19-3039; Rev 6; 12/06
KIT
ATION
EVALU
E
L
B
A
AVAIL
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
Features
The MAX9713/MAX9714 mono/stereo Class D audio
power amplifiers provide Class AB amplifier performance
with Class D efficiency, conserving board space and
eliminating the need for a bulky heatsink. Using a Class
D architecture, these devices deliver up to 6W while
offering greater than 85% efficiency. Proprietary and protected modulation and switching schemes render the traditional Class D output filter unnecessary.
The MAX9713/MAX9714 offer two modulation schemes:
a fixed-frequency mode (FFM), and a spread-spectrum
mode (SSM) that reduces EMI-radiated emissions due
to the modulation frequency. The device utilizes a fully
differential architecture, a full bridged output, and comprehensive click-and-pop suppression.
The MAX9713/MAX9714 feature high 76dB PSRR, low
0.07% THD+N, and SNR in excess of 95dB. Short-circuit and thermal-overload protection prevent the
devices from being damaged during a fault condition.
The MAX9713 is available in a 32-pin TQFN (5mm x
5mm x 0.8mm) package. The MAX9714 is available in a
32-pin TQFN (7mm x 7mm x 0.8mm) package. Both
devices are specified over the extended -40°C to
+85°C temperature range.
♦ Filterless Class D Amplifier
♦ Unique Spread-Spectrum Mode Offers 5dB
Emissions Improvement Over Conventional
Methods
♦ Up to 85% Efficient
♦ 6W Output Power into 8Ω
♦ Low 0.07% THD+N
♦ High PSRR (76dB at 1kHz)
♦ 10V to 25V Single-Supply Operation
♦ Differential Inputs Minimize Common-Mode Noise
♦ Pin-Selectable Gain Reduces Component Count
♦ Industry-Leading Integrated Click-and-Pop
Suppression
♦ Low Quiescent Current (18mA)
♦ Low-Power Shutdown Mode (0.2µA)
♦ Short-Circuit and Thermal-Overload Protection
♦ Available in Thermally Efficient, Space-Saving
Packages
32-Pin TQFN (5mm x 5mm x 0.8mm)–MAX9713
32-Pin TQFN (7mm x 7mm x 0.8mm)–MAX9714
Applications
Ordering Information
LCD Monitors
High-End Notebook
Audio
LCD TVs
Hands-Free Car
Phone Adaptors
Desktop PCs
LCD Projectors
PART
TEMP RANGE
PIN-PACKAGE
AMP
MAX9713ETJ+
-40oC to +85oC
32 TQFN-EP*
Mono
MAX9714ETJ+
-40oC to +85oC
32 TQFN-EP*
Stereo
*EP = Exposed paddle.
+Denotes lead-free package.
Block Diagrams
0.47μF
IN+
OUTL+
H-BRIDGE
0.47μF
MAX9713
0.47μF
MAX9714
INL+
INL-
OUTL-
INR+
OUTR+
OUT+
H-BRIDGE
0.47μF
IN-
OUT-
0.47μF
H-BRIDGE
0.47μF
INR-
OUTR-
Pin Configurations appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX9713/MAX9714
General Description
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.)
VDD to PGND, AGND .............................................................30V
OUTR_, OUTL_, C1N..................................-0.3V to (VDD + 0.3V)
C1P............................................(VDD - 0.3V) to (CHOLD + 0.3V)
CHOLD ........................................................(VDD - 0.3V) to +40V
All Other Pins to GND.............................................-0.3V to +12V
Duration of OUTR_/OUTL_
Short Circuit to GND, VDD ......................................Continuous
Continuous Input Current (VDD, PGND, AGND) ...................1.6A
Continuous Input Current (all other pins)..........................±20mA
Continuous Power Dissipation (TA = +70°C)
Single-Layer Board:
MAX9713 32-Pin TQFN (derate 21.3mW/°C
above +70°C)..........................................................1702.1mW
MAX9714 32-Pin TQFN (derate 27mW/°C
above +70°C)..........................................................2162.2mW
Multilayer Board:
MAX9713 32-Pin TQFN (derate 34.5mW/°C
above +70°C)..........................................................2758.6mW
MAX9714 32-Pin TQFN (derate 37mW/°C
above +70°C)..........................................................2963.0mW
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
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
(VDD = 15V, GND = PGND = 0V, SHDN ≥ VIH, AV = 16dB, CSS = CIN = 0.47µF, CREG = 0.01µF, C1 = 100nF, C2 = 1µF, FS1 = FS2 =
GND (fS = 330kHz), RL connected between OUTL+ and OUTL- and OUTR+ and OUTR-, TA = TMIN to TMAX, unless otherwise noted.
