19-2842; Rev 3; 6/09
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
General Description
The MAX4409 stereo headphone amplifier combines
Maxim’s DirectDrive
®
architecture and a common-
mode sense input, which allows the amplifier to reject
common-mode noise. Conventional headphone ampli-
fiers require a bulky DC-blocking capacitor between
the headphone and the amplifier. DirectDrive produces
a ground-referenced output from a single supply, elimi-
nating the need for large DC-blocking capacitors,
which saves cost, board space, and component height.
The common-mode voltage sensing corrects for any
difference between SGND of the amplifier and the
headphone return. This feature minimizes ground-loop
noise when the HP socket is used as a line out connec-
tion to other grounded equipment, for example, a PC
connected to a home hi-fi system.
The MAX4409 draws only 5mA of supply current, deliv-
ers up to 80mW per channel into a 16Ω load, and has a
low 0.002% THD+N. A high 86dB power-supply rejec-
tion ratio allows this device to operate from noisy digital
supplies without additional power-supply conditioning.
The MAX4409 includes ±8kV ESD protection on the
headphone outputs. Comprehensive click-and-pop cir-
cuitry eliminates audible clicks and pops on startup
and shutdown. A low-power shutdown mode reduces
supply current draw to only 6µA.
The MAX4409 operates from a single 1.8V to 3.6V sup-
ply, has short-circuit and thermal overload protection,
and is specified over the extended -40°C to +85°C tem-
perature range. The MAX4409 is available in a tiny 20-
pin thin QFN (4mm x 4mm x 0.8mm) package.
Features
♦
No Bulky DC-Blocking Capacitors Required
♦
Ground-Referenced Outputs Eliminate DC-Bias
Voltages on Headphone Ground Pin
♦
Common-Mode Voltage Sensing Eliminates
Ground-Loop Noise
♦
96dB CMRR
♦
No Degradation of Low-Frequency Response Due
to Output Capacitors
♦
80mW per Channel into 16Ω
♦
Low 0.002% THD+N
♦
High 86dB PSRR
♦
Integrated Click-and-Pop Suppression
♦
1.8V to 3.6V Single-Supply Operation
♦
Low Quiescent Current
♦
Low-Power Shutdown Mode
♦
Short-Circuit and Thermal-Overload Protection
♦
±8kV ESD-Protected Amplifier Outputs
♦
Available in a Space-Saving Package
20-Pin Thin QFN (4mm x 4mm x 0.8mm)
MAX4409
Ordering Information
PART
MAX4409ETP
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
20 Thin QFN-EP*
*EP
= Exposed pad.
Applications
Notebooks
Desktop PCs
Cellular Phones
PDAs
MP3 Players
Tablet PCs
Portable Audio Equipment
SHDN
LEFT
AUDIO
INPUT
Functional Diagram
MAX4409
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS
COM
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
Pin Configurations and Typical Application Circuit appear
at end of data sheet.
RIGHT
AUDIO
INPUT
COMMON-MODE
SENSE INPUT ELIMINATES
GROUND-LOOP NOISE
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
MAX4409
ABSOLUTE MAXIMUM RATINGS
PGND to SGND .....................................................-0.3V to +0.3V
PV
DD
to SV
DD .................................................................
-0.3V to +0.3V
PV
SS
to SV
SS
.........................................................-0.3V to +0.3V
PV
DD
and SV
DD
to PGND or SGND .........................-0.3V to +4V
PV
SS
and SV
SS
to PGND or SGND ..........................-4V to +0.3V
IN_ and COM to SGND.................................SV
SS
to (SV
DD
- 1V)
IN_ to COM .....................................(COM + 2V) to (COM - 0.3V)
SHDN_
to SGND........................(SGND - 0.3V) to (SV
DD
+ 0.3V)
OUT_ to SGND ............................(SV
SS
- 0.3V) to (SV
DD
+ 0.3V)
C1P to PGND.............................(PGND - 0.3V) to (PV
DD
+ 0.3V)
C1N to PGND .............................(PV
SS
- 0.3V) to (PGND + 0.3V)
Output Short Circuit to GND or V
DD
...........................Continuous
Thermal Limits (Note 1)
Continuous Power Dissipation (T
A
= +70°C)
20-Pin Thin QFN Multilayer (derate 25.6mW/°C
above +70°C)..........................................................2051mW
θ
JA
................................................................................39°C/W
θ
JC
...............................................................................5.7°C/W
Junction Temperature ......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a 4-layer
board. For detailed information on package thermal considerations see www.maxim-ic.com/thermal-tutorial.
