General Description
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 pro-
tected modulation and switching schemes render the tra-
ditional 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 com-
prehensive click-and-pop suppression.
The MAX9713/MAX9714 feature high 76dB PSRR, low
0.07% THD+N, and SNR in excess of 95dB. Short-cir-
cuit 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.
Applications
Features
♦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
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
________________________________________________________________ Maxim Integrated Products 1
19-3039; Rev 6; 12/06
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.
EVALUATION KIT
AVAILABLE
Ordering Information
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.
LCD Monitors
LCD TVs
Desktop PCs
LCD Projectors
High-End Notebook
Audio
Hands-Free Car
Phone Adaptors
MAX9714
0.47μFINL+ OUTL+
OUTL-INL-
0.47μFH-BRIDGE
0.47μFINR+ OUTR+
OUTR-INR-
0.47μFH-BRIDGE
Pin Configurations appear at end of data sheet.
MAX9713
0.47μFIN+ OUT+
OUT-
IN-
0.47μFH-BRIDGE
Block Diagrams
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
(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
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), RLconnected 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
GENERAL
Supply Voltage Range VDD Inferred from PSRR test 10 25 V
MAX9713 10
17.5
Quiescent Current IDD RL = ∞MAX9714 18 23
mA
Shutdown Current
ISHDN
0.2 1.5 µA
CSS = 470nF 100
Turn-On Time tON CSS = 180nF 50
ms
Amplifier Output Resistance in
Shutdown SHDN = GND 150 330
kΩ
AV = 13dB 35 58 80
AV = 16dB 30 48 65
AV = 19.1dB 23 39 55
Input Impedance RIN
AV = 22.1dB 20 31 42
kΩ
G1 = L, G2 = L
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
Voltage Gain AV
G1 = H, G2 = H
15.9
16
16.3
dB
Gain Matching Between channels (MAX9714) 0.5 %
Output Offset Voltage VOS ±6±30
mV
Common-Mode Rejection Ratio CMRR
fIN = 1kHz, input referred 60
dB
VDD = 10V to 25V 54 76
fRIPPLE = 1kHz 76
Power-Supply Rejection Ratio
(Note 3) PSRR 200mVP-P ripple fRIPPLE = 20kHz 60
dB
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(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), RLconnected 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
CONDITIONS
MIN
TYP
MAX
UNITS
RL = 16Ω8
Output Power POUT TH D + N = 10%,
f = 1kH zRL = 8Ω6W
Total Harmonic Distortion Plus
Noise
THD+N
fIN = 1kHz, either FFM or SSM, RL = 8Ω,
POUT = 4W
0.07
%
FFM 94
BW = 22Hz to
22kHz SSM 88
FFM 97
Signal-to-Noise Ratio SNR RL = 8Ω, POUT =
4W, f = 1kHz
A-weighted SSM 91
dB
FS1 = L, FS2 = L 300 335 370
FS1 = L, FS2 = H 460
FS1 = H, FS2 = L 236
Oscillator Frequency fOSC
FS1 = H, FS2 = H (spread-spectrum mode) 335
kHz
POUT = 5W, fIN = 1kHz, RL = 16Ω85
Efficiency ηPOUT = 4W, f = 1kHz, RL = 8Ω75 %
DIGITAL INPUTS (SHDN, FS_, G_)
VIH 2.5
Input Thresholds VIL 0.8 V
Input Leakage Current ±1µA
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.
