Post on 03-Feb-2022
General DescriptionThe MAX9791 combines a stereo 2W Class D poweramplifier, a stereo 180mW DirectDrive® headphoneamplifier, and a 120mA low-dropout (LDO) linear regu-lator in a single device. The MAX9792 combines amono 3W Class D power amplifier, a stereo 180mWDirectDrive headphone amplifier, and a 120mA LDOlinear regulator in a single device.The MAX9791/MAX9792 feature Maxim’s DirectDriveheadphone amplifier architecture that produces aground-referenced output from a single supply, eliminat-ing the need for large DC-blocking capacitors, savingcost, board space, and component height. High 107dBDC PSRR and low 0.006% THD+N ensure clean, low-distortion amplification of the audio signal.The ground sense feature senses and corrects for thevoltage difference between the output jack ground anddevice signal ground. This feature minimizes head-phone amplifier crosstalk by sensing the impedance inthe ground return trace and correcting for it at the out-put jack. This feature also minimizes ground-loop noisewhen the output socket is used as a line out connectionto other grounded equipment (for example, a PC con-nected to a home hi-fi system).The MAX9791/MAX9792 feature low RF susceptibility,allowing the amplifiers to successfully operate in closeproximity to wireless applications. The MAX9791/MAX9792 Class D amplifiers feature Maxim’s spread-spectrum modulation and active emissions limiting cir-cuitry. Industry-leading click-and-pop suppressioneliminates audible transients during power-up and shut-down cycles.The MAX9791/MAX9792 wake-on-beep feature wakesup the speaker and headphone amplifiers when a qual-ified beep signal is detected at the BEEP input.For maximum flexibility, separate speaker and head-phone amplifier control inputs provide independentshutdown of the speaker and headphone amplifiers.Additionally the LDO can be enabled independently ofthe audio amplifiers.The MAX9791/MAX9792 feature thermal-overload andoutput short-circuit protection. The devices are avail-able in 28-pin TQFN packages and are specified overthe -40°C to +85°C extended temperature range.
ApplicationsNotebook Computers
Tablet PCs
Portable Multimedia Players
Features Windows Vista® Premium Compliant Low EMI Filterless Class D Speaker Amplifiers
Pass EN55022B Emissions Limit with 30cm ofSpeaker Cable
180mW DirectDrive Headphone Amplifier Excellent RF Immunity Integrated 120mA LDO Eliminates Headphone Ground Loop Noise Wake-on-Beep Function Click-and-Pop Suppression Short-Circuit and Thermal-Overload Protection Thermally Efficient, Space-Saving Package
28-Pin TQFN-EP (4mm x 4mm x 0.75mm)
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________________________________________________________________ Maxim Integrated Products 1
19-4217; Rev 1; 6/10
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.
Ordering Information
PARTSTEREO/
MONOLDO
OUTPUTPIN-PACKAGE
MAX9791AETI+ Stereo 4.75V 28 TQFN-EP*
MAX9791BETI+ Stereo 3.3V 28 TQFN-EP*
MAX9791CETI+ Stereo 1.8V 28 TQFN-EP*
MAX9792AETI+ Mono 4.75V 28 TQFN-EP*
MAX9792CETI+ Mono 1.8V 28 TQFN-EP*
Note: All devices are specified over the -40°C to +85°Cextended temperature range.+Denotes a lead(Pb)-free/RoHS-compliant package.*EP = Exposed pad.
DirectDrive is a registered trademark of Maxim IntegratedProducts, Inc.
Windows Vista is a registered trademark of Microsoft Corp.
MAX9791
SPKR_ENHP_ENLDO_ENBEEP
SPEAKER AND LDOSUPPLY
2.7V TO 5.5VHEADPHONE SUPPLY
2.7V TO 5.5V
AVDD
LDO 1.8V, 3.3V, OR 4.75V
CLASS DAMP
CLASS DAMP
Simplified Block Diagrams
Simplified Block Diagrams continued at end of data sheet.
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ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2µF (CLDO = 4µF for 1.8V LDO option),C1 = C2 = 1µF. RL = ∞, unless otherwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF,CIN2 = CCOM = 1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functionaloperation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure toabsolute maximum rating conditions for extended periods may affect device reliability.
Supply Voltage(AVDD, PVDD, HPVDD to GND)........................-0.3V to +6.0V(AVDD to PVDD) .............................................................±0.3V
GND to PGND, CPGND......................................................±0.3VCPVSS, C1N to GND............................................-6.0V to + 0.3VHPL, HPR to CPVSS ...........................................-0.3V to lower of
(HPVDD - CPVSS + 0.3V) and +9VHPL, HPR to HPVDD..................................+0.3V to the higher of
(CPVSS - HPVDD - 0.3V) and -9VCOM, SENSE........................................................-0.3V to + 0.3VAny Other Pin ..........................................-0.3V to (AVDD + 0.3V)Duration of Short Circuit between OUT_+, OUT_- and GND,
PGND, AVDD, or PVDD..........................................ContinuousDuration of Short Circuit between LDO_OUT and AVDD,
GND (Note 1) .........................................................ContinuousDuration of Short Circuit between HPR, HPL and
GND .......................................................................ContinuousContinuous Current (PVDD, OUT_+, OUT_-, PGND)............1.7AContinuous Current (C1N, C1P, CPVSS, AVDD, HPVDD,
LDO_OUT, HPR, HPL) ..................................................850mA
Continuous Input Current (All Other Pins) ........................±20mAContinuous Power Dissipation (TA = +70°C)
28-Pin Thin QFN Single-Layer Board (derate 20.8mW/°Cabove +70°C)..........................................................1667mW
Junction-to-Ambient Thermal Resistance (θJA)(Note 2) .....................................................................40°C/W
Junction-to-Case Thermal Resistance (θJC)(Note 2) ....................................................................2.7°C/W
28-Pin Thin QFN Multilayer Board (derate 28.6mW/°Cabove +70°C)..........................................................2286mW
Junction-to-Ambient Thermal Resistance (θJA)(Note 2) .....................................................................35°C/W
Junction-to-Case Thermal Resistance (θJC)(Note 2) ....................................................................2.7°C/W
ESD Protection, Human Body Model ...................................±2kVOperating Temperature Range ...........................-40°C to +85°CJunction Temperature ......................................................+150°CStorage Temperature Range .............................-65°C to +150°CLead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
GENERAL
Supply Voltage VAVDD,VPVDD
Guaranteed by PSRR test (Note 4) 2.7 5.5 V
Headphone Supply Voltage VHPVDD Guaranteed by PSRR test 2.7 5.5 V
Undervoltage Lockout UVLO 2.65 V
SPKR_EN HP_EN LDO_EN
1 0 1 250 400 µA
1 1 0 4.4 6
0 0 0 10.5 15
