EVALUATION KIT AVAILABLE
MAX9723
Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I
2
C
General Description
The MAX9723 stereo DirectDrive
®
headphone amplifier
with BassMax and volume control is ideal for portable
audio applications where space is at a premium and
performance is essential. The MAX9723 operates from a
single 1.8V to 3.6V power supply and includes features
that reduce external component count, system cost,
board space, and improves audio reproduction.
The headphone amplifier uses Maxim’s DirectDrive archi-
tecture that produces a ground-referenced output from a
single supply, eliminating the need for large DCblocking
capacitors. The headphone amplifiers deliver 62mW into
a 16Ω load, feature low 0.006% THD+N, and high 90dB
PSRR. The MAX9723 features Maxim’s industry-leading
click-and-pop suppression.
The BassMax feature boosts the bass response of
the amplifier, improving audio reproduction when using
inexpensive headphones. The integrated volume control
features 32 discrete volume levels, eliminating the need
for an external potentiometer. BassMax and the volume
control are enabled through the I
2
C/SMBus™-compatible
interface. Shutdown is controlled through either the hard-
ware or software interfaces.
The MAX9723 consumes only 3.7mA of supply current at
1.8V, provides short-circuit and thermal-overload protection,
and is fully specified over the extended -40°C to +85°C tem-
perature range. The MAX9723 is available in a tiny (2mm x
2mm x 0.62mm) 16-bump chip-scale package (UCSP™) or
16-pin thin QFN (4mm x 4mm x 0.8mm) package.
Features
● 62mW, DirectDrive Headphone Amplifier Eliminates
Bulky DC-Blocking Capacitors
●
1.8V to 3.6V Single-Supply Operation
●
Integrated 32-Level Volume Control
● High 90dB PSRR at 1kHz
● Low 0.006% THD+N
●
Industry-Leading Click-and-Pop Suppression
● ±8kV HBM ESD-Protected Headphone Outputs
●
Short-Circuit and Thermal-Overload Protection
● Low-Power Shutdown Mode (5μA)
● Software-Enabled Bass Boost (BassMax)
●
I
2
C/SMBus-Compatible Interface
● Available in Space-Saving, Thermally Efficient
Packages:
• 16-Bump UCSP (2mm x 2mm x 0.62mm)
• 16-Pin Thin QFN (4mm x 4mm x 0.8mm)
Ordering Information
PART**
MAX9723_EBE-T*
TEMP RANGE
-40°C to +85°C
PIN-
PKG
PACKAGE
CODE
16 UCSP-16
B16-1
Applications
MAX9723_ETE+
-40°C to +85°C 16 TQFN
T1644-4
**Replace
the ‘_’ with the one-letter code that denotes the slave
address and maximum programmable gain. See the Selector
Guide.
+Denotes
a lead-free/RoHS-compliant package.
*Future
product—contact factory for availability.
Pin Configurations appears at end of data sheet.
●
PDA Audio
●
Portable CD Players
●
Mini Disc Players
● MP3-Enabled Cellular
●
Phones
●
MP3 Players
Block Diagram
1.8V TO 3.6V SUPPLY
Selector Guide
PART
MAX9723A
MAX9723B
MAX9723C
SLAVE ADDRESS
1001100
1001101
1001100
MAXIMUM GAIN (dB)
0
0
+6
SCL
SDA
I
2
C INTERFACE
∑
BBL
OUTL
BassMax
INL
INR
VOLUME
CONTROL
MAX9723D
1001101
+6
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
SMBus is a trademark of Intel Corp.
UCSP is a trademark of Maxim Integrated Products, Inc.