Typical values are at TA = +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
25
V
MAX9713
10
17.5
MAX9714
18
23
0.2
1.5
GENERAL
Supply Voltage Range
VDD
Quiescent Current
IDD
Shutdown Current
ISHDN
Turn-On Time
tON
Amplifier Output Resistance in
Shutdown
Input Impedance
RIN
Inferred from PSRR test
RL = ∞
10
CSS = 470nF
100
CSS = 180nF
50
Voltage Gain
AV
Gain Matching
150
330
AV = 13dB
35
58
80
AV = 16dB
30
48
65
AV = 19.1dB
23
39
55
Output Offset Voltage
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
(Note 3)
2
20
31
42
21.9
22.1
22.3
G1 = L, G2 = H
18.9
19.1
19.3
G1 = H, G2 = L
12.8
13
13.2
G1 = H, G2 = H
15.9
16
16.3
0.5
VOS
CMRR
±6
fIN = 1kHz, input referred
VDD = 10V to 25V
PSRR
kΩ
G1 = L, G2 = L
Between channels (MAX9714)
200mVP-P ripple
60
54
µA
ms
SHDN = GND
AV = 22.1dB
mA
kΩ
dB
%
±30
mV
dB
76
fRIPPLE = 1kHz
76
fRIPPLE = 20kHz
60
_______________________________________________________________________________________
dB
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
(VDD = 15V, GND = PGND = 0V, SHDN ≥ VIH, AV = 16dB, CSS = CIN = 0.47µF, CREG = 0.01µF, C1 = 100nF, C2 = 1µF, FS1 = FS2 =
GND (fS = 330kHz), RL connected between OUTL+ and OUTL- and OUTR+ and OUTR-, TA = TMIN to TMAX, unless otherwise noted.
Typical values are at TA = +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
Output Power
POUT
Total Harmonic Distortion Plus
Noise
THD+N
Signal-to-Noise Ratio
SNR
CONDITIONS
THD+N = 10%,
f = 1kHz
MIN
RL = 16Ω
8
RL = 8Ω
6
fIN = 1kHz, either FFM or SSM, RL = 8Ω,
POUT = 4W
RL = 8Ω, POUT =
4W, f = 1kHz
BW = 22Hz to
22kHz
A-weighted
Efficiency
fOSC
η
MAX
94
SSM
88
FFM
97
SSM
UNITS
W
0.07
FFM
FS1 = L, FS2 = L
Oscillator Frequency
TYP
%
dB
91
300
335
FS1 = L, FS2 = H
460
FS1 = H, FS2 = L
236
FS1 = H, FS2 = H (spread-spectrum mode)
335
POUT = 5W, fIN = 1kHz, RL = 16Ω
85
POUT = 4W, f = 1kHz, RL = 8Ω
75
370
kHz
%
DIGITAL INPUTS (SHDN, FS_, G_)
VIH
Input Thresholds
VIL
Input Leakage Current
2.5
0.8
±1
V
µA
Note 1: All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design.
Note 2: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For RL = 8Ω, L = 68µH.
For RL = 16Ω, L = 136µH.
Note 3: PSRR is specified with the amplifier inputs connected to GND through CIN.
_______________________________________________________________________________________
3
MAX9713/MAX9714
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(136µH with 16Ω, 68µH with 8Ω, part in SSM mode, unless otherwise noted.)
