MAX4409ETP+-MAX4409ETP+T-MAX4409EUD+ Fast Delivery |IC PHOENIX CO.,LIMITED

MAX4409ETP+ ,80mW, DirectDrive, Stereo Headphone Amplifier with Common-Mode SenseELECTRICAL CHARACTERISTICS(V = V = 3V, V = V = 0, SHDN = SV , C1 = C2 = 2.2µF, R = R = R1 = R2 = 10 ..
MAX4409ETP+T ,80mW, DirectDrive, Stereo Headphone Amplifier with Common-Mode SenseApplications Functional DiagramNotebooksDirectDrive OUTPUTS Desktop PCs ELIMINATE DC-BLOCKING MAX44 ..
MAX4409EUD+ ,80mW, DirectDrive, Stereo Headphone Amplifier with Common-Mode SenseFeaturesThe MAX4409 stereo headphone amplifier combines♦ No Bulky DC-Blocking Capacitors Required®M ..
MAX440CPI ,High-Speed Video Multiplixer/AmplifierELECTRICAL CHARACTERISTICS (V+ = 5V, V- = -5V, VNS = -5V, RL = 1500, TA = +25'C. unless otherwise ..
MAX440EPI ,High-Speed Video Multiplixer/AmplifierFeatures . 160MHz Unity Galn Bandwidth . 110MHz Bandwidth (Av = 6dB) . 0.037004% Differential ..
MAX440EWI ,High-Speed Video Multiplixer/AmplifierGeneral Description The MAX44O and MAX441 combine a unity-gain stable, wideband video amplifier ..
MAX823REXK+T ,5-Pin Microprocessor Supervisory Circuits with Watchdog Timer and Manual ResetELECTRICAL CHARACTERISTICS(V = +4.75V to +5.5V for MAX82_L, V = +4.5V to +5.5V for MAX82_M, V = +3. ..
MAX823SEUK ,Microprocessor supervisory circuit. Reset threshold 2.93V. Active-low reset. Watchdog input. Manual reset input.FeaturesThe MAX823/MAX824/MAX825* microprocessor (µP) ' Precision Monitoring of +3V, +3.3V, and +5V ..
MAX823SEUK+T ,5-Pin Microprocessor Supervisory Circuits with Watchdog Timer and Manual ResetMAX823/MAX824/MAX82519-0487; Rev 5; 12/055-Pin Microprocessor Supervisory Circuits WithWatchdog Tim ..
MAX823SEUK-T ,5-Pin Microprocessor Supervisory Circuits with Watchdog Timer and Manual ResetMAX823/MAX824/MAX82519-0487; Rev 5; 12/055-Pin Microprocessor Supervisory Circuits WithWatchdog Tim ..
MAX823SEXK+ ,5-Pin Microprocessor Supervisory Circuits with Watchdog Timer and Manual ResetMAX823/MAX824/MAX82519-0487; Rev 5; 12/055-Pin Microprocessor Supervisory Circuits WithWatchdog Tim ..
MAX823SEXK+T ,5-Pin Microprocessor Supervisory Circuits with Watchdog Timer and Manual ResetMAX823/MAX824/MAX82519-0487; Rev 5; 12/055-Pin Microprocessor Supervisory Circuits WithWatchdog Tim ..

MAX4409ETP+-MAX4409ETP+T-MAX4409EUD+
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 16Ωload, 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.
