MAX9715 [MAXIM]
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier; 2.8W ，低EMI，立体声，无需滤波的D类音频放大器
| 型号： | MAX9715 |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | 2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier |
| 文件： | 总14页 (文件大小：549K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
19-3589; Rev 1; 8/05
2.8W, Low-EMI, Stereo, Filterless
Class D Audio Amplifier
General Description
Features
The MAX9715 high-efficiency, stereo, Class D audio
power amplifier provides up to 2.8W per channel into a
4Ω speaker with a 5V supply. Maxim’s second-generation
Class D technology features robust output protection,
high efficiency, and high power-supply rejection (PSRR)
while eliminating the need for output filters. Selectable
gain settings, +10.5dB or +9.0dB, adjust the amplifier
gain to suit the audio input level and speaker load.
♦ 5V Single-Supply Operation
♦ Patented Spread-Spectrum Modulator Reduces EMI
♦ 2.8W, Class D, Stereo Speaker Amplifier (4Ω)
♦ Filterless Class D Requires No LC Output Filter
♦ High PSRR (71dB at 1kHz)
♦ 86% Efficiency (R = 8Ω, P
= 1W)
OUT
L
The MAX9715 features high PSRR (71dB at 1kHz),
allowing for operation from noisy supplies without addi-
tional regulation. Comprehensive click-and-pop sup-
pression eliminates audible clicks and pops at startup
and shutdown. The MAX9715 operates from a single 5V
supply and consumes only 12mA of supply current.
Integrated shutdown control reduces supply current to
less than 100nA.
♦ Low-Power Shutdown Mode
♦ Integrated Click-and-Pop Suppression
♦ Low Total Harmonic Distortion: 0.06% at 1kHz
♦ Short-Circuit and Thermal Protection
♦ Internal Gain, +9.0dB or +10.5dB
The MAX9715 is fully specified over the extended
-40°C to +85°C temperature range and is available in
thermally enhanced 16-pin thin QFN-EP and 16-pin
TSSOP packages.
♦ Available in Space-Saving Packages
16-Pin Thin QFN-EP (5mm x 5mm x 0.8mm)
16-Pin TSSOP
Applications
Ordering Information
High-End Notebook Audio
LCD Projectors
PART
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 TQFN-EP*
16 TSSOP
MAX9715ETE+
MAX9715EUE+
Portable Audio
+Denotes lead-free package.
*EP = Exposed paddle.
Multimedia Docking Stations
Typical Operating Circuit/Functional Diagram appears at
end of data sheet.
Pin Configurations
Block Diagram
TOP VIEW
4.5V TO 5.5V SUPPLY
12
11
10
9
BIAS 13
8
7
6
5
SHDN
GND
GAIN
N.C.
OUTR+
INR
V
DD
14
15
OUTR-
MAX9715
GAIN
INL
CLASS D
AMPLIFIER
INR
OUTL+
OUTL-
INL 16
1
2
3
4
MAX9715
TQFN
Pin Configurations 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.