VDD = +20V
AV = 13dB
RL = 8Ω
1
1
POUT = 4W
VDD = +15V
AV = 13dB
RL = 16Ω
1
POUT = 100mW
THD+N (%)
THD+N (%)
POUT = 100mW
10
THD+N (%)
VDD = +15V
AV = 13dB
RL = 8Ω
MAX9713 toc02
10
MAX9713 toc01
10
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9713 toc03
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
POUT = 4W
POUT = 5W
0.1
0.1
0.1
0.01
0.01
0.01
POUT = 55mW
10
100
1k
10k
10
100k
100
1k
10k
100k
10
100
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
VDD = +15V
AV = 13dB
POUT = 4W
RL = 8Ω
100
MAX9713 toc06
10
MAX9713 toc05
VDD = +20V
AV = 13dB
RL = 16Ω
VDD = 15V
AV = 13dB
RL = 8Ω
10
THD+N (%)
THD+N (%)
POUT = 7.5W
THD+N (%)
1
1
SSM
0.1
0.1
1
f = 1kHz
f = 10kHz
0.1
f = 100Hz
0.01
FFM
POUT = 120mW
0.01
0.01
10
100
1k
10k
100
1k
100k
0
1
2
3
4
5
6
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
1
f = 1kHz
0.1
f = 10kHz
f = 10kHz
f = 100Hz
3
4
5
OUTPUT POWER (W)
6
f = 1kHz
0.1
f = 10kHz
7
f = 100Hz
0.01
f = 100Hz
0.001
2
1
f = 10kHz
0.01
0.001
1
VDD = 20V
AV = 13dB
RL = 16Ω
10
THD+N (%)
THD+N (%)
0.1
VDD = 15V
AV = 13dB
RL = 16Ω
10
100
MAX9713 toc08
100
7
MAX9713 toc09
OUTPUT POWER (W)
f = 1kHz
0
0.001
FREQUENCY (Hz)
1
0.01
10k
FREQUENCY (Hz)
VDD = 20V
AV = 13dB
RL = 8Ω
10
10
100k
MAX9713 toc07
100
4
1k
FREQUENCY (Hz)
MAX9713 toc04
10
THD+N (%)
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
0.001
0
2
4
OUTPUT POWER (W)
6
8
0
5
10
OUTPUT POWER (W)
_______________________________________________________________________________________
15
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
70
RL = 8Ω
60
50
40
30
FFM
0.01
0.001
4
6
8
2
4
6
8
0
10
0
3
6
9
12
OUTPUT POWER
vs. SUPPLY VOLTAGE
OUTPUT POWER
vs. LOAD RESISTANCE
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
3
2
AV = 13dB
THD+N = 10%
RL = 8Ω
-30
6
5
4
3
22
-70
1
-80
-90
1
25
10
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX9713 toc16
0
-20
CROSSTALK (dB)
-20
-30
-40
-50
OUTPUT REFERRED
AV = 13dB
-40
-60
LEFT TO RIGHT
-80
FREQUENCY (Hz)
10k
100k
10k
100k
20
FFM MODE
POUT = 5W
f =1kHz
RL = 8Ω
UNWEIGHTED
0
-20
-40
-60
-80
-100
-120
-120
-70
1k
OUTPUT FREQUENCY SPECTRUM
RIGHT TO LEFT
1k
100
FREQUENCY (Hz)
-100
-60
100
10
CROSSTALK vs. FREQUENCY
VDD = 15V
AV = 13dB
VRIPPLE = 200mVP-P
RL = 16Ω
-10
100
LOAD RESISTANCE (Ω)
SUPPLY VOLTAGE (V)
0
-50
2
OUTPUT MAGNITUDE (dB)
19
-40
-60
THD+N = 1%
0
16
VDD = 15V
AV = 13dB
RL = 8Ω
-20
7
MAX9713 toc17
13
THD+N = 10%
8
0
-10
CMRR (dB)
4
VDD = 15V
AV = 13dB
9
MAX9713 toc14
10
MAX9713 toc13
5
10
VDD = 20V
AV = 13dB
10
OUTPUT POWER (W)
OUTPUT POWER (W)
OUTPUT POWER (W)
0
6
10
40
OUTPUT POWER (W)
7
0
RL = 8Ω
50
OUTPUT POWER (W)
8
1
60
20
VDD = 15V
AV = 13dB
0
2
0
70
30
20
10
PSRR (dB)
80
MAX9713 toc15
0.1
MAX9713 toc11
80
RL = 16Ω
90
MAX9713 toc18
SSM
EFFICIENCY vs. OUTPUT POWER
100
EFFICIENCY (%)
1
RL = 16Ω
90
EFFICIENCY (%)
VDD = 15V
AV = 13dB
f = 1kHz
RL = 8Ω
10
THD+N (%)
EFFICIENCY vs. OUTPUT POWER
100
MAX9713 toc10
100
MAX9713 toc12
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
-140
0.01
0.1
1
FREQUENCY (Hz)
10
100
0
5
10
15
20
FREQUENCY (Hz)
_______________________________________________________________________________________
5
MAX9713/MAX9714
Typical Operating Characteristics (continued)
(136µH with 16Ω, 68µH with 8Ω, part in SSM mode, unless otherwise noted.)
