19-3887; Rev 0; 2/06
KIT
ATION
EVALU
BLE
AVAILA
12W+12W, Low-EMI, Spread-Spectrum,
Stereo, Class D Amplifier
General Description
Features
♦
Low-EMI Class D Amplifier
♦
Spread-Spectrum Mode Reduces EMI
♦
Passes FCC EMI Limits with Ferrite Bead Filters
with 0.5m Cables
♦
12W+12W Continuous Output Power into 8Ω
♦
Low 0.1% THD+N
♦
High PSRR (80dB at 1kHz)
♦
10V to 25V Single-Supply Operation
♦
Differential Inputs Minimize Common-Mode Noise
♦
Pin-Selectable Gain Reduces Component Count
♦
Industry-Leading Click-and-Pop Suppression
♦
Short-Circuit and Thermal-Overload Protection
♦
Available in Thermally Efficient, Space-Saving
56-Pin TQFN (8mm x 8mm x 0.8mm) Package
MAX9741
The MAX9741 stereo Class D audio power amplifier
provides Class AB amplifier performance with Class D
efficiency, conserving board space and eliminating the
need for a bulky heatsink. Using a high-efficiency Class
D architecture, it delivers 12W continuous output power
into 8Ω loads. Proprietary modulation and switching
schemes render the traditional Class D EMI suppression
output filter unnecessary.
The MAX9741 offers two modulation schemes: a fixed-fre-
quency mode (FFM), and a spread-spectrum mode (SSM)
that reduces EMI-radiated emissions. The device utilizes a
fully differential architecture, a full bridged output, and
offers comprehensive click-and-pop suppression.
The MAX9741 features high 80dB PSRR, low 0.1%
THD+N, and SNR in excess of 100dB. Short-circuit and
thermal-overload protection prevent the device from
being damaged during a fault condition. The MAX9741
is available in a 56-pin TQFN (8mm x 8mm x 0.8mm)
package. The MAX9741 is specified over the extended
-40°C to +85°C temperature range.
Applications
LCD/PDP TVs
CRT TVs
PC Speakers
PART
MAX9741ETN+
Ordering Information
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
56 TQFN-EP*
PKG
CODE
T5688-3
+Denotes
lead-free package.
*EP
= Exposed paddle.
Simplified Block Diagram
INR+
DIFFERENTIAL AUDIO
INPUTS ELIMINATE
NOISE PICKUP
INR-
INL+
INL-
GAIN
CONTROL
G1
G2
PROGRAMMABLE
SWITCHING
FREQUENCY
2
OUTPUT
PROTECTION
CLASS D
AMPLIFIERS
DRIVE 2 X 12W
INTO 8Ω LOADS
CLASS D
MODULATOR
FS1, FS2
MAX9741
Pin Configuration appears 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.
12W+12W, Low-EMI, Spread-Spectrum,
Stereo, Class D Amplifier
MAX9741
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.)
V
DD
to PGND, AGND .............................................................30V
OUTR_, OUTL_, C1N..................................-0.3V to (V
DD
+ 0.3V)
C1P............................................(V
DD
- 0.3V) to (CHOLD + 0.3V)
CHOLD ........................................................(V
DD
- 0.3V) to +40V
SHDN, FS_, G_ ...........................................................-6.3V to 8V
All Other Pins to GND.............................................-0.3V to +12V
Duration of OUTR_/OUTL_
Short Circuit to GND, V
DD
......................................Continuous
Continuous Input Current (V
DD
, PGND) ..................................2A
Continuous Input Current (all other pins)..........................±20mA
Thermal Limits (Note 1)
Continuous Power Dissipation (T
A
= +70°C)
Single-Layer PC Board
56-Pin TQFN (derate 28.6mW/°C above +70°C) ............2.29W
θ
JA
................................................................................ 35°C/W
θ
JC
............................................................................... 0.6°C/W
Continuous Power Dissipation (T
A
= +70°C)
Multiple-Layer PC Board
56-Pin TQFN (derate 47.6mW/°C above +70°C) ............3.81W
θ
JA
................................................................................ 21°C/W
θ
JC
............................................................................... 0.6°C/W
Junction Temperature ......................................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1:
Thermal performance of this device is highly dependant on PC board layout. See the
Applications Information
for more
detail.
