19-4217; Rev 1; 6/10
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Features
o Windows Vista® Premium Compliant
o Low EMI Filterless Class D Speaker Amplifiers
Pass EN55022B Emissions Limit with 30cm of
Speaker Cable
o 180mW DirectDrive Headphone Amplifier
o Excellent RF Immunity
o Integrated 120mA LDO
o Eliminates Headphone Ground Loop Noise
o Wake-on-Beep Function
o Click-and-Pop Suppression
o Short-Circuit and Thermal-Overload Protection
o Thermally Efficient, Space-Saving Package
28-Pin TQFN-EP (4mm x 4mm x 0.75mm)
Ordering Information
PART
STEREO/
MONO
LDO
OUTPUT
PIN-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°C
extended temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Simplified Block Diagrams
SPEAKER AND LDO
SUPPLY
2.7V TO 5.5V
HEADPHONE SUPPLY
2.7V TO 5.5V
CLASS D
AMP
MAX9791
CLASS D
AMP
Applications
Notebook Computers
Tablet PCs
SPKR_EN
Portable Multimedia Players
DirectDrive is a registered trademark of Maxim Integrated
Products, Inc.
Windows Vista is a registered trademark of Microsoft Corp.
HP_EN
LDO_EN
BEEP
AVDD
LDO
1.8V, 3.3V, OR 4.75V
Simplified Block Diagrams continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX9791/MAX9792
General Description
The MAX9791 combines a stereo 2W Class D power
amplifier, a stereo 180mW DirectDrive ® headphone
amplifier, and a 120mA low-dropout (LDO) linear regulator in a single device. The MAX9792 combines a
mono 3W Class D power amplifier, a stereo 180mW
DirectDrive headphone amplifier, and a 120mA LDO
linear regulator in a single device.
The MAX9791/MAX9792 feature Maxim’s DirectDrive
headphone amplifier architecture that produces a
ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors, saving
cost, board space, and component height. High 107dB
DC PSRR and low 0.006% THD+N ensure clean, lowdistortion amplification of the audio signal.
The ground sense feature senses and corrects for the
voltage difference between the output jack ground and
device signal ground. This feature minimizes headphone amplifier crosstalk by sensing the impedance in
the ground return trace and correcting for it at the output jack. This feature also minimizes ground-loop noise
when the output socket is used as a line out connection
to other grounded equipment (for example, a PC connected to a home hi-fi system).
The MAX9791/MAX9792 feature low RF susceptibility,
allowing the amplifiers to successfully operate in close
proximity to wireless applications. The MAX9791/
MAX9792 Class D amplifiers feature Maxim’s spreadspectrum modulation and active emissions limiting circuitry. Industry-leading click-and-pop suppression
eliminates audible transients during power-up and shutdown cycles.
The MAX9791/MAX9792 wake-on-beep feature wakes
up the speaker and headphone amplifiers when a qualified beep signal is detected at the BEEP input.
For maximum flexibility, separate speaker and headphone amplifier control inputs provide independent
shutdown of the speaker and headphone amplifiers.
Additionally the LDO can be enabled independently of
the audio amplifiers.
The MAX9791/MAX9792 feature thermal-overload and
output short-circuit protection. The devices are available in 28-pin TQFN packages and are specified over
the -40°C to +85°C extended temperature range.
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
ABSOLUTE MAXIMUM RATINGS
Supply Voltage
(AVDD, PVDD, HPVDD to GND)........................-0.3V to +6.0V
(AVDD to PVDD) .............................................................±0.3V
GND to PGND, CPGND ......................................................±0.3V
CPVSS, C1N to GND ............................................-6.0V to + 0.3V
HPL, HPR to CPVSS ...........................................-0.3V to lower of
(HPVDD - CPVSS + 0.3V) and +9V
HPL, HPR to HPVDD..................................+0.3V to the higher of
(CPVSS - HPVDD - 0.3V) and -9V
COM, SENSE........................................................-0.3V to + 0.3V
Any Other Pin ..........................................-0.3V to (AVDD + 0.3V)
Duration of Short Circuit between OUT_+, OUT_- and GND,
PGND, AVDD, or PVDD..........................................Continuous
Duration of Short Circuit between LDO_OUT and AVDD,
GND (Note 1) .........................................................Continuous
Duration of Short Circuit between HPR, HPL and
GND .......................................................................Continuous
Continuous Current (PVDD, OUT_+, OUT_-, PGND)............1.7A
Continuous Current (C1N, C1P, CPVSS, AVDD, HPVDD,
LDO_OUT, HPR, HPL) ..................................................850mA
Continuous Input Current (All Other Pins) ........................±20mA
Continuous Power Dissipation (TA = +70°C)
28-Pin Thin QFN Single-Layer Board (derate 20.8mW/°C
above +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/°C
above +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 ...................................±2kV
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
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.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(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)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
GENERAL
Supply Voltage
VAVDD,
VPVDD
Guaranteed by PSRR test (Note 4)
2.7
Headphone Supply Voltage
VHPVDD
Guaranteed by PSRR test
2.7
Undervoltage Lockout
UVLO
MAX9791
Quiescent Current
IAVDD +
I PVD +
IHPVDD
MAX9792
V
V
µA
SPKR_EN
HP_EN
LDO_EN
1
0
1
250
400
1
1
0
4.4
6
0
0
0
10.5
15
0
1
0
14.4
21
1
0
1
250
400
1
1
0
4.4
6
0
0
0
10.5
18
0
1
0
14.4
24
3.3
7..3
Shutdown Current
I SHDN
SPKR_EN = 1.8V
Bias Voltage
VBIAS
HP_INR, HP_INL, SPKR_INR, SPKR_INL
2
5.5
2.65
0
_______________________________________________________________________________________
mA
µA
mA
µA
V
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
(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)
PARAMETER
Shutdown to Full Operation
SYMBOL
CONDITIONS
MIN
tON
Overtemperature Threshold
TYP
MAX
UNITS
0.4
ms
+150
°C
SPEAKER AMPLIFIER
THD+N = 1%,
f = 1kHz,
TA = +25°C
(Note 5)
Output Power
POUT
Total Harmonic Distortion Plus
Noise
THD+N
Power-Supply Rejection Ratio
PSRR
Feedback Impedance
RFSKR
RL = 4
(MAX9791)
1.7
RL = 8
(MAX9791)
1.2
RL = 3
(MAX9792)
3
W
RL = 4
THD+N = 10%, (MAX9791)
f = 1kHz,
RL = 8
TA = +25°C
(MAX9791)
(Note 5)
RL = 3
(MAX9792)
2.2
1.5
3.7
RL = 8, POUT = 500mW, f = 1kHz (Note 5)
0.04
RL = 4, POUT = 500mW, f = 1kHz (Note 5)
0.03
VAVDD = VPVDD = 2.7V to 5.5V, TA = +25°C
f = 217Hz, 200mVP-P
60
80
73
f = 1kHz, 200mV P-P
75
f = 10kHz, 200mVP-P
62