Typical Operating Characteristics (continued)
(136µH with 16Ω, 68µH with 8Ω, part in SSM mode, unless otherwise noted.)
-40
-60
-80
-100
-20
RBW = 10kHz
-20
-40
-60
-80
-30
-40
-50
-60
-70
-80
-120
-100
-140
-120
0
5k
10k
15k
-90
-100
0
20k
5k
10k
15k
10M
FREQUENCY (Hz)
WIDEBAND OUTPUT SPECTRUM
(SSM MODE)
TURN-ON/TURN-OFF RESPONSE
MAX9713 toc23
MAX9713toc22
0
-10
-20
OUTPUT AMPLITUDE (dB)
1M
20k
FREQUENCY (Hz)
FREQUENCY (Hz)
-30
CSS = 180pF
SHDN
5V/div
MAX9714
OUTPUT
1V/div
-40
-50
-60
-70
-80
f = 1kHz
RL = 8Ω
-90
-100
1M
10M
100M
20ms/div
FREQUENCY (Hz)
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
15
10
5
MAX9713 toc25
0.30
SUPPLY CURRENT (µA)
SUPPLY CURRENT (mA)
20
0.25
0.20
0.15
0.10
0.05
0
0
10
12
14
16
SUPPLY VOLTAGE (V)
6
0.35
MAX9713 toc24
25
18
20
10
12
14
16
18
20
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
100M
MAX1973toc21
0
0
-10
OUTPUT AMPLITUDE (dB)
-20
SSM MODE
POUT = 5W
f = 1kHz
RL = 8Ω
A-WEIGHTED
RBW = 10kHz
MAX9713 toc20
0
20
OUTPUT MAGNITUDE (dB)
SSM MODE
POUT = 5W
f = 1kHz
RL = 8Ω
UNWEIGHTED
MAX9713 toc19
20
WIDEBAND OUTPUT SPECTRUM
(FFM MODE)
OUTPUT FREQUENCY SPECTRUM
OUTPUT FREQUENCY SPECTRUM
OUTPUT MAGNITUDE (dB)
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
PIN
NAME
FUNCTION
MAX9713
MAX9714
1, 2, 23, 24
1, 2, 23, 24
PGND
3, 4, 21, 22
3, 4, 21, 22
VDD
Power-Supply Input
5
5
C1N
Charge-Pump Flying Capacitor Negative Terminal
6
6
C1P
Charge-Pump Flying Capacitor Positive Terminal
7
7
CHOLD
8, 17, 20, 25,
26, 31, 32
8
N.C.
No Connection. Not internally connected.
9
14
REG
6V Internal Regulator Output. Bypass with a 0.01µF capacitor to PGND.
10
13
AGND
Analog Ground
11
—
IN-
Negative Input
12
—
IN+
Positive Input
13
12
SS
Soft-Start. Connect a 0.47µF capacitor from SS to GND to enable soft-start feature.
14
11
SHDN
15
17
G1
Gain-Select Input 1
16
18
G2
Gain-Select Input 2
18
19
FS1
Frequency-Select Input 1
19
20
FS2
Frequency-Select Input 2
27, 28
—
OUT-
Negative Audio Output
29, 30
—
OUT+
Positive Audio Output
—
9
INL-
Left-Channel Negative Input
—
10
INL+
Left-Channel Positive Input
—
15
INR-
Right-Channel Negative Input
—
16
INR+
Right-Channel Positive Input
—
25, 26
OUTR-
Right-Channel Negative Audio Output
—
27, 28
OUTR+
Right-Channel Positive Audio Output
—
29, 30
OUTL-
Left-Channel Negative Audio Output
—
31, 32
OUTL+
Left-Channel Positive Audio Output
—
—
EP
Exposed Paddle. Connect to GND.
