General Description
The MAX4411 fixed-gain, stereo headphone amplifier is
designed for portable equipment where board space is
at a premium. The MAX4411 uses a unique DirectDrive
architecture to produce a ground-referenced output
from a single supply, eliminating the need for large DC-
blocking capacitors, saving cost, board space, and
component height. Additionally, the gain of the
amplifier is set internally (-1.5V/V, MAX4411 and
-2V/V, MAX4411B), further reducing component count.
The MAX4411 delivers up to 80mW per channel into a
16Ωload and has low 0.003% THD+N. An 86dB at
217Hz power-supply rejection ratio (PSRR) allows this
device to operate from noisy digital supplies without an
additional linear regulator. The MAX4411 includes ±8kV
ESD protection on the headphone outputs. Com-
prehensive click-and-pop circuitry suppresses audible
clicks and pops on startup and shutdown. Independent
left/right, low-power shutdown controls make it possible
to optimize power savings in mixed-mode, mono/stereo
applications.
The MAX4411 operates from a single 1.8V to 3.6V supply,
consumes only 5mA of supply current, has short-circuit
and thermal-overload protection, and is specified over the
extended -40°C to +85°C temperature range. The
MAX4411 is available in a tiny (2mm ✕2mm ✕0.6mm),
16-bump chip-scale package (UCSP™) and a 20-pin thin
QFN package (4mm ✕4mm ✕0.8mm).
Applications
Features
♦No Bulky DC-Blocking Capacitors Required
♦Fixed -1.5V/V Gain Eliminates External Feedback
Network
MAX4411: -1.5V/V
MAX4411B: -2V/V
♦Ground-Referenced Outputs Eliminate DC-Bias
Voltages on Headphone Ground Pin
♦No Degradation of Low-Frequency Response Due
to Output Capacitors
♦80mW per Channel into 16Ω
♦Low 0.003% THD+N
♦High PSRR (86dB at 217Hz)
♦Integrated Click-and-Pop Suppression
♦1.8V to 3.6V Single-Supply Operation
♦Low Quiescent Current (5mA)
♦Independent Left/Right, Low-Power
Shutdown Controls
♦Short-Circuit and Thermal-Overload Protection
♦±8kV ESD-Protected Amplifier Outputs
♦Available in Space-Saving Packages
16-Bump UCSP (2mm ✕2mm ✕0.6mm)
20-Pin Thin QFN (4mm ✕4mm ✕0.8mm)
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
________________________________________________________________ Maxim Integrated Products 1
LEFT
AUDIO
INPUT
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS
FIXED GAIN ELIMINATES
EXTERNAL RESISTOR
NETWORK
RIGHT
AUDIO
INPUT
SHDNL
SHDNR MAX4411
Functional Diagram
Ordering Information
19-2618; Rev 2; 9/06
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.
EVALUATION KIT
AVAILABLE
PART
TEMP RANGE
PIN/BUMP-
PACKAGE
GAIN
(V/V)
MAX4411EBE-T
-40°C to +85°C 16 UCSP-16
-1.5
MAX4411EBE+T
-40°C to +85°C 16 UCSP-16
-1.5
MAX4411ETP
-40°C to +85°C 20 Thin QFN
-1.5
Notebook PCs
Cellular Phones
PDAs
MP3 Players
Smart Phones
Portable Audio Equipment
UCSP is a trademark of Maxim Integrated Products, Inc.
Pin Configurations and Typical Application Circuit appear at end of data sheet.
Ordering Information continued at end of data sheet.
+Denotes lead-free package.
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(PVDD = SVDD = 3V, PGND = SGND = 0V, SHDNL = SHDNR = SVDD, C1 = C2 = 2.2µF, CIN = 1µF, RL= ∞, TA= TMIN to TMAX,
unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
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.
