19-4327; Rev 0; 10/08
KIT
ATION
EVALU
BLE
AVAILA
Mono 7W Class D Amplifier
General Description
Features
♦
8V to 28V Supply Voltage Range
♦
Spread-Spectrum Modulation Enables Low-EMI
Solution
♦
Passes EMI Limit with Up to 1m of Speaker Cable
♦
High 80dB PSRR
♦
Up to 88% Efficiency Eliminates Heatsink
♦
Thermal and Output Current Protection
♦
< 1µA Shutdown Mode
♦
Click-and-Pop Suppression
♦
< 10ms Turn-On Time
♦
Space-Saving, 4mm x 4mm x 0.8mm, 24-Pin TQFN
Package
MAX9737
The MAX9737 mono 7W Class D amplifier provides a
high-performance, thermally efficient amplifier solution
that offers up to 88% efficiency at a 12V supply. The
device operates from 8V to 28V and provides a high 80dB
PSRR, eliminating the need for a regulated power supply.
Filterless modulation allows the MAX9737 to pass CE
EMI limits with 1m cables using only a low-cost ferrite
bead and small-value capacitor on each output.
Comprehensive click-and-pop suppression circuitry
reduces noise on power-up/down or into and out of
shutdown or mute.
An input op amp allows the user to create a lowpass or
highpass filter, and select an optimal gain. The internal
precharge circuit ensures clickless/popless turn-on
within 10ms.
The MAX9737 is available in the 24-pin, TQFN-EP pack-
age and is specified over the -40°C to +85°C tempera-
ture range.
Applications
2.1 Notebook PCs
LCD/PDP/CRT Monitors
PC Surround Speakers
MP3 Docking Stations
PART
MAX9737ETG+
Ordering Information
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
24 TQFN-EP*
+Denotes
a lead-free/RoHS-compliant package.
*EP
= Exposed pad.
Simplified Diagram
8V TO 28V
PRECHARGE
AUDIO
INPUT
8Ω
SHDN
MUTE
INPUT RESISTORS AND
CAPACITORS SELECT GAIN
AND CUTOFF FREQUENCY
MAX9737
Pin Configuration and Typical Application Circuit appear at
end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
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.
Mono 7W Class D Amplifier
MAX9737
ABSOLUTE MAXIMUM RATINGS
PVDD to PGND.......................................................-0.3V to +30V
AGND to PGND .....................................................-0.3V to +0.3V
IN, PRE, PC, COM to AGND.....................-0.3V to (V
REG
+ 0.3V)
MUTE, SHDN
to AGND ............................................-0.3V to +6V
REG to AGND ...............................................-0.3V to (V
S
+ 0.3V)
V
S
to AGND ..............................................................-0.3V to +6V
OUT+, OUT- to PGND .............................-0.3V to (PVDD + 0.3V)
C1N to PGND ..........................................-0.3V to (PVDD + 0.3V)
C1P to PGND .........................(PVDD - 0.3V) to (V
CHOLD
+ 0.3V)
CHOLD to PGND .......................................(V
C1P
- 0.3V) to +36V
OUT+, OUT-, Short Circuit to PGND or PVDD ...........Continuous
Thermal Limits (Notes 1, 2)
Continuous Power Dissipation (T
A
= +70°C)
24-Pin TQFN Single-Layer PCB (derate 20.8mW/°C
above +70°C)........................................................1666.7mW
θ
JA
................................................................................48°C/W
θ
JC
..................................................................................3°C/W
Continuous Power Dissipation
24-Pin TQFN Multiple-Layer PCB
(derate 27.8mW/°C above +70°C) ........................2222.2mW
θ
JA
................................................................................36°C/W
θ
JC
..................................................................................3°C/W
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature ......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
Thermal performance of this device is highly dependent on PCB layout. See the
Applications Information
section for more detail.