dB
20
k
Gain
AV
RIN1 = 20k
12
dB
Output Offset Voltage
VOS
Measured between OUT_+ and OUT_-,
TA = +25°C
±3
KCP
RL = 8,
peak voltage,
A-weighted,
32 samples per second
(Notes 5, 6, and 7)
Click-and-Pop Level
Signal-to-Noise Ratio
Noise
Crosstalk
SNR
VN
Guaranteed by design
%
RL = 8
POUT = 1.2W fIN = 1kHz,
(Note 5)
Into shutdown
±10
mV
-52.4
dBV
Out of
shutdown
-54
A-weighted
98
20Hz to 20kHz
94
dB
A-weighted
38
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
HP to SPKR, RLSPKR = 8, PHP = 20mW,
RLHP = 32, f IN = 1kHz (Note 5)
77
µVRMS
dB
_______________________________________________________________________________________
3
MAX9791/MAX9792
ELECTRICAL CHARACTERISTICS (continued)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
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)
PARAMETER
Class D Switching Frequency
SYMBOL
CONDITIONS
f SPK
MIN
948
Spread-Spectrum Bandwidth
Efficiency
TYP
MAX
1158
UNITS
kHz
±15
kHz
POUT = 1.5W, f IN = 1kHz, RL = 8 (Note 5)
83
%
THD+N = 1%,
f = 1kHz,
TA = +25°C
RL = 16
100
RL = 32
180
HEADPHONE AMPLIFIER
Output Power
Total Harmonic Distortion Plus
Noise
POUT
THD+N
mW
RL = 32, f IN = 6kHz, 20kHz AES17,
VIN = -3dBFS = 212mVRMS
-78
RL = 10k, f IN = 6kHz, 20kHz AES17,
VIN = -3dBFS = 500mVRMS
-87
RL = 32, P OUT = 100mW, f = 1kHz
0.006
RL = 16, P OUT = 75mW, f = 1kHz
0.014
VHPVDD = 2.7V to 5.5V, TA = +25°C
Power-Supply Rejection Ratio
Feedback Impedance
Gain
Output Offset Voltage
Click-and-Pop Level
Signal-to-Noise Ratio
Noise
Maximum Capacitive Load
PSRR
91
80
38.2
RIN2 = 40.2k
TA = +25°C
±0.3
KCP
RL = 32,
peak voltage,
A-weighted, 32 samples
per second (Notes 6, 7)
SNR
RL = 32, P OUT = 40mW, A-weighted
f IN = 1kHz
20Hz to 20kHz
VN
A-weighted
CL
No sustained oscillations
Into shutdown
Out of
shutdown
42.2
k
±3
mV
dB
-81
dBV
-72.5
102
94
dB
8
µVRMS
100
pF
RL = 32, VIN =
-20dBFS = 30mVRMS
82
RL = 10k, VIN =
-20dBFS = 0.7mVRMS
89
RL = 32, VIN =
-20dBFS = 30mVRMS
64
RL = 10k, VIN =
-20dBFS = 70.7mVRMS
70
SPKR to HP, RLSPKR = 8, PSPKR = 1W,
RLHP = 32, f IN = 1Hz
4
40.2
dB
0
VOS
L to R, R to L, f IN
= 15kHz, COM
and SENSE
connected
%
107
f = 10kHz, VRIPPLE = 200mVP-P
L to R, R to L, f IN
= 1kHz, COM
and SENSE
connected
Crosstalk
70
f = 1kHz, VRIPPLE = 200mVP-P
RFHP
AV
dBFS
80
_______________________________________________________________________________________
dB
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
(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)
PARAMETER
SYMBOL
CONDITIONS
COM Input Range
VCOM
Inferred from CMRR test
Common-Mode Rejection Ratio
CMRR
-300mV < VCOM < +300mV
Slew Rate
Charge-Pump Frequency
MIN
TYP
-300
MAX
UNITS
+300
mV
60
dB
SR
0.38
V/µs
fOSC
530
kHz
0.4
ms
BEEP INPUT (LDO_EN = 1)
Beep Signal Minimum
fBEEP
Amplifier Turn-On Time
t ONBEEP
Four-cycle count
215
Amplifier Hold Time
tHOLDBEEP
LOW-DROPOUT LINEAR REGULATOR
LDO Ground Current
ILDO
Output Current
I OUT
Current Limit
ILIM
221
Output-Voltage Accuracy
Dropout Voltage
VDO
246
0.25
Inferred from load regulation
Speaker to LDO, VLDO_OUT = 4.75V,
f =1kHz, ILDO_OUT = 10mA, speaker POUT
= 1.2W, RL = 8 (Note 6)
Crosstalk
Hz
271
ms
0.4
mA
120
mA
300
mA
-80
dB
VLDO_OUT = 4.75V
±1.5
VLDO_OUT = 3.3V
±1.5
VLDO_OUT = 4.75V,
TA = +25°C (Note 8)
I OUT = 50mA
46
I OUT = 120mA
106
Startup Time
mV
30
Line Regulation
-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
-6.4
2.5
+6.4
Load Regulation
VLDO_OUT = 4.75V, 1mA < ILDO_OUT <
120mA
Ripple Rejection
VRIPPLE = 200mVP-P,
VLDO_OUT = 4.75V
ILDO_OUT = 10mA
0.22
f = 1kHz
56
f = 10kHz
40
mV/V
mV/mA
dB
20Hz to 20kHz, CLDO_OUT = 2 x 1µF,
ILDO_OUT = 120mA
Output-Voltage Noise
µs
VAVDD = 5V to 5.5V, VLDO_OUT = 4.75V,
ILDO_OUT = 1mA, CLDO = 2µF
VAVDD = 3V to 5.5V, VLDO_OUT = 1.8V,
ILDO_OUT = 1mA, CLDO = 4µF
%
130
µVRMS
DIGITAL INPUTS (SPKR_EN, HP_EN, LDO_EN, BEEP)
Input-Voltage High
VINH
Input-Voltage Low
VINL
Input Bias Current
1.4
-1
V
0.4
V
+1
µA
_______________________________________________________________________________________
5
MAX9791/MAX9792
ELECTRICAL CHARACTERISTICS (continued)
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)
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 mode
transitions 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.
Typical Operating Characteristics
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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
RL = 3Ω
VIN = -3dBFS
-20
-20
FS = 1VRMS
-50
-60
-70
-30
-40
FS = 707mVRMS
-50
-60
-80
FS = 707mVRMS
-90
1
10
100
-60
FS = 1VRMS
-90
-100
-100
0.1
0.01
FS = 707mVRMS
-50
-80
FS = 1VRMS
-90
-100
-40
-70
-70
-80
0.1
0.01
1
10
0.01
100
0.1
1
10
100
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (MAX9792 SPEAKER MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (MAX9791 SPEAKER MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (MAX9791 SPEAKER MODE)
100
100
100
10
RL = 4Ω
10
f = 6kHz
0.1
f = 6kHz
f = 1kHz
1
0.1
0.01
f = 100Hz
0.001
1.0
1.5
2.0
2.5
OUTPUT POWER (W)
3.0
3.5
4.0
1
f = 1kHz
0.1
0.01
f = 100Hz
f = 100Hz
0.001
0.001
0.5
10
THD+N (%)
THD+N (%)
f = 1kHz
0
RL = 8Ω
f = 6kHz
1
0.01
MAX9791 toc06
FREQUENCY (kHz)
MAX9791 toc05
FREQUENCY (kHz)
MAX9791 toc04
FREQUENCY (kHz)
RL = 3Ω
6
-20
THD+N (dBFS)
-40
RL = 8Ω
VIN = -3dBFS
-10
-30
THD+N (dBFS)
-30
THD+N (dBFS)
RL = 4Ω
VIN = -3dBFS
-10
0
MAX9791 toc02
0
MAX9791 toc01
0
-10
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (MAX9791 SPEAKER MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (MAX9791 SPEAKER MODE)
MAX9791 toc03
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (MAX9792 SPEAKER MODE)
THD+N (%)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
0
0.5
1.0
1.5
2.0
OUTPUT POWER (W)
2.5
3.0
0
0.5
1.0
OUTPUT POWER (W)
_______________________________________________________________________________________
1.5
2.0
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
2.0
OUTPUT POWER (W)
3.5
3.0
2.5
THD+N = 1%
2.0
1.5
1.5
THD+N = 10%
1.0
0.5
1.0
0.5
THD+N = 1%
0
0
10
1
10
1
100
OUTPUT POWER vs. LOAD RESISTANCE
(MAX9791 SPEAKER MODE)
1.25
2.0
THD+N = 1%
1.5
1.0
110
MAX9791 toc08a
THD+N = 10%
VPVDD = VAVDD = 3.7V
100
RL = 8Ω
90
80
1.00
0.75
EFFICIENCY (%)
OUTPUT POWER (W)
2.5
1.50
OUTPUT POWER (W)
f = 1kHz
EFFICIENCY vs. OUTPUT POWER
(MAX9792 SPEAKER MODE)
OUTPUT POWER vs. LOAD RESISTANCE
(MAX9791 SPEAKER MODE)
MAX9791 toc08
3.0
100
LOAD RESISTANCE (Ω)
LOAD RESISTANCE (Ω)
MAX9791 toc09
OUTPUT POWER (W)
THD+N = 10%
VPVDD = VAVDD = 3.7V
MAX9791 toc07a
f = 1kHz
4.5
4.0
2.5
MAX9791 toc07
5.0
THD+N = 10%
0.50
70
RL = 3Ω
60
50
40
30
0.5
20
THD+N = 1%
0.25
fIN = 1kHz
10
0
0
1
0.5
1.5
1.0
2.0
2.5
3.0
3.5
OUTPUT POWER (W)