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
ABSOLUTE MAXIMUM RATINGS
V
, PV , to GND ...............................................................+6V
Continuous Power Dissipation (T = +70°C)
A
DD
DD
GND to PGND .......................................................-0.3V to +0.3V
Any Other Pin to PGND ............................. -0.3V to (V + 0.3V)
16-Pin TQFN-EP (derate 20.8mW/°C above +70°C)..1666mW
16-Pin TSSOP (derate 9.4mW/°C above +70°C) ......754.7mW
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
DD
Duration of OUT__ Short Circuit to PGND or PV ....Continuous
DD
Duration of OUT_+ Short Circuit between OUT_- ......Continuous
Continuous Current Into/Out of (PV , OUT__, PGND)........1.7A
DD
Continuous Input Current (All Other Pins) ....................... 20mA
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 = PV = 5.0V, GND = PGND = 0V, V
= V , C
= 1µF, speaker impedance = 8Ω in series with 68µH connected between
DD
DD
SHDN
DD BIAS
OUT_+ and OUT_-, GAIN = +10.5dB, T = T
to T
, unless otherwise noted. Typical values are at T = +25°C.) (Notes 1, 2)
A
MIN
MAX A
PARAMETER
GENERAL
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage Range
Quiescent Current
V
Inferred from PSRR test
No load
4.5
5.5
16
V
DD
I
12.8
0.1
10
mA
µA
kΩ
ms
V
DD
Shutdown Supply Current
Input Resistance
I
V
= 0V
SHDN
2
SHDN
R
6.5
13.5
IN
ON
Turn-On Time
t
25
BIAS Voltage
V
1.8
BIAS
CLASS D SPEAKER AMPLIFIERS
T
T
= +25°C
12.6
45
70
A
A
Output Offset Voltage
V
mV
dB
OS
= T
to T
MAX
MIN
GAIN = 0
GAIN = 1
10.5
9.0
Maximum Speaker Amplifier Gain
(Note 3)
A
V
PV
5.5V
or V
= 4.5V to
DD
DD
52.4
75
Power-Supply Rejection Ratio
Output Power
PSRR
V
= 0V
dB
IN_
f = 1kHz, 100mV
71
60
P-P
f = 20kHz, 100mV
P-P
R = 8Ω
L
1.4
2.3
1.7
2.8
0.06
0.07
89
THD+N = 1%
R = 4Ω
L
P
W
%
OUT
R = 8Ω
L
THD+N = 10%
f = 1kHz
R = 4Ω
L
R = 8Ω, P
= 1.2W
= 2W
L
OUT
Total Harmonic Distortion Plus
Noise
THD+N
SNR
R = 4Ω, P
L
OUT
P
P
= 1W, BW = 22Hz to 22kHz
= 1W, A-weighted
OUT
OUT
Signal-to-Noise Ratio
Maximum Capacitive Load
Switching Frequency
dB
pF
93
C
200
L_MAX
Average frequency in spread-spectrum
operation
f
1.00
1.22
1.40
MHz
SW
2
_______________________________________________________________________________________
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V = PV = 5.0V, GND = PGND = 0V, V
= V , C
= 1µF, speaker impedance = 8Ω in series with 68µH connected between
DD
DD
SHDN
MIN
DD BIAS
OUT_+ and OUT_-, GAIN = +10.5dB, T = T
to T , unless otherwise noted. Typical values are at T = +25°C.) (Notes 1, 2)
MAX A
A
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Spread-Spectrum Modulation
120
kHz
Channel-to-channel, f = 10kHz, P
left to right or right to left
= 1W,
OUT
Crosstalk
72
-64
-46
86
dB
dBV
%
Peak voltage,
A-weighted,
Into shutdown
Click-and-Pop Level
Efficiency
K
CP
32 samples per
second (Note 4)
Out of shutdown
R = 8Ω in series with 68µH, P
= 1W
L
OUT
η
per channel, f = 1kHz
DIGITAL INPUTS (GAIN and SHDN)
Input High Voltage
V
2.0
V
V
IH
Input Low Voltage
V
0.8
1
IL
SHDN
Input Leakage Current
I
µA
LEAK
GAIN
1.5
Note 1: All devices are 100% production tested at T = +25°C. All temperature limits are guaranteed by design.
A
Note 2: Speaker amplifier gain is defined as A = (V
- V
) / V .
OUT_- IN
V
OUT_+
Note 3: Click-and-pop level testing performed with an 8Ω resistive load in series with 68µH inductive load connected across the
Class D BTL outputs. Mode transitions are controlled by the SHDN pin. Inputs AC-coupled to GND.
Note 4: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For R = 4Ω, L = 33µH.
L
For R = 8Ω, L = 68µH.