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
PVDD
= V
SVDD
= 3V, V
PGND
= V
SGND
= 0,
SHDN
= SV
DD
, C1 = C2 = 2.2µF, R
IN
= R
F
= R1 = R2 = 10kΩ, R
L
=
∞,
T
A
= T
MIN
to
T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Supply Voltage Range
Quiescent Supply Current
Shutdown Supply Current
SYMBOL
V
DD
I
DD
I
SHDN
SHDN
= GND
V
IH
SHDN
Thresholds
V
IL
SHDN
Input Leakage Current
SHDN
to Full Operation
CHARGE PUMP
Oscillator Frequency
AMPLIFIERS
Input Offset Voltage
Input Bias Current
COM Bias Current
Equivalent Input Offset Current
COM Input Range
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
V
OS
I
BIAS
I
COM
I
OS
V
COM
CMRR
PSRR
I
OS
= (I
BIAS(INR)
+ I
BIAS(INL)
- I
COM
) / 2
Inferred from CMRR test
-500mV
≤
V
COM
≤
+500mV, R
SOURCE
≤
10Ω
1.8V
≤
V
DD
≤
3.6V
V
DD
= 3.0V,
200mV
P-P
ripple (Note 4)
THD+N = 1%, T
A
= +25°C
DC (Note 3)
f
RIPPLE
= 1kHz
f
RIPPLE
= 20kHz
R
L
= 32Ω
R
L
= 16Ω
55
-500
75
75
96
86
76
48
65
80
mW
dB
R
L
= 32Ω
-700
-1400
0.5
-100
-200
±2
+500
2.4
0
0
mV
nA
nA
nA
mV
dB
f
OSC
272
320
368
kHz
t
SON
-1
175
0.7 x
SV
DD
0.3 x
SV
DD
+1
µA
µs
CONDITIONS
Guaranteed by PSRR test
MIN
1.8
5
6
TYP
MAX
3.6
8.4
10
UNITS
V
mA
µA
V
Output Power
P
OUT
2
_______________________________________________________________________________________
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
ELECTRICAL CHARACTERISTICS (continued)
(V
PVDD
= V
SVDD
= 3V, V
PGND
= V
SGND
= 0,
SHDN
= SV
DD
, C1 = C2 = 2.2µF, R
IN
= R
F
= R1 = R2 = 10kΩ, R
L
=
∞,
T
A
= T
MIN
to
T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Total Harmonic Distortion
Plus Noise
Signal-to-Noise Ratio (Note 4)
Slew Rate
Maximum Capacitive Load
Crosstalk
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
ESD Protection
Human Body Model (OUTR, OUTL)
SYMBOL
CONDITIONS
R
L
= 32Ω,
P
OUT
= 50mW
R
L
= 16Ω,
P
OUT
= 60mW
MIN
TYP
0.002
%
0.005
95
0.8
No sustained oscillations
R
L
= 16Ω, P
OUT
= 1.6mW, f
IN
= 10kHz
150
55
140
15
±8
dB
V/µs
pF
dB
°C
°C
kV
MAX
UNITS
MAX4409
THD+N
f
IN
= 1kHz
SNR
SR
C
L
R
L
= 32Ω, P
OUT
= 20mW, f
IN
= 1kHz
Note 2:
All specifications are 100% tested at T
A
= +25°C; temperature limits are guaranteed by design.
Note 3:
Inputs are connected to ground and COM.
Note 4:
Inputs are AC-coupled to ground. COM is connected to ground.
Typical Operating Characteristics
(
C1 = C2 = 2.2µF, R
IN
= R
F
= R1 = R2 = 10kΩ, THD+N measurement bandwidth = 22Hz to 22kHz, T
A
= +25°C, unless otherwise noted.
)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX4409 toc01
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
V
DD
= 3V
R
L
= 32Ω
MAX4409 toc02
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
V
DD
= 1.8V
R
L
= 16Ω
MAX4409 toc03
1
V
DD
= 3V
R
L
= 16Ω
1
1
0.1
THD+N (%)
P
OUT
= 60mW
P
OUT
= 10mW
THD+N (%)
0.1
THD+N (%)
0.1
P
OUT
= 15mW
P
OUT
= 5mW
0.01
0.01
P
OUT
= 50mW
P
OUT
= 10mW
0.01
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
_______________________________________________________________________________________
3
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
MAX4409
Typical Operating Characteristics (continued)
(
C1 = C2 = 2.2µF, R
IN
= R
F
= R1 = R2 = 10kΩ, THD+N measurement bandwidth = 22Hz to 22kHz, T
A
= +25°C, unless otherwise noted.