Power Ground
Charge-Pump Hold Capacitor. Connect a 1µF capacitor from CHOLD to VDD.
Active-Low Shutdown. Connect SHDN to GND to disable the device. Connect to
VDD for normal operation.
_______________________________________________________________________________________
7
MAX9713/MAX9714
Pin Description
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
Detailed Description
The MAX9713/MAX9714 filterless, Class D audio power
amplifiers feature several improvements to switchmode amplifier technology. The MAX9713 is a mono
amplifier, the MAX9714 is a stereo amplifier. These
devices offer Class AB performance with Class D efficiency, while occupying minimal board space. A
unique filterless modulation scheme and spread-spectrum switching mode create a compact, flexible, lownoise, efficient audio power amplifier. The differential
input architecture reduces common-mode noise pickup, and can be used without input-coupling capacitors.
The devices can also be configured as a single-ended
input amplifier.
Comparators monitor the device inputs and compare
the complementary input voltages to the triangle waveform. The comparators trip when the input magnitude of
the triangle exceeds their corresponding input voltage.
Operating Modes
Fixed-Frequency Modulation (FFM) Mode
The MAX9713/MAX9714 feature three FFM modes with
different switching frequencies (Table 1). In FFM mode,
the frequency spectrum of the Class D output consists of
the fundamental switching frequency and its associated
harmonics (see the Wideband Output Spectrum (FFM
Mode) graph in the Typical Operating Characteristics).
The MAX9713/ MAX9714 allow the switching frequency
to be changed by ±35%, should the frequency of one or
more of the harmonics fall in a sensitive band. This can
be done at any time and not affect audio reproduction.
VIN = 0V
Table 1. Operating Modes
FS2
SWITCHING MODE
(kHz)
L
L
335
L
H
460
FS1
H
L
236
H
H
335 ±7%
Spread-Spectrum Modulation (SSM) Mode
The MAX9713/MAX9714 feature a unique spread-spectrum mode that flattens the wideband spectral components, improving EMI emissions that may be radiated
by the speaker and cables. This mode is enabled by
setting FS1 = FS2 = H. In SSM mode, the switching frequency varies randomly by ±1.7%kHz around the center frequency (335kHz). The modulation scheme
remains the same, but the period of the triangle waveform changes from cycle to cycle. Instead of a large
amount of spectral energy present at multiples of the
switching frequency, the energy is now spread over a
bandwidth that increases with frequency. Above a few
megahertz, the wideband spectrum looks like white
noise for EMI purposes (Figure 2).
Efficiency
Efficiency of a Class D amplifier is attributed to the
region of operation of the output stage transistors. In a
Class D amplifier, the output transistors act as currentsteering 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 powers. Under normal operating levels (typical
music reproduction levels), efficiency falls below 30%,
whereas the MAX9714 still exhibits >80% efficiencies
under the same conditions (Figure 3).
Shutdown
OUT-
OUT+
The MAX9713/MAX9714 have a shutdown mode that
reduces power consumption and extends battery life.
Driving SHDN low places the device in low-power
(0.2µA) shutdown mode. Connect SHDN to a logic high
for normal operation.
Click-and-Pop Suppression
Figure 1. MAX9714 Outputs with No Input Signal Applied
8
The MAX9713/MAX9714 feature comprehensive clickand-pop suppression that eliminates audible transients
on startup and shutdown. While in shutdown, the Hbridge is pulled to GND through 300kΩ. During startup,
_______________________________________________________________________________________
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
MAX9713/MAX9714
Figure 2. SSM Radiated Emissions
EFFICIENCY vs. OUTPUT POWER
SS
100
GPIO
MUTE SIGNAL
MAX9714
90
MAX9713/
MAX9714
80
70
EFFICIENCY (%)
0.18µF
60
50
Figure 4. MAX9713/MAX9714 Mute Circuit
CLASS AB
40
30
20
using a MOSFET pulldown (Figure 4). Driving SS to
GND during the power-up/down or shutdown/turn-on
cycle optimizes click-and-pop suppression.