EFFICIENCY vs. OUTPUT POWER
(MAX9792 SPEAKER MODE)
EFFICIENCY vs. OUTPUT POWER
(MAX9791 SPEAKER MODE)
EFFICIENCY vs. OUTPUT POWER
(MAX9791 SPEAKER MODE)
40
30
70
60
RL = 4Ω
50
40
30
20
10
fIN = 1kHz
10
0
0.6
0.9
OUTPUT POWER (W)
1.2
1.5
MAX9791 toc10a
60
50
RL = 4Ω
40
30
VPVDD = VAVDD = 3.7V
fIN = 1kHz
10
0
0
0.3
RL = 8Ω
70
4.0
20
20
VPVDD = VAVDD = 3.7V
fIN = 1kHz
80
EFFICIENCY (%)
RL = 3Ω
50
80
EFFICIENCY (%)
60
RL = 8Ω
90
90
MAX9791 toc10
100
MAX9791 toc09a
RL = 8Ω
0
0
LOAD RESISTANCE (Ω)
70
EFFICIENCY (%)
100
LOAD RESISTANCE (Ω)
90
80
0
10
1
100
10
0
0.3
0.6
0.9
1.2
OUTPUT POWER (W)
1.5
1.8
0
0.2
0.4
0.6
0.8
1.0
OUTPUT POWER (W)
_______________________________________________________________________________________
7
MAX9791/MAX9792
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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
OUTPUT POWER vs. LOAD RESISTANCE
OUTPUT POWER vs. LOAD RESISTANCE
(MAX9792 SPEAKER MODE)
(MAX9792 SPEAKER MODE)
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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
THD+N = 10%
2.0
1.5
1.0
THD+N = 1%
2.5
1.5
THD+N = 10%
1.0
THD+N = 1%
0.5
3.0
3.5
4.0
4.5
5.0
5.5
1.0
THD+N = 1%
0
3.0
2.5
3.5
4.0
4.5
5.0
3.0
2.5
5.5
3.5
4.0
4.5
5.0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX9792 SPEAKER MODE)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY (SPEAKER MODE)
CROSSTALK vs. FREQUENCY
(SPEAKER MODE)
-20
PSRR (dB)
3.0
2.5
2.0
THD+N = 1%
1.5
-40
LEFT
-50
-60
-70
1.0
-80
0.5
-90
0
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE
5.0
5.5
FS = 1VRMS
VIN = -20dBFS
RL = 8Ω
-40
-50
-60
RIGHT TO LEFT
-70
-80
RIGHT
-90
LEFT TO RIGHT
-100
-110
-100
2.5
-20
-30
-30
THD+N = 10%
0
-10
CROSSTALK (dB)
3.5
VRIPPLE = 200mVP-P
RL = 8Ω
5.5
MAX9791 toc12
4.0
-10
MAX9791 toc11
f = 1kHz
RLOAD = 3Ω
4.5
0
MAX9791 toc10e
5.0
8
THD+N = 10%
1.5
0.5
0
2.5
f = 1kHz
RLOAD = 8Ω
2.0
0.5
0
MAX9791 toc10d
f = 1kHz
RLOAD = 8Ω
OUTPUT POWER (W)
OUTPUT POWER (W)
OUTPUT POWER (W)
f = 1kHz
RLOAD = 4Ω
2.5
2.0
MAX9791 toc10b
3.0
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX9792 SPEAKER MODE)
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX9791 SPEAKER MODE)
MAX9791 toc10c
OUTPUT POWER vs. SUPPLY VOLTAGE
(MAX9791 SPEAKER MODE)
OUTPUT POWER (W)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
0.01
0.1
1
FREQUENCY (kHz)
10
100
0.01
0.1
1
FREQUENCY (kHz)
_______________________________________________________________________________________
10
100
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
SPEAKER
SPEAKER SHUTDOWN WAVEFORM
SPEAKER STARTUP WAVEFORM
MAX9791 toc14
MAX9791 toc13
SPKR_EN
2V/div
SPEAKER OUT
SPEAKER OUT
200µs/div
200µs/div
WIDEBAND OUTPUT SPECTRUM
(SPEAKER MODE)
OUTPUT FREQUENCY SPECTRUM
(SPEAKER MODE)
-40
-50
-60
-70
-80
-90
-100
-40
-60
-80
-100
-120
RBW = 1kHz
INPUT AC GROUNDED
-110
-120
VOUT = -60dBV
f = 1kHz
RL = 8Ω
UNWEIGHTED
-20
OUTPUT MAGNITUDE (dBV)
-10
-20
-30
MAX9791 toc16
0
MAX9791 toc15
0
OUTPUT AMPLITUDE (dBV)
SPKR_EN
2V/div
-140
0
1
10
FREQUENCY (MHz)
100
1
5
10
15
20
FREQUENCY (kHz)
_______________________________________________________________________________________
9
MAX9791/MAX9792
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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.)
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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
FS = 300mVRMS
-80
FS = 300mVRMS
-70
-80
FS = 1VRMS
RL = 32Ω
VIN = -3dBFS
-60
THD+N (dBFS)
-70
VHPVDD = 3V
RL = 16Ω
VIN = -3dBFS
-60
THD+N (dBFS)
-60
-50
MAX9791 toc18
RL = 16Ω
VIN = -3dBFS
THD+N (dBFS)
-50
MAX9791 toc17
-50
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
MAX9791 toc19
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
-70
FS = 300mVRMS
-80
FS = 1VRMS
-90
-90
-90
FS = 1VRMS
-100
10
1
100
0.1
0.01
10
1
0.1
0.01
100
10
1
100
FREQUENCY (kHz)
FREQUENCY (kHz)
FREQUENCY (kHz)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
FS = 300mVRMS
-80
1
f = 6kHz
0.1
MAX9791 toc22
10
RL = 32Ω
10
THD+N (%)
-70
100
MAX9791 toc21
RL = 16Ω
THD+N (%)
VHPVDD = 3V
RL = 32Ω
VIN = -3dBFS
-60
100
MAX9791 toc20
-50
THD+N (dBFS)
-100
-100
0.1
0.01
1
f = 1kHz
0.1
f = 1kHz
f = 100Hz
-90
f = 100Hz
-100
0.001
0.001
0.1
0.01
f = 6kHz
0.01
0.01
FS = 1VRMS
10
1
100
40
0
80
120
160
0
200
50
100
200
150
250
OUTPUT POWER (mW)
OUTPUT POWER (mW)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
OUTPUT POWER vs. LOAD RESISTANCE
(HEADPHONE MODE)
VHPVDD = 3V
RL = 32Ω
1
f = 100Hz
0.1
f = 1kHz
1
0.1
f = 1kHz
f = 6kHz
f = 100Hz
0.01
0.01
f = 1kHz
THD+N = 10%
200
OUTPUT POWER (mW)
10
THD+N (%)
10
250
MAX9791 toc24A
100
MAX9791 toc23
VHPVDD = 3V
RL = 16Ω
150
MAX9791 toc25
FREQUENCY (kHz)
100
THD+N (%)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
THD+N = 1%
100
50
f = 6kHz
0.001
0.001
0
10
20
30
40
50
60
OUTPUT POWER (mW)
10
70
80
90
0
0
10
20
30
40
50
OUTPUT POWER (mW)
60
70
1
10
LOAD RESISTANCE (Ω)
______________________________________________________________________________________
100
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
HEADPHONE
THD+N = 1%
50
40
30
20
10
250
200
150
100
RL = 32Ω
50
100
10
150
MAX9791 toc28
RL = 32Ω
100
50
25
50
75
0
100 125 150 175 200
20
40
60
80
PER CHANNEL OUTPUT POWER (mW)
PER CHANNEL OUTPUT POWER (mW)
HEADPHONE OUTPUT POWER
vs. HPVDD
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY (HEADPHONE MODE)
CROSSTALK vs. FREQUENCY
(HEADPHONE MODE)
200
100
VRIPPLE = 200mVP-P
RL = 32Ω
-50
-60
-70
RIGHT
3.5
4.0
HPVDD (V)
4.5
5.0
5.5
-50
RL = 32Ω
RIGHT TO LEFT
FS = 300mVRMS
COM AND SENSE
VIN = -20dBFS
DISABLED
RIGHT TO LEFT
COM AND SENSE
DISABLED
-60
RIGHT TO LEFT
COM AND SENSE
-70
LEFT TO RIGHT
COM AND SENSE
-90
LEFT
-100
-120
3.0
-30
100
-80
-100
-110
0
-20
-40
-80
-90
RL = 16Ω
50
-20
-30
-40
PSRR (dB)
RL = 32Ω
150
0
-10
CROSSTALK (dB)
THD+N = 1%
f = 1kHz
2.5
200
LOAD RESISTANCE (Ω)
MAX9791 toc29
250
0
1000
RL = 16Ω
0
0
0
HEADPHONE OUTPUT POWER (mW)
300
VHPVDD = 3V
250
MAX9791 toc31
THD+N = 10%
60
RL = 16Ω
MAX9791 toc30
OUTPUT POWER (mW)
70
350
300
POWER DISSIPATION PER CHANNEL (mW)
80
400
MAX9791 toc27
VHPVDD = 3V
f = 1kHz
POWER DISSIPATION PER CHANNEL (mW)
90
POWER DISSIPATION vs. OUTPUT POWER
(HEADPHONE MODE)
POWER DISSIPATION vs. OUTPUT POWER
(HEADPHONE MODE)
MAX9791 toc26
OUTPUT POWER vs. LOAD RESISTANCE
(HEADPHONE MODE)
0.01
0.1
1
FREQUENCY (kHz)
10
100
0.01
0.1
1
10
100
FREQUENCY (kHz)
______________________________________________________________________________________
11
MAX9791/MAX9792
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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.)
