19-3509; Rev 1; 11/05
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 per-
formance is essential. The MAX9723 operates from a sin-
gle 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 patented
DirectDrive architecture that produces a ground-refer-
enced output from a single supply, eliminating the need
for large DC-blocking capacitors. The headphone ampli-
fiers 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 con-
trol 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 hardware 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 temperature 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)
MAX9723
Ordering Information
PART**
MAX9723_EBE-T*
MAX9723_ETE+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
16 UCSP-16
16 TQFN
PKG
CODE
B16-1
T1644-4
Applications
PDA Audio
Portable CD Players
Mini Disc Players
Automotive Multimedia
MP3-Enabled Cellular
Phones
MP3 Players
**Replace
the ‘_’ with the one-letter code that denotes the
slave address and maximum programmable gain. See the
Selector Guide.
+Denotes
lead-free package.
*Future
product—contact factory for availability.
Pin Configurations appear at end of data sheet.
Block Diagram
1.8V TO 3.6V SUPPLY
Selector Guide
PART
MAX9723A
MAX9723B
MAX9723C
MAX9723D
SLAVE ADDRESS
1001100
1001101
1001100
1001101
MAXIMUM GAIN (dB)
0
0
+6
+6
SCL
SDA
I
2
C INTERFACE
BBL
Σ
OUTL
BassMax
*Purchase
of I
2
C components from Maxim Integrated Products,
Inc. or one of its sublicensed Associated Companies, conveys
a license under the Philips I
2
C Patent Rights to use these com-
ponents in an I
2
C system, provided that the system conforms
to the I
2
C Standard Specification as defined by Philips.
SMBus is a trademark of Intel Corp.
UCSP is a trademark of Maxim Integrated Products, Inc.
INL
INR
VOLUME
CONTROL
OUTR
Σ
BBR
BassMax
MAX9723
________________________________________________________________
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.
Stereo DirectDrive Headphone Amplifier with
BassMax, Volume Control, and I
2
C
MAX9723
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 connect-
ed 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
±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
f = 1kHz, 100mV
P-P
ripple,
V
DD
= 3.0V
f = 20kHz, 100mV
P-P
ripple,
V
DD
= 3.0V
73
90
87
dB
86
61
±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
Power-Supply Rejection Ratio
PSRR
(Note 2)
2
_______________________________________________________________________________________
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 connect-
ed 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
C
OUT_SHDN
V
SHDN
= 0V, measured from OUT_ to
SGND
V
SHDN
= 0V, measured from OUT_ to
SGND
Into
shutdown
Out of
shutdown
Into
shutdown
Out of
shutdown
505
L to R or R to L, f = 10kHz,
V
OUT
= 1V
P-P
, R
L
= 32Ω, both channels
loaded
300
20
60
-69
-71
dB
-70
-69
600
700
kHz
MAX9723C/
MAX9723D
MAX
UNITS
mW
%
dB
dB
dB
V/µs
pF
kΩ
pF
MAX9723
R
L
= 16Ω, P
OUT
= 35mW, f
IN
= 1kHz
R
L
= 32Ω, P
OUT
= 45mW, f
IN
= 1kHz
MAX9723A/
MAX9723B
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
A
MAX
MAX9723C/
MAX9723D
R
L
= 32Ω,
V
OUT
= 1V
RMS
Signal-to-Noise Ratio
Slew Rate
Capacitive Drive
Output Resistance in Shutdown
Output Capacitance in Shutdown
SNR
SR
Click/Pop Level
K
CP
R
L
= 32Ω,
peak voltage,
A-weighted,
32 samples
per second
(Notes 2, 4)
MAX9723A/
MAX9723B
Charge-Pump Switching
Frequency
Crosstalk
DIGITAL INPUTS (SHDN, SDA, SCL)
Input High Voltage
Input Low Voltage
Input Leakage Current
DIGITAL OUTPUTS (SDA)
Output Low Voltage
Output High Current
f
CP
XTALK
80
dB
V
IH
V
IL
0.7 x
V
DD
0.3 x
V
DD
±1
V
V
µA
V
µA
V
OL
I
OH
I
OL
= 3mA
V
SDA
= V
DD
0.4
1
_______________________________________________________________________________________
3
Stereo DirectDrive Headphone Amplifier with
BassMax, Volume Control, and I
2
C
MAX9723
TIMING CHARACTERISTICS
(V
DD
=
SHDN
= 3V, PGND = SGND = 0V, C1 = C2 = 1µF, BB_ = 0V, gain = 0dB, maximum volume, BassMax disabled. Load connect-
ed 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
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
Note 1:
Note 2:
Note 3:
Note 4:
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 K
CP
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.
4
_______________________________________________________________________________________
Stereo DirectDrive Headphone Amplifier with
BassMax, Volume Control, and I
2
C
MAX9723
Typical Operating 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. Outputs in phase, both channels loaded. T
A
= +25°C, unless otherwise noted.)
(See
Functional Diagram/Typical Operating Circuit)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9723 toc01
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9723 toc02
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
V
DD
= 3V
R
L
= 16Ω
MAX9723 toc03
1
V
DD
= 2.4V
R
L
= 16Ω
1
V
DD
= 2.4V
R
L
= 32Ω
1
0.1
THD+N (%)
THD+N (%)
0.1
THD+N (%)
P
OUT
= 10mW
0.01
P
OUT
= 25mW
0.1
P
OUT
= 20mW
0.01
P
OUT
= 37mW
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
FREQUENCY (Hz)
10k
100k
P
OUT
= 10mW
0.01
P
OUT
= 23mW
0.001
10k
100k
0.001
10
100
1k
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9723 toc04
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9723 toc05
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
V
DD
= 2.4V
R
L
= 32Ω
10
MAX9723 toc06
1
V
DD
= 3V
R
L
= 32Ω
100
V
DD
= 2.4V
R
L
= 16Ω
10
100
0.1
THD+N (%)
THD+N (%)
1
f
IN
= 20Hz
f
IN
= 1kHz
f
IN
= 10kHz
THD+N (%)
1
f
IN
= 1kHz
f
IN
= 20Hz
P
OUT
= 10mW
0.01
0.01
P
OUT
= 30mW
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
0
20
40
60
OUTPUT POWER (mW)
0.001
0
20
40
60
OUTPUT POWER (mW)
0.1
0.1
f
IN
= 10kHz
0.01
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9723 toc07
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9723 toc08
POWER DISSIPATION
vs. OUTPUT POWER
160
POWER DISSIPATION (mW)
140
120
100
80
60
40
20
R
L
= 32Ω
V
DD
= 2.4V
f
IN
= 1kHz
P
OUT
= P
OUTL
+ P
OUTR
OUTPUTS IN PHASE
MAX9723 toc09
100
V
DD
= 3V
R
L
= 16Ω
10
100
V
DD
= 3V
R
L
= 32Ω
10
180
R
L
= 16Ω
THD+N (%)
1
f
IN
= 1kHz
0.1
f
IN
= 20Hz
0.01
f
IN
= 10kHz
THD+N (%)
1
f
IN
= 1kHz
f
IN
= 20Hz
0.01
f
IN
= 10kHz
0.1
0.001
0
20
40
60
80
100
OUTPUT POWER (mW)
0.001
0
20
40
60
80
100
OUTPUT POWER (mW)
0
0
20
40
60
80
OUTPUT POWER (mW)
_______________________________________________________________________________________
5
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