PGND to SGND .....................................................-0.3V to +0.3V
PVDD to SVDD .................................................................-0.3V to +0.3V
PVSS to SVSS .........................................................-0.3V to +0.3V
PVDD and SVDD to PGND or SGND .........................-0.3V to +4V
PVSS and SVSS to PGND or SGND ..........................-4V to +0.3V
IN_ to SGND ................................(SVSS - 0.3V) to (SVDD + 0.3V)
SHDN_to SGND........................(SGND - 0.3V) to (SVDD + 0.3V)
OUT_ to SGND .............................(SVSS - 0.3V) to (SVDD +0.3V)
C1P to PGND.............................(PGND - 0.3V) to (PVDD + 0.3V)
C1N to PGND .............................(PVSS - 0.3V) to (PGND + 0.3V)
Output Short Circuit to GND or VDD...........................Continuous
Continuous Power Dissipation (TA= +70°C)
16-Bump UCSP (derate 7.4mW/°C above +70°C)........589mW
20-Pin Thin QFN (derate 16.9mW/°C above +70°C) ..1349mW
Junction Temperature......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature (soldering)
Reflow ..........................................................................+230°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
TYP
MAX
UNITS
Supply Voltage Range VDD Guaranteed by PSRR test 1.8 3.6 V
One channel enabled 3.2
Quiescent Supply Current IDD Two channels enabled 5 8.4 mA
Shutdown Supply Current I SHDN SHDNL = SHDNR = GND 6 10 µA
VIH 0.7 x
SVDD
SHDN_ Thresholds
VIL 0.3 x
SVDD
V
SHDN_ Input Leakage Current -1 +1 µA
SHDN_ to Full Operation tSON
175
µs
CHARGE PUMP
Oscillator Frequency fOSC
272 320
368 kHz
AMPLIFIERS
MAX4411
-1.55 -1.5 -1.45
Voltage Gain AVMAX4411B
-2.1
-2
-1.9
V/V
Gain Match ΔAV1%
MAX4411 0.7 2.8
Total Output Offset Voltage VOS Input AC-coupled MAX4411B
0.75
3.0 mV
Input Resistance RIN 10 14 19 kΩ
1.8V ≤ VDD ≤ 3.6V,
MAX4411 DC (Note 2) 72 86
fRIPPLE = 217Hz 86
fRIPPLE = 1kHz 75
Power-Supply Rejection Ratio PSRR VDD = 3.0V, 200mVP-P
ripple, MAX4411
(Note 3) fRIPPLE = 20kHz 53
dB
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(PVDD = SVDD = 3V, PGND = SGND = 0V, SHDNL = SHDNR = SVDD, C1 = C2 = 2.2µF, CIN = 1µF, RL= ∞, TA= TMIN to TMAX,
unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
Note 1: All specifications are 100% tested at TA= +25°C; temperature limits are guaranteed by design.
Note 2: Inputs are connected directly to GND.
Note 3: Inputs are AC-coupled to ground.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
1.8V ≤ VDD ≤ 3.6V,
MAX4411B DC (Note 2) 69 86
fRIPPLE = 217Hz 86
fRIPPLE = 1kHz 73
Power-Supply Rejection Ratio PSRR VDD = 3.0V, 200mVP-P
ripple, MAX4411B
(Note 3) fRIPPLE = 20kHz 51
dB
RL = 32Ω65
Output Power POUT THD+N ≤ 1%
TA = +25°C RL = 16Ω55 80 mW
RL = 32Ω, POUT =
50mW
0.003
Total Harmonic Distortion Plus
Noise
THD+N
fIN = 1kHz
RL = 16Ω, POUT =
60mW
0.004
%
MAX4411 94
Signal-to-Noise Ratio SNR
RL = 32Ω, POUT =
20mW, fIN = 1kHz,
BW = 22Hz to 22kHz MAX4411B 95
dB
Slew Rate SR 0.8 V/µs
Maximum Capacitive Load CLNo sustained oscillations
150
pF
Crosstalk RL = 16Ω, POUT = 1.6mW, fIN = 10kHz 90 dB
Thermal Shutdown Threshold
140
°C
Thermal Shutdown Hysteresis 15 °C
ESD Protection Human Body Model (OUTR, OUTL) ±8kV
Typical Operating Characteristics
(C1 = C2 = 2.2µF, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX4411 toc01
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.01
0.1
1
0.001
10 100k
VDD = 3V
RL = 16Ω
POUT = 10mW
POUT = 25mW
POUT = 50mW
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX4411 toc02
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.01
0.1
1
0.001
10 100k
POUT = 5mW
POUT = 10mW
POUT = 25mW
VDD = 3V
RL = 32Ω
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX4411 toc03
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.01
0.1
1
0.001
10 100k
POUT = 5mW
POUT = 10mW
POUT = 20mW
VDD = 1.8V
RL = 16Ω
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
4 _______________________________________________________________________________________
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. FREQUENCY
MAX4411 toc04
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.01
0.1
1
0.001
10 100k
POUT = 5mW
POUT = 10mW
POUT = 20mW
VDD = 1.8V
RL = 32Ω
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc05
OUTPUT POWER (mW)
THD+N (%)
15010050
0.01
0.1
1
10
100
0.001
0 200
VDD = 3V