OUTR
∑
BBR
BassMax
MAX9723
19-3509; Rev 3; 7/14
MAX9723
Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I
2
C
Absolute Maximum Ratings
SGND to PGND .....................................................-0.3V to +0.3V
V
DD
to PGND...........................................................-0.3V to +4V
PV
SS
to SV
SS
.......................................................-0.3V to +0.3V
C1P to PGND.............................................-0.3V to (V
DD
+ 0.3V)
C1N to PGND...........................................(PV
SS
- 0.3V) to +0.3V
PV
SS
, SV
SS
to PGND..............................................+0.3V to -4V
IN_ to SGND.................................(SV
SS
- 0.3V) to (V
DD
+ 0.3V)
SDA, SCL to PGND..................................................-0.3V to +4V
SHDN
to PGND..........................................-0.3V to (V
DD
+ 0.3V)
OUT_ to SGND............................................................-3V to +3V
BB_ to SGND...............................................................-2V to +2V
Duration of OUT_ Short Circuit to _GND ....................Continuous
Continuous Current Into/Out of:
V
DD
, C1P, PGND, C1N, PV
SS
, SV
SS
, or OUT_...........±0.85A
Any Other Pin................................................................±20mA
Continuous Power Dissipation (T
A
= +70°C)
4 x 4 UCSP (derate 8.2mW/°C above +70°C)..........659.2mW
16-Pin Thin QFN (derate 16.9mW/°C above +70°C)....1349mW
Operating Temperature Range.............................-40°C to +85°C
Junction Temperature.......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature (soldering)
Reflow ..........................................................................+230°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Electrical Characteristics
(V
DD
=
SHDN
= 3V, PGND = SGND = 0V, C1 = C2 = 1μF, BB_ = 0V. gain = 0dB, maximum volume, BassMax disabled. Load connected
between OUT_ and SGND where specified. T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
GENERAL
Supply Voltage Range
Quiescent Supply Current
Shutdown Supply Current
Turn-On Time
Turn-Off Time
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
HEADPHONE AMPLIFIER
Gain = 0dB,
MAX9723A/
MAX9723B
Gain = +6dB,
MAX9723C/
MAX9723D
10
73
±0.7
±4.5
mV
±0.8
17
±10
DC, V
DD
= 1.8V to 3.6V
f = 217Hz, 100mV
P-P
ripple,
V
DD
= 3.0V
Power-Supply Rejection Ratio
PSRR
(Note 2)
f = 1kHz, 100mV
P-P
ripple,
V
DD
= 3.0V
f = 20kHz, 100mV
P-P
ripple,
V
DD
= 3.0V
90
87
86
61
dB
±5
27
±100
kΩ
nA
V
DD
I
DD
I
DD_SHDN
t
ON
t
OFF
T
THRES
T
HYST
No load
V
SHDN
= 0V
1.8
4
5
200
35
+143
12
3.6
6.5
8.5
V
mA
µA
µs
µs
°C
°C
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Output Offset Voltage
V
OS
Measured between
OUT_ and SGND
(Note 2)
Input Resistance
BBR, BBL Input Bias Current
R
IN
I
BIAS_BB
All volume levels
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Maxim Integrated
│
2
MAX9723
Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I
2
C
Electrical Characteristics (continued)
(V
DD
=
SHDN
= 3V, PGND = SGND = 0V, C1 = C2 = 1μF, BB_ = 0V. gain = 0dB, maximum volume, BassMax disabled. Load connected
between OUT_ and SGND where specified. T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Output Power
Total Harmonic Distortion Plus
Noise
SYMBOL
P
OUT
THD+N
THD+N = 1%,
f
IN
= 1kHz
CONDITIONS
R
L
= 32Ω
R
L
= 16Ω (Note 5)
38
MIN
TYP
59
60
0.006
0.004
0
-5
+6
+1
99
100
0.35
No sustained oscillations
R
OUT_SHDN
V
SHDN
= 0V, measured from OUT_ to
SGND
V
SHDN
= 0V, measured from OUT_ to
SGND
R
L
= 32Ω,
peak voltage,
A-weighted,
32 samples
per second
(Notes 2, 4)
MAX9723A/
MAX9723B
Into
shutdown
Out of
shutdown
Into
shutdown
Out of
shutdown
505
L to ≥ or ≥ to L, f = 10kHz,
V
OUT
= 1V
P-P
, R
L
= 32Ω, both channels
loaded
0.7 x
V
DD
0.3 x
V
DD
P1
V
OL
I
OH
I
OL
= 3mA
V
SDA
= V
DD
0.4
1
300
20
60
-69
-71
dB
-70
-69
600
80
700
kHz
dB
MAX
UNITS
mW
%
dB
dB
dB
V/µs
pF
kΩ
pF
R
L
= 16Ω, P
OUT
= 35mW, f
IN
= 1kHz
R
L
= 32Ω, P
OUT
= 45mW, f
IN
= 1kHz
MAX9723A/
MAX9723B
MAX9723C/
MAX9723D
R
L
= 32Ω,
V
OUT
= 1V
RMS
Gain range bit 5 = 1
Gain range bit 5 = 0
Gain range bit 5 = 1
Gain range bit 5 = 0
BW = 22Hz to 22kHz
A-weighted
Maximum Gain
AMAX
Signal-to-Noise Ratio
Slew Rate
Capacitive Drive
Output Resistance in Shutdown
SNR
SR
Output Capacitance in Shutdown C
OUT_SHDN
Click/Pop Level
K
CP
MAX9723C/
MAX9723D
Charge-Pump Switching
Frequency
Crosstalk
f
CP
XTALK
DIGITAL INPUTS (SHDN, SDA, SCL)
Input High Voltage
Input Low Voltage
Input Leakage Current
DIGITAL OUTPUTS (SDA)
Output Low Voltage
Output High Current
V
µA
V
IH
V
IL
V
V
µA
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Maxim Integrated
│
3
MAX9723
Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I
2
C
Timing Characteristics
(V
DD
=
SHDN
= 3V, PGND = SGND = 0V, C1 = C2 = 1μF, BB_ = 0V. gain = 0dB, maximum volume, BassMax disabled. Load con-
nected between OUT_ and SGND where specified. T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C, see
Timing Diagram.) (Notes 1, 3)
PARAMETER
Serial Clock Frequency
Bus Free Time Between a STOP
and a START Condition
START Condition Hold Time
Low Period of the SCL Clock
High Period of the SCL Clock
Setup Time for a Repeated
START Condition
Data Hold Time
Data Setup Time
Maximum Rise Time of SDA and
SCL Signals
Maximum Fall Time of SDA and
SCL Signals
Setup Time for STOP Condition
Pulse Width of Suppressed Spike
Maximum Capacitive Load for
Each Bus Line
Note
Note
Note
Note
1:
2:
3:
4:
SYMBOL
f
SCL
t
BUF
t
HD:STA
t
LOW
t
HIGH
t
SU:STA
t
HD:DAT
t
SU:DAT
t
r
t
f
t
SU:STO
t
SP
C
L_BUS
0.6
100
400
CONDITIONS
MIN
0
1.3
0.6
1.3
0.6
0.6
0
100
300
300
0.9
TYP
MAX
400
UNITS
kHz
µs
µs
µs
µs
µs
µs
ns
ns
ns
µs
ns
pF
All specifications are 100% tested at T
A
= +25°C. Temperature limits are guaranteed by design.