Applications
FeaturesNo Bulky DC-Blocking Capacitors RequiredGround-Referenced Outputs Eliminate DC-Bias
Voltages on Headphone Ground PinCommon-Mode Voltage Sensing Eliminates
Ground-Loop Noise96dB CMRRNo Degradation of Low-Frequency Response Due
to Output Capacitors80mW per Channel into 16ΩLow 0.002% THD+NHigh 86dB PSRRIntegrated Click-and-Pop Suppression1.8V to 3.6V Single-Supply OperationLow Quiescent CurrentLow-Power Shutdown ModeShort-Circuit and Thermal-Overload Protection±8kV ESD-Protected Amplifier OutputsAvailable in a Space-Saving Package
20-Pin Thin QFN (4mm x 4mm x 0.8mm)
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
LEFT
AUDIO
INPUT
RIGHT
AUDIO
INPUT
SHDN
COM
MAX4409
DirectDrive OUTPUTS
ELIMINATE DC-BLOCKING
CAPACITORS
COMMON-MODE
SENSE INPUT ELIMINATES
GROUND-LOOP NOISE
Functional Diagram
Ordering Information
19-2842; Rev 3; 6/09
PARTTEMP RANGEPIN-PACKAGE
MAX4409ETP-40°C to +85°C20 Thin QFN-EP*
Notebooks
Desktop PCs
Cellular Phones
PDAs
MP3 Players
Tablet PCs
Portable Audio Equipment
Pin Configurations and Typical Application Circuit appear
at end of data sheet.
*EP = Exposed pad.
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VPVDD= VSVDD= 3V, VPGND= VSGND= 0, SHDN= SVDD, C1 = C2 = 2.2µF, RIN= RF= R1 = R2 = 10kΩ, RL= ∞, TA= TMINto
TMAX, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)
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
PVDDto SVDD.................................................................-0.3V to +0.3V
PVSSto SVSS.........................................................-0.3V to +0.3V
PVDDand SVDDto PGND or SGND.........................-0.3V to +4V
PVSSand SVSSto PGND or SGND..........................-4V to +0.3V
IN_ and COM to SGND.................................SVSSto (SVDD- 1V)
IN_ to COM.....................................(COM + 2V) to (COM - 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
Thermal Limits (Note 1)
Continuous Power Dissipation (TA= +70°C)
20-Pin Thin QFN Multilayer (derate 25.6mW/°C
above +70°C)..........................................................2051mWθJA................................................................................39°C/WθJC...............................................................................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
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
Supply Voltage RangeVDDGuaranteed by PSRR test1.83.6V
Quiescent Supply CurrentIDD58.4mA
Shutdown Supply CurrentI SHDNSHDN = GND610µA
VIH0.7 x
SVDDSHDN Thresholds
VIL0.3 x
SVDD
SHDN Input Leakage Current-1+1µA
SHDN to Full OperationtSON175µs
CHARGE PUMP
Oscillator FrequencyfOSC272320368kHz
AMPLIFIERS
Input Offset VoltageVOSRL = 32Ω0.52.4mV
Input Bias CurrentIBIAS-700-1000nA
COM Bias CurrentICOM-1400-2000nA
Equivalent Input Offset CurrentIOSIOS = (IBIAS(INR) + IBIAS(INL) - ICOM) / 2±2nA
COM Input RangeVCOMInferred from CMRR test-500+500mV
Common-Mode Rejection RatioCMRR-500mV ≤ VCOM ≤ +500mV, RSOURCE ≤ 10Ω7596dB
1.8V ≤ VDD ≤ 3.6VDC (Note 3)7586
fRIPPLE = 1kHz76Power-Supply Rejection RatioPSRRVDD = 3.0V,
200mVP-P ripple (Note 4)fRIPPLE = 20kHz48
RL = 32Ω65Output PowerPOUTTHD+N = 1%, TA = +25°CmW
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 /thermal-tutorial.
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
ELECTRICAL CHARACTERISTICS (continued)
(VPVDD= VSVDD= 3V, VPGND= VSGND= 0, SHDN= SVDD, C1 = C2 = 2.2µF, RIN= RF= R1 = R2 = 10kΩ, RL= ∞, TA= TMINto
TMAX, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)
Note 2:All specifications are 100% tested at TA= +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.