RL = 16Ω
fIN = 20Hz
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc06
OUTPUT POWER (mW)
THD+N (%)
15010050
0.01
0.1
1
10
100
0.001
0200
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 3V
RL = 16Ω
fIN = 1kHz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc07
OUTPUT POWER (mW)
THD+N (%)
15010050
0.01
0.1
1
10
100
0.001
0200
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 3V
RL = 16Ω
fIN = 10kHz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc08
OUTPUT POWER (mW)
THD+N (%)
100755025
0.01
0.1
1
10
100
0.001
0 125
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 3V
RL = 32Ω
fIN = 20Hz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc09
OUTPUT POWER (mW)
THD+N (%)
100755025
0.01
0.1
1
10
100
0.001
0125
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 3V
RL = 32Ω
fIN = 1kHz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc10
OUTPUT POWER (mW)
THD+N (%)
100755025
0.01
0.1
1
10
100
0.001
0 125
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 3V
RL = 32Ω
fIN = 10kHz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc11
OUTPUT POWER (mW)
THD+N (%)
5040302010
0.01
0.1
1
10
100
0.001
060
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 1.8V
RL = 16Ω
fIN = 20Hz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc12
OUTPUT POWER (mW)
THD+N (%)
5040302010
0.01
0.1
1
10
100
0.001
060
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 1.8V
RL = 16Ω
fIN = 1kHz
Typical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
_______________________________________________________________________________________ 5
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc16
OUTPUT POWER (mW)
THD+N (%)
40302010
0.01
0.1
1
10
100
0.001
050
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 1.8V
RL = 32Ω
fIN = 10kHz
CROSSTALK vs. FREQUENCY
MAX4411 toc21
FREQUENCY (Hz)
CROSSTALK (dB)
10k1k100
-120
-100
-80
-60
-40
-20
0
-140
10 100k
VDD = 3V
POUT = 1.6mW
RL = 16Ω
LEFT TO RIGHT
RIGHT TO LEFT
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc13
OUTPUT POWER (mW)
THD+N (%)
5040302010
0.01
0.1
1
10
100
0.001
060
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 1.8V
RL = 16Ω
fIN = 10kHz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc14
OUTPUT POWER (mW)
THD+N (%)
40302010
0.01
0.1
1
10
100
0.001
050
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 1.8V
RL = 32Ω
fIN = 20Hz
TOTAL HARMONIC DISTORTION PLUS NOISE
vs. OUTPUT POWER
MAX4411 toc15
OUTPUT POWER (mW)
THD+N (%)
40302010
0.01
0.1
1
10
100
0.001
050
OUTPUTS IN
PHASE
OUTPUTS 180°
OUT OF PHASE
ONE CHANNEL
DRIVEN
VDD = 1.8V
RL = 32Ω
fIN = 1kHz
Typical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
0
-100
10 100 1k 10k 100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-80
MAX4411 toc18
FREQUENCY (Hz)
PSRR (dB)
-60
-40
-20
-30
-50
-70
-90
-10 VDD = 1.8V
RL = 16Ω
0
-100
10 100 1k 10k 100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-80
MAX4411 toc19
FREQUENCY (Hz)
PSRR (dB)
-60
-40
-20
-30
-50
-70
-90
-10 VDD = 3V
RL = 32Ω
10 100 1k 10k 100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4411 toc20
FREQUENCY (Hz)
VDD = 1.8V
RL = 32Ω
0
-100
-80
PSRR (dB)
-60
-40
-20
-30
-50
-70
-90
-10
0
-100
10 100 1k 10k 100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-80
MAX4411 toc17
FREQUENCY (Hz)
PSRR (dB)
-60
-40
-20
-30
-50
-70
-90
-10 VDD = 3V
RL = 16Ω
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
POWER DISSIPATION
vs. OUTPUT POWER
MAX4411 toc30
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
16012040 80
50
100
150
200
250
300
350
400
0
0200
INPUTS 180°
OUT OF PHASE
fIN = 1kHz
RL = 16Ω
VDD = 3V
POUT = POUTL + POUTR
INPUTS
IN PHASE
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4411 toc22
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
3.33.02.72.42.1
20
40
60
80
100
120
140
160
180
200
0
1.8 3.6
fIN = 1kHz
RL = 16Ω
THD+N = 1%
INPUTS
IN PHASE
INPUTS 180°
OUT OF PHASE
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4411 toc23
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
3.33.02.72.42.1
50
100
150
200
250
300
0
1.8 3.6
fIN = 1kHz
RL = 16Ω
THD+N = 10%
INPUTS
IN PHASE
INPUTS 180°
OUT OF PHASE
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4411 toc24
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
3.33.02.72.42.1
20
40
60
80
100
120
140
0
1.8 3.6
fIN = 1kHz
RL = 32Ω
