
LOCAL GROUND
MAX9722B
0Ω
Open
15kΩ
30kΩ
Open
Open
0Ω
Not installed
EV KIT USES
SINGLE-ENDED
INPUTS, OUTPUT
SENSES REMOTE
GROUND
MAX9722B
0Ω
Open
Open
Open
30kΩ
15kΩ
10Ω
Installed
COMPONENT
U1
R1, R5
R2, R6
R3, R7
R4, R8
R9
R10
R11
JU2
_______________________________________________________________________________________
MAX9722A Evaluation Kit
Evaluates: MAX9722A/MAX9722B
OUTR
J1
3
1
2
R9
OPEN
R10
OPEN
C11
1µF
INPUTL-
R11
0Ω
SGND
OUTL
12
C1
1µF
R1
10kΩ
R2
10kΩ
14
INL-
INR-
OUTL
OUTR
10
R6
10kΩ
8
C3
1µF
R5
10kΩ
INR+
INPUTR-
JU2
INR+
INPUTL+
C2
1µF
R3
10kΩ
15
R4
10kΩ
INL+
U1
MAX9722A
INR+
7
R8
10kΩ
11
5
C10
1µF
2
4
3
C9
1µF
R7
10kΩ
C4
1µF
INPUTR+
SV
SS
PVDD
PGND
C5
10µF
C6
1µF
13
C7
1µF
9
PVDD
SHDN
1
2
3
C8
1µF
16
1
PV
DD
PV
SS
SV
DD
C1P
C1N
SV
DD
PGND
JU1
SHDN
SGND
6
Figure 1. MAX9722A EV Kit Schematic
_______________________________________________________________________________________
3
MAX9722A Evaluation Kit
Evaluates: MAX9722A/MAX9722B
Figure 2. MAX9722A EV Kit Component Placement Guide—
Component Side
Figure 3. MAX9722A EV Kit PC Board Layout—Component
Side
Figure 4. MAX9722A EV Kit PC Board Layout—Solder Side
Figure 5. MAX9722A EV Kit Component Placement Guide—
Solder Side
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.
4
_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2004 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.
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