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
4 _______________________________________________________________________________________
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9713 toc01
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.1
1
10
0.01
10 100k
VDD = +15V
AV = 13dB
RL = 8Ω
POUT = 4W
POUT = 100mW
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9713 toc02
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.1
1
10
0.01
10 100k
VDD = +20V
AV = 13dB
RL = 8Ω
POUT = 4W
POUT = 100mW
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9713 toc03
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.1
1
10
0.01
10 100k
VDD = +15V
AV = 13dB
RL = 16Ω
POUT = 5W
POUT = 55mW
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9713 toc04
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.1
1
10
0.01
10 100k
VDD = +20V
AV = 13dB
RL = 16Ω
POUT = 7.5W
POUT = 120mW
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9713 toc07
OUTPUT POWER (W)
THD+N (%)
123456
0.01
0.1
1
10
100
0.001
07
VDD = 20V
AV = 13dB
RL = 8Ω
f = 100Hz
f = 1kHz
f = 10kHz
f = 10kHz
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. FREQUENCY
MAX9713 toc05
FREQUENCY (Hz)
THD+N (%)
10k1k100
0.1
1
10
0.01
10 100k
VDD = +15V
AV = 13dB
POUT = 4W
RL = 8Ω
SSM
FFM
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9713 toc06
OUTPUT POWER (W)
THD+N (%)
4321
0.01
0.1
1
10
100
0.001
0765
VDD = 15V
AV = 13dB
RL = 8Ω
f = 100Hz
f = 1kHz
f = 10kHz
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9713 toc08
OUTPUT POWER (W)
THD+N (%)
642
0.01
0.1
1
10
100
0.001
08
VDD = 15V
AV = 13dB
RL = 16Ω
f = 100Hz
f = 1kHz
f = 10kHz
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9713 toc09
OUTPUT POWER (W)
THD+N (%)
105
0.01
0.1
1
10
100
0.001
015
VDD = 20V
AV = 13dB
RL = 16Ω
f = 100Hz
f = 1kHz
f = 10kHz
Typical Operating Characteristics
(136µH with 16Ω, 68µH with 8Ω, part in SSM mode, unless otherwise noted.)
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
_______________________________________________________________________________________ 5
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT POWER
MAX9713 toc10
OUTPUT POWER (W)
THD+N (%)
642
0.01
0.1
1
10
100
0.001
08
VDD = 15V
AV = 13dB
f = 1kHz
RL = 8Ω
SSM
FFM
EFFICIENCY vs. OUTPUT POWER
MAX9713 toc11
OUTPUT POWER (W)
EFFICIENCY (%)
8642
10
20
30
40
50
60
70
80
90
100
0
010
RL = 16Ω
RL = 8Ω
VDD = 15V
AV = 13dB
EFFICIENCY vs. OUTPUT POWER
MAX9713 toc12
OUTPUT POWER (W)
EFFICIENCY (%)
963
10
20
30
40
50
60
70
80
90
100
0
012
RL = 16Ω
RL = 8Ω
VDD = 20V
AV = 13dB
OUTPUT POWER
vs. SUPPLY VOLTAGE
MAX9713 toc13
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
22191613
8
7
6
5
4
3
2
1
0
10 25
AV = 13dB
THD+N = 10%
RL = 8Ω
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
MAX9713 toc16
FREQUENCY (Hz)
PSRR (dB)
10k1k100
-60
-50
-40
-30
-20
-10
0
-70
10 100k
VDD = 15V
AV = 13dB
VRIPPLE = 200mVP-P
RL = 16Ω
10
9
8
7
6
5
4
3
2
1
0
1 10 100
OUTPUT POWER
vs. LOAD RESISTANCE
MAX9713 toc14
LOAD RESISTANCE (Ω)
OUTPUT POWER (W)
VDD = 15V
AV = 13dB
THD+N = 10%
THD+N = 1%
COMMON-MODE REJECTION RATIO
vs. FREQUENCY
MAX9713 toc15
FREQUENCY (Hz)
CMRR (dB)
10k1k100
-80
-70
-60
-50
-40
-30
-20
-10
0
-90
10 100k
VDD = 15V
AV = 13dB
RL = 8Ω
CROSSTALK vs. FREQUENCY
MAX9713 toc17
FREQUENCY (Hz)
CROSSTALK (dB)
1010.1
-80
-100
-60
-40
-20
0
-120
0.01 100
LEFT TO RIGHT
RIGHT TO LEFT
OUTPUT REFERRED
AV = 13dB
OUTPUT FREQUENCY SPECTRUM
MAX9713 toc18
FREQUENCY (Hz)
OUTPUT MAGNITUDE (dB)
15105
-120
-100
-80
-60
-40
-20
0
20
-140
020
FFM MODE
POUT = 5W
f =1kHz
RL = 8Ω
UNWEIGHTED
Typical Operating Characteristics (continued)
(136µH with 16Ω, 68µH with 8Ω, part in SSM mode, unless otherwise noted.)