THD+N = 1% INPUTS 180°
OUT OF PHASE
INPUTS
IN PHASE
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4411 toc25
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
3.33.02.72.42.1
40
20
60
80
100
120
140
160
180
0
1.8 3.6
fIN = 1kHz
RL = 32Ω
THD+N = 10%
INPUTS
IN PHASE
INPUTS 180°
OUT OF PHASE
OUTPUT POWER vs. LOAD RESISTANCE
MAX4411 toc26
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
10k1k100
40
20
60
80
100
120
140
160
0
10 100k
VDD = 3V
fIN = 1kHz
THD+N = 1%
INPUTS 180°
OUT OF PHASE
INPUTS
IN PHASE
OUTPUT POWER vs. LOAD RESISTANCE
MAX4411 toc27
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
10k1k100
50
100
150
200
250
0
10 100k
INPUTS
IN PHASE
INPUTS 180°
OUT OF PHASE
VDD = 3V
fIN = 1kHz
THD+N = 10%
OUTPUT POWER vs. LOAD RESISTANCE
MAX4411 toc28
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
10k1k100
5
10
15
20
25
30
35
40
45
0
10 100k
INPUTS 180°
OUT OF PHASE
INPUTS IN
PHASE
VDD = 1.8V
fIN = 1kHz
THD+N = 1%
OUTPUT POWER vs. LOAD RESISTANCE
MAX4411 toc29
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
10k1k100
10
20
30
40
50
60
70
0
10 100k
INPUTS 180°
OUT OF PHASE
INPUTS IN
PHASE
VDD = 1.8V
fIN = 1kHz
THD+N = 10%
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
_______________________________________________________________________________________ 7
Typical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
GAIN FLATNESS vs. FREQUENCY
MAX4411 toc34
FREQUENCY (Hz)
GAIN (dB)
100k10k1k100
-20
-25
-15
-10
-5
0
5
10
-30
10 1M
VDD = 3V
RL = 16Ω
AV = -1.5V/V AV = -2V/V
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4411 toc38
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
2.71.80.9
2
4
6
8
10
0
03.6
POWER DISSIPATION
vs. OUTPUT POWER
MAX4411 toc31
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
16012040 80
20
40
60
80
120
100
140
160
180
0
0 200
INPUTS 180°
OUT OF PHASE
fIN = 1kHz
RL = 32Ω
VDD = 3V
POUT = POUTL + POUTR
INPUTS
IN PHASE
POWER DISSIPATION
vs. OUTPUT POWER
MAX4411 toc32
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
50403010 20
20
40
60
80
100
120
140
0
060
INPUTS 180°
OUT OF PHASE
fIN = 1kHz
RL = 16Ω
VDD = 1.8V
POUT = POUTL + POUTR
INPUTS
IN PHASE
POWER DISSIPATION
vs. OUTPUT POWER
MAX4411 toc33
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
50403010 20
10
20
30
40
50
60
70
0
060
INPUTS 180°
OUT OF PHASE
fIN = 1kHz
RL = 32Ω
VDD = 1.8V
POUT = POUTL + POUTR
INPUTS
IN PHASE
CHARGE-PUMP OUTPUT RESISTANCE
vs. SUPPLY VOLTAGE
MAX4411 toc35
SUPPLY VOLTAGE (V)
OUTPUT RESISTANCE (Ω)
3.33.02.72.42.1
2
4
6
8
10
0
1.8 3.6
VIN_ = GND
IPVSS = 10mA
NO LOAD
OUTPUT POWER vs. CHARGE-PUMP
CAPACITANCE AND LOAD RESISTANCE
MAX4411 toc36
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
403020
20
10
30
40
50
60
70
80
90
0
10 50
fIN = 1kHz
THD+N = 1%
INPUTS IN PHASE
C1 = C2 = 1μF
C1 = C2 = 0.47μF
C1 = C2 = 0.68μF
C1 = C2 = 2.2μF
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4411 toc39
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (μA)
2.71.80.9
2
4
6
8
10
0
03.6
SHDNL = SHDNR = GND
FREQUENCY (kHz)
101
0.1 100
OUTPUT SPECTRUM vs. FREQUENCY
MAX4411 toc37
OUTPUT SPECTRUM (dB)
-100
-80
-60
-40
-20
0
-120
VOUT = 1VP-P
fIN = 1kHz
RL = 32Ω
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
8 _______________________________________________________________________________________
Pin Description
PIN BUMP
QFN UCSP NAME FUNCTION
1 A4 C1P Flying Capacitor Positive Terminal
2 B4 PGND Power Ground. Connect to ground (0V).
3 C4 C1N Flying Capacitor Negative Terminal
4, 6, 8, 12,
16, 20 — N.C. No Connection. Not internally connected.
5D4PV
SS Charge-Pump Output
7D3SV
SS Amplifier Negative Power Supply. Connect to PVSS.
9 D2 OUTL Left-Channel Output
10 D1 SVDD Amplifier Positive Power Supply. Connect to positive supply (1.8V to 3.6V).
11 C2 OUTR Right-Channel Output
13 C1 INL Left-Channel Audio Input
14 B1 SHDNR Active-Low Right-Channel Shutdown. Connect to VDD for normal operation.
15 A1 INR Right-Channel Audio Input
17 A2 SGND Signal Ground. Connect to ground (0V).
18 B2 SHDNL Active-Low Left-Channel Shutdown. Connect to VDD for normal operation.
19 A3 PVDD Charge-Pump Power Supply. Powers charge-pump inverter, charge-pump logic, and
oscillator. Connect to positive supply (1.8V to 3.6V).
—— EP
Exposed Paddle. Leave unconnected. Do not connect to any voltage including
GND or VDD.