)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX4409 toc04
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc05
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
V
DD
= 3V
f = 1kHz
R
L
= 16Ω
MAX4409 toc06
1
V
DD
= 1.8V
R
L
= 32Ω
100
V
DD
= 3V
f = 20Hz
R
L
= 16Ω
100
10
10
0.1
THD+N (%)
THD+N (%)
1
THD+N (%)
OUTPUTS
IN PHASE
1
OUTPUTS IN
PHASE
P
OUT
= 15mW
0.01
P
OUT
= 5mW
0.1
0.1
0.01
0.001
10
100
1k
FREQUENCY (Hz)
10k
100k
0.001
0
30
60
90
120
OUTPUTS
OUT OF
PHASE
150
180
0.01
0.001
0
30
60
90
120
OUTPUTS
OUT OF
PHASE
150
180
OUTPUT POWER (W)
OUTPUT POWER (W)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc07
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc08
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
V
DD
= 3V
f = 1kHz
R
L
= 32Ω
MAX4409 toc09
100
V
DD
= 3V
f = 10kHz
R
L
= 16Ω
OUTPUTS IN
PHASE
100
10
1
THD+N (%)
0.1
0.01
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
V
DD
= 3V
f = 20Hz
R
L
= 32Ω
100
10
10
THD+N (%)
THD+N (%)
1
1
OUTPUTS IN
PHASE
0.1
0.1
OUTPUTS
OUT OF
PHASE
0
30
60
90
120
150
180
0.01
0.001
OUTPUT POWER (W)
0.001
0.0001
0
20
40
60
80
0.01
0.001
OUTPUTS
OUT OF
PHASE
0
20
40
60
80
100
120
100
120
OUTPUT POWER (W)
OUTPUT POWER (W)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
V
DD
= 3V
f = 10kHz
R
L
= 32Ω
OUTPUTS IN
PHASE
MAX4409 toc10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc11
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
V
DD
= 1.8V
f = 1kHz
R
L
= 16Ω
MAX4409 toc12
100
100
V
DD
= 1.8V
f = 20Hz
R
L
= 16Ω
OUTPUTS IN
PHASE
100
10
10
10
THD+N (%)
THD+N (%)
1
THD+N (%)
1
1
OUTPUTS IN
PHASE
0.1
0.01
0.001
0
20
OUTPUTS
OUT OF
PHASE
0.1
OUTPUTS
OUT OF
PHASE
0.1
OUTPUTS
OUT OF
PHASE
0
10
20
30
40
50
60
0.01
0.001
0.01
0.001
60
80
OUTPUT POWER (W)
40
100
120
0
10
20
30
40
50
60
OUTPUT POWER (W)
OUTPUT POWER (W)
4
_______________________________________________________________________________________
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
Typical Operating Characteristics (continued)
(
C1 = C2 = 2.2µF, R
IN
= R
F
= R1 = R2 = 10kΩ, THD+N measurement bandwidth = 22Hz to 22kHz, T
A
= +25°C, unless otherwise noted.
)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc13
MAX4409
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc14
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
V
DD
= 1.8V
f = 1kHz
R
L
= 32Ω
MAX4409 toc15
100
V
DD
= 1.8V
f = 10kHz
R
L
= 16Ω
100
V
DD
= 1.8V
f = 20Hz
R
L
= 32Ω
100
10
10
10
THD+N (%)
OUTPUTS IN
PHASE
0.1
OUTPUTS IN
PHASE
THD+N (%)
1
THD+N (%)
1
1
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
0
10
20
OUTPUT POWER (W)
30
40
0.1
0.1
0.01
0.001
0
10
20
30
40
OUTPUTS
OUT OF
PHASE
50
60
0.01
0.001
0
10
20
OUTPUT POWER (W)
OUTPUTS
OUT OF
PHASE
30
40
0.01
0.001
OUTPUT POWER (W)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc16
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4409 toc17
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-10
-20
-30
PSRR (dB)
-40
-50
-60
-70
-80
-90
V
DD
= 3V
V
IN
= 200mV
P-P
R
L
= 16Ω
MAX4410 toc18
100
V
DD
= 1.8V
f = 10kHz
R
L
= 32Ω
0
-10
-20
-30
V
DD
= 3V
V
IN
= 200mV
P-P
R
L
= 16Ω
0
10
THD+N (%)
PSRR (dB)
OUTPUTS
OUT OF
PHASE
20
30
40
1
OUTPUTS IN
PHASE
-40
-50
-60
0.1
0.01
0.001
0
10
OUTPUT POWER (W)
-70
-80
-90
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
FREQUENCY (Hz)
10k
100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4410 toc19
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4410 toc20
CROSSTALK vs. FREQUENCY
-10
-20
CROSSTALK (dB)
-30
-40
-50
-60
-70
-80
-90
LEFT TO RIGHT
RIGHT TO LEFT
V
IN
= 200mV
P-P
MAX4410 toc21
0
-10
-20
-30
PSRR (dB)
V
DD
= 1.8V
V
IN
= 200mV
P-P
R
L
= 16Ω
0
-10
-20
-30
PSRR (dB)
-40
-50
-60
-70
-80
-90
V
DD
= 1.8V
V
IN
= 200mV
P-P
R
L
= 32Ω
0
-40
-50
-60
-70
-80
-90
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
FREQUENCY (Hz)
10k
100k
_______________________________________________________________________________________
5
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