L
Typical Operating Characteristics
(V
DD
= 5.0V, C
= 3 x 0.1µF, C
= 1µF, C
= C
= 1µF, A = +10.5dB, T = +25°C, unless otherwise noted.) (See the
VDD
BIAS
INL
INR V A
Typical Operating Circuit/Functional Diagram)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. FREQUENCY
100
10
1
1
V = 5V
DD
V
= 5V
DD
R = 8Ω
L
R = 4Ω
L
P
= 0.35W
OUT
P
= 0.5W
OUT
f
IN
= 1kHz AND 20Hz
0.1
0.01
0.1
0.01
1
P
= 2W
P
= 1.25W
OUT
OUT
0.1
f
IN
= 10kHz
0.01
V
= 5V
DD
R = 4Ω
L
0.001
0.001
0.001
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
OUTPUT POWER (W)
10
100
1k
10k
100k
10
100
1k
FREQUENCY (Hz)
10k
100k
FREQUENCY (Hz)
_______________________________________________________________________________________
3
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
Typical Operating Characteristics (continued)
(V
DD
= 5.0V, C
= 3 x 0.1µF, C
= 1µF, C
= C
= 1µF, A = +10.5dB, T = +25°C, unless otherwise noted.) (See the
VDD
BIAS
INL
INR V A
Typical Operating Circuit/Functional Diagram)
TOTAL HARMONIC DISTORTION
PLUS NOISE vs. OUTPUT POWER
EFFICIENCY
vs. OUTPUT POWER
100
10
100
90
80
70
60
50
40
30
20
10
0
R = 8Ω
f
= 1kHz
L
IN
R = 4Ω
L
f
IN
= 20Hz
1
0.1
f
IN
= 10kHz
V
DD
= 5V
f
= 1kHz
IN
0.01
P
OUT
= P
+ P
OUTL OUTR
V
DD
= 5V
OUTPUTS IN-PHASE
R = 8Ω
L
0.001
0
4
6
0
0.5
1.0
1.5
2.0
2.5
1
5
2
3
OUTPUT POWER (W)
OUTPUT POWER (W)
EFFICIENCY
OUTPUT POWER
vs. SUPPLY VOLTAGE
vs. LOAD RESISTANCE
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
100
V
= 5V
R = 8Ω
L
DD
90
80
70
60
50
40
30
20
10
0
f
= 1kHz
IN
L
LOAD
= 33µH
R = 4Ω
L
THD+N = 10%
f
P
= 1kHz
IN
OUT
= P
+ P
OUTL OUTR
OUTPUTS IN-PHASE
THD+N = 1%
THD+N = 1%
4.5
4.8
5.0
5.3
5.5
1
10
100
1k
SUPPLY VOLTAGE (V)
LOAD RESISTANCE (Ω)
OUTPUT POWER
vs. SUPPLY VOLTAGE
OUTPUT POWER
vs. SUPPLY VOLTAGE
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
2.5
2.0
1.5
1.0
0.5
0
THD+N = 10%
THD+N = 10%
THD+N = 1%
THD+N = 1%
f
= 1kHz
f
= 1kHz
IN
IN
R = 4Ω
L
R = 8Ω
L
4.5
4.8
5.0
5.3
5.5
4.5
4.8
5.0
5.3
5.5
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
4
_______________________________________________________________________________________
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
Typical Operating Characteristics (continued)
(V
DD
= 5.0V, C
= 3 x 0.1µF, C
= 1µF, C
= C
= 1µF, A = +10.5dB, T = +25°C, unless otherwise noted.) (See the
VDD
BIAS
INL
INR
V
A
Typical Operating Circuit/Functional Diagram)
POWER-SUPPLY REJECTION RATIO
CROSSTALK
vs. FREQUENCY
OUTPUT SPECTRUM
vs. FREQUENCY
vs. FREQUENCY
0
0
-20
-40
-60
-80
-40
-50
P
= 1W
R = 8Ω
OUT
L
R = 8Ω
L
-10
R = 8Ω
V
f
= 5V
= 1kHz
L
DD
IN
A = +10.5dB
-20
-30
-40
-50
-60
-70
-80
-90
-100
-60
f
= 10kHz
IN
-70
-80
-90
RIGHT TO LEFT
LEFT TO RIGHT
-100
-110
-120
-130
-140
-100
-120
0.01
0.1
1
10
100
0.01
0.1
1
10
100
0
5
10
15
20
FREQUENCY (Hz)
FREQUENCY (kHz)
FREQUENCY (kHz)
OUTPUT SPECTRUM
vs. FREQUENCY (A-WEIGHTED)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
WIDEBAND SPECTRUM
0
-20
-40
-50
20
18
16
14
12
10
8
R = 8Ω
DD
L
NO LOAD
INPUTS AC GROUNDED
V
= 5V
f
= 1kHz
IN
-60
-70
-40
-80
-60
-90
-100
-110
-120
-130
-140
-80
6
V
= 5V
4
DD
-100
-120