POWER-UP/DOWN WAVEFORM
MAX4411 toc41
OUT_
OUT_FFT
VDD
3V
20dB/div
10mV/div
0V
200ms/div
FFT: 25Hz/div
-100dB
RL = 32Ω
VIN_ = GND
Typical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
EXITING SHUTDOWN
MAX4411 toc40
OUTR
SHDNR
2V/div
500mV/div
200μs/div
fIN = 1kHz
RL = 32Ω
SHDNL = GND
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
_______________________________________________________________________________________ 9
Detailed Description
The MAX4411 fixed-gain, stereo headphone driver fea-
tures Maxim’s DirectDrive architecture, eliminating the
large output-coupling capacitors required by conven-
tional single-supply headphone drivers. The device con-
sists of two 80mW Class AB headphone drivers, internal
feedback network, undervoltage lockout (UVLO)/shut-
down control, charge pump, and comprehensive click-
and-pop suppression circuitry (see Typical Application
Circuit). The charge pump inverts the positive supply
(PVDD), creating a negative supply (PVSS). The head-
phone drivers operate from these bipolar supplies with
their outputs biased about GND (Figure 1). The drivers
have almost twice the supply range compared to other
3V single-supply drivers, increasing the available output
power. The benefit of this GND bias is that the driver out-
puts do not have a DC component typically VDD/2. The
large DC-blocking capacitors required with convention-
al headphone drivers are unnecessary, thus conserving
board space, system cost, and improving frequency
response.
Each channel has independent left/right, active-low
shutdown controls, optimizing power savings in mixed-
mode, mono/stereo operation. The device features an
undervoltage lockout that prevents operation from an
insufficient power supply and click-and-pop suppres-
sion that eliminates audible transients on startup and
shutdown. Additionally, the MAX4411 features thermal-
overload and short-circuit protection and can withstand
±8kV ESD strikes on the output pins.
Fixed Gain
The MAX4411 utilizes an internally fixed gain configura-
tion of either -1.5V/V (MAX4411) or -2V/V (MAX4411B).
All gain-setting resistors are integrated into the device,
reducing external component count. The internally set
gain, in combination with DirectDrive, results in a head-
phone amplifier that requires only five tiny 1µF capaci-
tors to complete the amplifier circuit: two for the charge
pump, two for audio input coupling, and one for power-
supply bypassing (see Typical Application Circuit).
DirectDrive
Conventional single-supply headphone drivers have their
outputs biased about a nominal DC voltage (typically half
the supply) for maximum dynamic range. Large coupling
capacitors are needed to block this DC bias from the
headphone. Without these capacitors, a significant
amount of DC current flows to the headphone, resulting
in unnecessary power dissipation and possible damage
to both headphone and headphone driver.
Maxim’s DirectDrive architecture uses a charge pump
to create an internal negative supply voltage.
This allows the MAX4411 outputs to be biased about
GND, almost doubling dynamic range while operating
from a single supply. With no DC component, there is
no need for the large DC-blocking capacitors. Instead
of two large (220µF, typ) tantalum capacitors, the
MAX4411 charge pump requires two small ceramic
capacitors, conserving board space, reducing cost,
and improving the frequency response of the head-
phone driver. See the Output Power vs. Charge-Pump
Capacitance and Load Resistance graph in the Typical
Operating Characteristics for details of the possible
capacitor sizes. There is a low DC voltage on the driver
outputs due to amplifier offset. However, the offset of
the MAX4411 is typically 0.7mV, which, when com-
bined with a 32Ωload, results in less than 23µA of DC
current flow to the headphones.
Previous attempts to eliminate the output-coupling capac-
itors involved biasing the headphone return (sleeve) to
the DC-bias voltage of the headphone amplifiers. This
+VDD
-VDD
GND
VOUT
CONVENTIONAL DRIVER-BIASING SCHEME
DirectDrive BIASING SCHEME
VDD/2
VDD
GND
VOUT
Figure 1. Conventional Driver Output Waveform vs. MAX4411
Output Waveform
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
10 ______________________________________________________________________________________
method raises some issues:
• The sleeve is typically grounded to the chassis.
Using this biasing approach, the sleeve must be
isolated from system ground, complicating product
design.
• During an ESD strike, the driver’s ESD structures
are the only path to system ground. Thus, the driver
must be able to withstand the full ESD strike.
• When using the headphone jack as a line out to other
equipment, the bias voltage on the sleeve may con-
flict with the ground potential from other equipment,
resulting in possible damage to the drivers.
• When using a combination microphone and speaker
headset, the microphone typically requires a GND
reference. The driver DC bias on the sleeve conflicts
with the microphone requirements (Figure 2).
Low-Frequency Response
In addition to the cost and size disadvantages of the DC-
blocking capacitors required by conventional head-
phone amplifiers, these capacitors limit the amplifier’s
low-frequency response and can distort the audio signal:
1) The impedance of the headphone load and the DC-
blocking capacitor forms a highpass filter with the
-3dB point set by:
where RLis the impedance of the headphone and
COUT is the value of the DC-blocking capacitor.
The highpass filter is required by conventional sin-
gle-ended, single power-supply headphone drivers
to block the midrail DC-bias component of the audio
signal from the headphones. The drawback to the
filter is that it can attenuate low-frequency signals.
Larger values of COUT reduce this effect but result
in physically larger, more expensive capacitors.
Figure 3 shows the relationship between the size of
COUT and the resulting low-frequency attenuation.
Note that the -3dB point for a 16Ωheadphone with a
100µF blocking capacitor is 100Hz, well within the nor-
mal audio band, resulting in low-frequency attenuation
of the reproduced signal.