MAX9791
0 1 0 14.4 21
mA
1 0 1 250 400 µA
1 1 0 4.4 6
0 0 0 10.5 18
Quiescent Current IAVDD +IPVD + IHPVDD
MAX9792
0 1 0 14.4 24
mA
Shutdown Current ISHDN SPKR_EN = 1.8V 3.3 7..3 µA
Bias Voltage VBIAS HP_INR, HP_INL, SPKR_INR, SPKR_INL 0 V
Note 1: If short is present at power-up.Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
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PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Shutdown to Full Operation tON 0.4 ms
Overtemperature Threshold +150 °C
SPEAKER AMPLIFIER
RL = 4(MAX9791)
1.7
RL = 8(MAX9791)
1.2
THD+N = 1%, f = 1kHz, TA = +25°C(Note 5) RL = 3
(MAX9792) 3
RL = 4(MAX9791)
2.2
RL = 8(MAX9791)
1.5
Output Power POUT
THD+N = 10%, f = 1kHz, TA = +25°C(Note 5) RL = 3
(MAX9792) 3.7
W
RL = 8 , POUT = 500mW, f = 1kHz (Note 5) 0.04 Total Harmonic Distortion Plus Noise
THD+N RL = 4 , POUT = 500mW, f = 1kHz (Note 5) 0.03
%
VAVDD = VPVDD = 2.7V to 5.5V, TA = +25°C 60 80
f = 217Hz, 200mVP-P 73
f = 1kHz, 200mVP-P 75 Power-Supply Rejection Ratio PSRR
f = 10kHz, 200mVP-P 62
dB
Feedback Impedance RFSKR Guaranteed by design 20 k
Gain AV RIN1 = 20k 12 dB
Output Offset Voltage VOS Measured between OUT_+ and OUT_-, TA = +25°C
±3 ±10 mV
Into shutdown -52.4
Click-and-Pop Level KCP
RL = 8 ,peak voltage, A-weighted, 32 samples per second (Notes 5, 6, and 7)
Out of shutdown
-54
dBV
A-weighted 98 Signal-to-Noise Ratio SNR
RL = 8POUT = 1.2W fIN = 1kHz, (Note 5) 20Hz to 20kHz 94
dB
Noise VN A-weighted 38 µVRMS
L to R, R to L, RL = 8 , VIN = -20dBFS = 100mVRMS, fIN = 1kHz (Note 5)
78
L to R, R to L, RL = 8 , VIN = -20dBFS = 100mVRMS, fIN = 15kHz (Note 5)
70 Crosstalk
HP to SPKR, RLSPKR = 8 , PHP = 20mW, RLHP = 32 , fIN = 1kHz (Note 5)
77
dB
ELECTRICAL CHARACTERISTICS (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2µF (CLDO = 4µF for 1.8V LDO option),C1 = C2 = 1µF. RL = ∞, unless otherwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF,CIN2 = CCOM = 1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
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PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Class D Switching Frequency fSPK 948 1158 kHz
Spread-Spectrum Bandwidth ±15 kHz
Efficiency POUT = 1.5W, fIN = 1kHz, RL = 8 (Note 5) 83 %
HEADPHONE AMPLIFIER
RL = 16 100 Output Power POUT
THD+N = 1%, f = 1kHz, TA = +25°C RL = 32 180
mW
RL = 32 , fIN = 6kHz, 20kHz AES17, VIN = -3dBFS = 212mVRMS
-78
RL = 10k , fIN = 6kHz, 20kHz AES17, VIN = -3dBFS = 500mVRMS
-87
dBFS
RL = 32 , POUT = 100mW, f = 1kHz 0.006
Total Harmonic Distortion Plus Noise
THD+N
RL = 16 , POUT = 75mW, f = 1kHz 0.014 %
VHPVDD = 2.7V to 5.5V, TA = +25°C 70 107
f = 1kHz, VRIPPLE = 200mVP-P 91 Power-Supply Rejection Ratio PSRR
f = 10kHz, VRIPPLE = 200mVP-P 80
dB
Feedback Impedance RFHP 38.2 40.2 42.2 k
Gain AV RIN2 = 40.2k 0 dB
Output Offset Voltage VOS TA = +25°C ±0.3 ±3 mV
Into shutdown -81
Click-and-Pop Level KCP
RL = 32 ,peak voltage, A-weighted, 32 samples per second (Notes 6, 7)
Out of shutdown
-72.5 dBV
A-weighted 102 Signal-to-Noise Ratio SNR
RL = 32 , POUT = 40mW, fIN = 1kHz 20Hz to 20kHz 94
dB
Noise VN A-weighted 8 µVRMS
Maximum Capacitive Load CL No sustained oscillations 100 pF
RL = 32 , VIN = -20dBFS = 30mVRMS
82 L to R, R to L, fIN= 1kHz, COM and SENSE connected
RL = 10k , VIN = -20dBFS = 0.7mVRMS
89
RL = 32 , VIN = -20dBFS = 30mVRMS
64 L to R, R to L, fIN= 15kHz, COM and SENSE connected
RL = 10k , VIN = -20dBFS = 70.7mVRMS
70
Crosstalk
SPKR to HP, RLSPKR = 8 , PSPKR = 1W, RLHP = 32 , fIN = 1Hz
80
dB
ELECTRICAL CHARACTERISTICS (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2µF (CLDO = 4µF for 1.8V LDO option),C1 = C2 = 1µF. RL = ∞, unless otherwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF,CIN2 = CCOM = 1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
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PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
COM Input Range VCOM Inferred from CMRR test -300 +300 mV
Common-Mode Rejection Ratio CMRR -300mV < VCOM < +300mV 60 dB
Slew Rate SR 0.38 V/µs
Charge-Pump Frequency fOSC 530 kHz
BEEP INPUT (LDO_EN = 1)
Beep Signal Minimum fBEEP Four-cycle count 215 Hz
Amplifier Turn-On Time tONBEEP 0.4 ms
Amplifier Hold Time tHOLDBEEP 221 246 271 ms LOW-DROPOUT LINEAR REGULATORLDO Ground Current ILDO 0.25 0.4 mA
Output Current IOUT Inferred from load regulation 120 mA
Current Limit ILIM 300 mA
Crosstalk Speaker to LDO, VLDO_OUT = 4.75V, f =1kHz, ILDO_OUT = 10mA, speaker POUT= 1.2W, RL = 8 (Note 6)
-80 dB
VLDO_OUT = 4.75V ±1.5 Output-Voltage Accuracy
VLDO_OUT = 3.3V ±1.5 %
IOUT = 50mA 46 Dropout Voltage VDO
VLDO_OUT = 4.75V, TA = +25°C (Note 8) IOUT = 120mA 106
mV
Startup Time 30 µs
VAVDD = 5V to 5.5V, VLDO_OUT = 4.75V, ILDO_OUT = 1mA, CLDO = 2µF
-4.8 1.5 +4.8
VAVDD = 4.5V to 5.5V, VLDO_OUT = 3.3V, ILDO_OUT = 1mA, CLDO = 2µF
-4 0.2 +4 Line Regulation
VAVDD = 3V to 5.5V, VLDO_OUT = 1.8V, ILDO_OUT = 1mA, CLDO = 4µF
-6.4 2.5 +6.4
mV/V
Load Regulation VLDO_OUT = 4.75V, 1mA < ILDO_OUT < 120mA
0.22 mV/mA
f = 1kHz 56 Ripple Rejection
VRIPPLE = 200mVP-P,VLDO_OUT = 4.75V ILDO_OUT = 10mA f = 10kHz 40
dB
Output-Voltage Noise 20Hz to 20kHz, CLDO_OUT = 2 x 1µF, ILDO_OUT = 120mA
130 µVRMS
DIGITAL INPUTS (SPKR_EN, HP_EN, LDO_EN, BEEP)
Input-Voltage High VINH 1.4 V
Input-Voltage Low VINL 0.4 V
Input Bias Current -1 +1 µA
ELECTRICAL CHARACTERISTICS (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2µF (CLDO = 4µF for 1.8V LDO option),C1 = C2 = 1µF. RL = ∞, unless otherwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF,CIN2 = CCOM = 1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
Typical Operating Characteristics(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
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Note 3: All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design.Note 4: AVDD and PVDD must be tied together. If LDO is enabled, set AVDD and PVDD as specified in the Line Regulation row of
the Electrical Characteristics table.Note 5: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For RL = 3Ω, L = 22µH.
For RL = 4Ω, L = 33µH. For RL = 8Ω, L = 68µH.Note 6: Specified at TA = +25°C with an 8Ω + 68µH load connected across BTL output for speaker amplifier. Specified at TA = +25°C
with a 32Ω resistive load connected between HPR, HPL and GND for headphone amplifier. Speaker and headphone modetransitions are controlled by SPKR_EN and HP_EN inputs, respectively.
Note 7: Amplifier Inputs AC-coupled to GND.Note 8: Guaranteed by ATE characterization; limits are not production tested.
TOTAL HARMONIC DISTORTION + NOISEvs. FREQUENCY (MAX9792 SPEAKER MODE)
MAX
9791
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1
FREQUENCY (kHz)
THD+
N (d
BFS)
0.1 1 10
-90
-80
-50
-40
-30
-70
-60
-20
-10
0
-1000.01 100
RL = 3ΩVIN = -3dBFS
FS = 707mVRMS
FS = 1VRMS