Inputs AC-coupled to SGND.
Guaranteed by design.
Headphone mode testing performed with a 32Ω resistive load connected to GND. Mode transitions are controlled by
SHDN.
The KCP level is calculated as: 20 x log [(level peak voltage during mode transition, no input signal)/(peak voltage under
normal operation at rated power)]. Units are expressed in dB.
Note 5:
Output power MIN is specified at T
A
= +25°C.
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Maxim Integrated
│
4
MAX9723
Stereo DirectDrive Headphone Amplifier
with BassMax, Volume Control, and I
2
C
Typical Operating Characteristics
(V
DD
=
SHDN
= 3V, PGND = SGND = 0V, C1 = C2 = 1μF, BB_ = 0V, gain = 0dB, maximum volume, BassMax disabled. Load connected
between OUT_ and SGND where specified. Outputs in phase, both channels loaded. T
A
= +25°C, unless otherwise noted.) (See
Func-
tional Diagram/Typical Operating Circuit)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9723 toc01
MAX9723 toc02
V
DD
= 2.4V
R
L
= 16Ω
V
DD
= 2.4V
R
L
= 32Ω
V
DD
= 3V
R
L
= 16Ω
THD+N (%)
THD+N (%)
THD+N (%)
0.1
0.1
P
OUT
= 10mW
0.01
0.1
P
OUT
= 20mW
0.01
P
OUT
= 10mW
0.01
P
OUT
= 25mW
P
OUT
= 23mW
100k
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
10
100
P
OUT
= 37mW
0.001
10
100
1k
FREQUENCY (Hz)
10k
1k
FREQUENCY (Hz)
10k
100k
MAX9723 toc04
MAX9723 toc05
V
DD
= 3V
R
L
= 32Ω
10
THD+N (%)
1
0.1
0.01
V
DD
= 2.4V
R
L
= 16Ω
10
THD+N (%)
1
0.1
0.01
0.001
V
DD
= 2.4V
R
L
= 32Ω
THD+N (%)
0.1
P
OUT
= 10mW
0.01
f
IN
= 20Hz
f
IN
= 1kHz
f
IN
= 10kHz
f
IN
= 1kHz
f
IN
= 20Hz
f
IN
= 10kHz
P
OUT
= 30mW
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
0
20
40
60
0
20
40
60
OUTPUT POWER (mW)
OUTPUT POWER (mW)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9723 toc07
MAX9723 toc08
POWER DISSIPATION (mW)
10
THD+N (%)
1
0.1
0.01
0.001
V
DD
= 3V
R
L
= 16Ω
10
THD+N (%)
1
0.1
0.01
0.001
V
DD
= 3V
R
L
= 32Ω
160
140
120
100
80
60
40
20
V
DD
= 2.4V
f
IN
= 1kHz
P
OUT
= P
OUTL
+ P
OUTR
OUTPUTS IN PHASE
R
L
= 16Ω
R
L
= 32Ω
f
IN
= 1kHz
f
IN
= 20Hz
f
IN
= 10kHz
f
IN
= 1kHz
f
IN
= 20Hz
f
IN
= 10kHz
0
20
40
60
80
100
OUTPUT POWER (mW)
0
20
40
60
80
100
0
0
20
40
60
80
OUTPUT POWER (mW)
OUTPUT POWER (mW)
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│ 5
MAX9723 toc09
100
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
100
180
POWER DISSIPATION
vs. OUTPUT POWER
MAX9723 toc06
1
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
100
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
100
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9723 toc03
1
1
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
1
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
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