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
(V
PVDD
= 12V, V
AGND
= V
PGND
= 0, V
SHDN
= V
MUTE
= 5V, C1 = 0.1µF, C
IN
= 0.47µF, C2 = C
COM
= C
REG
= 1µF, R
IN
= R
FB
= 20kΩ,
R
L
=
∞,
AC measurement bandwidth 22Hz to 22kHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
(Note 3)
PARAMETER
Speaker-Supply Voltage Range
Undervoltage Lockout
Quiescent Supply Current
Shutdown Supply Current
REG Voltage
Preregulator Voltage
COM Voltage
Capacitive Drive
Output Swing
Open-Loop Gain
Input Offset Voltage
Input Amplifier Slew Rate
Input Amplifier Unity-Gain
Bandwidth
A
VO
V
OS
IN to COM
SYMBOL
PVDD
UVLO
I
PVDD
I
SHDN
V
REG
V
S
V
COM
C
L
No sustained oscillation
Sinking ±1mA (Note 4)
1.94
T
A
= +25°C
V
SHDN
= 0, T
A
= +25°C
4.0
CONDITIONS
Inferred from PSRR test
MIN
8
6.8
15
1
4.2
4.85
2.06
30
2.05
88
±2
2.5
3.5
2.16
20
25
10
4.5
TYP
MAX
28
UNITS
V
V
mA
µA
V
V
V
pF
V
dB
mV
V/µs
MHz
AMPLIFIER DC CHARACTERISTICS
INPUT AMPLIFIER CHARACTERISTICS
2
_______________________________________________________________________________________
Mono 7W Class D Amplifier
MAX9737
ELECTRICAL CHARACTERISTICS (continued)
(V
PVDD
= 12V, V
AGND
= V
PGND
= 0, V
SHDN
= V
MUTE
= 5V, C1 = 0.1µF, C
IN
= 0.47µF, C2 = C
COM
= C
REG
= 1µF, R
IN
= R
FB
= 20kΩ,
R
L
=
∞,
AC measurement bandwidth 22Hz to 22kHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
(Note 3)
PARAMETER
Output Amplifier Gain
Output Current Limit
Output Offset
Power-Supply Rejection Ratio
Output Power
THD + Noise
Signal-to-Noise Ratio
Noise
Efficiency
V
OS
PSRR
P
OUT
THD+N
SNR
V
N
η
OUT+ to OUT-, T
A
= +25°C
V
PVDD
= 8V to 28V, T
A
= +25°C
f = 1kHz, 100mV
P-P
ripple
THD+N = 10%, R
L
= 8Ω (Note 5)
THD+N = 10%, R
L
= 4Ω (Note 6)
P
OUT
= 2W, f = 1kHz, R
L
= 8Ω (Note 5)
A-weighted, P
OUT
= THD+N at 1%,
f
IN
= 1kHz
A-weighted (Note 4)
P
OUT
= 4W
Peak voltage, 32
samples/second,
A-weighted
(Notes 4, 5, 8)
Into shutdown
Out of shutdown
Into mute
Out of mute
270
6
65
SYMBOL
A
V
CONDITIONS
Preamplifier gain = 0dB (Note 7)
MIN
13.1
3
TYP
13.6
4.6
±2
80
88
7.4
13
0.06
97
100
85
38
38
38
38
300
±4
+160
30
t
ON
V
INH
V
INL
50
T
A
= +25°C
±10
From shutdown to full operation
2
0.8
9
10
330
kHz
kHz
°C
°C
ms
V
V
mV
µA
dBV
±10
MAX
14.1
UNITS
dB
A
mV
dB
W
%
dB
µV
RMS
%
OUTPUT AMPLIFIER CHARACTERISTICS
Click-and-Pop Level
K
CP
Switching Frequency
Spread-Spectrum Bandwidth
Thermal-Shutdown Level
Thermal-Shutdown Hysteresis
Turn-On Time
DIGITAL INTERFACE (SHDN,
MUTE)
Input-Voltage High
Input-Voltage Low
Input-Voltage Hysteresis
Input Leakage Current
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
All devices are 100% production tested at T
A
= +25°C, and all temperature limits are guaranteed by design.
Amplifier inputs AC-coupled to GND.
8Ω resistive load in series with 68mH inductive load connected across OUT+ and OUT- outputs.
4Ω resistive load in series with 33µH inductive load connected across OUT+ and OUT- outputs for V
PVDD
≤
12V.
Output amplifier gain is defined as:
⎛
| (V
)
−
(V
OUT
−
) |
⎞
20
×
log
⎜
OUT
+
⎟
| V
PRE
|
⎝
⎠
Note 8:
Mode transition controlled by
SHDN
and
MUTE.