2) The voltage coefficient of the DC-blocking capacitor
contributes distortion to the reproduced audio signal
as the capacitance value varies as the function of
the voltage across the capacitor changes. At low
frequencies, the reactance of the capacitor domi-
nates at frequencies below the -3dB point and the
voltage coefficient appears as frequency-depen-
dent distortion. Figure 4 shows the THD+N intro-
fRC
dB L OUT
−=
3
1
2π
0
-30
10 100 1k 10k 100k
LOW-FREQUENCY ROLLOFF
(RL = 16Ω)
-24
-27
-12
-15
-18
-21
-6
-9
-3
FREQUENCY (Hz)
ATTENUATION (dB)
DirectDrive
330μF
220μF
100μF
33μF
Figure 3. Low-Frequency Attenuation for Common DC-Blocking
Capacitor Values
HEADPHONE DRIVER
MICROPHONE
AMPLIFIER
MICROPHONE
AMPLIFIER
OUTPUT
AUDIO
INPUT
AUDIO
INPUT
MICROPHONE
BIAS
MAX4411
Figure 2. Earbud Speaker/Microphone Combination Headset
Configuration
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
______________________________________________________________________________________ 11
duced by two different capacitor dielectric types.
Note that below 100Hz, THD+N increases rapidly.
The combination of low-frequency attenuation and fre-
quency-dependent distortion compromises audio repro-
duction in portable audio equipment that emphasizes
low-frequency effects such as multimedia laptops, as
well as MP3, CD, and DVD players. By eliminating the
DC-blocking capacitors through DirectDrive technology,
these capacitor-related deficiencies are eliminated.
Charge Pump
The MAX4411 features a low-noise charge pump. The
320kHz switching frequency is well beyond the audio
range, and thus does not interfere with the audio sig-
nals. The switch drivers feature a controlled switching
speed that minimizes noise generated by turn-on and
turn-off transients. By limiting the switching speed of the
charge pump, the di/dt noise caused by the parasitic
bond wire and trace inductance is minimized. Although
not typically required, additional high-frequency noise
attenuation can be achieved by increasing the size of
C2 (see Typical Application Circuit).
Shutdown
The MAX4411 features two shutdown controls allowing
either channel to be shut down or muted independently.
SHDNL controls the left channel while SHDNR controls
the right channel. Driving either SHDN_low disables
the respective channel, sets the driver output imped-
ance to 1kΩ, and reduces the supply current. When
both SHDN_inputs are driven low, the charge pump is
also disabled, further reducing supply current draw to
6µA. The charge pump is enabled once either SHDN_
input is driven high.
Click-and-Pop Suppression
In conventional single-supply audio drivers, the output-
coupling capacitor is a major contributor of audible
clicks and pops. Upon startup, the driver charges the
coupling capacitor to its bias voltage, typically half the
supply. Likewise, on shutdown, the capacitor is dis-
charged to GND. This results in a DC shift across the
capacitor, which in turn, appears as an audible transient
at the speaker. Since the MAX4411 does not require
output-coupling capacitors, this does not arise.
Additionally, the MAX4411 features extensive click-and-
pop suppression that eliminates any audible transient
sources internal to the device. The Power-Up/Down
Waveform in the Typical Operating Characteristics
shows that there are minimal spectral components in the
audible range at the output upon startup or shutdown.
In most applications, the output of the preamplifier dri-
ving the MAX4411 has a DC bias of typically half the
supply. At startup, the input-coupling capacitor is
charged to the preamplifier’s DC-bias voltage through
the RFof the MAX4411, resulting in a DC shift across
the capacitor and an audible click/pop. Delaying the
rise of the SHDN_signals 4 to 5 time constants (80ms
to 100ms) based on RIN and CIN, relative to the startup
of the preamplifier, eliminates this click/pop caused by
the input filter.
Applications Information
Power Dissipation
Under normal operating conditions, linear power ampli-
fiers can dissipate a significant amount of power. The
maximum power dissipation for each package is given
in the Absolute Maximum Ratings section under
Continuous Power Dissipation or can be calculated by
the following equation:
where TJ(MAX) is +150°C, TAis the ambient tempera-
ture, and θJA is the reciprocal of the derating factor in
°C/W as specified in the Absolute Maximum Ratings
section. For example, θJA of the QFN package is
+59.3°C/W.
The MAX4411 has two power dissipation sources, the
charge pump and the two drivers. If the power dissipa-
tion for a given application exceeds the maximum
allowed for a given package, either reduce VDD,
increase load impedance, decrease the ambient tem-
perature, or add heatsinking to the device. Large
PTT
DISSPKG MAX
J MAX A
JA
()
()
=−
θ
ADDITIONAL THD+N DUE
TO DC-BLOCKING CAPACITORS
MAX4411 fig04
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.001
0.01
0.1
1
10
0.0001
10 100k
TANTALUM
ALUM/ELEC
Figure 4. Distortion Contributed by DC-Blocking Capacitors
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
12 ______________________________________________________________________________________
output, supply, and ground traces improve the maxi-
mum power dissipation in the package.