TOTAL HARMONIC DISTORTION + NOISEvs. FREQUENCY (MAX9791 SPEAKER MODE)
MAX
9791
toc0
2
FREQUENCY (kHz)
THD+
N (d
BFS)
0.1 1 10
-90
-80
-50
-40
-30
-70
-60
-20
-10
0
-1000.01 100
RL = 4ΩVIN = -3dBFS
FS = 707mVRMS
FS = 1VRMS
TOTAL HARMONIC DISTORTION + NOISEvs. FREQUENCY (MAX9791 SPEAKER MODE)
MAX
9791
toc0
3
FREQUENCY (kHz)
THD+
N (d
BFS)
0.1 1 10
-90
-80
-50
-40
-30
-70
-60
-20
-10
0
-1000.01 100
RL = 8ΩVIN = -3dBFS
FS = 707mVRMS
FS = 1VRMS
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (MAX9792 SPEAKER MODE)
MAX
9791
toc0
4
OUTPUT POWER (W)
THD+
N (%
)
1.0 2.0 3.0
0.01
0.1
1
10
100
0.0010 4.00.5 1.5 2.5 3.5
RL = 3Ω
f = 6kHz
f = 1kHz
f = 100Hz
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (MAX9791 SPEAKER MODE)
MAX
9791
toc0
5
OUTPUT POWER (W)
THD+
N (%
)
2.01.51.0
0.01
0.1
1
10
100
0.0010 3.02.50.5
RL = 4Ω
f = 6kHzf = 1kHz
f = 100Hz
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (MAX9791 SPEAKER MODE)
MAX
9791
toc0
6
OUTPUT POWER (W)
THD+
N (%
)
0.5 1.0
0.01
0.1
1
10
100
0.0010 2.01.5
RL = 8Ω
f = 6kHzf = 1kHz
f = 100Hz
ELECTRICAL CHARACTERISTICS (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2µF (CLDO = 4µF for 1.8V LDO option),C1 = C2 = 1µF. RL = ∞, unless otherwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF,CIN2 = CCOM = 1µF, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3)
SPEAKER
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
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OUTPUT POWER vs. LOAD RESISTANCE(MAX9792 SPEAKER MODE)
MAX
9791
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7
LOAD RESISTANCE (Ω)
OUTP
UT P
OWER
(W)
10
1.0
2.0
3.0
4.0
5.0
0
1.5
2.5
3.5
4.5
0.5
1 100
f = 1kHz
THD+N = 10%
THD+N = 1%
OUTPUT POWER vs. LOAD RESISTANCE(MAX9792 SPEAKER MODE)
MAX
9791
toc0
7a
LOAD RESISTANCE (Ω)
OUTP
UT P
OWER
(W)
10
0.5
1.0
1.5
2.0
2.5
01 100
VPVDD = VAVDD = 3.7V
THD+N = 10%
THD+N = 1%
OUTPUT POWER vs. LOAD RESISTANCE(MAX9791 SPEAKER MODE)
MAX
9791
toc0
8
LOAD RESISTANCE (Ω)
OUTP
UT P
OWER
(W)
10
1.0
2.0
3.0
0
1.5
2.5
0.5
1 100
f = 1kHz
THD+N = 10%
THD+N = 1%
OUTPUT POWER vs. LOAD RESISTANCE(MAX9791 SPEAKER MODE)
MAX
9791
toc0
8a
LOAD RESISTANCE (Ω)
OUTP
UT P
OWER
(W)
10
0.25
0.50
0.75
1.00
1.25
1.50
01 100
VPVDD = VAVDD = 3.7V
THD+N = 10%
THD+N = 1%
EFFICIENCY vs. OUTPUT POWER(MAX9792 SPEAKER MODE)
MAX
9791
toc0
9
OUTPUT POWER (W)
EFFI
CIEN
CY (%
)
1.0 2.0 3.0
70
80
90
100
110
20
10
30
40
50
60
00 4.00.5 1.5 2.5 3.5
RL = 8Ω
RL = 3Ω
fIN = 1kHz
EFFICIENCY vs. OUTPUT POWER(MAX9792 SPEAKER MODE)
MAX
9791
toc0
9a
OUTPUT POWER (W)
EFFI
CIEN
CY (%
)
1.20.90.60.3
10
20
30
40
50
60
70
80
90
00 1.5
VPVDD = VAVDD = 3.7VfIN = 1kHz
RL = 8Ω
RL = 3Ω
EFFICIENCY vs. OUTPUT POWER(MAX9791 SPEAKER MODE)
MAX
9791
toc1
0
OUTPUT POWER (W)
EFFI
CIEN
CY (%
)
1.50.90.6
70
80
90
100
20
10
30
40
50
60
00 1.81.20.3
RL = 8Ω
RL = 4Ω
fIN = 1kHz
EFFICIENCY vs. OUTPUT POWER(MAX9791 SPEAKER MODE)
MAX
9791
toc1
0a
OUTPUT POWER (W)
EFFI
CIEN
CY (%
)
0.80.60.40.2
10
20
30
40
50
60
70
80
90
00 1.0
VPVDD = VAVDD = 3.7VfIN = 1kHz
RL = 8Ω
RL = 4Ω
SPEAKER
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OUTPUT POWER vs. SUPPLY VOLTAGE(MAX9791 SPEAKER MODE)
MAX
9791
toc1
0b
SUPPLY VOLTAGE (V)
OUTP
UT P
OWER
(W)
5.04.54.03.53.0
0.5
1.0
1.5
2.0
2.5
3.0
02.5 5.5
f = 1kHzRLOAD = 4Ω
THD+N = 10%
THD+N = 1%
OUTPUT POWER vs. SUPPLY VOLTAGE(MAX9791 SPEAKER MODE)
MAX
9791
toc1
0cSUPPLY VOLTAGE (V)
OUTP
UT P
OWER
(W)
5.04.54.03.53.0
0.5
1.0
1.5
2.0
02.5 5.5
f = 1kHzRLOAD = 8Ω
THD+N = 10%
THD+N = 1%
OUTPUT POWER vs. SUPPLY VOLTAGE(MAX9792 SPEAKER MODE)
MAX
9791
toc1
0d
SUPPLY VOLTAGE (V)
OUTP
UT P
OWER
(W)
5.04.54.03.53.0
0.5
1.0
1.5
2.0
2.5
02.5 5.5
f = 1kHzRLOAD = 8Ω
THD+N = 10%
THD+N = 1%
OUTPUT POWER vs. SUPPLY VOLTAGE(MAX9792 SPEAKER MODE)
MAX
9791
toc1
0e
SUPPLY VOLTAGE
OUTP
UT P
OWER
(W)
5.04.54.03.53.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
02.5 5.5
f = 1kHzRLOAD = 3Ω
THD+N = 10%
THD+N = 1%
POWER-SUPPLY REJECTION RATIOvs. FREQUENCY (SPEAKER MODE)
MAX
9791
toc1
1
FREQUENCY (kHz)
PSRR
(dB)
1
-30
-20
-10
-80
-90
-70
-60
-50
-40
-1000.01 100
LEFT
RIGHT
0.1 10
0VRIPPLE = 200mVP-PRL = 8Ω
CROSSTALK vs. FREQUENCY(SPEAKER MODE)
MAX
9791
toc1
2
FREQUENCY (kHz)
CROS
STAL
K (d
B)
1
-30
-20
-10
-80
-90
-100
-70
-60
-50
-40
-1100.01 100
RIGHT TO LEFT
LEFT TO RIGHT
0.1 10
0FS = 1VRMSVIN = -20dBFSRL = 8Ω
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
SPEAKER
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
_______________________________________________________________________________________ 9
SPEAKER STARTUP WAVEFORMMAX9791 toc13
SPKR_EN2V/div
SPEAKER OUT
200µs/div
SPEAKER SHUTDOWN WAVEFORMMAX9791 toc14
SPKR_EN2V/div
SPEAKER OUT
200µs/div
WIDEBAND OUTPUT SPECTRUM(SPEAKER MODE)
MAX
9791
toc1
5
FREQUENCY (MHz)
OUTP
UT A
MPL
ITUD
E (d
BV)
101
-110-100-90-80-70-60-50-40-30-20-10
0
-1200 100
RBW = 1kHzINPUT AC GROUNDED
OUTPUT FREQUENCY SPECTRUM(SPEAKER MODE)
MAX
9791
toc1
6
FREQUENCY (kHz)
OUTP
UT M
AGNI
TUDE
(dBV
)
10
-100
-60
0
-140
-80
-40
-20
-120
1 205 15
VOUT = -60dBVf = 1kHzRL = 8ΩUNWEIGHTED
SPEAKER
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
10 ______________________________________________________________________________________
TOTAL HARMONIC DISTORTION + NOISEvs. FREQUENCY (HEADPHONE MODE)
MAX
9791
toc1
7
FREQUENCY (kHz)
THD+
N (d
BFS)
1
-80
-90
-70
-60
-1000.01 100
FS = 300mVRMS
FS = 1VRMS
0.1 10
-50RL = 16ΩVIN = -3dBFS
TOTAL HARMONIC DISTORTION + NOISEvs. FREQUENCY (HEADPHONE MODE)
MAX
9791
toc1
8
FREQUENCY (kHz)
THD+
N (d
BFS)
1
-80
-90
-70
-60
-1000.01 100
FS = 300mVRMS
FS = 1VRMS
0.1 10
-50VHPVDD = 3VRL = 16ΩVIN = -3dBFS
TOTAL HARMONIC DISTORTION + NOISEvs. FREQUENCY (HEADPHONE MODE)
MAX
9791
toc1
9
FREQUENCY (kHz)
THD+
N (d
BFS)
1
-80
-90
-70
-60
-1000.01 100
FS = 300mVRMS
FS = 1VRMS
0.1 10
-50RL = 32ΩVIN = -3dBFS
TOTAL HARMONIC DISTORTION + NOISEvs. FREQUENCY (HEADPHONE MODE)
MAX
9791
toc2
0
FREQUENCY (kHz)
THD+
N (d
BFS)
1
-80
-90
-70
-60
-1000.01 100
FS = 300mVRMS
FS = 1VRMS
0.1 10
-50VHPVDD = 3VRL = 32ΩVIN = -3dBFS
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (HEADPHONE MODE)
MAX
9791
toc2
1
OUTPUT POWER (mW)
THD+
N (%
)
160
0.1
0.01
1
10
0.0010 200
f = 6kHz
f = 1kHz
f = 100Hz
12040 80
100RL = 16Ω
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (HEADPHONE MODE)
MAX
9791
toc2
2
OUTPUT POWER (mW)
THD+
N (%
)
0.1
0.01
1
10
0.0010 50 250
f = 6kHz
f = 1kHz
f = 100Hz
200150100
100RL = 32Ω
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (HEADPHONE MODE)
MAX
9791
toc2
3
OUTPUT POWER (mW)
THD+
N (%
)
10
0.1
0.01
1
10
0.0010 5040 90
f = 6kHzf = 1kHz
f = 100Hz
8070603020
100VHPVDD = 3VRL = 16Ω
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (HEADPHONE MODE)
MAX
9791
toc2
4A
OUTPUT POWER (mW)
THD+
N (%
)
10
0.1
0.01
1
10
0.0010 5040 70
f = 6kHz
f = 1kHzf = 100Hz
603020
100VHPVDD = 3VRL = 32Ω
OUTPUT POWER vs. LOAD RESISTANCE(HEADPHONE MODE)
