19-0731; Rev 0; 1/07
KIT
ATION
EVALU
BLE
AVAILA
Single-/Dual-Supply, Stereo 16W,
Class D Amplifier with Differential Inputs
General Description
The MAX9742 stereo Class D audio power amplifier
delivers up to 2 x 16W into 4Ω loads. The MAX9742
features high-power efficiency (92% with 8Ω loads),
eliminating the need for a bulky heatsink and conserv-
ing power. The MAX9742 operates from a 20V to 40V
single supply or a ±10V to ±20V dual supply. Features
include fully differential inputs, comprehensive click-
and-pop suppression, low-power shutdown mode, and
an externally adjustable gain. Short-circuit and thermal-
overload protection prevent the device from being
damaged during a fault condition.
The MAX9742 is available in a thermally efficient 36-pin
TQFN (6mm x 6mm x 0.8mm) package and is specified
over the -40°C to +85°C extended temperature range.
o
o
o
o
o
o
o
o
o
Features
2 x 16W Output Power (R
L
= 4Ω, THD+N = 10%)
High Efficiency: Up to 92% with R
L
= 8Ω
Mute and Shutdown Modes
Differential Inputs Suppress Common-Mode Noise
Adjustable Gain
Integrated Click-and-Pop Suppression
Low 0.06% THD+N at 3.5W, R
L
= 8Ω
Output Short-Circuit and Thermal Protection
Available in Space-Saving, 6mm x 6mm, 36-Pin
TQFN Package
MAX9742
Ordering Information
PART
MAX9742ETX+
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
36 TQFN-EP*
PKG
CODE
T3666-3
Applications
CRT TVs
Flat-Panel Display TVs
Audio Docking Stations
Multimedia Monitors
+Denotes
lead-free package.
*EP
= Exposed paddle.
Pin Configuration located at end of data sheet.
Simplified Block Diagrams
SINGLE-SUPPLY CONFIGURATION
C
FBL
20V TO 40V
R
F1
FBL V
DD
LEFT NEGATIVE
AUDIO INPUT
C
IN
R
IN1
INL-
MAX9742
L
F
C
OUT
LEFT POSITIVE
AUDIO INPUT
C
IN
R
IN2
INL+
CLASS D
MODULATOR AND
HALF-BRIDGE
OUTL
R
F2
V
DD
2
R
F2
RIGHT POSITIVE
AUDIO INPUT
C
IN
R
IN2
C
FBL
C
F
MID
R
ZBL
C
ZBL
C
FBR
INR+
CLASS D
MODULATOR AND
HALF-BRIDGE
OUTR
L
F
C
OUT
RIGHT NEGATIVE
AUDIO INPUT
C
IN
R
ZBL
R
IN1
INR-
CONTROL LOGIC/
POWER-UP
SEQUENCING
FBR
C
FBR
R
F1
OFF
V
SS
SHDN
ON
SFT
C
SFT
C
F
C
ZBL
Simplified Block Diagrams continued at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Single-/Dual-Supply, Stereo 16W,
Class D Amplifier with Differential Inputs
MAX9742
ABSOLUTE MAXIMUM RATINGS
V
DD
to V
SS
, NSENSE ..............................................-0.3V to +45V
MID, LGND, LV
DD
, REGM, REGP, OUTR,
OUTL to V
SS
.......................................................-0.3V to +45V
MID, LGND, LV
DD
, REGM, REGP, OUTR,
OUTL to V
DD
.......................................................-45V to +0.3V
REGLS to V
SS
.........................................................-0.3V to +12V
MID to REGP, REGM...............(V
REGM
- 0.3V) to (V
REGP
+ 0.3V)
REGP to REGM.......................................................-0.3V to +12V
LV
DD
to LGND ..........................................................-0.3V to +6V
SHDN
to LGND.........................................................-0.3V to +4V
SFT to LGND ............................................................-0.3V to +6V
FB_, IN_+, IN_-, REFCUR to REGP,
REGM..................................(V
REGM
- 0.3V) to (V
REGP
+ 0.3V)
BOOTR to OUTR ....................................................-0.3V to +12V
BOOTL to OUTL .....................................................-0.3V to +12V
OUTR, OUTL Shorted to LGND..................................Continuous
Continuous Power Dissipation (T
A
= +70°C) (Note 1)
Single-Layer Board:
36-Pin TQFN (derate 26.3mW/°C above +70°C) ...........2.11W
Multilayer Board:
36-Pin TQFN (derate 35.7mW/°C above +70°C) ...........2.86W
Junction-to-Ambient Thermal Resistance (θ
JA
)
Single-Layer Board:
36-Pin TQFN.................................................................38°C/W
Multilayer Board:
36-Pin TQFN.................................................................28°C/W
Junction-to-Case Thermal Resistance (θ
JC
) ...................1.4°C/W
Operating Temperature Range ...........................-40°C to +85°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
Actual power capabilities are dependent on PCB layout. See the
Thermal Considerations
section.