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
6 _______________________________________________________________________________________
OUTPUT FREQUENCY SPECTRUM
MAX9713 toc19
FREQUENCY (Hz)
OUTPUT MAGNITUDE (dB)
15k10k5k
-120
-100
-80
-60
-40
-20
0
20
-140
0 20k
SSM MODE
POUT = 5W
f = 1kHz
RL = 8Ω
UNWEIGHTED
OUTPUT FREQUENCY SPECTRUM
MAX9713 toc20
FREQUENCY (Hz)
OUTPUT MAGNITUDE (dB)
15k10k5k
-120
-100
-80
-60
-40
-20
0
20
0 20k
SSM MODE
POUT = 5W
f = 1kHz
RL = 8Ω
A-WEIGHTED
RBW = 10kHz
0
-100
1M 10M 100M
WIDEBAND OUTPUT SPECTRUM
(FFM MODE)
-80
MAX1973toc21
FREQUENCY (Hz)
OUTPUT AMPLITUDE (dB)
-60
-40
-20
-30
-50
-70
-90
-10 RBW = 10kHz
0
-100
1M 10M 100M
WIDEBAND OUTPUT SPECTRUM
(SSM MODE)
-80
MAX9713toc22
FREQUENCY (Hz)
OUTPUT AMPLITUDE (dB)
-60
-40
-20
-30
-50
-70
-90
-10
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9713 toc25
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
18161412
0.10
0.05
0.15
0.20
0.25
0.30
0.35
0
10 20
TURN-ON/TURN-OFF RESPONSE
MAX9713 toc23
20ms/div
MAX9714
OUTPUT
1V/div
5V/divSHDN
f = 1kHz
RL = 8Ω
CSS = 180pF
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9713 toc24
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
18161412
5
10
15
20
25
0
10 20
Typical Operating Characteristics (continued)
(136µH with 16Ω, 68µH with 8Ω, part in SSM mode, unless otherwise noted.)
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
_______________________________________________________________________________________ 7
PIN
MAX9713 MAX9714
NAME FUNCTION
1, 2, 23, 24 1, 2, 23, 24 PGND Power Ground
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
77
CHOLD
Charge-Pump Hold Capacitor. Connect a 1µF capacitor from CHOLD to VDD.
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 Active-Low Shutdown. Connect SHDN to GND to disable the device. Connect to
VDD for normal operation.
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.
Pin Description
MAX9713/MAX9714
Detailed Description
The MAX9713/MAX9714 filterless, Class D audio power
amplifiers feature several improvements to switch-
mode amplifier technology. The MAX9713 is a mono
amplifier, the MAX9714 is a stereo amplifier. These
devices offer Class AB performance with Class D effi-
ciency, while occupying minimal board space. A
unique filterless modulation scheme and spread-spec-
trum switching mode create a compact, flexible, low-
noise, efficient audio power amplifier. The differential
input architecture reduces common-mode noise pick-
up, 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 wave-
form. 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.
Spread-Spectrum Modulation (SSM) Mode
The MAX9713/MAX9714 feature a unique spread-spec-
trum mode that flattens the wideband spectral compo-
nents, 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 fre-
quency varies randomly by ±1.7%kHz around the cen-
ter frequency (335kHz). The modulation scheme
remains the same, but the period of the triangle wave-
form 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 current-
steering switches and consume negligible additional
power. Any power loss associated with the Class D out-
put 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
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
The MAX9713/MAX9714 feature comprehensive click-
and-pop suppression that eliminates audible transients
on startup and shutdown. While in shutdown, the H-
bridge is pulled to GND through 300kΩ. During startup,
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
8 _______________________________________________________________________________________
Table 1. Operating Modes
FS1 FS2 SWITCHING MODE
(kHz)
L L 335
L H 460
H L 236
H H 335 ±7%
Figure 1. MAX9714 Outputs with No Input Signal Applied
VIN = 0V
OUT-
OUT+
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 H-
bridge is subsequently enabled. Following startup, a
soft-start function gradually un-mutes the input ampli-
fiers. 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
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.