INPUTS AC GROUNDED
R = 8Ω
L
2
0
1
10
100
1000
0
5
10
15
20
4.5
4.8
5.0
5.3
5.5
FREQUENCY (MHz)
FREQUENCY (kHz)
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
Typical Operating Characteristics (continued)
(V
DD
= 5.0V, C
= 3 x 0.1µF, C
= 1µF, C
= C
= 1µF, A = +10.5dB, T = +25°C, unless otherwise noted.) (See the
VDD
BIAS
INL
INR
V
A
Typical Operating Circuit/Functional Diagram)
SHUTDOWN CURRENT
vs. SUPPLY VOLTAGE
POWER-ON/OFF WAVEFORM
MAX9715 toc17
0.40
SHDN
5V/div
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
I
OUT
200mA/div
4.5
4.8
5.0
5.3
5.5
10ms/div
SUPPLY VOLTAGE (V)
Pin Description
PIN
NAME
FUNCTION
TQFN
1, 12
2
TSSOP
4, 13
PGND
OUTL+
OUTL-
Power Ground
5
6
Left-Channel Positive Speaker Output
Left-Channel Negative Speaker Output
3
Positive Speaker Power-Supply Input. Power-supply input for speaker amplifier output stages.
Connect to V and bypass with 0.1µF to PGND.
DD
4, 9
7, 10
PV
DD
5
6
—
8
N.C.
GAIN
GND
No connection. Not internally connected.
Gain Select. Sets the internal amplifier gain. See the Gain Selection section.
Ground
7
1, 14
9
8
SHDN
OUTR-
Shutdown Control. Drive SHDN low to shut down the MAX9715.
Right-Channel Negative Speaker Output
10
11
13
14
15
16
EP
11
12
15
16
2
OUTR+ Right-Channel Positive Speaker Output
BIAS Bias Voltage Output. V = 1.8V, bypass BIAS to GND with a 1µF ceramic capacitor.
BIAS
V
Positive Power-Supply Input. Bypass to GND with a 0.1µF ceramic capacitor.
Right-Channel Input
DD
INR
INL
EP
3
Left-Channel Input
—
Exposed Paddle. Connect EP to an electrically isolated copper pad or GND.
6
_______________________________________________________________________________________
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
50
45
40
35
30
25
20
15
280
120
240
30
60
100
140 160 180
FREQUENCY (MHz)
220
260
300
80
200
Figure 1. MAX9715 Radiated Emissions with 75mm of Speaker Cable
Detailed Description
The MAX9715 2.8W, Class D speaker amplifier with
gain control offers Class AB performance with Class D
efficiency while occupying minimal board space. A
unique modulation scheme and spread-spectrum
switching allow filterless operation to create a compact,
flexible, low-noise, efficient audio power amplifier. The
MAX9715 features high 71dB at 1kHz PSRR, low 0.06%
THD+N, industry-leading click-and-pop performance
and a low-power shutdown mode.
V
= 0V
IN
OUT-
OUT+
The MAX9715 features an undervoltage lockout that pre-
vents operation from an insufficient power supply and
click-and-pop suppression that eliminates audible tran-
sients at startup and shutdown. The speaker amplifier
includes thermal-overload and short-circuit protection.
V
- V = 0V
OUT+ OUT-
The MAX9715 features unique, spread-spectrum opera-
tion that reduces the amplitude of spectral components at
high frequencies, reducing EMI emissions that might oth-
erwise be radiated by the speaker and cables. The
switching frequency varies randomly by 120kHz around
the center frequency (1.22MHz). The modulation scheme
is consistent with Maxim’s Class D amplifiers but the peri-
od of the triangle waveform changes from cycle to cycle.