VDD = 15V
f = 1kHz
RL = 16Ω
10
0
0
2
4
6
OUTPUT POWER (W)
Applications Information
Filterless Operation
Figure 3. MAX9714 Efficiency vs. Class AB Efficiency
or power-up, the input amplifiers are muted and an
internal loop sets the modulator bias voltages to the
correct levels, preventing clicks and pops when the Hbridge is subsequently enabled. Following startup, a
soft-start function gradually un-mutes the input amplifiers. The value of the soft-start capacitor has an impact
on the click/pop levels. For optimum performance, CSS
should be at least 0.18µF.
Mute Function
The MAX9713/MAX9714 feature a clickless/popless
mute mode. When the device is muted, the outputs
stop switching, muting the speaker. Mute only affects
the output state, and does not shut down the device. To
mute the MAX9713/MAX9714, drive SS to GND by
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 amplifier, and can decrease efficiency. The traditional PWM scheme uses large differential output
swings (2 ✕ VDD peak-to-peak) and causes large ripple
currents. Any parasitic resistance in the filter components results in a loss of power, lowering the efficiency.
The MAX9713/MAX9714 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, more efficient solution.
Because the frequency of the MAX9713/MAX9714 output is well beyond the bandwidth of most speakers,
voice coil movement due to the square-wave frequency
_______________________________________________________________________________________
9
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
Table 2. Gain Settings
GAIN (dB)
DIFF INPUT
(VRMS)
0.47µF
RL (Ω)
POUT
at 10%
THD+N (W)
13.0
1.27
16
8
16.1
0.89
16
8
19.1
0.63
16
8
22.1
0.45
16
8
13.0
0.78
8
6
16.1
0.54
8
6
19.1
0.39
8
6
22.1
0.27
8
6
is very small. Although this movement is small, a speaker not designed to handle the additional power can be
damaged. For optimum results, use a speaker with a
series inductance > 30µH. Typical 8Ω speakers exhibit
series inductances in the range of 30µH to 100µH.
Optimum efficiency is achieved with speaker inductances > 60µH.
Gain Selection
Table 2 shows the suggested gain settings to attain a
maximum output power from a given peak input voltage
and given load.
Internal Regulator Output (VREG)
The MAX9713/MAX9714 feature an internal, 6V regulator output (VREG). The MAX9713/MAX9714 REG output
pin simplifies system design and reduces system cost
by providing a logic voltage high for the MAX9713/
MAX9714 logic pins (G_, FS_). VREG is not available as
a logic voltage high in shutdown mode. Do not apply
V REG as an input voltage high to the MAX9713/
MAX9714 SHDN pin. Do not apply VREG as a 6V potential to surrounding system components. Bypass REG
with a 6.3V, 0.01µF capacitor to GND.
Output Offset
Unlike a Class AB amplifier, the output offset voltage of
Class D amplifiers does not noticeably increase quiescent current draw when a load is applied. This is due to
the power conversion of the Class D amplifier. For
example, an 8mV DC offset across an 8Ω load results
in 1mA extra current consumption in a Class AB device.
In the Class D case, an 8mV offset into 8Ω equates
to an additional power drain of 8µW. Due to the high
efficiency of the Class D amplifier, this represents an
additional quiescent current draw of: 8µW/(VDD/100 ✕ η),
which is on the order of a few microamps.
10
SINGLE-ENDED
AUDIO INPUT
IN+
MAX9713/
IN- MAX9714
0.47µF
Figure 5. Single-Ended Input
Input Amplifier
Differential Input
The MAX9713/MAX9714 feature a differential input structure, making them compatible with many CODECs, and
offering improved noise immunity over a single-ended
input amplifier. In devices such as PCs, noisy digital signals can be picked up by the amplifier’s input traces.
The signals appear at the amplifiers’ inputs as commonmode noise. A differential input amplifier amplifies the
difference of the two inputs, any signal common to both
inputs is canceled.
Single-Ended Input
The MAX9713/MAX9714 can be configured as singleended input amplifiers by capacitively coupling either
input to GND and driving the other input (Figure 5).