Applications Information
Filterless Operation
Traditional Class D amplifiers require an output filter to
recover the audio signal from the amplifier’s PWM out-
put. The filters add cost, increase the solution size of
the amplifier, and can decrease efficiency. The tradi-
tional PWM scheme uses large differential output
swings (2 ✕VDD peak-to-peak) and causes large ripple
currents. Any parasitic resistance in the filter compo-
nents 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 speak-
er 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 out-
put is well beyond the bandwidth of most speakers,
voice coil movement due to the square-wave frequency
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
_______________________________________________________________________________________ 9
Figure 3. MAX9714 Efficiency vs. Class AB Efficiency
0
30
20
10
40
50
60
70
80
90
100
0246
EFFICIENCY vs. OUTPUT POWER
OUTPUT POWER (W)
EFFICIENCY (%)
MAX9714
VDD = 15V
f = 1kHz
RL = 16Ω
CLASS AB
Figure 2. SSM Radiated Emissions
MAX9713/
MAX9714
SS
0.18µF
GPIO
MUTE SIGNAL
Figure 4. MAX9713/MAX9714 Mute Circuit
MAX9713/MAX9714
is very small. Although this movement is small, a speak-
er not designed to handle the additional power can be
damaged. For optimum results, use a speaker with a
series inductance > 30µH. Typical 8Ωspeakers exhibit
series inductances in the range of 30µH to 100µH.
Optimum efficiency is achieved with speaker induc-
tances > 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 regula-
tor 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
VREG as an input voltage high to the MAX9713/
MAX9714 SHDN pin. Do not apply VREG as a 6V poten-
tial 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 quies-
cent 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 8Ωload results
in 1mA extra current consumption in a Class AB device.
In the Class D case, an 8mV offset into 8Ωequates
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.
Input Amplifier
Differential Input
The MAX9713/MAX9714 feature a differential input struc-
ture, making them compatible with many CODECs, and
offering improved noise immunity over a single-ended
input amplifier. In devices such as PCs, noisy digital sig-
nals can be picked up by the amplifier’s input traces.
The signals appear at the amplifiers’ inputs as common-
mode 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 single-
ended 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 high-
pass 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:
Choose CIN so f-3dB is well below the lowest frequency
of interest. Setting f-3dB too high affects the low-fre-
quency 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 100mΩfor opti-
mum performance. Low-ESR ceramic capacitors mini-
mize the output resistance of the charge pump. For
best performance over the extended temperature
range, select capacitors with an X7R dielectric.
fRC
-3dB IN IN
1
2
=π
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
10 ______________________________________________________________________________________
Table 2. Gain Settings
GAIN (dB)
DIFF INPUT
(VRMS)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
MAX9713/
MAX9714
IN+
IN-
0.47µF
0.47µF
SINGLE-ENDED
AUDIO INPUT
Figure 5. Single-Ended Input
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 charge-
pump output resistance to an extent. Above 1µF, the on-
resistance of the switches and the ESR of C1 and C2
dominate.
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 rip-
ple 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 emis-
sions 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 con-
cern. 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 ampli-
fiers). 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-sup-
ply 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.
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
______________________________________________________________________________________ 11
PGND
PGND
VDD
VDD
N.C.
FS2
FS1
N.C.
PGND
PGND
VDD
VDD
C1N
CHOLD
N.C.
9
10
11
12
13
14
15
REG.
AGND
IN-
IN+
SS
SHDN
G1
32
31
30
29
28
27
26
N.C.
N.C.
OUT+
OUT+
OUT-
OUT-
N.C.
MAX9713
25
12345678
24
++
23 22 21 20 19 18 17
N.C. 16 G2
TOP VIEW
TQFN (5mm x 5mm)
C1P
TQFN (7mm x 7mm)
PGND
PGND
VDD
VDD
FS2
FS1
G2
G1
PGND
PGND
VDD
VDD
C1N
CHOLD
N.C.
9
10
11
12
13
14
15
INL-
INL+
SHDN
SS
AGND
REG.