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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
OUTPUT FREQUENCY SPECTRUM
(HEADPHONE MODE)
STARTUP WAVEFORM
MAX9791 toc32
MAX9791 toc33
OUTPUT FREQUENCY SPECTRUM (dB)
RIGHT AND LEFT
FS = 707mVRMS
VIN = -60dBFS
RL = 32Ω
0
-20
-40
HP_EN
2V/div
-60
-80
HP_
500mV/div
-100
-120
-140
0
5
10
15
200µs/div
20
FREQUENCY (kHz)
HEADPHONE RF IMMUNITY
vs. FREQUENCY
SHUTDOWN WAVEFORM
MAX9791 toc35
MAX9791 toc34
RL = 32Ω
-10
-30
HP_EN
2V/div
HP_
500mV/div
AMPLITUDE (dBV)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
-50
LEFT
-70
-90
RIGHT
-110
-130
200µs/div
500
1000
1500
2000
2500
FREQUENCY (MHz)
12
______________________________________________________________________________________
3000
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
LINE OUT
-10
-20
RL = 10kΩ
10
-50
-60
FS = 707mVRMS
-70
FS = 1VRMS
1
-40
THD+N (%)
-40
-80
-50
-60
FS = 707mVRMS
-70
FS = 1VRMS
f = 6kHz
0.1
f = 100Hz
0.01
-80
-90
-90
-100
-100
-110
-110
0.1
0.01
1
10
100
0.001
f = 1kHz
0.0001
0.01
0.1
1
10
0
100
0.5
1.0
1.5
2.0
2.5
3.0
3.5
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
CROSSTALK vs. FREQUENCY
(HEADPHONE MODE)
OUTPUT FREQUENCY SPECTRUM
(HEADPHONE MODE)
1
0.1
f = 6kHz
f = 100Hz
0.01
RL = 10kΩ
FS = 707mVRMS
VIN = -20dBFS
-30
-40
CROSSTALK (dB)
10
-20
MAX9791 toc39
VHPVDD = 3V
RL = 10kΩ
-50
-60
RIGHT TO LEFT
COM AND SENSE
-70
-80
-90
-100
0.001
LEFT TO RIGHT
COM AND SENSE
-110
f = 1kHz
0.0001
0.5
1.0
1.5
2.0
OUTPUT POWER (mW)
2.5
3.0
-20
-40
-60
-80
-100
-120
-140
-120
0
RIGHT AND LEFT
RL = 10kΩ
FS = 300mVRMS
VIN = -60dBFS
0
4.0
MAX9791 toc41
OUTPUT POWER (mW)
OUTPUT FREQUENCY SPECTRUM (dB)
FREQUENCY (kHz)
MAX9791 toc40
FREQUENCY (kHz)
100
THD+N (%)
VHPVDD = 3V
RL = 10kΩ
VIN = -3dBFS
-30
THD+N (dBFS)
THD+N (dBFS)
-30
100
MAX9791 toc37
RL = 10kΩ
VIN = -3dBFS
-20
0
MAX9791 toc36
0
-10
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
MAX9791 toc38
TOTAL HARMONIC DISTORTION + NOISE
vs. FREQUENCY (HEADPHONE MODE)
0.01
0.1
1
FREQUENCY (kHz)
10
100
0
5
10
15
20
FREQUENCY (kHz)
______________________________________________________________________________________
13
MAX9791/MAX9792
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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.)
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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
SPKR_EN = 0
HP_EN = 0
5
10
SPKR_EN = 1
SPKR_EN = 0
5
SPKR_EN = 1
HP_EN = 0
SPKR_EN = 1
HP_EN = 1
5.00
5.25
SUPPLY VOLTAGE (V)
6
5
4
3
2
1
0
-5
4.75
SPKR_EN = 1
HP_EN = 0
LDO_EN = 0
7
SPKR_EN = 1
-5
4.50
MAX9791 toc43
MAX9791 toc42a
15
0
0
14
SPKR_EN = 0
8
SHUTDOWN CURRENT (µA)
10
SPKR_EN = 0
HP_EN = 1
LDO_EN = 1
VLDO_OUT = 1.8V
SUPPLY CURRENT (mA)
15
20
MAX9791 toc42
LDO_EN = 1, VLDO = 3.3V OR 4.75V
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. SUPPLY VOLTAGE
20
SUPPLY CURRENT (mA)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
5.50
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
5.0
5.5
2.5
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
______________________________________________________________________________________
5.0
5.5
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
LDO
1.0
0.5
0
-0.5
-1.0
-1.5
0.07
0.06
0.05
0.04
0.03
0.02
MAX9791 toc46
0.08
1.0
VLDO_OUT = 1.8V
0.5
VLDO_OUT = 3.3V
0
VLDO_OUT = 4.75V
-0.5
0.01
-1.0
0
25
50
75
100
125
150
0
300
600
900
1200
AMPLIFIER OUTPUT POWER (mW)
LDO DROPOUT VOLTAGE vs. LOAD
LDO POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX9791 toc47
40
LDO_OUT = 4.75V
250
20
VRIPPLE = 200mVP-P
ILOAD = 10mA
PSRR (dB)
150
100
-20
VLDO_OUT = 3.3V
-40
VLDO_OUT = 4.75V
-60
50
10
35
60
85
LDO OUTPUT NOISE
0
200
-15
TEMPERATURE (°C)
LOAD CURRENT (mA)
300
-40
1500
200
CLOAD = 2 x 1µF
ILOAD = 120mA
175
LDO OUTPUT NOISE (µV)
0
MAX9791 toc49
-2.0
LDO DROPOUT VOLTAGE (mV)
MAX9791 toc45
0.09
MAX9791 toc48
LDO OUTPUT ACCURACY (%)
1.5
LDO OUTPUT ACCURACY
vs. TEMPERATURE
0.10
LDO OUTPUT ACCURACY (%)
MAX9791 toc44
2.0
LDO OUTPUT ACCURACY
vs. AMPLIFIER OUTPUT POWER
LDO OUTPUT ACCURACY (%)
LDO OUTPUT ACCURACY
vs. LOAD CURRENT
150
125
100
75
-80
VLDO_OUT = 1.8V
0
-100
0
50
100
150
ILOAD (mA)
200
250
300
50
0.01
0.1
1
FREQUENCY (kHz)
10
100
0.01
0.1
1
10
100
FREQUENCY (kHz)
______________________________________________________________________________________
15
MAX9791/MAX9792
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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.)
Typical Operating Characteristics (continued)
(VAVDD = VPVDD = VHPVDD = 5V, VGND = VPGND = VCPGND = 0, ILDO_OUT = 0, CLDO = 2 x 1µF, C1 = C2 = 1µF. RL = ∞, unless otherwise 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
LOAD-TRANSIENT RESPONSE
LINE-TRANSIENT RESPONSE
MAX9791 toc51
MAX9791 toc50
ILDO_OUT
50mA/div
CH1 LOW
4.560V
CH1 HIGH
5.500V
CH2 LOW
800.0µV
AC-COUPLED
VLDO_OUT
10mV/div
CH2 HIGH
1.000mV
100ms/div
1.00ms/div
CROSSTALK vs. FREQUENCY
SPEAKER TO LDO
MAX9791 toc52
LDO_EN
2V/div
VLDO_EN
2V/div
200µs/div
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
MAX9791 toc53
SHUTDOWN RESPONSE
CROSSTALK (dB)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
BOTH SPEAKERS WITH SIGNAL
PSPKR = 1.2W
RLSPKR = 8W
ILDO = 10mA
LEFT CHANNEL TO LDO
RIGHT CHANNEL TO LDO
0.01
0.1
1
10
100
FREQUENCY (kHz)
16
______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
PIN
NAME
1
SPKR_INL
FUNCTION
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
7
AVDD
8
LDO_EN
9
HPR
Right-Channel Headphone Amplifier Output
10
HPL
Left-Channel Headphone Amplifier Output
Left-Channel Speaker Amplifier Input
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.