Thermal-overload protection limits total power dissipa-
tion in the MAX4411. When the junction temperature
exceeds +140°C, the thermal protection circuitry dis-
ables the amplifier output stage. The amplifiers are
enabled once the junction temperature cools by 15°C.
This results in a pulsing output under continuous thermal-
overload conditions.
Output Power
The device has been specified for the worst-case sce-
nario—when both inputs are in phase. Under this con-
dition, the drivers simultaneously draw current from the
charge pump, leading to a slight loss in headroom of
VSS. In typical stereo audio applications, the left and
right signals have differences in both magnitude and
phase, subsequently leading to an increase in the max-
imum attainable output power. Figure 5 shows the two
extreme cases for in and out of phase. In reality, the
available power lies between these extremes.
Powering Other Circuits from a
Negative Supply
An additional benefit of the MAX4411 is the internally
generated, negative supply voltage (PVSS). This volt-
age provides the ground-referenced output level. PVSS
can, however, also be used to power other devices
within a design limit current drawn from PVSS to 5mA;
exceeding this affects the headphone driver operation.
A typical application is a negative supply to adjust the
contrast of LCD modules.
PVSS is roughly proportional to PVDD and is not a regu-
lated voltage. The charge-pump output impedance
must be taken into account when powering other
devices from PVSS. The charge-pump output imped-
ance plot appears in the Typical Operating
Characteristics. For best results, use 2.2µF charge-
pump capacitors.
Component Selection
Input Filtering
The input capacitor (CIN), in conjunction with the inter-
nal RIN, forms a highpass filter that removes the DC
bias from an incoming signal (see Typical Application
Circuit). The AC-coupling capacitor allows the amplifier
to bias the signal to an optimum DC level. Assuming
zero-source impedance, the -3dB point of the highpass
filter is given by:
RIN is the amplifier’s internal input resistance value
given in the Electrical Characteristics. Choose the CIN
such that f-3dB is well below the lowest frequency of
interest. Setting f-3dB too high affects the amplifier’s low-
frequency response. Use capacitors whose dielectrics
have low-voltage coefficients, such as tantalum or
aluminum electrolytic ones. Capacitors with high-voltage
coefficients, such as ceramics, may result in increased
distortion at low frequencies.
Charge-Pump Capacitor Selection
Use capacitors with an ESR less than 100mΩfor opti-
mum performance. Low-ESR ceramic capacitors mini-
mize the output resistance of the charge pump. For best
performance over the extended temperature range,
select capacitors with an X7R dielectric. Table 1 lists sug-
gested manufacturers.
Flying Capacitor (C1)
The value of the flying capacitor (C1) affects the charge
pump’s load regulation and output resistance. A C1
value that is too small degrades the device’s ability to
provide sufficient current drive, which leads to a loss of
output voltage. Increasing the value of C1 improves
load regulation and reduces the charge-pump output
resistance to an extent. See the Output Power vs.
Charge-Pump Capacitance and Load Resistance
graph in the Typical Operating Characteristics. Above
2.2µF, the on-resistance of the switches and the ESR of
C1 and C2 dominate.
Hold Capacitor (C2)
The hold capacitor value and ESR directly affect the
ripple at PVSS. Increasing the value of C2 reduces
fRC
dB IN IN
−=
3
1
2π
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4411 fig05
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
3.33.02.72.42.1
50
100
150
200
250
300
0
1.8 3.6
fIN = 1kHz
RL = 16Ω
THD+N = 10%
INPUTS
IN PHASE
INPUTS 180°
OUT OF PHASE
Figure 5. Output Power vs. Supply Voltage with Inputs In/Out of
Phase
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
______________________________________________________________________________________ 13
output ripple. Likewise, decreasing the ESR of C2
reduces both ripple and output resistance. Lower
capacitance values can be used in systems with low
maximum output power levels. See the Output Power
vs. Charge-Pump Capacitance and Load Resistance
graph in the Typical Operating Characteristics.
Power-Supply Bypass Capacitor
The power-supply bypass capacitor (C3) lowers the out-
put impedance of the power supply, and reduces the
impact of the MAX4411’s charge-pump switching tran-
sients. Bypass PVDD with C3, the same value as C1, and
place it physically close to the PVDD and PGND pins.
Adding Volume Control
The addition of a digital potentiometer provides simple
volume control. Figure 6 shows the MAX4411 with the
MAX5408 dual log taper digital potentiometer used as
an input attenuator. Connect the high terminal of the
MAX5408 to the audio input, the low terminal to
ground, and the wiper to CIN. Setting the wiper to the
top position passes the audio signal unattenuated.
Setting the wiper to the lowest position fully attenuates
the input.
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Connect PGND and SGND together at a
single point on the PC board. Connect all components
associated with the charge pump (C2 and C3) to the
PGND plane. Connect PVDD and SVDD together at the
device. Connect PVSS and SVSS together at the
device. Bypassing of both supplies is accomplished by
charge-pump capacitors C2 and C3 (see Typical
Application Circuit). Place capacitors C2 and C3 as
close to the device as possible. Route PGND and all
traces that carry switching transients away from SGND
and the traces and components in the audio signal
path.