INR-
32
31
30
29
28
27
26
OUTL+
OUTL+
OUTL-
OUTL-
OUTR+
OUTR+
OUTR-
MAX9714
25
12345678
24 23 22 21 20 19 18 17
OUTR- 16 INR+
C1P
Pin Configurations
Chip Information
MAX9713 TRANSISTOR COUNT: 3093
MAX9714 TRANSISTOR COUNT: 4630
PROCESS: BiCMOS
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
12 ______________________________________________________________________________________
MAX9713
0.47µFIN+12
11
18
14
15
16
13
10 AGND
9
6
5
19
IN-
FS1
V
REG
VREG
VREG
VREG
FS2
G1
G2
SS
REG
0.47µFMODULATOR
OSCILLATOR
CHARGE PUMP
C1P C1
0.1µF
25V†
C1N
0.18µF
10V
GAIN
CONTROL
SHUTDOWN
CONTROL
0.01µF
10V
SHDN
H-BRIDGE
OUT+
OUT+
OUT-
OUT-
30
29
28
27
PGND VDD VDD PGND
1 34212223242
10V TO +25V
100µF
25V†
0.1µF
25V†
0.1µF
25V†
C2
1µF
25V†
CHOLD
VDD
7
LOGIC INPUTS SHOWN FOR AV = 16dB (SSM).
†CHOOSE A CAPACITOR VOLTAGE RATING ≥ VDD.
*SYSTEM-LEVEL REQUIREMENT.
VREG
*
Functional Diagrams
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
______________________________________________________________________________________ 13
MAX9714
0.47µFINL+10
9
19
11
17
18
12
13 AGND
14
6
5
20
INL-
FS1
VREG
VREG
VREG
VREG
FS2
G1
G2
SS
REG
0.47µFMODULATOR
OSCILLATOR
CHARGE PUMP
C1P
C1N
GAIN
CONTROL
SHUTDOWN
CONTROL
SHDN
H-BRIDGE
OUTL+
OUTL+
OUTL-
OUTL-
32
31
30
29
PGND VDD VDD PGND
1 34212223242
10V TO +25V
CHOLD
VDD
7
0.47µFINR+16
15 INR-
0.47µFMODULATOR H-BRIDGE
OUTR+
OUTR+
OUTR-
OUTR-
28
27
26
25
C1
0.1µF
25V†
0.18µF
10V 0.01µF
10V
100µF
25V†
0.1µF
25V†
0.1µF
25V†
C2
1µF
25V†
LOGIC INPUTS SHOWN FOR AV = 16dB (SSM).
†CHOOSE A CAPACITOR VOLTAGE RATING ≥ VDD.
*SYSTEM-LEVEL REQUIREMENT.
VREG
*
Functional Diagrams (continued)
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
14 ______________________________________________________________________________________
MAX9714
MAX9722B
0.47µF
VDD
INL-
VDD
OUTL-
SHDN
OUTL+INL+
CODEC
INR+ OUTR+
OUTR-
0.18µF
5V
VDD
OUTL
OUTR
PVSS
SVSS
INL+
INL-
INR+
INR-
C1P
1µF
1µF
CIN
100kΩ
INR-
0.47µF
0.47µF
0.47µF
1µF
SS
SHDN
LOGIC INPUTS SHOWN FOR AV = 16dB (SSM)
100µF*
30kΩ30kΩ
15kΩ
15kΩ
1µF
1µF
1µF
OUTL-
OUTL+
OUTR+
OUTR-
*SYSTEM-LEVEL REQUIREMENT.
System Diagram
MAX9713/MAX9714
6W, Filterless, Spread-Spectrum
Mono/Stereo Class D Amplifiers
______________________________________________________________________________________ 15
32, 44, 48L QFN.EPS
e
L
e
L
A1 A
A2
E/2
E
D/2
D
DETAIL A
D2/2
D2
b
L
k
E2/2
E2
(NE-1) X e
(ND-1) X e
e
C
L
C
L
C
L
C
L
k
PACKAGE OUTLINE
21-0144
2
1
F
32, 44, 48, 56L THIN QFN, 7x7x0.8mm
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
16 ______________________________________________________________________________________
PACKAGE OUTLINE
21-0144
2
2
F
32, 44, 48, 56L THIN QFN, 7x7x0.8mm
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
______________________________________________________________________________________ 17
QFN THIN.EPS
PACKAGE OUTLINE,
21-01402
1
K
16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
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
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.
PACKAGE OUTLINE,
21-0140 2
2
K
16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
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.)
Revision History
Pages changed at Rev 6: 1, 3, 18