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
RL = 32Ω,
POUT = 50mW0.002
Total Harmonic Distortion
Plus NoiseTHD+NfIN = 1kHz
RL = 16Ω,
POUT = 60mW0.005
Signal-to-Noise Ratio (Note 4)SNRRL = 32Ω, POUT = 20mW, fIN = 1kHz95dB
Slew RateSR0.8V/µs
Maximum Capacitive LoadCLNo sustained oscillations150pF
CrosstalkRL = 16Ω, POUT = 1.6mW, fIN = 10kHz55dB
Thermal Shutdown Threshold140°C
Thermal Shutdown Hysteresis15°C
ESD ProtectionHuman Body Model (OUTR, OUTL)±8kV
Typical Operating Characteristics
(C1 = C2 = 2.2µF, RIN= RF= R1 = R2 = 10kΩ, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)10010k1k100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX4409 toc01
FREQUENCY (Hz)
THD+N (%)
VDD = 3V
RL = 16Ω
POUT = 10mW
POUT = 60mW
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX4409 toc02
THD+N (%)10010k1k100k
FREQUENCY (Hz)
VDD = 3V
RL = 32Ω
POUT = 50mW
POUT = 10mW
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX4409 toc03
THD+N (%)
VDD = 1.8V
RL = 16Ω
POUT = 5mW
POUT = 15mW10010k1k100k
FREQUENCY (Hz)
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Senseypical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, RIN= RF= R1 = R2 = 10kΩ, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX4409 toc04
VDD = 1.8V
RL = 32Ω
THD+N (%)
POUT = 15mW
POUT = 5mW10010k1k100k
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc05
OUTPUT POWER (W)
THD+N (%)
VDD = 3V
f = 20Hz
RL = 16Ω
OUTPUTS
OUT OF
PHASE
OUTPUTS
IN PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc06
OUTPUT POWER (W)
THD+N (%)
VDD = 3V
f = 1kHz
RL = 16Ω
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc07
OUTPUT POWER (W)
THD+N (%)
VDD = 3V
f = 10kHz
RL = 16Ω
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc08
OUTPUT POWER (W)
THD+N (%)
VDD = 3V
f = 20Hz
RL = 32Ω
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc09
OUTPUT POWER (W)
THD+N (%)
VDD = 3V
f = 1kHz
RL = 32Ω
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc10
OUTPUT POWER (W)
THD+N (%)
VDD = 3V
f = 10kHz
RL = 32Ω
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc11
OUTPUT POWER (W)
THD+N (%)
VDD = 1.8V
f = 20Hz
RL = 16Ω
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc12
OUTPUT POWER (W)
VDD = 1.8V
f = 1kHz
RL = 16Ω
THD+N (%)
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc13
OUTPUT POWER (W)
VDD = 1.8V
f = 10kHz
RL = 16Ω
THD+N (%)
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc14
OUTPUT POWER (W)
THD+N (%)
VDD = 1.8V
f = 20Hz
RL = 32Ω
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc15
OUTPUT POWER (W)
THD+N (%)
VDD = 1.8V
f = 1kHz
RL = 32Ω
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX4409 toc16
OUTPUT POWER (W)
THD+N (%)
VDD = 1.8V
f = 10kHz
RL = 32Ω
OUTPUTS IN
PHASE
OUTPUTS
OUT OF
PHASE10010k1k100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4409 toc17
FREQUENCY (Hz)
PSRR (dB)
VDD = 3V
VIN = 200mVP-P
RL = 16Ω10010k1k100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4410 toc18
FREQUENCY (Hz)
PSRR (dB)
VDD = 3V
VIN = 200mVP-P
RL = 16Ω10010k1k100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4410 toc19
FREQUENCY (Hz)
PSRR (dB)
VDD = 1.8V
VIN = 200mVP-P
RL = 16Ω10010k1k100k
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX4410 toc20
FREQUENCY (Hz)
PSRR (dB)
VDD = 1.8V