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—Single-Supply, Single-Ended Output
(V
DD
= 24V, V
SS
= V
SUB
= LGND = 0V, V
SHDN
= 3.3V, V
MID
= 12V, C
VDD
= 660µF, C
MID1
= 10µF, C
MID2
= 10µF, R1 = R2 = R3 =
10kΩ, C
SFT
= 0.47µF, C
OUT
= 1000µF, C
FB_1
= 150pF, C
FB_2
= 10pF, C
BOOT
= 0.1µF, C
REGP
= C
REGM
= 1µF, R
IN_
= 30.1kΩ,
R
F1A
= 121kΩ, R
F1B
= 562kΩ, R
F2
= 681kΩ, R
REF
= 68kΩ, R
L
=
∞,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 2)
PARAMETER
Supply Voltage Range
Supply Current
Mute Mode Supply Current
Shutdown Current
Switching Frequency
Power-Supply Rejection Ratio
(Note 4)
Crosstalk
(Notes 5 and 6)
f
SW
PSRR
V
DD
= 24V + 500mV
P-P
, f = 1kHz
L to R, R to L, R
L
= 8Ω, P
OUT
= 1W, f = 1kHz
R
L
= 8Ω, f
IN
= 1kHz, THD+N = 10%
Continuous Output Power
(Notes 5, 6, and 7)
P
OUT
R
L
= 8Ω, f
IN
= 1kHz, THD+N = 10%,
V
DD
= 35V
R
L
= 4Ω, f
IN
= 1kHz, THD+N = 10%
Efficiency
(Notes 5, 6, and 7)
R
L
= 8Ω, P
OUT
= 9.5W, THD+N = 10%
SYMBOL
V
DD
I
DD
(Note 3)
No load, output filter removed
No load, V
SFT
= 0V (outputs not switching)
No load, V
SHDN
= 0V
CONDITIONS
MIN
20
15
8
0.8
300
68
-78
9.5
20.5
16
92
%
W
1.3
TYP
MAX
40
UNITS
V
mA
mA
mA
kHz
dB
dB
2
_______________________________________________________________________________________
Single-/Dual-Supply, Stereo 16W,
Class D Amplifier with Differential Inputs
ELECTRICAL CHARACTERISTICS—Single-Supply, Single-Ended Output (continued)
(V
DD
= 24V, V
SS
= V
SUB
= LGND = 0V, V
SHDN
= 3.3V, V
MID
= 12V, C
VDD
= 660µF, C
MID1
= 10µF, C
MID2
= 10µF, R1 = R2 = R3 =
10kΩ, C
SFT
= 0.47µF, C
OUT
= 1000µF, C
FB_1
= 150pF, C
FB_2
= 10pF, C
BOOT
= 0.1µF, C
REGP
= C
REGM
= 1µF, R
IN_
= 30.1kΩ,
R
F1A
= 121kΩ, R
F1B
= 562kΩ, R
F2
= 681kΩ, R
REF
= 68kΩ, R
L
=
∞,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at
T
A
= +25°C.) (Note 2)
PARAMETER
Total Harmonic Distortion Plus
Noise
SYMBOL
THD+N
CONDITIONS
f
IN
= 1kHz,
BW = 22Hz to 22kHz
(Notes 5, 6, and 7)
P
OUT
= 9.5W, R
L
= 8Ω,
BW = 22Hz to 22kHz
(Notes 5 and 6)
R
L
= 8Ω, P
OUT
= 3.5W
R
L
= 4Ω, P
OUT
= 5W
Unweighted
A-weighted
MIN
TYP
0.06
%
0.08
88
dB
93
0.4
No load (Note 4)
-1
I
MID
t
SON
t
PU
T
SH
I
SC
K
CP
V
SHDN
= 3.3V
Junction temperature
OUT_ shorted to V
DD
or V
SS
Peak voltage, 32-samples
per second, A-weighted
(Notes 4 and 8)
Into shutdown
Out of shutdown
2.9
V
DD
= 24V, no load
68
1.5
150
4.5
-38
dBV
-40
50
+1
50
0.7
Ω
ns
µA
µA
ms
s
o
MAX9742
MAX
UNITS
Signal-to-Noise Ratio
Half-Bridge Switch
On-Resistance
Switch Rise and Fall Times
IN_ Input Bias Current
MID Input Bias Current
Shutdown-to-Full Operation
Power-On to Full Operation
Thermal-Overload Threshold
Temperature
Short-Circuit Output Current
Click-and-Pop
DIGITAL INPUTS (SHDN) (Note 9)
Logic-Input Low Voltage
Logic-Input High Voltage
Input Leakage Current