MAX
9791
toc2
5
LOAD RESISTANCE (Ω)
OUTP
UT P
OWER
(mW
)
10
50
150
250
0
100
200
1 100
f = 1kHz
THD+N = 10%
THD+N = 1%
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.) HEADPHONE
MA
X9
79
1/M
AX
97
92
HEADPHONE OUTPUT POWERvs. HPVDD
MAX
9791
toc2
9
HPVDD (V)
HEAD
PHON
E OU
TPUT
POW
ER (m
W)
5.04.54.03.53.0
50
100
150
200
250
02.5 5.5
THD+N = 1%f = 1kHz
RL = 32Ω
RL = 16Ω
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 11
OUTPUT POWER vs. LOAD RESISTANCE(HEADPHONE MODE)
MAX
9791
toc2
6
LOAD RESISTANCE (Ω)
OUTP
UT P
OWER
(mW
)
100
50
70
90
0
60
80
10
30
20
40
10 1000
VHPVDD = 3Vf = 1kHz
THD+N = 10%
THD+N = 1%
POWER DISSIPATION vs. OUTPUT POWER(HEADPHONE MODE)
MAX
9791
toc2
7PER CHANNEL OUTPUT POWER (mW)
POW
ER D
ISSI
PATI
ON P
ER C
HANN
EL (m
W)
50 100 150
200
250
300
50
100
150
350
400
00 20025 75 125 175
RL = 32Ω
RL = 16Ω
POWER DISSIPATION vs. OUTPUT POWER(HEADPHONE MODE)
MAX
9791
toc2
8
PER CHANNEL OUTPUT POWER (mW)
POW
ER D
ISSI
PATI
ON P
ER C
HANN
EL (m
W)
20
100
150
200
50
250
300
00 1008040 60
RL = 32Ω
VHPVDD = 3V RL = 16Ω
POWER-SUPPLY REJECTION RATIOvs. FREQUENCY (HEADPHONE MODE)
MAX
9791
toc3
0
FREQUENCY (kHz)
PSRR
(dB)
0.1 1 10
-90-80
-110-100
-50
-40-30
-70-60
-20
-100
-1200.01 100
VRIPPLE = 200mVP-PRL = 32Ω
LEFT
RIGHT
CROSSTALK vs. FREQUENCY(HEADPHONE MODE)
MAX
9791
toc3
1
FREQUENCY (kHz)
CROS
STAL
K (d
B)
0.1 1 10
-90
-80
-50
-40
-30
-70
-60
-20
-1000.01 100
RIGHT TO LEFTCOM AND SENSEDISABLED
RIGHT TO LEFTCOM AND SENSEDISABLED
LEFT TO RIGHTCOM AND SENSE
RL = 32ΩFS = 300mVRMSVIN = -20dBFS
RIGHT TO LEFTCOM AND SENSE
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
HEADPHONE
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
12 ______________________________________________________________________________________
OUTPUT FREQUENCY SPECTRUM(HEADPHONE MODE)
MAX
9791
toc3
2
FREQUENCY (kHz)
OUTP
UT F
REQU
ENCY
SPE
CTRU
M (d
B)
5 10 15
-120
-100
-40
-20
0
-80
-60
-1400 20
RIGHT AND LEFTFS = 707mVRMSVIN = -60dBFSRL = 32Ω
MAX9791 toc33
HP_EN2V/div
HP_500mV/div
200µs/div
STARTUP WAVEFORM
MAX9791 toc34
HP_EN2V/div
HP_500mV/div
200µs/div
SHUTDOWN WAVEFORM
-130
-90
-110
-50
-70
-30
-10
500 15001000 2000 2500 3000
HEADPHONE RF IMMUNITYvs. FREQUENCY
MAX
9791
toc3
5
FREQUENCY (MHz)
AMPL
ITUD
E (d
BV)
LEFT
RIGHT
RL = 32Ω
HEADPHONE
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 13
TOTAL HARMONIC DISTORTION + NOISEvs. FREQUENCY (HEADPHONE MODE)
MAX
9791
toc3
6
FREQUENCY (kHz)
THD+
N (d
BFS)
0.1 1 10
-90
-100
-80
-50
-40
-30
-70
-60
-20
-10
0
-1100.01 100
RL = 10kΩVIN = -3dBFS
FS = 707mVRMS FS = 1VRMS
TOTAL HARMONIC DISTORTION + NOISEvs. FREQUENCY (HEADPHONE MODE)
MAX
9791
toc3
7FREQUENCY (kHz)
THD+
N (d
BFS)
0.1 1 10
-90
-100
-80
-50
-40
-30
-70
-60
-20
-10
0
-1100.01 100
VHPVDD = 3VRL = 10kΩVIN = -3dBFS
FS = 707mVRMS FS = 1VRMS
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (HEADPHONE MODE)
MAX
9791
toc3
8
OUTPUT POWER (mW)
THD+
N (%
)
1.0 2.0 3.0
0.001
0.01
0.1
1
10
100
0.00010 4.00.5 1.5 2.5 3.5
RL = 10kΩ
f = 6kHz
f = 1kHz
f = 100Hz
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (HEADPHONE MODE)
MAX
9791
toc3
9
OUTPUT POWER (mW)
THD+
N (%
)
2.01.51.0
0.001
0.01
0.1
1
10
100
0.00010 3.02.50.5
VHPVDD = 3VRL = 10kΩ
f = 6kHz
f = 1kHz
f = 100Hz
CROSSTALK vs. FREQUENCY(HEADPHONE MODE)
MAX
9791
toc4
0
FREQUENCY (kHz)
CROS
STAL
K (d
B)
0.1 1 10
-90
-80
-110
-100
-50
-40
-30
-70
-60
-20
-1200.01 100
LEFT TO RIGHTCOM AND SENSE
RL = 10kΩFS = 707mVRMSVIN = -20dBFS
RIGHT TO LEFTCOM AND SENSE
OUTPUT FREQUENCY SPECTRUM(HEADPHONE MODE)
MAX
9791
toc4
1
FREQUENCY (kHz)
OUTP
UT F
REQU
ENCY
SPE
CTRU
M (d
B)
5 10 15
-120
-100
-40
-20
0
-80
-60
-1400 20
RIGHT AND LEFTRL = 10kΩFS = 300mVRMSVIN = -60dBFS
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
LINE OUT
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
14 ______________________________________________________________________________________
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX
9791
toc4
2
SUPPLY VOLTAGE (V)
SUPP
LY C
URRE
NT (m
A)
4.75 5.00
0
5
10
15
20
-54.50 5.505.25
LDO_EN = 1, VLDO = 3.3V OR 4.75V
SPKR_EN = 1HP_EN = 0
SPKR_EN = 0HP_EN = 1
SPKR_EN = 0HP_EN = 0
SPKR_EN = 1HP_EN = 1
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX
9791
toc4
2aSUPPLY VOLTAGE (V)
SUPP
LY C
URRE
NT (m
A)
5.04.54.03.53.0
0
5
10
15
20
-52.5 5.5
LDO_EN = 1VLDO_OUT = 1.8V
SPKR_EN = 1
SPKR_EN = 1
SPKR_EN = 0
SPKR_EN = 0
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
MAX
9791
toc4
3
SUPPLY VOLTAGE (V)
SHUT
DOW
N CU
RREN
T (µ
A)
5.04.53.0 3.5 4.0
1
2
3
4
5
6
7
8
02.5 5.5
SPKR_EN = 1HP_EN = 0LDO_EN = 0
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
GENERAL
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 15
LDO OUTPUT ACCURACYvs. LOAD CURRENT
MAX
9791
toc4
4
LOAD CURRENT (mA)
LDO
OUTP
UT A
CCUR
ACY
(%)
12575
-1.0
-1.5
0
0.5
1.0
-0.5
1.5
2.0
-2.00 15025 10050
LDO OUTPUT ACCURACYvs. AMPLIFIER OUTPUT POWER
MAX
9791
toc4
5AMPLIFIER OUTPUT POWER (mW)
LDO
OUTP
UT A
CCUR
ACY
(%)
300
0.04
0.03
0.02
0.01
0.06
0.07
0.08
0.05
0.09
0.10
00 15001200600 900
LDO OUTPUT ACCURACYvs. TEMPERATURE
MAX
9791
toc4
6
TEMPERATURE (°C)
LDO
OUTP
UT A
CCUR
ACY
(%)
603510-15
-0.5
0
0.5
1.0
-1.0-40 85
VLDO_OUT = 3.3VVLDO_OUT = 1.8V
VLDO_OUT = 4.75V
0
100
50
200
150
250
300
0 100 15050 200 250 300
LDO DROPOUT VOLTAGE vs. LOAD
MAX
9791
toc4
7
ILOAD (mA)
LDO
DROP
OUT
VOLT
AGE
(mV)
LDO_OUT = 4.75V
LDO POWER-SUPPLY REJECTION RATIOvs. FREQUENCY
MAX
9791
toc4
8
FREQUENCY (kHz)
PSRR
(dB)
1010.1
-80
-60
-40
-20
0
20
40
-1000.01 100
VRIPPLE = 200mVP-PILOAD = 10mA
VLDO_OUT = 3.3V
VLDO_OUT = 1.8V
VLDO_OUT = 4.75V
LDO OUTPUT NOISE
MAX
9791
toc4
9
FREQUENCY (kHz)
LDO
OUTP
UT N
OISE
(µV)
1010.1
75
100
125
150
175
200
500.01 100
CLOAD = 2 x 1µFILOAD = 120mA
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
LDO
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
16 ______________________________________________________________________________________
1.00ms/div
LINE-TRANSIENT RESPONSE
CH1 LOW4.560V
CH1 HIGH5.500V
CH2 HIGH1.000mV
CH2 LOW800.0µV
MAX9791 toc50
100ms/div
LOAD-TRANSIENT RESPONSE
ILDO_OUT50mA/div
MAX9791 toc51
AC-COUPLEDVLDO_OUT10mV/div
200µs/div
SHUTDOWN RESPONSE
LDO_EN2V/div
MAX9791 toc52
VLDO_EN2V/div
CROSSTALK vs. FREQUENCYSPEAKER TO LDO
MAX
9791
toc5
3
FREQUENCY (kHz)
CROS
STAL
K (d
B)
1010.1
-120-110-100-90-80-70-60-50-40-30-20-10
0
-1300.01 100
BOTH SPEAKERS WITH SIGNALPSPKR = 1.2WRLSPKR = 8WILDO = 10mA
LEFT CHANNEL TO LDO
RIGHT CHANNEL TO LDO
Typical Operating Characteristics (continued)(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless oth-erwise specified. RIN1 = 20kΩ (AVSPKR = 12dB), RIN2 = 40.2kΩ (AVHP = 0dB), CIN1 = 470nF, CIN2 = CCOM = 1µF, measurement BW= 20kHz AES17, TA = +25°C, unless otherwise noted. Speaker mode: SPKR_EN = 0, HP_EN = 0. Headphone mode: SPKR_EN = 1,HP_EN = 1.)