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
DD
= 18V, GND = PGND = 0V,
SHDN
≥
V
IH
, A
V
= 16dB, C
SS
= C
IN
= 0.47µF, C
REG
= 0.01µF, C1 = 100nF, C2 = 1µF, FS1 = FS2 =
GND (f
S
= 670kHz), R
L
connected between OUTL+ and OUTL- and OUTR+ and OUTR-, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
GENERAL
Supply Voltage Range
Quiescent Current
Shutdown Current
Turn-On Time
Amplifier Output Resistance in
Shutdown
V
DD
I
DD
I
SHDN
t
ON
C
SS
= 470nF
C
SS
= 180nF
SHDN
= GND
A
V
= 13dB
Input Impedance
R
IN
A
V
= 16dB
A
V
= 19.1dB
A
V
= 29.6dB
G1 = L, G2 = L
Voltage Gain
A
V
G1 = L, G2 = H
G1 = H, G2 = L
G1 = H, G2 = H
Gain Matching
Output Offset Voltage
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
(Note 3)
V
OS
CMRR
PSRR
f
IN
= 1kHz, input referred
V
DD
= 10V to 25V
200mV
P-P
ripple
f
RIPPLE
= 1kHz
f
RIPPLE
= 20kHz
48
Between channels
150
35
30
23
10
29.4
18.9
12.8
15.9
Inferred from PSRR test
R
L
= Open
10
26
0.2
100
50
320
53
45
36
14.3
29.6
19.1
13
16
0.5
±5
60
83
80
60
dB
±30
80
65
55
22
29.8
19.3
13.2
16.3
%
mV
dB
dB
kΩ
25
37
1.5
V
mA
µA
ms
kΩ
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
12W+12W, Low-EMI, Spread-Spectrum,
Stereo, Class D Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 18V, GND = PGND = 0V,
SHDN
≥
V
IH
, A
V
= 16dB, C
SS
= C
IN
= 0.47µF, C
REG
= 0.01µF, C1 = 100nF, C2 = 1µF, FS1 = FS2 =
GND (f
S
= 670kHz), R
L
connected between OUTL+ and OUTL- and OUTR+ and OUTR-, T
A
= T
MIN
to T
MAX
, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
V
DD
= 18V, THD+N =
10%, f = 1kHz
Continuous Output Power
(Notes 4, 5)
P
CONT
V
DD
= 24V, THD+N =
10%, f = 1kHz
V
DD
= 12V, THD+N =
10%, f = 1kHz
Total Harmonic Distortion Plus
Noise
THD+N
R
L
= 8Ω
R
L
= 4Ω
R
L
= 8Ω
R
L
= 4Ω
R
L
= 8Ω
R
L
= 4Ω
MIN
TYP
12
6.5
11
5
8
8.5
0.1
95.8
91.8
99.1
95.7
65
560
670
930
470
670
±7%
78
%
V
DD
= 18V, R
L
= 8Ω, P
OUT
= 10W
78
6
V
IH
V
IL
2.5
0.8
±1
V
kHz
800
dB
dB
%
W
MAX
UNITS
MAX9741
f
IN
= 1kHz, either FFM or SSM, R
L
= 8Ω,
P
OUT
= 4W
R
L
= 8Ω,
P
OUT
= 4W,
f = 1kHz
BW = 22Hz to 22kHz
Unweighted
A-weighted
FFM
SSM
FFM
SSM
Signal-to-Noise Ratio
SNR
Crosstalk
Left to right, right to left, 8Ω load, f
IN
= 10kHz
FS1 = L, FS2 = L
FS1 = L, FS2 = H
Oscillator Frequency
f
OSC
FS1 = H, FS2 = L
FS1 = H, FS2 = H (spread-spectrum mode)
Efficiency (Note 4)
Regulator Output
DIGITAL INPUTS (SHDN, FS_, G_)
Input Thresholds
Input Leakage Current
η
V
REG
V
DD
= 12V, R
L
= 8Ω, P
OUT
= 8W
V
µA
Note 2:
All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design.
Note 3:
PSRR is specified with the amplifier inputs connected to GND through C
IN
.
Note 4:
Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For R
L
= 8Ω, L = 68µH.
For R
L
= 12Ω, L = 100µH. For R
L
= 16Ω, L = 120µH.
Note 5:
Output power measured at T
A
= +25°C, with a soak time of 15 minutes.