Component Selection
Input Filter
An input capacitor, CIN, in conjunction with the input
impedance of the MAX9713/MAX9714, forms a highpass filter that removes the DC bias from an incoming
signal. 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:
f -3dB =
1
2πRINCIN
Choose CIN so f-3dB is well below the lowest frequency
of interest. Setting f-3dB too high affects the low-frequency response of the amplifier. Use capacitors
whose dielectrics have low-voltage coefficients, such
as tantalum or aluminum electrolytic. Capacitors with
high-voltage coefficients, such as ceramics, may 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.
______________________________________________________________________________________
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
Output Capacitor (C2)
The output capacitor value and ESR directly affect the
ripple at CHOLD. Increasing C2 reduces output ripple.
Likewise, decreasing the ESR of C2 reduces both ripple and output resistance. Lower capacitance values
can be used in systems with low maximum output
power levels.
Output Filter
The MAX9713/MAX9714 do not require an output filter.
The device passes FCC emissions standards with
36cm of unshielded speaker cables. However, output
filtering can be used if a design is failing radiated emissions due to board layout or cable length, or the circuit
is near EMI-sensitive devices. Use a ferrite bead filter
when radiated frequencies above 10MHz are of concern. Use an LC filter when radiated frequencies below
10MHz are of concern, or when long leads connect the
amplifier to the speaker. Refer to the MAX9714
Evaluation Kit schematic for details of this filter.
Sharing Input Sources
In certain systems, a single audio source can be shared
by multiple devices (speaker and headphone amplifiers). When sharing inputs, it is common to mute the
unused device, rather than completely shutting it down,
preventing the unused device inputs from distorting the
input signal. Mute the MAX9713/MAX9714 by driving SS
low through an open-drain output or MOSFET (see the
System Diagram). Driving SS low turns off the Class D
output stage, but does not affect the input bias levels of
the MAX9713/MAX9714. Be aware that during normal
operation, the voltage at SS can be up to 7V, depending
on the MAX9713/MAX9714 supply.
Supply Bypassing/Layout
Proper power-supply bypassing ensures low distortion
operation. For optimum performance, bypass VDD to
PGND with a 0.1µF capacitor as close to each VDD pin
as possible. A low-impedance, high-current power-supply connection to VDD is assumed. Additional bulk
capacitance should be added as required depending on
the application and power-supply characteristics. AGND
and PGND should be star connected to system ground.
Refer to the MAX9714 Evaluation Kit for layout guidance.
VDD
VDD
N.C.
FS2
FS1
N.C.
PGND
PGND
VDD
VDD
FS2
FS1
G2
24
23
22
21
20
19
18 17
24
23
22
21
20
19
18 17
G1
PGND
TOP VIEW
PGND
Pin Configurations
N.C.
25
16
G2
OUTR-
25
16
INR+
N.C.
26
15
G1
OUTR-
26
15
INR-
OUT-
27
14
SHDN
OUTR+
27
14
REG.
OUT-
28
13
SS
OUTR+
28
13
AGND
OUT+
29
12
IN+
OUTL-
29
12
SS
OUT+
30
11
IN-
OUTL-
30
11
SHDN
N.C.
31
10
AGND
OUTL+
31
10
INL+
N.C.
32
9
REG.
OUTL+
32
9
INL-
VDD
C1N
C1P
CHOLD
N.C.
2
3
4
5
6
7
8
N.C.
VDD
TQFN (5mm x 5mm)
1
CHOLD
8
C1P
7
C1N
6
VDD
5
VDD
4
PGND
3
+
MAX9714
PGND
2
PGND
1
PGND
+
MAX9713
TQFN (7mm x 7mm)
Chip Information
MAX9713 TRANSISTOR COUNT: 3093
MAX9714 TRANSISTOR COUNT: 4630
PROCESS: BiCMOS
______________________________________________________________________________________
11
MAX9713/MAX9714
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. Increasing the value of
C1 improves load regulation and reduces the chargepump output resistance to an extent. Above 1µF, the onresistance of the switches and the ESR of C1 and C2
dominate.