LDO
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 17
MAX9791 Pin Description PIN NAME FUNCTION
1 SPKR_INL Left-Channel Speaker Amplifier Input
2 HP_INR Right-Channel Headphone Amplifier Input
3 HP_INL Left-Channel Headphone Amplifier Input
4 COM Common-Mode Voltage Sense Input
5 GND Signal Ground. Star connect to PGND.
6 LDO_OUT LDO Output. Bypass the MAX9791A/MAX9791B with two 1µF ceramic low ESR capacitors to GND. Bypass the MAX9791C with two 2µs ceramic low ESR capacitors to GND.
7 AVDD Positive Power-Supply and LDO Input. Bypass with a 0.1µF and two 1µF capacitors to GND.
8 LDO_EN LDO Enable. Connect LDO_EN to AVDD to enable the LDO.
9 HPR Right-Channel Headphone Amplifier Output
10 HPL Left-Channel Headphone Amplifier Output
11 SENSE Headphone Ground Sense
12 CPVSS Headphone Amplifier Negative Power Supply. Connect a 1µF capacitor between CPVSS and PGND.
13 C1N Charge-Pump Flying Capacitor Negative Terminal. Connect a 1µF capacitor between C1P and C1N.
14 CPGND Charge-Pump Ground. Connect directly to PGND plane.
15 C1P Charge-Pump Flying Capacitor Positive Terminal. Connect a 1µF capacitor between C1P and C1N.
16 HPVDD Headphone Amplifier Positive Power Supply. Connect a 10µF capacitor between HPVDD and PGND.
17, 26 PVDD Speaker Amplifier Power-Supply Input. Bypass with a 0.1µF capacitor to PGND.
18 OUTL- Left-Channel Speaker Amplifier Output, Negative Phase
19 OUTL+ Left-Channel Speaker Amplifier Output, Positive Phase
20, 23 PGND Power Ground. Star connect to GND.
21 BEEP PC Beep Input. Connect to GND if beep detection function is disabled.
22 HP_EN Active-High Headphone Amplifier Enable
24 OUTR+ Right-Channel Speaker Amplifier Output, Positive Phase
25 OUTR- Right-Channel Speaker Amplifier Output, Negative Phase
27 SPKR_EN Active-Low Speaker Amplifier Enable
28 SPKR_INR Right-Channel Speaker Amplifier Input
— EP Exposed Pad. Connect to GND.
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Detailed DescriptionThe MAX9791 combines a stereo 2W Class D poweramplifier, a stereo 175mW DirectDrive headphoneamplifier, and a 120mA LDO linear regulator in a singledevice. The MAX9792 combines a mono 3W Class Dpower amplifier, a stereo 175mW DirectDrive head-phone amplifier, and a 120mA LDO linear regulator in asingle device.
The MAX9791/MAX9792 feature wake-on-beep detec-tion, comprehensive click-and-pop suppression, low-power shutdown mode, and excellent RF immunity.These devices incorporate an integrated LDO thatserves as a clean power supply for CODEC or other cir-cuits. The MAX9791/MAX9792 are Windows VistaPremium compliant. See Table 1 for a comparison of theWindows Vista Premium specifications and MAX9791/MAX9792 specifications.
The MAX9791/MAX9792 feature spread-spectrum mod-ulation and active emission limiting circuitry that offerssignificant improvements to switch-mode amplifier tech-nology. These devices offer Class AB performance withClass D efficiency in a minimal board-space solution.
The headphone amplifiers use Maxim’s DirectDrivearchitecture to eliminate the bulky output DC-blockingcapacitors required by traditional headphone ampli-fiers. A charge pump inverts the positive supply(HPVDD) to create a negative supply (CPVSS). Theheadphone amplifiers operate from these bipolar sup-plies with their outputs biased about GND. The bene-fit of the GND bias is that the amplifier outputs nolonger have a DC component (typically VDD/2). Thisfeature eliminates the large DC-blocking capacitorsrequired with conventional headphone amplifiers to
MAX9792 Pin Description PIN NAME FUNCTION
1, 5 GND Signal Ground. Star connect to PGND.
2 HP_INR Right-Channel Headphone Amplifier Input
3 HP_INL Left-Channel Headphone Amplifier Input
4 COM Common-Mode Voltage Sense Input
6 LDO_OUT LDO Output. Bypass with two 1µF ceramic low ESR capacitors to GND.
7 AVDD Positive Power Supply and LDO Input. Bypass with a 0.1µF and two 1µF capacitors to GND.
8 LDO_EN LDO Enable. Connect LDO_EN to AVDD to enable the LDO.
9 HPR Right-Channel Headphone Amplifier Output
10 HPL Left-Channel Headphone Amplifier Output
11 SENSE Headphone Ground Sense
12 CPVSS Headphone Amplifier Negative Power Supply. Connect a 1µF capacitor between CPVSS and PGND.
13 C1N Charge-Pump Flying Capacitor Negative Terminal. Connect a 1µF capacitor between C1P and C1N.
14 CPGND Charge-Pump Ground. Connect directly to PGND plane.
15 C1P Charge-Pump Flying Capacitor Positive Terminal. Connect a 1µF capacitor between C1P and C1N.
16 HPVDD H ead p hone Am p l i fi er P osi ti ve P ow er S up p l y. C onnect a 10µF cap aci tor b etw een H P V D D and P GN D .
17, 26 PVDD Speaker Amplifier Power-Supply Input. Bypass with a 0.1µF capacitor to PGND.
18, 25 OUT- Speaker Amplifier Output, Negative Phase
19, 24 OUT+ Speaker Amplifier Output, Positive Phase
20, 23 PGND Power Ground. Star connect to GND.
21 BEEP PC Beep Input. Connect to GND if beep detection function is disabled.
22 HP_EN Active-High Headphone Amplifier Enable
27 SPKR_EN Active-Low Speaker Amplifier Enable
28 SPKR_IN Speaker Amplifier Input
— EP Exposed Pad. Connect to GND.
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conserve board space and system cost, as well asimprove low-frequency response and distortion.
The MAX9791/MAX9792 amplifiers feature an under-voltage lockout that prevents operation from an insuffi-cient power supply and click-and-pop suppression thateliminates audible transients on startup and shutdown.The amplifiers include thermal overload and short-cir-cuit protection.
Class D Speaker AmplifierThe MAX9791/MAX9792 integrate a filterless class Damplifier that offers much higher efficiency than class ABamplifiers. The high efficiency of a Class D amplifier isdue to the switching operation of the output stage tran-sistors. In a Class D amplifier, the output transistors actas current steering switches and consume negligibleadditional power. Any power loss associated with theClass D output stage is mostly due to the I2R loss of theMOSFET on-resistance and quiescent current overhead.
The theoretical best efficiency of a linear amplifier is78%, however, that efficiency is only exhibited at peakoutput power. Under normal operating levels (typicalmusic reproduction levels), efficiency falls below 45%,whereas the MAX9791/MAX9792 exhibit 67% efficiencyunder the same conditions (Figure 1).
Ultra-Low EMI Filterless Output StageIn traditional Class D amplifiers, the high dv/dt of therising and falling edge transitions resulted in increasedelectromagnetic-interference (EMI) emissions, whichrequired the use of external LC filters or shielding tomeet EN55022B EMI regulation standards. Limiting thedv/dt normally results in decreased efficiency. Maxim’sactive emissions limiting circuitry actively limits thedv/dt of the rising and falling edge transitions, providingreduced EMI emissions while maintaining up to 83%efficiency.
0
20
10
50
40
30
80
70
60
90
0 0.500.25 0.75 1.00 1.25 1.50
EFFICIENCY vs. IDEALCLASS AB EFFICIENCY
OUTPUT POWER (W)
EFFI
CIEN
CY (%
)
IDEAL CLASS AB
MAX9791
Figure 1. MAX9791 Efficiency vs. Class AB Efficiency
DEVICE TYPE REQUIREMENTWINDOWS PREMIUM
MOBILE VISTASPECIFICATIONS
MAX9791/MAX9792TYPICAL PERFORMANCE
THD+N ≤ -65dB FS [100Hz, 20kHz] 87dBFS [100Hz, 20kHz]
Dynamic range with signalpresent
≤ -80dBV, A-weighted [20Hz,20kHz]
-98.9dB A-weighted [20Hz, 20kHz]Analog Line-Out Jack(RL = 10kΩ, FS =0.707VRMS)
Line output crosstalk ≤ -50dB [20Hz, 15kHz] 64dB [20Hz, 15kHz]
THD+N ≤ -45dB FS [100Hz, 20kHz] 82dBFS [100Hz, 20kHz]
Dynamic range with signalpresent
≤ -60dBV, A-weighted [20Hz,20kHz]
-91.5dB A-weighted [20Hz, 20kHz]Analog Headphone-OutJack (RL = 32Ω, FS =0.300VRMS) Headphone output
crosstalk≤ -50dB [20Hz, 15kHz] 64dB [20Hz, 15kHz]
Table 1. Windows Premium Mobile Vista Specifications vs. MAX9791/MAX9792Specifications
Note: THD+N, dynamic range with signal present, and crosstalk should be measured in accordance with AES17 audio measure-ments standards.