SNR
R
DS(ON)
C
A
V
IL
V
IH
2.4
-1
0.4
+1
V
V
µA
ELECTRICAL CHARACTERISTICS—Dual Supplies
(V
DD
= 15V, V
SS
= V
SUB
= -15V, V
SHDN
= 3.3V, V
MID
= LGND = 0V, C
VDD
= C
VSS
= 1000µF, C
BYP
= 1µF, C
SFT
= 0.22µF, C
FB_1
=
150pF, C
FB_2
= 10pF, C
BOOT
= 0.1µF, C
REGP
= C
REGM
= 1µF, R
IN_
= 30.1kΩ, R
F1A
= 121kΩ, R
F1B
= 562kΩ, R
F2
= 681kΩ, R
REF
=
68kΩ, R
L
=
∞,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Positive Supply Voltage Range
Negative Supply Voltage
Range
Positive Supply Mute Mode
Current
Negative Supply Mute Mode
Current
SYMBOL
V
DD
V
SS
(Note 3)
(Note 3)
No load, V
SFT
= 0V (outputs not switching)
No load, V
SFT
= 0V (outputs not switching)
-12
CONDITIONS
MIN
10
-20
8
-8
TYP
MAX
20
-10
11
UNITS
V
V
mA
mA
_______________________________________________________________________________________
3
Single-/Dual-Supply, Stereo 16W,
Class D Amplifier with Differential Inputs
MAX9742
ELECTRICAL CHARACTERISTICS—Dual Supplies (continued)
(V
DD
= 15V, V
SS
= V
SUB
= -15V, V
SHDN
= 3.3V, V
MID
= LGND = 0V, C
VDD
= C
VSS
= 1000µF, C
BYP
= 1µF, C
SFT
= 0.22µF, C
FB_1
=
150pF, C
FB_2
= 10pF, C
BOOT
= 0.1µF, C
REGP
= C
REGM
= 1µF, R
IN_
= 30.1kΩ, R
F1A
= 121kΩ, R
F1B
= 562kΩ, R
F2
= 681kΩ, R
REF
=
68kΩ, R
L
=
∞,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Positive Supply Current
Negative Supply Current
Positive Supply Shutdown
Current
Negative Supply Shutdown
Current
Output Offset Voltage
IN_ Input Bias Current
V
DD
= 10V to 20V
Power-Supply Rejection Ratio
(Note 4)
PSRR
V
SS
= -10V to -20V
V
DD
= 15V + 500mV
P-P
, f = 1kHz
V
SS
= -15V + 500mV
P-P
, f = 1kHz
Crosstalk
(Notes 5 and 6)
L to R, R to L, R
L
= 8Ω, P
OUT
= 1W, f = 1kHz
R
L
= 8Ω
Continuous Output Power
P
OUT
R
L
= 8Ω, V
DD
= 18V,
f
IN
= 1kHz,
V
SS
= -18V
THD+N = 10%
(Notes 5, 6, and 7) R = 4Ω, V
L
DD
= 12V,
V
SS
= -12V
R
L
= 8Ω, P
OUT
= 15W, THD+N = 10%
f
IN
= 1kHz,
BW = 22Hz to 22kHz
(Notes 5, 6, and 7)
P
OUT
= 14W,
R
L
= 8Ω, BW = 22Hz to
22kHz (Notes 5 and 6)
R
L
= 8Ω, P
OUT
= 5W
R
L
= 4Ω, P
OUT
= 10W
Unweighted
A-weighted
SYMBOL
I
DD
I
SS
CONDITIONS
No load, output filter removed
No load, output filter removed
No load, V
SHDN
= 0V
No load, V
SHDN
= 0V
Output referred, affected by R
IN_
and R
F_
tolerances (Note 4)
-1
97
100
67
64
-61
14
21
9.5
93
0.06
%
0.08
89
dB
94
68
OUT_ shorted to V
DD
or V
SS
Peak voltage, 32-samples
per second, A-weighted
(Notes 4 and 8)
Into shutdown
Out of shutdown
2.9
4.5
-36
dBV
-36
ms
A
%
W
dB
dB
-1
-36
MIN
TYP
23
-23
0.001
-0.03
5
30
+1
1
MAX
36
UNITS
mA
mA
µA
µA
mV
µA
Efficiency
(Notes 5, 6, and 7)
Total Harmonic Distortion
Plus Noise
THD+N
Signal-to-Noise Ratio
Shutdown-to-Full Operation
Short-Circuit Output Current
Click-and-Pop
SNR
t
SON
I
SC
K
CP
4
_______________________________________________________________________________________
Single-/Dual-Supply, Stereo 16W,