Audio reproduction is not affected by the spread-spec-
trum switching scheme. Instead of a large amount of
spectral energy present at multiples of the switching fre-
quency that energy is now spread over a range of fre-
quencies. The spreading is increased with frequency so
that above a few megahertz, the wideband spectrum
looks like white noise for EMI purposes (Figure 1).
Figure 2. MAX9715 Output without Input Signal Applied
Filterless Modulation/Common-Mode Idle
The spread-spectrum modulation scheme eliminates the
LC filter required by traditional Class D amplifiers, improv-
ing efficiency, reducing component count, conserving
board space and system cost. Conventional Class D
amplifiers output a 50% duty cycle square wave when no
signal is present. With no filter, the output square wave
appears across the load, resulting in finite load current,
which increases power consumption. When no signal is
present at the input, the MAX9715 outputs switch as
shown in Figure 2. The two outputs cancel each other
because the MAX9715 drives the speaker differently,
minimizing power consumption as there is no net idle-
mode voltage across the speaker.
_______________________________________________________________________________________
7
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
Efficiency
EFFICIENCY
Efficiency of a Class D amplifier is attributed to the region
vs. OUTPUT POWER
of operation of the output-stage transistors. In a Class D
100
amplifier, the output transistors act as current-steering
90
MAX9715
switches and consume negligible additional power. Any
80
power loss associated with the Class D output stage is
mostly due to the I2R loss of the MOSFET on-resistance,
70
switching losses, and quiescent current overhead.
60
50
40
30
20
10
0
The theoretical best efficiency of a linear amplifier is
78%, however, that efficiency is only exhibited at peak
output powers. Under normal operating levels (typical
music or voice reproduction levels), efficiency falls
below 30%. Under the same conditions, the MAX9715
still exhibits >80% efficiencies (Figure 3).
CLASS AB
V
= 5V
DD
L
R = 8Ω
f
= 1kHz
IN
0
0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00
OUTPUT POWER (W)
Gain Selection
Drive GAIN high to set the gain of the speaker ampli-
fiers to +9dB, drive GAIN low to set the gain of the
speaker amplifiers to +10.5dB (see Table 1). The gain
of the MAX9715 is calculated by the following equation:
Figure 3. MAX9715 Class D Efficiency vs. Typical Class AB
Efficiency
V
− V
OUT−
OUT+
20 × log
Table 1. MAX9715 Maximum Gain Settings
V
IN
GAIN
SPEAKER MODE GAIN (dB)
Table 2 shows the speaker amplifier input voltage need-
ed to attain maximum output power from a given gain set-
ting and load.
0
1
+10.5
+9.0
Shutdown
The MAX9715 features a 0.1µA low-power shutdown
mode that reduces quiescent current consumption and
extends battery life. Driving SHDN low disables the out-
put amplifiers, bias circuitry, and drives BIAS to GND.
Connect SHDN to logic 1 for normal operation.
Table 2. MAX9715 Input Voltage and Gain
Settings for Maximum Output Power
GAIN (dB)
10.5
INPUT (V
)
R (Ω)
P
(W)
OUT
RMS
L
0.90
4
4
8
8
2.3
9.0
1.08
2.3
1.4
1.4
Click-and-Pop Suppression
The MAX9715 speaker amplifiers feature Maxim’s com-
prehensive, industry-leading click-and-pop suppression
that eliminates any audible transients at startup. The out-
puts are high-impedance while in shutdown. During
startup or power-up, the modulator bias voltage is set to
the correct level while the input amplifiers are muted. The
input amplifiers are muted for 25ms allowing the input
10.5
1.00
9.0
1.19
amplifier, and can decrease efficiency. The traditional
PWM scheme uses large differential output swings (2 x
V
), which causes large ripple currents. Any para-
DD(P-P)
sitic resistance in the filter components results in a loss
of power, lowering the efficiency.
capacitors to charge to the bias voltage (V
). The
BIAS
amplifiers are then unmuted, ensuring click-free startup.
The MAX9715 does not require an output filter. The
device relies 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. The elimination of the output filter
results in a smaller, less costly, more efficient solution.