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In addition to active emission limiting, the MAX9791/MAX9792 feature spread-spectrum modulation that flat-tens the wideband spectral components. Proprietarytechniques ensure that the cycle-to-cycle variation of theswitching period does not degrade audio reproductionor efficiency (see the Typical Operating Characteristics).In spread-spectrum modulation mode, the switching fre-quency varies randomly by ±15kHz around the centerfrequency (530kHz). The effect is to reduce the peakenergy at harmonics of the switching frequency. Above10MHz, the wideband spectrum looks like noise for EMIpurposes (see Figure 2).
Speaker Current LimitWhen the output current of the speaker amplifierexceeds the current limit (2A, typ) the MAX9791/MAX9792 disable the outputs for approximately 100µs.At the end of 100µs, the outputs are re-enabled. If thefault condition still exists, the MAX9791/MAX9792 con-tinue to disable and re-enable the outputs until the faultcondition is removed.
DirectDrive Headphone AmplifierTraditional single-supply headphone amplifiers bias theoutputs at a nominal DC voltage (typically half the sup-ply). Large coupling capacitors are needed to blockthis DC bias from the headphone. Without these capac-itors, a significant amount of DC current flows to theheadphone, resulting in unnecessary power dissipationand possible damage to both headphone and head-phone amplifier.
Maxim’s DirectDrive architecture uses a charge pumpto create an internal negative supply voltage. Thisallows the headphone outputs of the MAX9791/MAX9792 to be biased at GND while operating from asingle supply (Figure 3). Without a DC component,there is no need for the large DC-blocking capacitors.Instead of two large (220µF, typ) capacitors, theMAX9791/MAX9792 charge pump requires two small1µF ceramic capacitors, conserving board space,reducing cost, and improving the frequency responseof the headphone amplifier.
The MAX9791/MAX9792 feature a low-noise chargepump. The nominal switching frequency of 530kHz iswell beyond the audio range, and thus does not inter-fere with audio signals. The switch drivers feature acontrolled switching speed that minimizes noise gener-ated by turn-on and turn-off transients. By limiting theswitching speed of the charge pump, the di/dt noisecaused by the parasitic trace inductance is minimized.
CLASS D EMI PLOT
FREQUENCY (MHz)
AMPL
ITUD
E (d
BµV/
m)
100
10
15
20
25
30
35
40
530 1000
EN55022B LIMIT
Figure 2. EMI with 30cm of Speaker Cable
VDD
VDD/2
GNDCONVENTIONAL AMPLIFIER BIASING SCHEME
DirectDrive AMPLIFIER BIASING SCHEME
+VDD
GND
-VDD
VOUT
VOUT
Figure 3. Traditional Amplifier Output vs. MAX9791/MAX9792DirectDrive Output
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Common-Mode SenseWindows Vista-compliant platforms are restricted to only115mΩ of ground return impedance. If the headphonejack ground is connected close to the audio deviceground using a solid ground plane, the return path resis-tance can be quite low. However, it is often necessary tolocate some jacks far from the audio device. TheMAX9791/MAX9792 COM and SENSE inputs allow theheadphone jack to be placed further away from thedevice without degrading crosstalk performance.
The MAX9791/MAX9792 SENSE and COM inputs senseand correct for the difference between the headphonereturn and device ground. When using common-modesense, connect COM through a resistor to GND of thedevice (Figure 4). For optimum common-mode rejec-tion, use the same value resistors for RIN2 and RCOM.To improve AC CMRR, add a capacitor equal to CIN2between GND and RCOM.
Configuring SENSE and COM in this way improves sys-tem crosstalk performance by reducing the negativeeffects of the headphone jack ground return resistance.
The headphone amplifier output impedance, traceresistance, and contact resistance of the jack aregrouped together to represent the source resistance,RS. The resistance between the load and the sleeve,the sleeve contact resistance, and the system groundreturn resistance are grouped together to represent theground resistance, RG.
Assuming a typical source resistance of 5Ω, the groundreturn impedance would need to be limited to 115mΩto meet Windows Vista’s crosstalk specification of 50dB(Figure 5). This is further complicated by the fact thatthe impedance of the sleeve connection in the 3.5mmstereo jack can make up 30mΩ–90mΩ alone.
The MAX9791/MAX9792 COM and SENSE inputsreduce crosstalk performance by eliminating effects of28.5mΩ of ground return path resistance. If groundsensing is not required, connect COM directly to GNDand leave SENSE unconnected (Figure 6).
Wake-on-BeepThe MAX9791/MAX9792 beep-detection circuit wakesup the device (speaker and headphone amplifiers)once a qualified beep signal is detected at BEEP andthe LDO is enabled. The amplifier wake command fromthe beep-detection circuit overrides the logic signalapplied at HP_EN and SPKR_EN.
Crosstalk in dBR
R RG
L S=
+⎛
⎝⎜⎞
⎠⎟20 log
RIN2
RFHP
RFHP
RFHP
COM
HP_INL
HPL
RCOM
SENSE
RIN2
HP_INR
HPR
CIN2
CCOM
CIN2
Figure 4. Connecting COM for Ground Sense
-80
-75
-70
-65
-60
-55
-50
-45
-40
0 0.0500.025 0.075 0.100 0.125 0.150
CROSSTALKvs. GROUND RESISTANCE (RG)
RG (Ω)
CROS
STAL
K (d
B)
RS = 5ΩRL = 32Ω
Figure 5. Crosstalk vs. Ground Resistance
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A qualified BEEP signal consists of a 3.3V typical,215Hz minimum signal that is present at BEEP for fourconsecutive cycles. Once the first rising edge transitionis detected at BEEP, the beep circuit wakes up andbegins counting the beep cycles. Once four consecu-tive cycles of a qualified beep signal are counted, thedevice (speaker and headphone amplifiers) enableswithin 400µs. If the first rising edge is not followed bythree consecutive rising edges within 16ms, the deviceremains shutdown (i.e., glitch protection).
The device (speaker and headphone amplifiers) returnsto its programmed logic state once 246ms has elapsedfrom the time the last rising edge was detected. This246ms amplifier hold time ensures complete beep pro-files are passed to the amplifier outputs (Figure 7).Ground BEEP when the wake-on-beep feature is notused. Do not leave BEEP unconnected.
Low-Dropout Linear RegulatorThe LDO regulator can be used to provide a cleanpower supply to a CODEC or other circuitry. The LDOcan be enabled independently of the audio amplifiers.Set LDO_EN = AVDD to enable the LDO or set LDO_EN= GND to disable the LDO. The LDO can provide up to120mA of continuous current.
Speaker and Headphone Amplifier EnableThe MAX9791/MAX9792 feature control inputs for theindependent enabling of the speaker and headphoneamplifiers, allowing both to be active simultaneouslyif required. Driving SPKR_EN high disables the speakeramplifiers. Driving HP_EN low independently disablesthe headphone amplifiers. For applications thatrequire only one of the amplifiers to be on at a given
time, connect SPKR_EN and HP_EN together, allowinga single logic voltage to enable either the speaker orthe headphone amplifier as shown in Figure 8.
ShutdownThe MAX9791/MAX9792 feature a low-power shutdownmode, drawing 3.3µA of supply current. By disablingthe speaker, headphone amplifiers, and the LDO, theMAX9791/MAX9792 enter low-power shutdown mode.Set SPKR_EN to AVDD and HP_EN and LDO_EN toGND to disable the speaker amplifiers, headphoneamplifiers, and LDO, respectively.
CROSSTALK vs. FREQUENCY(HEADPHONE MODE)
FREQUENCY (kHz)
CROS
STAL
K (d
B)
1010.1
-90
-80
-70
-60
-50
-40
-30
-20
-1000.01 100
RL = 32ΩFS = 300mVRMSVOUT = -20dBFS
LEFT TO RIGHTCOM AND SENSE
RIGHT TO LEFTCOM AND SENSE
LEFT TO RIGHTCOM AND SENSEDISABLED
RIGHT TO LEFTCOM AND SENSEDISABLED
Figure 6. MAX9791/MAX9792 COM and SENSE Inputs ReduceCrosstalk
1 2 3 4BEEP
SPKR AND HPAMPS ENABLE
400µs
240ms
16ms
Figure 7. Qualified BEEP Signal Timing
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Click-and-Pop SuppressionThe MAX9791/MAX9792 feature a common-mode biasvoltage of 0V. A 0V BIAS allows the MAX9791/MAX9792to quickly turn on/off with no resulting clicks and pops.With the HDA CODEC outputs biased and theMAX9791/MAX9792 inputs sitting as 0V in shutdownand normal operation, the RIN x CIN time constant iseliminated.
Speaker AmplifierThe MAX9791/MAX9792 speaker amplifiers featureMaxim’s comprehensive, industry leading click-and-pop suppression. During startup and shutdown, theclick-and-pop suppression circuitry eliminates anyaudible transient sources internal to the device.