Positive Power-Supply and LDO Input. Bypass with a 0.1µF and two 1µF capacitors to GND.
LDO Enable. Connect LDO_EN to AVDD to enable the LDO.
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
15
C1P
16
HPVDD
Charge-Pump Ground. Connect directly to PGND plane.
Charge-Pump Flying Capacitor Positive Terminal. Connect a 1µF capacitor between C1P and C1N.
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
22
HP_EN
Active-High Headphone Amplifier Enable
24
OUTR+
Right-Channel Speaker Amplifier Output, Positive Phase
25
OUTR-
27
SPKR_EN
28
SPKR_INR
—
EP
PC Beep Input. Connect to GND if beep detection function is disabled.
Right-Channel Speaker Amplifier Output, Negative Phase
Active-Low Speaker Amplifier Enable
Right-Channel Speaker Amplifier Input
Exposed Pad. Connect to GND.
______________________________________________________________________________________
17
MAX9791/MAX9792
MAX9791 Pin Description
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
MAX9791/MAX9792
MAX9792 Pin Description
PIN
NAME
FUNCTION
1, 5
GND
2
HP_INR
Right-Channel Headphone Amplifier Input
3
HP_INL
Left-Channel Headphone Amplifier Input
4
COM
6
LDO_OUT
Signal Ground. Star connect to PGND.
Common-Mode Voltage Sense Input
LDO Output. Bypass with two 1µF ceramic low ESR capacitors to GND.
7
AVDD
8
LDO_EN
Positive Power Supply and LDO Input. Bypass with a 0.1µF and two 1µF capacitors to GND.
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
15
C1P
LDO Enable. Connect LDO_EN to AVDD to enable the LDO.
Charge-Pump Ground. Connect directly to PGND plane.
Charge-Pump Flying Capacitor Positive Terminal. Connect a 1µF capacitor between C1P and C1N.
16
HPVDD
17, 26
PVDD
Speaker Amplifier Power-Supply Input. Bypass with a 0.1µF capacitor to PGND.
Headphone Amplifier Positive Power Supply. Connect a 10µF capacitor between HPVDD and 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
27
SPKR_EN
Active-Low Speaker Amplifier Enable
Active-High Headphone Amplifier Enable
28
SPKR_IN
Speaker Amplifier Input
—
EP
Exposed Pad. Connect to GND.
Detailed Description
The MAX9791 combines a stereo 2W Class D power
amplifier, a stereo 175mW DirectDrive headphone
amplifier, and a 120mA LDO linear regulator in a single
device. The MAX9792 combines a mono 3W Class D
power amplifier, a stereo 175mW DirectDrive headphone amplifier, and a 120mA LDO linear regulator in a
single device.
The MAX9791/MAX9792 feature wake-on-beep detection, comprehensive click-and-pop suppression, lowpower shutdown mode, and excellent RF immunity.
These devices incorporate an integrated LDO that
serves as a clean power supply for CODEC or other circuits. The MAX9791/MAX9792 are Windows Vista
Premium compliant. See Table 1 for a comparison of the
Windows Vista Premium specifications and MAX9791/
MAX9792 specifications.
18
The MAX9791/MAX9792 feature spread-spectrum modulation and active emission limiting circuitry that offers
significant improvements to switch-mode amplifier technology. These devices offer Class AB performance with
Class D efficiency in a minimal board-space solution.
The headphone amplifiers use Maxim’s DirectDrive
architecture to eliminate the bulky output DC-blocking
capacitors required by traditional headphone amplifiers. A charge pump inverts the positive supply
(HPVDD) to create a negative supply (CPVSS). The
headphone amplifiers operate from these bipolar supplies with their outputs biased about GND. The benefit of the GND bias is that the amplifier outputs no
longer have a DC component (typically VDD/2). This
feature eliminates the large DC-blocking capacitors
required with conventional headphone amplifiers to
______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
MAX9791/MAX9792
Table 1. Windows Premium Mobile Vista Specifications vs. MAX9791/MAX9792
Specifications
DEVICE TYPE
REQUIREMENT
Analog Line-Out Jack
(RL = 10kΩ, FS =
0.707VRMS)
Analog Headphone-Out
Jack (RL = 32Ω, FS =
0.300VRMS)
WINDOWS PREMIUM
MOBILE VISTA
SPECIFICATIONS
MAX9791/MAX9792
TYPICAL PERFORMANCE
THD+N
≤ -65dB FS [100Hz, 20kHz]
Dynamic range with signal
present
≤ -80dBV, A-weighted [20Hz,
20kHz]
87dBFS [100Hz, 20kHz]
Line output crosstalk
≤ -50dB [20Hz, 15kHz]
THD+N
≤ -45dB FS [100Hz, 20kHz]
Dynamic range with signal
present
≤ -60dBV, A-weighted [20Hz,
20kHz]
Headphone output
crosstalk
≤ -50dB [20Hz, 15kHz]
-98.9dB A-weighted [20Hz, 20kHz]
64dB [20Hz, 15kHz]
82dBFS [100Hz, 20kHz]
-91.5dB A-weighted [20Hz, 20kHz]
64dB [20Hz, 15kHz]
Note: THD+N, dynamic range with signal present, and crosstalk should be measured in accordance with AES17 audio measurements standards.
Class D Speaker Amplifier
The MAX9791/MAX9792 integrate a filterless class D
amplifier that offers much higher efficiency than class AB
amplifiers. The high efficiency of a Class D amplifier is
due to the switching operation of the output stage transistors. In a Class D amplifier, the output transistors act
as current steering switches and consume negligible
additional power. Any power loss associated with the
Class D output stage is mostly due to the I2R loss of the
MOSFET on-resistance and quiescent current overhead.
The theoretical best efficiency of a linear amplifier is
78%, however, that efficiency is only exhibited at peak
output power. Under normal operating levels (typical
music reproduction levels), efficiency falls below 45%,
whereas the MAX9791/MAX9792 exhibit 67% efficiency
under the same conditions (Figure 1).
EFFICIENCY vs. IDEAL
CLASS AB EFFICIENCY
90
80
70
EFFICIENCY (%)
conserve board space and system cost, as well as
improve low-frequency response and distortion.
The MAX9791/MAX9792 amplifiers feature an undervoltage lockout that prevents operation from an insufficient power supply and click-and-pop suppression that
eliminates audible transients on startup and shutdown.
The amplifiers include thermal overload and short-circuit protection.
60
MAX9791
50
40
IDEAL CLASS AB
30
20
10
0
0
0.25
0.50
0.75
1.00
1.25
1.50
OUTPUT POWER (W)
Figure 1. MAX9791 Efficiency vs. Class AB Efficiency
Ultra-Low EMI Filterless Output Stage
In traditional Class D amplifiers, the high dv/dt of the
rising and falling edge transitions resulted in increased
electromagnetic-interference (EMI) emissions, which
required the use of external LC filters or shielding to
meet EN55022B EMI regulation standards. Limiting the
dv/dt normally results in decreased efficiency. Maxim’s
active emissions limiting circuitry actively limits the
dv/dt of the rising and falling edge transitions, providing
reduced EMI emissions while maintaining up to 83%
efficiency.
______________________________________________________________________________________
19
VDD
CLASS D EMI PLOT
40
EN55022B LIMIT
35
VOUT
AMPLITUDE (dBµV/m)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
VDD/2
30
25
GND
20
CONVENTIONAL AMPLIFIER BIASING SCHEME
15
+VDD
10
5
30
100
1000
FREQUENCY (MHz)
VOUT
GND
Figure 2. EMI with 30cm of Speaker Cable
In addition to active emission limiting, the MAX9791/
MAX9792 feature spread-spectrum modulation that flattens the wideband spectral components. Proprietary
techniques ensure that the cycle-to-cycle variation of the
switching period does not degrade audio reproduction
or efficiency (see the Typical Operating Characteristics).
In spread-spectrum modulation mode, the switching frequency varies randomly by ±15kHz around the center
frequency (530kHz). The effect is to reduce the peak
energy at harmonics of the switching frequency. Above
10MHz, the wideband spectrum looks like noise for EMI
purposes (see Figure 2).
Speaker Current Limit
When the output current of the speaker amplifier
exceeds 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 the
fault condition still exists, the MAX9791/MAX9792 continue to disable and re-enable the outputs until the fault
condition is removed.
DirectDrive Headphone Amplifier
Traditional single-supply headphone amplifiers bias the
outputs at a nominal DC voltage (typically half the supply). 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 amplifier.