Applications Information
Filterless Operation
Traditional Class D amplifiers require an output filter to
recover the audio signal from the amplifier’s PWM output.
The filters add cost, increase the solution size of the
8
_______________________________________________________________________________________
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
Voice coil movement due to the square-wave frequency
is very small because the switching frequency of the
MAX9715 is well beyond the bandwidth of most speak-
ers. Although this movement is small, a speaker not
designed to handle the additional power may be
damaged. Use a speaker with a series inductance
> 30µH for optimum efficiency. Typical 8Ω speakers
exhibit series inductances in the 30µH to 100µH range.
The highest efficiency is achieved with speaker induc-
tances > 60µH.
R
is the amplifier’s internal input resistance value given
IN
in the Electrical Characteristics table. Choose C so
IN
f
is well below the lowest frequency of interest.
-3dB
Setting f
too high affects the amplifier’s low-frequency
-3dB
response. Use capacitors with low-voltage coefficient
dielectrics, such as tantalum or aluminum electrolytic.
Capacitors with high-voltage coefficients, such as ceram-
ics, may result in increased distortion at low frequencies.
The inability of small diaphragm speakers to reproduce
low frequencies can be exploited to improve click-and-
pop performance. Set the cutoff frequency of the
MAX9715’s input highpass filter to match the speaker’s
frequency response. Doing so will allow for smaller C
values and reduce click-and-pop.
Component Selection
Input Filter
IN
The input capacitor (C ), in conjunction with the amplifier
IN
input resistance (R ), forms a highpass filter that
IN
removes the DC bias from an incoming signal (see the
Typical Application Circuit). The AC-coupling 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:
Output Filter
The MAX9715 speaker amplifiers do not require output
filters. However, output filtering can be used if a design
is failing radiated emissions due to board layout, cable
length, or the circuit is near EMI-sensitive devices. Use
a ferrite bead filter or a common-mode choke when radi-
ated frequencies above 10MHz are of concern. Use an
LC filter when radiated frequencies below 10MHz are of
concern, or when long cables (>75mm) connect the
amplifier to the speaker. Figure 4 shows possible output
filter connections.
1
f
=
−3dB
2π × R × C
IN
IN
OUTL+
OUTL-
OUTL+
OUTL-
OUTL+
OUTL-
MAX9715
MAX9715
MAX9715
OUTR+
OUTR-
OUTR+
OUTR-
OUTR+
OUTR-
(a)
(b)
COMMON-MODE CHOKE FOR
APPLICATIONS USING CABLE LENGTHS
GREATER THAN 150mm.
(c)
TYPICAL APPLICATION
<75mm OF SPEAKER CABLE.
LC FILTER WHEN USING LONG CABLE
LENGTHS OR IN APPLICATIONS
THAT ARE SENSITIVE TO EMI.
Figure 4. Optional Speaker Amplifier Output Filter—Guidelines for FCC Compliance
_______________________________________________________________________________________
9
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
heat conduction path from the die to the PC board.
Supply Bypassing, Layout,
and Grounding
Connect the exposed thermal pad to an electrically iso-
lated pad of copper. A bigger pad area provides better
thermal performance. Connect EP to GND if PC board
layout rules do not allow for isolated pads of copper. If
EP is connected to GND, ensure that high-current return
paths do not flow through EP.
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. Large traces also aid in moving
heat away from the package. Proper grounding improves
audio performance, minimizes crosstalk between chan-
nels, and prevents any switching noise from coupling into
the audio signal. Route ground return paths that carry
switching transients to power ground (PGND). Keep high-
current return paths that connect to PGND short and
route them away from analog ground (GND) and any
traces or components in the audio input signal path. Use
a star connection to connect GND and PGND together at
one point on the PC board.
Biamp Configuration
The Typical Application Circuit shows the MAX9715
configured as a mid-/high-frequency amplifier and the
MAX9713 is configured as a mono bass amplifier.
Capacitors C1 and C2 set the highpass cutoff frequen-
cy according to the following equation:
1
f =
2π × R × C1
IN
Bypass each PV
with a 0.1µF capacitor to PGND.