Class D Amplifier with Differential Inputs
ELECTRICAL CHARACTERISTICS—Single-Supply, BTL Configuration
(V
DD
= 24V, V
SS
= V
SUB
= LGND = 0V, V
SHDN
= 3.3V, V
MID
= 12V, C
VDD
= 660µF, C
MID1
= 10µF, C
MID2
= 10µF, R1 = R2 = R3 =
10kΩ, C
SFT
= 0.47µF, C
OUT
= 1000µF, C
FB_1
= 150pF, C
FB_2
= 10pF, C
BOOT
= 0.1µF, C
REGP
= C
REGM
= 1µF, R
IN_
= 30.1kΩ, R
F1A
= 121kΩ, R
F1B
= 562kΩ, R
F2
= 681kΩ, R
REF
= 68kΩ, R
L
=
∞,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
=
+25°C.) (Note 2)
PARAMETER
Output Offset Voltage
Power-Supply Rejection Ratio
(Note 4)
Continuous Output Power
Efficiency
Total Harmonic Distortion Plus
Noise (Notes 6, 10, and 11)
PSRR
P
OUT
SYMBOL
(Note 4)
V
DD
= 20V to 40V
V
DD
= 24V + 500mV
P-P
, f = 1kHz
R
L
= 8Ω, f
IN
= 1kHz, THD+N = 10%,
(Notes 6, 10, and 11)
R
L
= 8Ω, P
OUT
= 10W, THD+N = 10%,
(Notes 5 and 6)
THD+N
f
IN
= 1kHz, BW = 22Hz to 22kHz,
R
L
= 8Ω, P
OUT
= 10W
P
OUT
= 32W, R
L
= 8Ω,
BW = 22Hz to 22kHz
(Notes 6, 10, and 11)
Unweighted
A-weighted
CONDITIONS
MIN
TYP
7
88
77
32
83
MAX
UNITS
mV
dB
W
%
MAX9742
0.08
90
96
68
%
Signal-to-Noise Ratio
Shutdown-to-Full Operation
Click-and-Pop
SNR
t
SON
K
CP
dB
ms
dBV
Peak voltage, 32-samples
per second, A-weighted
(Notes 4, 11, and 12)
Into shutdown
Out of shutdown
-47
-32
Note 2:
All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design.
Note 3:
Supply pumping may occur at high output powers with low audio frequencies. Use proper supply bypassing to prevent the
device from entering overvoltage protection due to supply pumping. See the
Supply Pumping Effects
and the
Supply
Undervoltage and Overvoltage Protection
sections.
Note 4:
Amplifier inputs AC-coupled to ground.
Note 5:
For R
L
= 4Ω, L
F
= 22µH and C
F
= 0.68µF. For R
L
= 6Ω, L
F
= 33µH and C
F
= 0.47µF. For R
L
= 8Ω, L
F
= 47µH and C
F
=
0.33µF.
Note 6:
Testing performed with four-layer PCB.
Note 7:
Both channels driven in phase.
Note 8:
Testing performed with an 8Ω resistor connected between LC filter output and ground. Mode transitions are controlled by
SHDN.
K
CP
level is calculated as 20log[(peak voltage during mode transition, no input signal) / 1V
RMS
].
Note 9:
Digital input specifications apply to both single-supply and dual-supply operation.
Note 10:
Channels driven 180° out-of-phase. Load connected between LC filter outputs.
Note 11:
L
F
= 22µH and C
F
= 0.68µF.
Note 12:
Testing performed with an 8Ω resistor connected between LC filter outputs. Mode transitions are controlled by
SHDN.
K
CP
level is calculated as 20log[(peak voltage during mode transition, no input signal) / 1V
RMS
].
_______________________________________________________________________________________
5
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