Headphone AmplifierIn conventional single-supply headphone amplifiers,the output-coupling capacitor is a major contributor ofaudible clicks and pops. Upon startup, the amplifiercharges the coupling capacitor to its bias voltage, typi-cally VDD/2. During shutdown, the capacitor is dis-charged to GND; a DC shift across the capacitorresults, which in turn appears as an audible transient atthe speaker. Because the MAX9791/MAX9792 do notrequire output-coupling capacitors, no audible transientoccurs.
The MAX9791/MAX9792 headphone amplifiers featureextensive click-and-pop suppression that eliminatesany audible transient sources internal to the device.
Applications InformationFilterless Class D Operation
Traditional Class D amplifiers require an output filter torecover the audio signal from the amplifier’s output. Thefilters add cost and size and can decrease efficiencyand THD+N performance. The traditional PWM schemeuses large differential output swings (2 x PVDD peak-to-peak) causing large ripple currents. Any parasiticresistance in the filter components results in a loss ofpower, lowering the efficiency.
The MAX9791/MAX9792 do not require an output filter.The devices rely on the inherent inductance of the speak-er coil and the natural filtering of both the speaker andthe human ear to recover the audio component of thesquare-wave output. Eliminating the output filter results ina smaller, less costly, and more efficient solution.
Because the frequency of the MAX9791/MAX9792 out-put is well beyond the bandwidth of most speakers,voice coil movement due to the square-wave frequencyis very small. For optimum results, use a speaker with aseries inductance > 10µH. Typical 8Ω speakers exhibitseries inductances in the 20µH to 100µH range.
MAX9791MAX9792
SPKR_ENSINGLE
CONTROL
HP_EN
Figure 8. Enabling Either the Speaker or Headphone Amplifierwith a Single Control Pin
MAX9791
SPKR_IN_RIN1OUT_+
OUT_-
MONOCLASS D
AMPLIFIER
RFB20kΩ
CIN1
Figure 9. Setting Speaker Amplifier Gain
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Setting Speaker Amplifier GainExternal input resistors in conjunction with the internalfeedback resistors (RFSPKR) set the speaker amplifiergain of the MAX9791/MAX9792. Set gain by usingresistor RIN1 as follows (Figure 9):
where AVSPKR is the desired voltage gain. An RIN1 of20kΩ yields a gain of 4V/V, or 12dB.
Component SelectionOptional Ferrite Bead Filter
In applications where speaker leads exceed 15cm, usea filter constructed from a ferrite bead and a capacitorto ground (Figure 10) to provide additional EMI sup-pression. Use a ferrite bead with low DC resistance,high frequency (> 1.2MHz) impedance of 100Ω to600Ω, and rated for at least 1A. The capacitor valuevaries based on the ferrite bead chosen and the actualspeaker lead length. Select the capacitor value basedon EMI performance.
Output Power (Headphone Amplifier)The headphone amplifiers are specified for the worst-case scenario when both inputs are in phase. Underthis condition, the drivers simultaneously draw currentfrom the charge pump, leading to a slight loss in head-room of CPVSS. In typical stereo audio applications, theleft and right signals have differences in both magni-tude and phase, subsequently leading to an increase inthe maximum attainable output power. Figure 11 showsthe two extreme cases for in and out of phase. In mostcases, the available power l ies between theseextremes.
Headphone Amplifier GainGain-Setting Resistors
External input resistors in conjunction with the internalfeedback resistors (RFHP) set the headphone amplifiergain of the MAX9791/MAX9792. Set gain by usingresistor RIN2 (Figure 4) as follows:
where AVHP is the desired voltage gain. An RIN2 of40.2kΩ yields a gain of 1V/V, or 0dB.
Power SuppliesThe MAX9791/MAX9792 speaker amplifiers are pow-ered from PVDD with a range from 2.7V to 5.5V. Theheadphone amplifiers are powered from HPVDD andCPVSS. HPVDD is the positive supply of the headphoneamplifiers and charge pump ranging from 2.7V to 5.5V.CPVSS is the negative supply of the headphone ampli-fiers. The charge pump inverts the voltage at HPVDD,and the resulting voltage appears at CPVSS. AVDDpowers the LDO and the remainder of the device.AVDD and PVDD must be tied together. If LDO isenabled, set AVDD and PVDD as specified in the LineRegulation row of the Electrical Characteristics table.
Ak
RV VVHP
IN=
⎛⎝⎜
⎞⎠⎟
-40 2
2
./
Ω
Ak
RV VVSPKR
IN=
⎛⎝⎜
⎞⎠⎟
-420
1
Ω/
MAX9791MAX9792
L1*
L2*330pF 330pF
*L1 = L2 = WÜRTH 742792040
Figure 10. Optional Ferrite Bead Filter
TOTAL HARMONIC DISTORTION + NOISEvs. OUTPUT POWER (HEADPHONE MODE)
OUTPUT POWER (mW)
THD+
N (%
)
20015010050
0.01
0.1
1
10
100
0.0010 250
RL = 32Ω
OUT OF PHASE
IN PHASE
Figure 11. Output Power vs. Supply Voltage with Inputs In/Outof Phase; 32Ω Load Conditions and 3.5dB Gain
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Component SelectionSpeaker Amplifier Power-Supply Input (PVDD)
PVDD powers the speaker amplifiers. PVDD rangesfrom 2.7V to 5.5V. AVDD and PVDD must be tiedtogether. If LDO is enabled, set AVDD and PVDD asspecified in the Line Regulation row of the ElectricalCharacteristics table. Bypass PVDD with a 0.1µFcapacitor to PGND. Apply additional bulk capacitanceat the device if long input traces between PVDD andthe power source are used.
Headphone Amplifier Power-Supply Input(HPVDD and CPVSS)
The headphone amplifiers are powered from HPVDDand CPVSS. HPVDD is the positive supply of the head-phone amplifiers and ranges from 2.7V to 5.5V. BypassHPVDD with a 10µF capacitor to PGND. CPVSS is thenegative supply of the headphone amplifiers. BypassCPVSS with a 1µF capacitor to PGND. The chargepump inverts the voltage at HPVDD, and the resultingvoltage appears at CPVSS. A 1µF capacitor should beconnected between C1N and C1P.
Positive Power Supply and LDO Input (AVDD)The internal LDO and the remainder of the device arepowered by AVDD. AVDD ranges from 2.7V to 5.5V.AVDD and PVDD must be tied together. If LDO isenabled, set AVDD and PVDD as specified in LDO lineregulation. Bypass AVDD with a 0.1µF capacitor toGND and two 1µF capacitors to GND. Note additionalbulk capacitance is required at the device if long inputtraces between AVDD and the power source are used.
Input FilteringThe input capacitor (CIN_), in conjunction with the ampli-fier input resistance (RIN_), forms a highpass filter thatremoves the DC bias from the incoming signal. The AC-coupling capacitor allows the amplifier to bias the signalto an optimum DC level. Assuming zero source imped-ance, the -3dB point of the highpass filter is given by:
RIN_ is the amplifier’s external input resistance value.Choose CIN_ such that f-3dB is well below the lowestfrequency of interest. Setting f-3dB too high affectsthe amplifier’s low frequency response. Use capaci-tors with adequately low-voltage coefficients (seeFigure 12). Capacitors with higher voltage coeffi-cients, such as ceramics, result in increased distor-tion at low frequencies.
Charge-Pump Capacitor SelectionUse capacitors with an ESR less than 100mΩ for opti-mum performance. Low ESR ceramic capacitors mini-mize the output resistance of the charge pump. Forbest performance over the extended temperaturerange, select capacitors with an X7R dielectric.
Flying Capacitor (C1)The value of the flying capacitor (C1) affects the loadregulation and output resistance of the charge pump. AC1 value that is too small degrades the device’s abilityto provide sufficient current drive, which leads to a lossof output voltage. Connect a 1µF capacitor betweenC1P and C1N.
fR CdB
IN IN-3
12
=π _ _
INPUT COUPLING CAPACITOR-INDUCED THD+Nvs. FREQUENCY (HEADPHONE MODE)
FREQUENCY (kHz)
THD+
N (d
BFS)
100
-90
-80
-70
-60
-50
-10010 1000
0603 10V X5R 10% 1µF
0805 50V X7R 10% 1µF
VOUT - -3dBFSFS = 1VRMSRL =32Ω
0603 10V X7R 10% 1µF
0402 6.3V X5R 10% 1µF
Figure 12. Input Coupling Capacitor-Induced THD+N vs.Frequency
SPEAKER RF IMMUNITYvs. FREQUENCY
FREQUENCY (MHz)
AMPL
ITUD
E (d
BV)
2500200015001000500
-120-110-100-90-80-70-60-50-40-30-20-10
0
-1300 3000
RIGHT
LEFT
Figure 13. Speaker RF Immunity
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Charge-Pump Output Capacitor (C2)Connect a 1µF capacitor between CPVSS and PGND.
LDO Output Capacitor (CLDO)Connect 2 x 1µF capacitors between LDO_OUT andGND for 4.75V and 3.3V LDO options (MAX979_A andMAX979_B, respectively). Connect two parallel 2µFcapacitors between LDO_OUT and GND for the 1.8VLDO option (MAX979_C).
Layout and GroundingProper layout and grounding are essential for optimumperformance. Use large traces for the power-supplyinputs and amplifier outputs to minimize losses due toparasitic trace resistance, as well as route heat awayfrom the device. Good grounding improves audio per-formance, minimizes crosstalk between channels, andprevents switching noise from coupling into the audiosignal. Connect PGND and GND together at a singlepoint on the PCB. Route PGND and all traces that carryswitching transients away from GND, and the tracesand components in the audio signal path.