VIN = 200mVP-P
RL = 32Ω
CROSSTALK vs. FREQUENCY
MAX4410 toc21
FREQUENCY (Hz)
CROSSTALK (dB)
10k1k100
-90100k
LEFT TO RIGHT
RIGHT TO LEFT
VIN = 200mVP-Pypical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, RIN= RF= R1 = R2 = 10kΩ, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Senseypical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, RIN= RF= R1 = R2 = 10kΩ, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
MAX4409 toc22
FREQUENCY (Hz)
CMRR (dB)
10k1k100
-100100k
VIN = 500mVP-P
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4409 toc23
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
fIN = 1kHz
RL = 16Ω
THD+N = 1%
INPUTS
IN PHASE
INPUTS 180°
OUT OF PHASE
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4409 toc24
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
fIN = 1kHz
RL = 16Ω
THD+N = 10%
INPUTS
IN PHASE
INPUTS 180°
OUT OF PHASE
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4409 toc25
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
fIN = 1kHz
RL = 32Ω
THD+N = 1%INPUTS 180°
OUT OF PHASE
INPUTS
IN PHASE
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX4409 toc26
SUPPLY VOLTAGE (V)
OUTPUT POWER (mW)
fIN = 1kHz
RL = 32Ω
THD+N = 10%
INPUTS
IN PHASE
INPUTS 180°
OUT OF PHASE
OUTPUT POWER vs. LOAD RESISTANCE
MAX4409 toc27
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
10k1k100
160100k
VDD = 3V
fIN = 1kHz
THD+N = 1%
INPUTS 180°
OUT OF PHASE
INPUTS
IN PHASE
OUTPUT POWER vs. LOAD RESISTANCE
MAX4409 toc28
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
10k1k100
250100k
INPUTS
IN PHASE
INPUTS 180°
OUT OF PHASE
VDD = 3V
fIN = 1kHz
THD+N = 10%
OUTPUT POWER vs. LOAD RESISTANCE
MAX4409 toc29
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
10k1k100100k
INPUTS 180°
OUT OF PHASE
INPUTS IN
PHASE
VDD = 1.8V
fIN = 1kHz
THD+N = 1%
OUTPUT POWER vs. LOAD RESISTANCE
MAX4409 toc30
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)
10k1k100100k
INPUTS 180°
OUT OF PHASE
INPUTS IN
PHASE
VDD = 1.8V
fIN = 1kHz
THD+N = 10%
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
POWER DISSIPATION
vs. OUTPUT POWER
MAX4409 toc31
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
INPUTS 180°
OUT OF PHASE
fIN = 1kHz
RL = 16Ω
VDD = 3V
POUT = POUTL + POUTR
INPUTS
IN PHASE
POWER DISSIPATION
vs. OUTPUT POWER
MAX4409 toc32
OUTPUT POWER (mW)
POWER DISSIPATION (mW)
INPUTS 180°
OUT OF PHASE
fIN = 1kHz
RL = 32Ω
VDD = 3V
POUT = POUTL + POUTR
INPUTS
IN PHASE
POWER DISSIPATION
vs. OUTPUT POWER
MAX4409 toc33
OUTPUT POWER (mW)
POWER DISSIPATION (mW)40301020
INPUTS 180°
OUT OF PHASE
fIN = 1kHz
RL = 16Ω
VDD = 1.8V
POUT = POUTL + POUTR
INPUTS
IN PHASE
POWER DISSIPATION
vs. OUTPUT POWER
MAX4409 toc34
OUTPUT POWER (mW)
POWER DISSIPATION (mW)40301020
INPUTS 180°
OUT OF PHASE
fIN = 1kHz
RL = 32Ω
VDD = 1.8V
POUT = POUTL + POUTR
INPUTS
IN PHASE
10010k100k1M10M
GAIN AND PHASE vs. FREQUENCY
MAX4409 toc35
FREQUENCY (Hz)
GAIN/PHASE (dB/DEGREES)
VDD = 3V
AV = 1000V/V
RL = 16Ω
GAIN
PHASE1k10k1M100k10M
GAIN FLATNESS vs. FREQUENCY
MAX4410 toc36
FREQUENCY (Hz)
GAIN
(dB)
VDD = 3V
AV = -1V/V
RL = 16Ω
CHARGE-PUMP OUTPUT RESISTANCE
vs. SUPPLY VOLTAGE
MAX4409 toc37
SUPPLY VOLTAGE (V)
OUTPUT RESISTANCE (
VIN_ = GND
IPVSS = 10mA
NO LOAD
OUTPUT POWER vs. CHARGE-PUMP