20
-VDD
DirectDrive AMPLIFIER BIASING SCHEME
Figure 3. Traditional Amplifier Output vs. MAX9791/MAX9792
DirectDrive Output
Maxim’s DirectDrive architecture uses a charge pump
to create an internal negative supply voltage. This
allows the headphone outputs of the MAX9791/
MAX9792 to be biased at GND while operating from a
single supply (Figure 3). Without a DC component,
there is no need for the large DC-blocking capacitors.
Instead of two large (220µF, typ) capacitors, the
MAX9791/MAX9792 charge pump requires two small
1µF ceramic capacitors, conserving board space,
reducing cost, and improving the frequency response
of the headphone amplifier.
The MAX9791/MAX9792 feature a low-noise charge
pump. The nominal switching frequency of 530kHz is
well beyond the audio range, and thus does not interfere with audio signals. 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 trace inductance is minimized.
______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
MAX9791/MAX9792
RFHP
CROSSTALK
vs. GROUND RESISTANCE (RG)
CIN2
-40
HP_INL
HPL
HPR
CCOM
COM
RFHP
SENSE
RCOM
RS = 5Ω
RL = 32Ω
-45
-50
CROSSTALK (dB)
RIN2
-55
-60
-65
-70
CIN2
HP_INR
-75
RIN2
-80
RFHP
0
0.025
0.050
0.075
0.100
0.125
0.150
RG (Ω)
Figure 4. Connecting COM for Ground Sense
Figure 5. Crosstalk vs. Ground Resistance
Common-Mode Sense
Windows Vista-compliant platforms are restricted to only
115mΩ of ground return impedance. If the headphone
jack ground is connected close to the audio device
ground using a solid ground plane, the return path resistance can be quite low. However, it is often necessary to
locate some jacks far from the audio device. The
MAX9791/MAX9792 COM and SENSE inputs allow the
headphone jack to be placed further away from the
device without degrading crosstalk performance.
The headphone amplifier output impedance, trace
resistance, and contact resistance of the jack are
grouped together to represent the source resistance,
RS. The resistance between the load and the sleeve,
the sleeve contact resistance, and the system ground
return resistance are grouped together to represent the
ground resistance, RG.
Assuming a typical source resistance of 5Ω, the ground
return impedance would need to be limited to 115mΩ
to meet Windows Vista’s crosstalk specification of 50dB
(Figure 5). This is further complicated by the fact that
the impedance of the sleeve connection in the 3.5mm
stereo jack can make up 30mΩ–90mΩ alone.
The MAX9791/MAX9792 COM and SENSE inputs
reduce crosstalk performance by eliminating effects of
28.5mΩ of ground return path resistance. If ground
sensing is not required, connect COM directly to GND
and leave SENSE unconnected (Figure 6).
The MAX9791/MAX9792 SENSE and COM inputs sense
and correct for the difference between the headphone
return and device ground. When using common-mode
sense, connect COM through a resistor to GND of the
device (Figure 4). For optimum common-mode rejection, use the same value resistors for RIN2 and RCOM.
To improve AC CMRR, add a capacitor equal to CIN2
between GND and RCOM.
Configuring SENSE and COM in this way improves system crosstalk performance by reducing the negative
effects of the headphone jack ground return resistance.
⎛ RG ⎞
Crosstalk in dB = 20 log ⎜
⎟
⎝ RL + R S ⎠
Wake-on-Beep
The MAX9791/MAX9792 beep-detection circuit wakes
up the device (speaker and headphone amplifiers)
once a qualified beep signal is detected at BEEP and
the LDO is enabled. The amplifier wake command from
the beep-detection circuit overrides the logic signal
applied at HP_EN and SPKR_EN.
______________________________________________________________________________________
21
A qualified BEEP signal consists of a 3.3V typical,
215Hz minimum signal that is present at BEEP for four
consecutive cycles. Once the first rising edge transition
is detected at BEEP, the beep circuit wakes up and
begins counting the beep cycles. Once four consecutive cycles of a qualified beep signal are counted, the
device (speaker and headphone amplifiers) enables
within 400µs. If the first rising edge is not followed by
three consecutive rising edges within 16ms, the device
remains shutdown (i.e., glitch protection).
The device (speaker and headphone amplifiers) returns
to its programmed logic state once 246ms has elapsed
from the time the last rising edge was detected. This
246ms amplifier hold time ensures complete beep profiles are passed to the amplifier outputs (Figure 7).
Ground BEEP when the wake-on-beep feature is not
used. Do not leave BEEP unconnected.
CROSSTALK vs. FREQUENCY
(HEADPHONE MODE)
-20
-30
RL = 32Ω
FS = 300mVRMS
VOUT = -20dBFS
RIGHT TO LEFT
COM AND SENSE
DISABLED
-40
CROSSTALK (dB)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
LEFT TO RIGHT
COM AND SENSE
DISABLED
-50
-60
RIGHT TO LEFT
COM AND SENSE
-70
-80
LEFT TO RIGHT
COM AND SENSE
-90
-100
0.01
0.1
1
10
100
FREQUENCY (kHz)
Low-Dropout Linear Regulator
The LDO regulator can be used to provide a clean
power supply to a CODEC or other circuitry. The LDO
can 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 to
120mA of continuous current.
Figure 6. MAX9791/MAX9792 COM and SENSE Inputs Reduce
Crosstalk
time, connect SPKR_EN and HP_EN together, allowing
a single logic voltage to enable either the speaker or
the headphone amplifier as shown in Figure 8.
Speaker and Headphone Amplifier Enable
The MAX9791/MAX9792 feature control inputs for the
independent enabling of the speaker and headphone
amplifiers, allowing both to be active simultaneously
if required. Driving SPKR_EN high disables the speaker
amplifiers. Driving HP_EN low independently disables
the headphone amplifiers. For applications that
require only one of the amplifiers to be on at a given
Shutdown
The MAX9791/MAX9792 feature a low-power shutdown
mode, drawing 3.3µA of supply current. By disabling
the speaker, headphone amplifiers, and the LDO, the
MAX9791/MAX9792 enter low-power shutdown mode.
Set SPKR_EN to AVDD and HP_EN and LDO_EN to
GND to disable the speaker amplifiers, headphone
amplifiers, and LDO, respectively.
16ms
BEEP
1
2
3
4
240ms
SPKR AND HP
AMPS ENABLE
400µs
Figure 7. Qualified BEEP Signal Timing
22
______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
SINGLE
CONTROL
SPKR_EN
CIN1
RIN1
SPKR_IN_
MONO
CLASS D
AMPLIFIER
OUT_+
OUT_-
HP_EN
Figure 8. Enabling Either the Speaker or Headphone Amplifier
with a Single Control Pin
Click-and-Pop Suppression
The MAX9791/MAX9792 feature a common-mode bias
voltage of 0V. A 0V BIAS allows the MAX9791/MAX9792
to quickly turn on/off with no resulting clicks and pops.
With the HDA CODEC outputs biased and the
MAX9791/MAX9792 inputs sitting as 0V in shutdown
and normal operation, the RIN x CIN time constant is
eliminated.
Speaker Amplifier
The MAX9791/MAX9792 speaker amplifiers feature
Maxim’s comprehensive, industry leading click-andpop suppression. During startup and shutdown, the
click-and-pop suppression circuitry eliminates any
audible transient sources internal to the device.
Headphone Amplifier
In conventional single-supply headphone amplifiers,
the output-coupling capacitor is a major contributor of
audible clicks and pops. Upon startup, the amplifier
charges the coupling capacitor to its bias voltage, typically V DD/2. During shutdown, the capacitor is discharged to GND; a DC shift across the capacitor
results, which in turn appears as an audible transient at
the speaker. Because the MAX9791/MAX9792 do not
require output-coupling capacitors, no audible transient
occurs.
The MAX9791/MAX9792 headphone amplifiers feature
extensive click-and-pop suppression that eliminates
any audible transient sources internal to the device.
Figure 9. Setting Speaker Amplifier Gain
Applications Information
Filterless Class D Operation
Traditional Class D amplifiers require an output filter to
recover the audio signal from the amplifier’s output. The
filters add cost and size and can decrease efficiency
and THD+N performance. The traditional PWM scheme
uses large differential output swings (2 x PVDD peakto-peak) causing large ripple currents. Any parasitic
resistance in the filter components results in a loss of
power, lowering the efficiency.
The MAX9791/MAX9792 do not require an output filter.
The devices rely on the inherent inductance of the speaker coil and the natural filtering of both the speaker and
the human ear to recover the audio component of the
square-wave output. Eliminating the output filter results in
a smaller, less costly, and more efficient solution.