DD
Bypass V
to GND with a 0.1µF capacitor. Place a bulk
DD
where R is the input resistance of the MAX9715 and
IN
capacitor between V
and PGND. Place the bypass
DD
C1 = C2. The 10µF capacitors on the output of the
MAX9715 ensure a two-pole roll-off with the 5Ω load
shown.
capacitors as close to the MAX9715 as possible.
Use large, low-resistance output traces. Current drawn
from the output increases as load impedance decreases.
High-output-trace resistance decreases the power deliv-
ered to the load. For example, when compared to a 0Ω
trace, a 100mΩ trace reduces the power delivered to a
4Ω load from 2.1W to 2.0W. Large output, supply, and
GND traces decrease the thermal impedance of the cir-
cuit and allow more heat to be radiated from the MAX9715
to the air.
The stereo signal is summed to a mono signal and then
sent to a two-pole lowpass filter. The filtered signal is
then amplified by the MAX9713. The passband gain of
the lowpass filter, for coherent left and right signals is
(-2 x R3) / R1, where R1 = R2. The cutoff frequency of
the lowpass filter is set by the following equation:
1
2π
1
f =
×
The MAX9715 thin QFN-EP package features an
exposed thermal pad on its underside. This pad lowers
the package’s thermal impedance by providing a direct-
C3 × C4 × R3 × R4
10 ______________________________________________________________________________________
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
Typical Application Circuit
5V
22µF
22µF
C1
15nF
LEFT IN
8Ω
8Ω
C2
15nF
MAX9715
RIGHT IN
R3
7.5kΩ
C4
2.2nF
C5
1µF
R1
15kΩ
R4
15kΩ
12V
C6
1µF
1µF
1µF
R2
15kΩ
C3
22nF
2.5V
MAX4480
MAX9713
______________________________________________________________________________________ 11
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
Typical Operating Circuit/Functional Diagram
4.5V TO 5.5V
SHUTDOWN
CONTROL
0.1µF
0.1µF
0.1µF
*
V
DD
PV
DD
PV
DD
SHDN
SHDN
CONTROL
MAX9715
1µF
1µF
OUTL+
OUTL-
V
R
DD
DD
IN
CLASS D
MODULATOR
AND H-BRIDGE
INL
LEFT
AUDIO
GAIN-SELECT
LOGIC
GAIN
GAIN
SELECT
V
BIAS
OSCILLATOR
V
OUTR+
OUTR-
CLASS D
MODULATOR
AND H-BRIDGE
R
IN
INR
RIGHT
AUDIO
V
BIAS
BIAS
BIAS
GENERATOR
GND
PGND
PGND
1µF
*BULK PC BOARD DECOUPLING, TYPICALLY GREATER THAN 10µF.
Pin Configurations (continued)
Chip Information
TRANSISTOR COUNT: 11,721
PROCESS: BiCMOS
TOP VIEW
GND
1
2
3
4
5
6
7
8
16 V
DD
INR
INL
15 BIAS
14 GND
PGND
OUTL+
OUTL-
MAX9715
13 PGND
12 OUTR+
11 OUTR-
PV
DD
10 PV
DD
GAIN
9
SHDN
TSSOP
12 ______________________________________________________________________________________
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
D2
D
b
0.10 M
C A B
C
L
D2/2
D/2
k
L
MARKING
XXXXX
E/2
E2/2
C
(NE-1) X
e
L
E2
E
PIN # 1 I.D.
0.35x45°
DETAIL A
e/2
PIN # 1
I.D.
e
(ND-1) X
e
DETAIL B
e
L
C
C
L
L1
L
L
L
e
e
0.10
C
A
0.08
C
C
A3
A1
PACKAGE OUTLINE,
16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
1
21-0140
H
-DRAWING NOT TO SCALE-
2
COMMON DIMENSIONS
20L 5x5 28L 5x5
EXPOSED PAD VARIATIONS
D2 E2
MIN. NOM. MAX. MIN. NOM. MAX. ±0.15
PKG.
SYMBOL MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX.
16L 5x5
32L 5x5
40L 5x5
DOWN
BONDS
ALLOWED
L
PKG.