CAPACITANCE AND LOAD RESISTANCE
MAX4409 toc38
LOAD RESISTANCE (Ω)
OUTPUT POWER (mW)302050
fIN = 1kHz
THD+N = 1%
INPUTS IN PHASE
C1 = C2 = 1μF
C1 = C2 = 0.47μF
C1 = C2 = 0.68μF
C1 = C2 = 2.2μF
FREQUENCY (Hz)
10k1k100100k
OUTPUT SPECTRUM vs. FREQUENCY
MAX4409 toc39
OUTPUT SPECTRUM (dB)
VIN = 1VP-P
fIN = 1kHz
RL = 32Ω
AV = -1V/Vypical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, RIN= RF= R1 = R2 = 10kΩ, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
Pin Description
PINNAMEFUNCTIONCOMCommon-Mode Voltage Sense InputPVDDCharge-Pump Power Supply. Powers charge-pump inverter, charge-pump logic, and oscillator.C1PFlying Capacitor Positive TerminalPGNDPower Ground. Connect to SGND.C1NFlying Capacitor Negative Terminal
5PVSSCharge-Pump Output
7SVSSAmplifier Negative Power Supply. Connect to PVSS.OUTLLeft-Channel OutputSVDDAmplifier Positive Power Supply. Connect to PVDD.INLLeft-Channel Audio InputOUTRRight-Channel OutputSHDNActive-Low Shutdown. Connect to VDD for normal operation.INRRight-Channel Audio InputSGNDSignal Ground. Connect to PGND.
4, 6, 8, 12,
16, 20N.C.No Connection. Not internally connected.EPExposed Pad. Leave unconnected. Do not connect to VDD or GND.ypical Operating Characteristics (continued)
(C1 = C2 = 2.2µF, RIN= RF= R1 = R2 = 10kΩ, THD+N measurement bandwidth = 22Hz to 22kHz, TA= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4409 toc40
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX4409 toc41
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (
SHDN = GND
POWER-UP/DOWN WAVEFORM
MAX4409 toc42
OUT_
OUT_FFT
VDD
20dB/div
10mV/div
200ms/div
FFT: 25Hz/div
-100dB
RL = 32Ω, VIN_ = GND
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
Detailed Description
The MAX4409 stereo headphone driver features Maxim’s
patented DirectDrive architecture, eliminating the large
output-coupling capacitors required by traditional single-
supply headphone drivers. The device consists of two
80mW Class AB headphone drivers, undervoltage lock-
out (UVLO)/shutdown control, charge-pump, and com-
prehensive click-and-pop suppression circuitry (see
Typical Application Circuit). The charge pump inverts the
positive supply (PVDD), creating a negative supply
(PVSS). The headphone drivers operate from these bipo-
lar supplies with their outputs biased about GND (Figure
1). The drivers have almost twice the supply range com-
pared to other 3V single-supply drivers, increasing the
available output power. The benefit of this GND bias is
that the driver outputs do not have a DC component typi-
cally VDD/2. Thus, the large DC-blocking capacitors are
unnecessary, improving frequency response while con-
serving board space and system cost.
The MAX4409 also features a common-mode voltage
sense input that corrects for mismatch between the
SGND of the device and the potential at the headphone
jack return. A low-power shutdown mode reduces sup-
ply current to 6µA. The device features an undervoltage
lockout that prevents operation from an insufficient
power supply and click-and-pop suppression that elim-
inates audible transients on startup and shutdown.
Additionally, the MAX4409 features thermal overload
and short-circuit protection and can withstand ±8kV
ESD strikes on the output pins.