The QFN package features an exposed paddle that
improves thermal efficiency of the package. However,
the MAX4411 does not require additional heatsinking.
Ensure that the exposed paddle is isolated from
GND or VDD. Do not connect the exposed paddle to
GND or VDD.
When using the MAX4411 in a UCSP package, make
sure the traces to OUTR (bump C2) are wide enough to
handle the maximum expected current flow. Multiple
traces may be necessary.
UCSP Applications Information
For the latest application details on UCSP construction,
dimensions, tape carrier information, printed circuit
board techniques, bump-pad layout, and recommend-
ed reflow temperature profile, as well as the latest infor-
mation on reliability testing results, go to Maxim’s
website at www.maxim-ic.com/ucsp and look up the
Application Note: UCSP–A Wafer-Level Chip-Scale
Package.
Table 1. Suggested Capacitor Manufacturers
SUPPLIER PHONE FAX WEBSITE
Taiyo Yuden 800-348-2496 847-925-0899 www.t-yuden.com
TDK 847-803-6100 847-390-4405 www.component.tdk.com
Note: Please indicate you are using the MAX4411 when contacting these component suppliers.
OUTL
MAX4411
INL
13
MAX5408
H0
L0
5
6
W0A 7
LEFT AUDIO
INPUT
15
W1A 10
CIN
CIN
RIGHT AUDIO
INPUT
INR OUTR 11
9
H1
L1
12
11
Figure 6. MAX4411 and MAX5408 Volume Control Circuit
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
14 ______________________________________________________________________________________
MAX9710
MAX961
OUTR+
OUTR-
OUTL-
OUTL+
INR
INL
BIAS
PVDD
VDD
SHDN
15kΩ
15kΩ
15kΩ
15kΩ
VDD
0.1μF
0.1μF
0.1μF
1μF
MAX4060
MAX4411
Q
Q
IN+
IN-
0.1μF
OUTL
OUTR
C1P CIN
PVSS
PVDD
SVDD
SVSS
SHDNL
SHDNR
1μF
1μF
1μF
INL
INR
AUX_IN
BIAS
IN+
IN-
2.2kΩ
0.1μF
0.1μF
0.1μF
CODEC
OUT
1μF
100kΩ
100kΩ
VCC
VCC
10kΩ
10kΩ
1μF
VCC
VCC
1μF
System Diagram
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
______________________________________________________________________________________ 15
Typical Application Circuit
CHARGE
PUMP
UVLO/
SHUTDOWN
CONTROL
CLICK-AND-POP
SUPPRESSION
C1N
C1P
PVSS SVSS PGND SGND INR
PVDD SVDD SHDNL SHDNR
SVSS
SVDD
SGND
INL
RIN
14kΩ
RF
RIN
14kΩ
OUTR
LEFT
CHANNEL
AUDIO IN
RIGHT
CHANNEL
AUDIO IN
HEADPHONE
JACK
18
(B2)
19
(A3)
1
(A4)
2
(B4)
3
(C4)
5
(D4)
7
(D3)
9
(D2)
10
(D1)
13
(C1)
11
(C2)
14
(B1)
17
(A2)
MAX4411
C1
1μF
C2
1μF
*MAX4411: 21kΩ, MAX4411B: 28kΩ
( ) UCSP BUMPS.
1.8V TO 3.6V
C3
1μF
CIN
1μF
SVSS
SVDD
SGND
OUTL
CIN
1μF
15
(A1)
RF*
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
16 ______________________________________________________________________________________
Chip Information
TRANSISTOR COUNT: 4295
PROCESS: BiCMOS
123
C
B
A
D
UCSP (B16-2)
TOP VIEW
(BUMPS SIDE
DOWN) 4
SVDD OUTL SVSS PVSS
INR SGND PVDD C1P
PGND
INL OUTR C1N
MAX4411
SHDNR SHDNL
TOP VIEW
19
20
18
17
7
6
8
PGND
N.C.
PVSS
9
C1P
SHDNR
N.C.
OUTR
INR
12
SHDNL
45
15 14 12 11
PVDD
N.C.
OUTL
N.C.
SVSS
N.C.
MAX4411
C1N INL
3
13
SGND
16 10 SVDD
N.C.
TQFN
Pin Configurations
Ordering Information (continued)
PART
TEMP RANGE
PIN/BUMP-
PACKAGE
GAIN
(V/V)
MAX4411ETP+
-40°C to +85°C 20 Thin QFN
-1.5
MAX4411BEBE-T -40°C to +85°C 16 UCSP-16
-2
MAX4411BEBE+T -40°C to +85°C 16 UCSP-16
-2
MAX4411BETP
-40°C to +85°C 20 Thin QFN
-2
MAX4411BETP+
-40°C to +85°C 20 Thin QFN
-2
+Denotes lead-free package.
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
______________________________________________________________________________________ 17
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
16L,UCSP.EPS
H1
1
21-0101
PACKAGE OUTLINE, 4x4 UCSP
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
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.
18 ____________________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.
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
24L QFN THIN.EPS