Connect C2 to the PGND plane. Place the charge-pump capacitors (C1, C2) as close as possible to thedevice. Bypass PVDD with a 0.1µF capacitor to PGND.Place the bypass capacitors as close as possible to thedevice.
The MAX9791/MAX9792 is inherently designed forexcellent RF immunity. For best performance, addground fills around all signal traces on top or bottomPCB planes.
Use large, low-resistance output traces. As load imped-ance decreases, the current drawn from the device out-puts increase. At higher current, the resistance of theoutput traces decrease the power delivered to the load.For example, if 2W is delivered from the speaker outputto a 4Ω load through a 100mΩ trace, 49mW is wastedin the trace. If power is delivered through a 10mΩtrace, only 5mW is wasted in the trace. Large output,supply, and GND traces also improve the power dissi-pation of the device.
The MAX9791/MAX9792 thin QFN package features anexposed thermal pad on its underside. This pad lowersthe package’s thermal resistance by providing a directheat conduction path from the die to the printed circuitboard. Connect the exposed thermal pad to GND byusing a large pad and multiple vias to the GND plane.
Chip InformationPROCESS: BiCMOS
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MAX9792
SPKR_ENHP_EN
LDO_EN
BEEP
SPEAKER AND LDOSUPPLY
2.7V TO 5.5VHEADPHONE SUPPLY
2.7V TO 5.5V
SPKR_IN
HP_INR
HP_INL
CLASS DAMP
AVDD
LDO 1.8V OR 4.75V
Simplified Block Diagrams(continued)
26
27
25
24
10
9
11
HP_I
NR
COM
GND
LDO_
OUT
AVDD
12
SPKR
_INL
PGND
OUTL
-
PVDD
BEEP
HPVD
D
C1P
1 2
OUTR-
4 5 6 7
2021 19 17 16 15
PVDD
SPKR_EN
CPVSS
SENSE
HPL
HPR
MAX9791
HP_I
NLOU
TL+
3
18
28 8SPKR_INR LDO_EN
OUTR+
23 13 C1NPGND
22 14 CPGNDHP_EN
TQFN(4mm x 4mm x 0.75mm)
TOP VIEW
+*EP
*EP = EXPOSED PAD
26
27
25
24
10
9
11
HP_I
NR
COM
GND
LDO_
OUT
AVDD
12
GND
PGND
OUT-
PVDD
BEEP
HPVD
D
C1P
1 2
OUT-
4 5 6 7
2021 19 17 16 15
PVDD
SPKR_EN
CPVSS
SENSE
HPL
HPR
MAX9792
HP_I
NLOU
T+
3
18
28 8SPKR_IN LDO_EN
OUT+
23 13 C1NPGND
22 14 CPGNDHP_EN
TQFN(4mm x 4mm x 0.75mm)
TOP VIEW
+
*EP = EXPOSED PAD
*EP
Pin Configurations
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
28 ______________________________________________________________________________________
MAX9791AMAX9791B
LDO_EN 8
HP_INL 3
HP_INR 2
LDO_OUT 6
HP_EN 22
BEEP 21
SPKR_EN 27
STEREOCLASS D
AMPLIFIER
CONTROL
CHARGEPUMP
LDO BLOCK
TO HPVDD
TO CPVSS
1
19 OUTL+
OUTL-
OUTR+
OUTR-
HPL
HPR
HPVDD
C1P
C1N
CPGND
18
24
25
10
9
16
15
14
13
12
CPVSS
C21.0µF
20, 23
PGNDGND
5
SPKR_INL
SPKR_INR 28
1.0µF1.0µF
2.7V TO 5.5V
2.7V TO 5.5V
TO CODEC
NOTE: LOGIC PINS CONFIGURED FOR:LDO_EN = 1, LDO ENABLEDSPKR_EN = 0, SPEAKER AMPLIFIERS ENABLEDHP_EN = 1, HEADPHONE AMPLIFIER ENABLED
C11.0µF
0.1µF
PVDD
17, 26
2.7V TO 5.5V
AVDD
7
0.1µF1.0µF1.0µF 10µF
C310µF
RIN3
RIN1
CIN3
CIN1
RIN1CIN1
RIN3CIN3
RIN2CIN2
RIN2CIN2
11 SENSE
40.2kΩ
40.2kΩ
40.2kΩ
TO HPVDD
20kΩ
20kΩ
4CCOM RCOM
µC BEEP INPUT
COM
MAX9791A/MAX9791B Block Diagram
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 29
MAX9791C
LDO_EN 8
HP_INL 3
HP_INR 2
LDO_OUT 6
HP_EN 22
BEEP 21SPKR_EN 27
STEREOCLASS D
AMPLIFIER
CONTROL
CHARGEPUMP
LDO BLOCK
TO HPVDD
TO CPVSS
1
19 OUTL+
OUTL-
OUTR+
OUTR-
HPL
HPR
HPVDD
C1P
C1N
CPGND
18
24
25
10
9
16
15
14
13
12
CPVSS
C21.0µF
20, 23
PGNDGND
5
SPKR_INL
SPKR_INR 28
2.0µF2.0µF
2.7V TO 5.5V
2.7V TO 5.5V
TO CODEC
NOTE: LOGIC PINS CONFIGURED FOR:LDO_EN = 1, LDO ENABLEDSPKR_EN = 0, SPEAKER AMPLIFIER ENABLEDHP_EN = 1, HEADPHONE AMPLIFIER ENABLED
C11.0µF
0.1µF
PVDD
17, 26
2.7V TO 5.5V
AVDD
7
0.1µF1.0µF1.0µF 10µF
C310µF
RIN3
RIN1
CIN3
CIN1
RIN1CIN1
RIN3CIN3
RIN2CIN2
RIN2CIN2
11 SENSE
40.2kΩ
40.2kΩ
40.2kΩ
TO HPVDD
20kΩ
20kΩ
4CCOM RCOM
µC BEEP INPUT
COM
MAX9791C Block Diagram
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
30 ______________________________________________________________________________________
MAX9792A
LDO_EN 8
HP_INL 3
HP_INR 2
LDO_OUT 6
HP_EN 22
BEEP 21SPKR_EN 27
MONOCLASS D
AMPLIFIER
CONTROL
CHARGEPUMP
LDO BLOCK
TO HPVDD
TO CPVSS
28
19, 24 OUT+
OUT-
HPL
HPR
HPVDD
C1P
C1N
CPGND
18, 25
10
9
16
15
14
13
12
CPVSS
C21.0µF
20, 23
PGNDGND
1, 5
SPKR_IN
1.0µF1.0µF
2.7V TO 5.5V
2.7V TO 5.5V
TO CODEC
NOTE: LOGIC PINS CONFIGURED FOR:LDO_EN = 1, LDO ENABLEDSPKR_EN = 0, SPEAKER AMPLIFIER ENABLEDHP_EN = 1, HEADPHONE AMPLIFIER ENABLED
C11.0µF
C310µF
RIN1CIN1
RIN2CIN2
RIN2CIN2
11 SENSE
TO HPVDD
4CCOM RCOM
µC BEEP INPUT
RIN3CIN3
20kΩ
40.2kΩ
40.2kΩ
40.2kΩ
COM
0.1µF
PVDD
17, 26
2.7V TO 5.5V
AVDD
7
0.1µF1.0µF1.0µF 10µF
MAX9792A Block Diagram
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 31
MAX9792C
LDO_EN 8
HP_INL 3
HP_INR 2
LDO_OUT 6
HP_EN 22
BEEP 21
SPKR_EN 27
MONOCLASS D
AMPLIFIER
CONTROL
CHARGEPUMP
LDO BLOCK
TO HPVDD
TO CPVSS
28
19, 24 OUT+
OUT-
HPL
HPR
HPVDD
C1P
C1N
CPGND
18, 25
10
9
16
15
14
13
12
CPVSS
C21.0µF
20, 23
PGNDGND
1, 5
SPKR_IN
2.0µF2.0µF
2.7V TO 5.5V
2.7V TO 5.5V
TO CODEC
NOTE: LOGIC PINS CONFIGURED FOR:LDO_EN = 1, LDO ENABLEDSPKR_EN = 0, SPEAKER AMPLIFIER ENABLEDHP_EN = 1, HEADPHONE AMPLIFIER ENABLED
C11.0µF
C310µF
RIN1CIN1
RIN2CIN2
RIN2CIN2
11 SENSE
TO HPVDD
4CCOM RCOM
µC BEEP INPUT
RIN3CIN3
20kΩ
40.2kΩ
40.2kΩ
40.2kΩ
COM
0.1µF
PVDD
17, 26
2.7V TO 5.5V
AVDD
7
0.1µF1.0µF1.0µF 10µF
MAX9792C Block Diagram
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
32 ______________________________________________________________________________________
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
28 TQFN-EP T2844-1 21-0139 90-0068
Package InformationFor the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in thepackage code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to thepackage regardless of RoHS status.
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
______________________________________________________________________________________ 33
Package Information (continued)For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in thepackage code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to thepackage regardless of RoHS status.
MA
X9
79
1/M
AX
97
92
Windows Vista-Compliant Class D SpeakerAmplifiers with DirectDrive Headphone Amplifiers
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses areimplied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
34 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision HistoryREVISION NUMBER
REVISION DATE
DESCRIPTIONPAGES
CHANGED
0 11/08 Initial release —
1 6/10 Adding MAX9791C/MAX9792C versions 1–7, 10, 13–16,
19, 21–30