Common-Mode Sense
When the headphone jack is used as a line out to inter-
face between other equipment (notebooks, desktops,
and stereo receivers), potential differences between
the equipment grounds can create ground loops and
excessive ground current flow. The MAX4409 COM
input senses and corrects for the difference between
the headphone return and device ground. Connect
COM through a resistive voltage-divider between the
headphone jack return and SGND of the device (see
Typical Application Circuit). For optimum common-
mode rejection, use the same value resistors for R2 and
RIN, and R1 and RF. Improve DC CMRR by adding a
capacitor in between with SGND and R2 (see Typical
Application Circuit). If ground sensing is not required,
connect COM directly to SGND through a 5kΩresistor.
DirectDrive
Traditional 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 signif-
icant amount of DC current flows to the headphone,
resulting in unnecessary power dissipation and possi-
ble damage to both headphone and headphone driver.
Maxim’s patented DirectDrive architecture uses a
charge pump to create an internal negative supply volt-
age. This allows the outputs of the MAX4409 to be
biased about GND, almost doubling dynamic range
while operating from a single supply. With no DC com-
ponent, there is no need for the large DC-blocking
capacitors. Instead of two large (220µF, typ) tantalum
capacitors, the MAX4409 charge pump requires two
small ceramic capacitors, thereby conserving board
space, reducing cost, and improving the frequency
response of the headphone driver. See the Output
Power vs. Charge-Pump Capacitance and Load
Resistance graph in the Typical Operating Char-
acteristicsfor 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 MAX4409 is
+VDD
-VDD
GNDVOUT
CONVENTIONAL DRIVER-BIASING SCHEME
DirectDrive BIASING SCHEME
VDD/2
VDD
GND
VOUT
Figure 1. Traditional Driver Output Waveform vs. MAX4409
Output Waveform
MAX4409
80mW, DirectDrive, Stereo Headphone
Amplifier with Common-Mode Sense
typically 0.5mV, which, when combined with a 32Ω
load, results in less than 16µA 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
method raises some issues:When combining a microphone and headphone on
a single connector, the microphone bias scheme
typically requires a 0V reference.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.
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:The impedance of the headphone load and the DC-
blocking capacitor form a highpass filter with the
-3dB point set by:
where RLis the headphone impedance and COUTis
the DC-blocking capacitor value. The highpass filter
is required by conventional single-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
COUTreduce this effect but result in physically larg-
er, more expensive capacitors. Figure 2 shows the
relationship between the size of COUTand the result-
ing low-frequency attenuation. Note that the -3dB
point for a 16Ωheadphone with a 100µF blocking
capacitor is 100Hz, well within the normal audio
band, resulting in low-frequency attenuation of the
reproduced signal.The voltage coefficient of the DC-blocking capacitor
contributes distortion to the reproduced audio signal
as the capacitance value varies as a function of the
voltage change across the capacitor. At low fre-
quencies, the reactance of the capacitor dominates
at frequencies below the -3dB point and the voltage
coefficient appears as frequency-dependent distor-
tion. Figure 3 shows the THD+N introduced 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
reproduction in portable audio equipment that empha-
sizes low-frequency effects such as multimedia lap-RCdBLOUT-231=π
LF ROLL OFF (16Ω LOAD)
MAX4409 fig02
FREQUENCY (Hz)
ATTENUATION (dB)
-10-3dB CORNER FOR
100μF IS 100Hz-15
-351k
33μF
330μF
220μF
100μF
Figure 2. Low-Frequency Attenuation for Common DC-Blocking
Capacitor Values
ADDITIONAL THD+N DUE
TO DC-BLOCKING CAPACITORS
MAX4409 fig03
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.0001100k
TANTALUM
ALUM/ELEC
Figure 3. Distortion Contributed by DC-Blocking Capacitors

Partno	Mfg	Dc	Qty	Available	Descript
MAX4409ETP+	MAXIM	N/a	3700	avai	80mW, DirectDrive, Stereo Headphone Amplifier with Common-Mode Sense
MAX4409ETP+T \|MAX4409ETPT	MAXIM	N/a	1735	avai	80mW, DirectDrive, Stereo Headphone Amplifier with Common-Mode Sense
MAX4409EUD+	MAIXM	N/a	2500	avai	80mW, DirectDrive, Stereo Headphone Amplifier with Common-Mode Sense