Because the frequency of the MAX9791/MAX9792 output is well beyond the bandwidth of most speakers,
voice coil movement due to the square-wave frequency
is very small. For optimum results, use a speaker with a
series inductance > 10µH. Typical 8Ω speakers exhibit
series inductances in the 20µH to 100µH range.
______________________________________________________________________________________
23
MAX9791/MAX9792
MAX9791
RFB
20kΩ
MAX9791
MAX9792
Setting Speaker Amplifier Gain
External input resistors in conjunction with the internal
feedback resistors (RFSPKR) set the speaker amplifier
gain of the MAX9791/MAX9792. Set gain by using
resistor RIN1 as follows (Figure 9):
L1*
MAX9791
MAX9792
⎛ 20kΩ ⎞
A VSPKR = -4 ⎜
V/V
⎝ RIN1 ⎟⎠
where AVSPKR is the desired voltage gain. An RIN1 of
20kΩ yields a gain of 4V/V, or 12dB.
Component Selection
Optional Ferrite Bead Filter
In applications where speaker leads exceed 15cm, use
a filter constructed from a ferrite bead and a capacitor
to ground (Figure 10) to provide additional EMI suppression. Use a ferrite bead with low DC resistance,
high frequency (> 1.2MHz) impedance of 100Ω to
600Ω, and rated for at least 1A. The capacitor value
varies based on the ferrite bead chosen and the actual
speaker lead length. Select the capacitor value based
on EMI performance.
L2*
330pF
330pF
*L1 = L2 = WÜRTH 742792040
Figure 10. Optional Ferrite Bead Filter
TOTAL HARMONIC DISTORTION + NOISE
vs. OUTPUT POWER (HEADPHONE MODE)
100
RL = 32Ω
10
THD+N (%)
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
OUT OF PHASE
1
IN PHASE
0.1
Output Power (Headphone Amplifier)
The headphone amplifiers are specified for the worstcase scenario when both inputs are in phase. Under
this condition, the drivers simultaneously draw current
from the charge pump, leading to a slight loss in headroom of CPVSS. In typical stereo audio applications, the
left and right signals have differences in both magnitude and phase, subsequently leading to an increase in
the maximum attainable output power. Figure 11 shows
the two extreme cases for in and out of phase. In most
cases, the available power lies between these
extremes.
Headphone Amplifier Gain
Gain-Setting Resistors
External input resistors in conjunction with the internal
feedback resistors (RFHP) set the headphone amplifier
gain of the MAX9791/MAX9792. Set gain by using
resistor RIN2 (Figure 4) as follows:
⎛ 40.2kΩ ⎞
A VHP = - ⎜
V/V
⎝ RIN2 ⎟⎠
where AVHP is the desired voltage gain. An RIN2 of
40.2kΩ yields a gain of 1V/V, or 0dB.
24
0.01
0.001
0
50
100
150
200
250
OUTPUT POWER (mW)
Figure 11. Output Power vs. Supply Voltage with Inputs In/Out
of Phase; 32Ω Load Conditions and 3.5dB Gain
Power Supplies
The MAX9791/MAX9792 speaker amplifiers are powered from PVDD with a range from 2.7V to 5.5V. The
headphone amplifiers are powered from HPVDD and
CPVSS. HPVDD is the positive supply of the headphone
amplifiers and charge pump ranging from 2.7V to 5.5V.
CPVSS is the negative supply of the headphone amplifiers. The charge pump inverts the voltage at HPVDD,
and the resulting voltage appears at CPVSS. AVDD
powers the LDO and the remainder of the device.
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.
______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
-50
THD+N (dBFS)
-60
-70
VOUT - -3dBFS
FS = 1VRMS
RL =32Ω
AMPLITUDE (dBV)
0402 6.3V X5R 10% 1µF
0603 10V X5R 10% 1µF
-80
0805 50V X7R 10% 1µF
-90
0603 10V X7R 10% 1µF
-100
10
100
1000
FREQUENCY (kHz)
Figure 12. Input Coupling Capacitor-Induced THD+N vs.
Frequency
Component Selection
Speaker Amplifier Power-Supply Input (PVDD)
PVDD powers the speaker amplifiers. PVDD ranges
from 2.7V to 5.5V. 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. Bypass PVDD with a 0.1µF
capacitor to PGND. Apply additional bulk capacitance
at the device if long input traces between PVDD and
the power source are used.
Headphone Amplifier Power-Supply Input
(HPVDD and CPVSS)
The headphone amplifiers are powered from HPVDD
and CPVSS. HPVDD is the positive supply of the headphone amplifiers and ranges from 2.7V to 5.5V. Bypass
HPVDD with a 10µF capacitor to PGND. CPVSS is the
negative supply of the headphone amplifiers. Bypass
CPVSS with a 1µF capacitor to PGND. The charge
pump inverts the voltage at HPVDD, and the resulting
voltage appears at CPVSS. A 1µF capacitor should be
connected between C1N and C1P.
Positive Power Supply and LDO Input (AVDD)
The internal LDO and the remainder of the device are
powered by AVDD. AVDD ranges from 2.7V to 5.5V.
AVDD and PVDD must be tied together. If LDO is
enabled, set AVDD and PVDD as specified in LDO line
regulation. Bypass AVDD with a 0.1µF capacitor to
GND and two 1µF capacitors to GND. Note additional
bulk capacitance is required at the device if long input
traces between AVDD and the power source are used.
MAX9791/MAX9792
SPEAKER RF IMMUNITY
vs. FREQUENCY
INPUT COUPLING CAPACITOR-INDUCED THD+N
vs. FREQUENCY (HEADPHONE MODE)
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
RIGHT
LEFT
0
500
1000
1500
2000
2500
3000
FREQUENCY (MHz)
Figure 13. Speaker RF Immunity
Input Filtering
The input capacitor (CIN_), in conjunction with the amplifier input resistance (RIN_), forms a highpass filter that
removes the DC bias from the incoming signal. The ACcoupling 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:
1
f -3dB =
2πRIN _ CIN _
RIN_ is the amplifier’s external input resistance value.
Choose 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 with adequately low-voltage coefficients (see
Figure 12). Capacitors with higher voltage coefficients, such as ceramics, result in increased distortion at low frequencies.
Charge-Pump Capacitor Selection
Use capacitors with an ESR less than 100mΩ for optimum performance. Low ESR ceramic capacitors minimize the output resistance of the charge pump. For
best performance over the extended temperature
range, select capacitors with an X7R dielectric.
Flying Capacitor (C1)
The value of the flying capacitor (C1) affects the load
regulation and output resistance of the charge pump. 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. Connect a 1µF capacitor between
C1P and C1N.
______________________________________________________________________________________
25
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
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 and
GND for 4.75V and 3.3V LDO options (MAX979_A and
MAX979_B, respectively). Connect two parallel 2µF
capacitors between LDO_OUT and GND for the 1.8V
LDO option (MAX979_C).
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Use large traces for the power-supply
inputs and amplifier outputs to minimize losses due to
parasitic trace resistance, as well as route heat away
from the device. Good grounding improves audio performance, minimizes crosstalk between channels, and
prevents switching noise from coupling into the audio
signal. Connect PGND and GND together at a single
point on the PCB. Route PGND and all traces that carry
switching transients away from GND, and the traces
and components in the audio signal path.
Connect C2 to the PGND plane. Place the chargepump capacitors (C1, C2) as close as possible to the
device. Bypass PVDD with a 0.1µF capacitor to PGND.
Place the bypass capacitors as close as possible to the
device.
26
The MAX9791/MAX9792 is inherently designed for
excellent RF immunity. For best performance, add
ground fills around all signal traces on top or bottom
PCB planes.
Use large, low-resistance output traces. As load impedance decreases, the current drawn from the device outputs increase. At higher current, the resistance of the
output traces decrease the power delivered to the load.
For example, if 2W is delivered from the speaker output
to a 4Ω load through a 100mΩ trace, 49mW is wasted
in the trace. If power is delivered through a 10mΩ
trace, only 5mW is wasted in the trace. Large output,
supply, and GND traces also improve the power dissipation of the device.
The MAX9791/MAX9792 thin QFN package features an
exposed thermal pad on its underside. This pad lowers
the package’s thermal resistance by providing a direct
heat conduction path from the die to the printed circuit
board. Connect the exposed thermal pad to GND by
using a large pad and multiple vias to the GND plane.