_______________________________________________________________________________________
3
12W+12W, Low-EMI, Spread-Spectrum,
Stereo, Class D Amplifier
MAX9741
Typical Operating Characteristics
(V
DD
= 18V, R
L
= 8Ω, f
IN
= 1kHz, 33µH with 4Ω, 68µH with 8Ω, part in SSM mode, 136µH with 16Ω, measurement BW = 22Hz to
22kHz, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9741 toc01
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9741 toc02
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9741 toc03
10
R
L
= 8Ω
V
DD
= 12V
V
DD
= 18V
10
R
L
= 4Ω
V
DD
= 12V
1
THD+N (%)
V
DD
= 18V
10
1
THD+N (%)
THD+N (%)
V
DD
= 24V
1
V
DD
= 24V
P
OUT
= 8W
0.1
0.1
0.1
P
OUT
= 500mW
0.01
0
5
10
OUTPUT POWER (W)
15
20
0.01
0
5
10
15
OUTPUT POWER (W)
0.01
10
100
1k
FREQUENCY (Hz)
10k
100k
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX974 toc04
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9741 toc05
EFFICIENCY vs. OUTPUT POWER
90
80
EFFICIENCY (%)
70
60
50
40
30
V
DD
= 18V
V
DD
= 24V
V
DD
= 12V
R
L
= 8Ω
MAX9741 toc06
10
10
100
P
OUT
= 8W
THD+N (%)
1
THD+N (%)
SSM
1
f = 100Hz
f = 10kHz
0.1
FFM
f = 1kHz
0.01
10
100
1k
FREQUENCY (Hz)
10k
100k
0
5
10
OUTPUT POWER (W)
15
20
0.1
20
10
0.01
0
0
4
8
OUTPUT POWER (W)
12
16
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX9741 toc07
OUTPUT POWER vs. LOAD RESISTANCE
18
16
OUTPUT POWER (W)
14
12
10
8
6
4
2
0
-70
-80
1
10
LOAD RESISTANCE (Ω)
100
10
THD+N = 1%
CMRR (dB)
-30
-40
-50
-60
MAX9741 toc08
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
-10
-20
MAX9741 toc09
20
18
16
OUTPUT POWER (W)
14
12
10
8
6
4
2
0
10
13
16
19
SUPPLY VOLTAGE (V)
22
R
L
= 16Ω
R
L
= 8Ω
20
THD+N = 10%
0
25
100
1k
FREQUENCY (Hz)
10k
100k
4
_______________________________________________________________________________________
12W+12W, Low-EMI, Spread-Spectrum,
Stereo, Class D Amplifier
MAX9741
Typical Operating Characteristics (continued)
(V
DD
= 18V, R
L
= 8Ω, f
IN
= 1kHz, 33µH with 4Ω, 68µH with 8Ω, part in SSM mode, 136µH with 16Ω, measurement BW = 22Hz to
22kHz, unless otherwise noted.)
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX9741 toc10
CROSSTALK vs. FREQUENCY
MAX9741 toc11
OUTPUT FREQUENCY SPECTRUM
0
OUTPUT MAGNITUDE (dB)
-20
-40
-60
-80
-100
-120
-140
0
2
4
6
8
10 12 14 16 18 20
FFM MODE
UNWEIGHTED
f
IN
= 1kHz
P
OUT
= 5W
MAX9741 toc12
0
200mV
P-P
INPUT
-20
-40
PSRR (dB)
-60
-80
-100
-120
10
100
1k
FREQUENCY (Hz)
10k
0
-20
CROSSTALK (dB)
-40
LEFT TO RIGHT
-60
-80
RIGHT TO LEFT
-100
-120
20
100k
10
100
1k
FREQUENCY (Hz)
10k
100k
FREQUENCY (kHz)
OUTPUT FREQUENCY SPECTRUM
MAX941 toc13
OUTPUT FREQUENCY SPECTRUM
MAX9741 toc14
WIDEBAND OUTPUT SPECTRUM
(FFM MODE)
RBW = 10kHz
-20
OUTPUT AMPLITUDE (dBV)
-40
-60
-80
-100
-120
MAX9741 toc15
20
0
OUTPUT MAGNITUDE (dB)
-20
-40
-60
-80
-100
-120
-140
0
2
4
6
8
OUTPUT MAGNITUDE (dB)
SSM MODE
UNWEIGHTED
f
IN
= 1kHz
P
OUT
= 5W
20
0
-20
-40
-60
-80
-100
-120
-140
SSM MODE
A-WEIGHTED
f
IN
= 1kHz
P
OUT
= 5W
0
10 12 14 16 18 20
0
2
4
FREQUENCY (kHz)
6 8 10 12 14 16 18 20
FREQUENCY (kHz)
100k
1M
10M
100M
FREQUENCY (Hz)
_______________________________________________________________________________________
5
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