CODES
A
0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80
T1655-1
T1655-2
3.00 3.10 3.20 3.00 3.10 3.20
3.00 3.10 3.20 3.00 3.10 3.20
NO
**
**
**
**
A1
A3
b
0
0.02 0.05
0.20 REF.
0
0.02 0.05
0.20 REF.
0
0.02 0.05
0.20 REF.
0
0.02 0.05
0.20 REF.
0
0.02 0.05
0.20 REF.
YES
NO
T1655N-1 3.00 3.10 3.20 3.00 3.10 3.20
0.25 0.30 0.35 0.25 0.30 0.35 0.20 0.25 0.30 0.20 0.25 0.30 0.15 0.20 0.25
4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10
4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10
T2055-2
T2055-3
T2055-4
T2055-5
3.00 3.10 3.20 3.00 3.10 3.20
3.00 3.10 3.20 3.00 3.10 3.20
3.00 3.10 3.20 3.00 3.10 3.20
NO
YES
NO
D
E
**
**
e
0.80 BSC.
0.25
0.65 BSC.
0.25
0.50 BSC.
0.25
0.50 BSC.
0.25
0.40 BSC.
YES
3.15 3.25 3.35 3.15 3.25 3.35 0.40
k
-
-
-
-
-
-
-
-
0.25 0.35 0.45
T2855-1
T2855-2
3.15 3.25 3.35 3.15 3.25 3.35
2.60 2.70 2.80 2.60 2.70 2.80
NO
NO
L
**
**
**
**
0.30 0.40 0.50 0.45 0.55 0.65 0.45 0.55 0.65 0.30 0.40 0.50 0.40 0.50 0.60
L1
-
-
-
-
-
-
-
-
-
-
-
-
0.30 0.40 0.50
40
T2855-3
T2855-4
3.15 3.25 3.35 3.15 3.25 3.35
2.60 2.70 2.80 2.60 2.70 2.80
2.60 2.70 2.80 2.60 2.70 2.80
3.15 3.25 3.35 3.15 3.25 3.35
YES
YES
NO
N
ND
NE
16
20
28
32
4
4
5
5
7
7
8
8
10
10
T2855-5
T2855-6
T2855-7
T2855-8
**
**
**
WHHB
WHHC
WHHD-1
WHHD-2
-----
JEDEC
NO
YES
2.80
3.35
3.35
3.20
2.60 2.70
3.15 3.25
2.60 2.70 2.80
3.15 3.25 3.35
3.15 3.25 3.35
3.00 3.10 3.20
0.40
YES
NO
NO
NOTES:
T2855N-1 3.15 3.25
**
**
**
1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.
2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.
3. N IS THE TOTAL NUMBER OF TERMINALS.
T3255-2
T3255-3
T3255-4
3.00 3.10
3.00 3.10 3.20 3.00 3.10 3.20
3.00 3.10 3.20 3.00 3.10 3.20
YES
NO
**
**
**
4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL
CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE
OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1
IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE.
NO
T3255N-1 3.00 3.10 3.20 3.00 3.10 3.20
T4055-1 3.20 3.30 3.40 3.20 3.30 3.40
YES
**SEE COMMON DIMENSIONS TABLE
5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN
0.25 mm AND 0.30 mm FROM TERMINAL TIP.
6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.
7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.
8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
9. DRAWING CONFORMS TO JEDEC MO220, EXCEPT EXPOSED PAD DIMENSION FOR T2855-1,
T2855-3, AND T2855-6.
10. WARPAGE SHALL NOT EXCEED 0.10 mm.
11. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY.
12. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY.
13. LEAD CENTERLINES TO BE AT TRUE POSITION AS DEFINED BY BASIC DIMENSION "e", ±0.05.
PACKAGE OUTLINE,
16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
2
-DRAWING NOT TO SCALE-
21-0140
H
2
______________________________________________________________________________________ 13
2.8W, Low-EMI, Stereo, Filterless Class D
Audio Amplifier
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
PACKAGE OUTLINE, TSSOP 4.40mm BODY
1
21-0066
G
1
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.
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