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
PGND 23
13
OUTR+ 24
OUTR- 25
MAX9791
PVDD 26
*EP
SPKR_EN 27
+
1
2
3
4
5
6
7
SPKR_INL
HP_INR
HP_INL
COM
GND
LDO_OUT
AVDD
SPKR_INR 28
PVDD
HPVDD
C1P
18
17
16
15
HP_EN 22
14
CPGND
C1N
PGND 23
13
C1N
12
CPVSS
OUT+ 24
12
CPVSS
11
SENSE
OUT- 25
11
SENSE
10
HPL
PVDD 26
10
HPL
9
HPR
SPKR_EN 27
9
HPR
8
LDO_EN
SPKR_IN 28
8
LDO_EN
MAX9792
*EP
+
TQFN
(4mm x 4mm x 0.75mm)
1
2
3
4
5
6
7
AVDD
CPGND
19
LDO_OUT
14
20
GND
HP_EN 22
21
OUT+
15
OUT-
C1P
16
COM
HPVDD
17
HP_INL
PVDD
18
PGND
OUTL-
19
HP_INR
OUTL+
20
BEEP
PGND
21
TOP VIEW
GND
BEEP
TOP VIEW
TQFN
(4mm x 4mm x 0.75mm)
*EP = EXPOSED PAD
*EP = EXPOSED PAD
Simplified Block Diagrams
(continued)
SPEAKER AND LDO
SUPPLY
2.7V TO 5.5V
HEADPHONE SUPPLY
2.7V TO 5.5V
CLASS D
AMP
SPKR_IN
MAX9792
HP_INR
HP_INL
SPKR_EN
HP_EN
AVDD
LDO_EN
BEEP
LDO
1.8V OR 4.75V
______________________________________________________________________________________
27
MAX9791/MAX9792
Pin Configurations
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
MAX9791/MAX9792
MAX9791A/MAX9791B Block Diagram
2.7V TO 5.5V
1.0µF
1.0µF
0.1µF
0.1µF
PVDD
AVDD
17, 26
7
CIN3
CIN1
RIN3
RIN1
CIN1
RIN1
CIN3
RIN3
MAX9791A
MAX9791B
20kΩ
SPKR_INL
SPKR_INR
10µF
1
STEREO
CLASS D
AMPLIFIER
28
19
OUTL+
18
OUTL-
24
OUTR+
25
OUTR-
10
HPL
9
HPR
20kΩ
CIN2
CIN2
RIN2
HP_INL
3
HP_INR
2
40.2kΩ
TO HPVDD
RIN2
2.7V TO 5.5V
TO CPVSS
LDO_EN
8
HP_EN
22
BEEP
µC BEEP INPUT
21
CONTROL
SPKR_EN 27
CCOM RCOM
COM
TO HPVDD
40.2kΩ
4
40.2kΩ
LDO_OUT
TO CODEC
1.0µF
6
CHARGE
PUMP
5
28
SENSE
16
HPVDD
15
C1P
14
CPGND
13
C1N
LDO BLOCK
1.0µF
NOTE: LOGIC PINS CONFIGURED FOR:
LDO_EN = 1, LDO ENABLED
SPKR_EN = 0, SPEAKER AMPLIFIERS ENABLED
HP_EN = 1, HEADPHONE AMPLIFIER ENABLED
11
20, 23
GND
PGND
12
CPVSS
C2
1.0µF
______________________________________________________________________________________
2.7V TO 5.5V
C3
10µF
C1
1.0µF
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
2.7V TO 5.5V
1.0µF
1.0µF
0.1µF
0.1µF
PVDD
AVDD
17, 26
7
CIN3
CIN1
MAX9791C
RIN3
RIN1
CIN1
RIN1
CIN3
RIN3
10µF
20kΩ
SPKR_INL
SPKR_INR
1
STEREO
CLASS D
AMPLIFIER
28
19
OUTL+
18
OUTL-
24
OUTR+
25
OUTR-
10
HPL
9
HPR
20kΩ
CIN2
CIN2
RIN2
HP_INL
3
HP_INR
2
40.2kΩ
TO HPVDD
RIN2
2.7V TO 5.5V
TO CPVSS
LDO_EN
8
HP_EN
22
CONTROL
µC BEEP INPUT
BEEP 21
SPKR_EN 27
CCOM RCOM
COM
TO HPVDD
40.2kΩ
4
40.2kΩ
LDO_OUT
TO CODEC
2.0µF
6
CHARGE
PUMP
SENSE
16
HPVDD
15
C1P
14
CPGND
13
C1N
2.7V TO 5.5V
C3
10µF
C1
1.0µF
LDO BLOCK
2.0µF
5
NOTE: LOGIC PINS CONFIGURED FOR:
LDO_EN = 1, LDO ENABLED
SPKR_EN = 0, SPEAKER AMPLIFIER ENABLED
HP_EN = 1, HEADPHONE AMPLIFIER ENABLED
11
20, 23
GND
PGND
12
CPVSS
C2
1.0µF
______________________________________________________________________________________
29
MAX9791/MAX9792
MAX9791C Block Diagram
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
MAX9791/MAX9792
MAX9792A Block Diagram
2.7V TO 5.5V
1.0µF
1.0µF
PVDD
AVDD
17, 26
7
CIN3
CIN1
CIN2
CIN2
10µF
0.1µF
0.1µF
MAX9792A
RIN3
20kΩ
RIN1
SPKR_IN
RIN2
MONO
CLASS D
AMPLIFIER
28
HP_INL
3
HP_INR
2
19, 24
OUT+
18, 25
OUT-
40.2kΩ
TO HPVDD
RIN2
10
HPL
9
HPR
2.7V TO 5.5V
TO CPVSS
LDO_EN
8
HP_EN
22
CONTROL
µC BEEP INPUT
BEEP 21
SPKR_EN 27
CCOM RCOM
COM
TO HPVDD
40.2kΩ
4
40.2kΩ
LDO_OUT
TO CODEC
1.0µF
6
CHARGE
PUMP
1, 5
30
SENSE
16
HPVDD
15
C1P
14
CPGND
13
C1N
LDO BLOCK
1.0µF
NOTE: LOGIC PINS CONFIGURED FOR:
LDO_EN = 1, LDO ENABLED
SPKR_EN = 0, SPEAKER AMPLIFIER ENABLED
HP_EN = 1, HEADPHONE AMPLIFIER ENABLED
11
GND
20, 23
PGND
12
CPVSS
C2
1.0µF
______________________________________________________________________________________
2.7V TO 5.5V
C3
10µF
C1
1.0µF
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
2.7V TO 5.5V
1.0µF
1.0µF
AVDD
PVDD
7
CIN3
CIN1
CIN2
CIN2
10µF
0.1µF
0.1µF
17, 26
MAX9792C
RIN3
20kΩ
RIN1
SPKR_IN
RIN2
MONO
CLASS D
AMPLIFIER
28
HP_INL
3
HP_INR
2
18, 25
OUT-
40.2kΩ
2.7V TO 5.5V
10
HPL
9
HPR
TO CPVSS
LDO_EN
µC BEEP INPUT
8
HP_EN
22
BEEP
21
CONTROL
SPKR_EN 27
CCOM RCOM
COM
TO HPVDD
40.2kΩ
4
40.2kΩ
LDO_OUT
2.0µF
OUT+
TO HPVDD
RIN2
TO CODEC
19, 24
6
CHARGE
PUMP
SENSE
16
HPVDD
15
C1P
14
CPGND
13
C1N
2.7V TO 5.5V
C3
10µF
C1
1.0µF
LDO BLOCK
2.0µF
1, 5
NOTE: LOGIC PINS CONFIGURED FOR:
LDO_EN = 1, LDO ENABLED
SPKR_EN = 0, SPEAKER AMPLIFIER ENABLED
HP_EN = 1, HEADPHONE AMPLIFIER ENABLED
11
GND
20, 23
PGND
12
CPVSS
C2
1.0µF
______________________________________________________________________________________
31
MAX9791/MAX9792
MAX9792C Block Diagram
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
32
PACKAGE TYPE
PACKAGE CODE
OUTLINE NO.
LAND PATTERN NO.
28 TQFN-EP
T2844-1
21-0139
90-0068
______________________________________________________________________________________
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
______________________________________________________________________________________
33
MAX9791/MAX9792
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the
package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the
package regardless of RoHS status.
MAX9791/MAX9792
Windows Vista-Compliant Class D Speaker
Amplifiers with DirectDrive Headphone Amplifiers
Revision History
REVISION
NUMBER
REVISION
DATE
0
11/08
1
6/10
DESCRIPTION
Initial release
PAGES
CHANGED
—
Adding MAX9791C/MAX9792C versions
1–7, 10, 13–16,
19, 21–30
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.
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.