_______________________________________________________________________________________
3
Mono 7W Class D Amplifier
MAX9737
Typical Operating Characteristics
(V
PVDD
= 12V, V
GND
= V
PGND
= 0, V
SHDN
= V
MUTE
= 5V, R
IN
= R
FB
= 20kΩ, unless otherwise noted.)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX9737 toc01
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
MAX9737 toc02
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
PVDD = 12V,
8Ω LOAD
MAX9737 toc03
1
PVDD = 12V,
8Ω LOAD
1
PVDD = 12V,
4Ω LOAD
10
1
THD+N (%)
0.1
0.1
THD+N (%)
4W
THD+N (%)
P
OUT
= 4W
6kHz
0.1
2W
P
OUT
= 2W
20Hz
0.01
10
100
1k
FREQUENCY (Hz)
10k
100k
0.01
10
100
1k
FREQUENCY (Hz)
10k
100k
0.01
0
1
2
3
4
5
6
7
8
OUTPUT POWER (W)
1kHz
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9737 toc04
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
MAX9737 toc05
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
PVDD = 12V,
4Ω LOAD
MAX9737 toc06
10
PVDD = 18V,
8Ω LOAD
10
PVDD = 24V,
8Ω LOAD
10
1
THD+N (%)
THD+N (%)
1
1kHz
THD+N (%)
6kHz
1
6kHz
0.1
1kHz
6kHz
0.1
1kHz
0.1
20Hz
0.01
0
1
2
3
4
5
6
7
8
OUTPUT POWER (W)
0.01
0
1
2
3
4
5
6
20Hz
0.01
7
8
0
2
4
6
8
10
20Hz
12
14
16
OUTPUT POWER (W)
OUTPUT POWER (W)
EFFICIENCY
vs. TOTAL OUTPUT POWER
100
90
80
EFFICEINCY (%)
70
60
50
40
30
20
10
0
0
1
2
3
4
5
6
7
8
TOTAL OUTPUT POWER (W)
POWER DISSIPATION
EFFICIENCY
PVDD = 12V,
8Ω LOAD
MAX9737 toc07
EFFICIENCY
vs. TOTAL OUTPUT POWER
10
9
8
POWER DISSIPATION (W)
7
6
5
4
3
2
1
0
EFFICEINCY (%)
100
90
80
70
60
50
40
30
20
10
0
0
1
2
3
4
5
6
7
8
TOTAL OUTPUT POWER (W)
POWER DISSIPATION
EFFICIENCY
PVDD = 18V,
8Ω LOAD
MAX9737 toc08
10
9
8
7
6
5
4
3
2
1
0
POWER DISSIPATION (W)
4
_______________________________________________________________________________________
Mono 7W Class D Amplifier
Typical Operating Characteristics (continued)
(V
PVDD
= 12V, V
GND
= V
PGND
= 0, V
SHDN
= V
MUTE
= 5V, R
IN
= R
FB
= 20kΩ, unless otherwise noted.)
EFFICIENCY
vs. TOTAL OUTPUT POWER
90
80
70
EFFICEINCY (%)
60
50
40
30
20
10
0
0
1
2
3
4
5
6
7
8
TOTAL OUTPUT POWER (W)
POWER DISSIPATION
EFFICIENCY
MAX9737 toc09
MAX9737
EFFICIENCY
vs. TOTAL OUTPUT POWER
10
9
8
POWER DISSIPATION (W)
7
6
5
4
3
2
1
0
EFFICEINCY (%)
100
90
80
70
60
50
40
30
20
10
0
0
2
4
6
8
10
12
14
16
TOTAL OUTPUT POWER (W)
POWER DISSIPATION
EFFICIENCY
PVDD = 12V,
4Ω LOAD
MAX9737 toc10
10
9
8
7
6
5
4
3
2
1
0
POWER DISSIPATION (W)
PVDD = 24V,
8Ω LOAD
TOTAL OUTPUT POWER vs. PVDD
MAX9737 toc11
TOTAL OUTPUT POWER
vs. LOAD RESISTANCE
PVDD = 12V
16
TOTAL OUTPUT POWER (W)
14
12
10
8
6
4
1% THD+N
2
0
0
5
10
15
20
25
30
10% THD+N
MAX9737 toc12
TOTAL OUTPUT POWER
vs. LOAD RESISTANCE
10
TOTAL OUTPUT POWER (W)
9
8
7
6
5
4
3
2
1
0
0
5
10
15
20
25
30
1% THD+N
10% THD+N
PVDD = 8V
MAX9737 toc13
9
8
TOTAL OUTPUT POWER (W)
7
6
5
4
3
2
1
0
8
10
8Ω LOAD
f = 1kHz
10% THD+N
1% THD+N
18
11
12 14 16 18 20 22 24 26 28
SUPPLY VOLTAGE (V)
LOAD RESISTANCE (Ω)
LOAD RESISTANCE (Ω)
INBAND OUTPUT SPECTRUM
MAX9737 toc14
WIDEBAND OUTPUT SPECTRUM
-10
OUTPUT AMPLITUDE (dBV)
-20
-30
-40
-50
-60
-70
-80
8Ω LOAD
MAX9737 toc15
SUPPLY CURRENT
vs. PVDD SUPPLY VOLTAGE
18
16
SUPPLY CURRENT (mA)
14
12
10
8
6
4
2
0
MAX9737 toc16
20
8Ω LOAD
0
OUTPUT AMPLITUDE (dBV)
-20
-40
-60
-80
-100
-120
0
5k
10k
15k
FREQUENCY (Hz)
0
20
-90
-100
20k
100k
1M
10M
100M
FREQUENCY (Hz)
8
10 12 14 16 18 20 22 24 26 28
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
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