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
MAX9713/MAX9714
Functional Diagrams
10V TO +25V
100µF *
25V†
0.1µF
25V†
1
2
PGND
0.47µF
0.47µF
0.1µF
25V†
3
4
21 22
VDD
VDD
23 24
PGND
12 IN+
OUT+ 30
MODULATOR
11 IN-
H-BRIDGE
OUT+ 29
OUT- 28
OUT- 27
VREG
VREG
VREG
VREG
18 FS1
19 FS2
14 SHDN
15 G1
16 G2
13 SS
0.18µF
10V
VREG
0.01µF
10V
9 REG
OSCILLATOR
GAIN
CONTROL
C1P 6
SHUTDOWN
CONTROL
CHARGE PUMP
5
C1
0.1µF
25V†
C1N
10 AGND
LOGIC INPUTS SHOWN FOR AV = 16dB (SSM).
†CHOOSE A CAPACITOR VOLTAGE RATING ≥ VDD.
*SYSTEM-LEVEL REQUIREMENT.
12
MAX9713
CHOLD
7 C2
1µF
25V†
VDD
______________________________________________________________________________________
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
10V TO +25V
100µF *
25V†
0.1µF
25V†
1
2
PGND
0.47µF
0.47µF
0.1µF
25V†
3
4
21 22
VDD
VDD
23 24
PGND
10 INL+
OUTL+ 32
MODULATOR
9 INL-
H-BRIDGE
OUTL+ 31
OUTL- 30
OUTL- 29
VREG
VREG
0.47µF
0.47µF
19 FS1
20 FS2
OSCILLATOR
16 INR+
OUTR+ 28
MODULATOR
15 INR-
H-BRIDGE
OUTR+ 27
OUTR- 26
OUTR- 25
VREG
VREG
11 SHDN
17 G1
18 G2
12 SS
0.18µF
10V
VREG
0.01µF
10V
14 REG
GAIN
CONTROL
MAX9714
C1P 6
SHUTDOWN
CONTROL
CHARGE PUMP
5
C1N
13 AGND
LOGIC INPUTS SHOWN FOR AV = 16dB (SSM).
†CHOOSE A CAPACITOR VOLTAGE RATING ≥ VDD.
*SYSTEM-LEVEL REQUIREMENT.
C1
0.1µF
25V†
CHOLD
7 C2
1µF
25V†
VDD
______________________________________________________________________________________
13
MAX9713/MAX9714
Functional Diagrams (continued)
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
MAX9713/MAX9714
System Diagram
VDD
100µF*
0.47µF
OUTL-
VDD
SHDN
INL-
OUTL-
INL+
OUTL+
0.47µF
OUTL+
CODEC
MAX9714
0.47µF
OUTR+
INR+
OUTR+
INR-
OUTR-
0.47µF
OUTR-
5V
SS
100kΩ
0.18µF
SHDN
1µF
VDD
INL1µF
1µF
15kΩ
MAX9722B
INL+
OUTL
INR+
OUTR
INR-
PVSS
SVSS
15kΩ
1µF
30kΩ
30kΩ
C1P
CIN
1µF
1µF
LOGIC INPUTS SHOWN FOR AV = 16dB (SSM)
*SYSTEM-LEVEL REQUIREMENT.
14
______________________________________________________________________________________
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
DETAIL A
32, 44, 48L QFN.EPS
E
(NE-1) X e
E/2
k
e
D/2
C
L
(ND-1) X e
D
D2
D2/2
b
L
E2/2
C
L
k
E2
C
L
C
L
L
L
e
A1
A2
e
A
PACKAGE OUTLINE
32, 44, 48, 56L THIN QFN, 7x7x0.8mm
21-0144
F
1
2
______________________________________________________________________________________
15
MAX9713/MAX9714
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.)
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
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
32, 44, 48, 56L THIN QFN, 7x7x0.8mm
21-0144
16
______________________________________________________________________________________
F
2
2
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
QFN THIN.EPS
PACKAGE OUTLINE,
16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
21-0140
K
1
2
______________________________________________________________________________________
17
MAX9713/MAX9714
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.)
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
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,
16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
21-0140
K
2
2
Revision History
Pages changed at Rev 6: 1, 3, 18
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.
18 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2006 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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