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19-4327; Rev 0; 10/08
KIT ATION EVALU BLE AVAILA
Mono 7W Class D Amplifier
General Description Features
8V to 28V Supply Voltage Range Spread-Spectrum Modulation Enables Low-EMI Solution Passes EMI Limit with Up to 1m of Speaker Cable High 80dB PSRR Up to 88% Efficiency Eliminates Heatsink Thermal and Output Current Protection < 1A Shutdown Mode Click-and-Pop Suppression < 10ms Turn-On Time Space-Saving, 4mm x 4mm x 0.8mm, 24-Pin TQFN Package
MAX9737
The MAX9737 mono 7W Class D amplifier provides a high-performance, thermally efficient amplifier solution that offers up to 88% efficiency at a 12V supply. The device operates from 8V to 28V and provides a high 80dB PSRR, eliminating the need for a regulated power supply. Filterless modulation allows the MAX9737 to pass CE EMI limits with 1m cables using only a low-cost ferrite bead and small-value capacitor on each output. Comprehensive click-and-pop suppression circuitry reduces noise on power-up/down or into and out of shutdown or mute. An input op amp allows the user to create a lowpass or highpass filter, and select an optimal gain. The internal precharge circuit ensures clickless/popless turn-on within 10ms. The MAX9737 is available in the 24-pin, TQFN-EP package and is specified over the -40C to +85C temperature range.
Applications
2.1 Notebook PCs LCD/PDP/CRT Monitors PC Surround Speakers MP3 Docking Stations
PART MAX9737ETG+
Ordering Information
TEMP RANGE -40C to +85C PIN-PACKAGE 24 TQFN-EP*
+Denotes a lead-free/RoHS-compliant package. *EP = Exposed pad.
Simplified Diagram
8V TO 28V
PRECHARGE AUDIO INPUT
8
SHDN MUTE INPUT RESISTORS AND CAPACITORS SELECT GAIN AND CUTOFF FREQUENCY
MAX9737
Pin Configuration and Typical Application Circuit appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Mono 7W Class D Amplifier MAX9737
ABSOLUTE MAXIMUM RATINGS
PVDD to PGND.......................................................-0.3V to +30V AGND to PGND .....................................................-0.3V to +0.3V IN, PRE, PC, COM to AGND.....................-0.3V to (VREG + 0.3V) MUTE, SHDN to AGND ............................................-0.3V to +6V REG to AGND ...............................................-0.3V to (VS + 0.3V) VS to AGND ..............................................................-0.3V to +6V OUT+, OUT- to PGND .............................-0.3V to (PVDD + 0.3V) C1N to PGND ..........................................-0.3V to (PVDD + 0.3V) C1P to PGND .........................(PVDD - 0.3V) to (VCHOLD + 0.3V) CHOLD to PGND .......................................(VC1P - 0.3V) to +36V OUT+, OUT-, Short Circuit to PGND or PVDD ...........Continuous Thermal Limits (Notes 1, 2) Continuous Power Dissipation (TA = +70C) 24-Pin TQFN Single-Layer PCB (derate 20.8mW/C above +70C)........................................................1666.7mW JA ................................................................................48C/W JC ..................................................................................3C/W Continuous Power Dissipation 24-Pin TQFN Multiple-Layer PCB (derate 27.8mW/C above +70C) ........................2222.2mW JA ................................................................................36C/W JC ..................................................................................3C/W Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Junction Temperature ......................................................+150C Lead Temperature (soldering, 10s) .................................+300C
Note 1: Thermal performance of this device is highly dependent on PCB layout. See the Applications Information section for more detail. Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial.
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VPVDD = 12V, VAGND = VPGND = 0, VSHDN = VMUTE = 5V, C1 = 0.1F, CIN = 0.47F, C2 = CCOM = CREG = 1F, RIN = RFB = 20k, RL = , AC measurement bandwidth 22Hz to 22kHz, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 3)
PARAMETER Speaker-Supply Voltage Range Undervoltage Lockout Quiescent Supply Current Shutdown Supply Current REG Voltage Preregulator Voltage COM Voltage Capacitive Drive Output Swing Open-Loop Gain Input Offset Voltage Input Amplifier Slew Rate Input Amplifier Unity-Gain Bandwidth AVO VOS IN to COM SYMBOL PVDD UVLO IPVDD ISHDN VREG VS VCOM CL No sustained oscillation Sinking 1mA (Note 4) 1.94 TA = +25C VSHDN = 0, TA = +25C 4.0 CONDITIONS Inferred from PSRR test MIN 8 6.8 15 1 4.2 4.85 2.06 30 2.05 88 2 2.5 3.5 2.16 20 25 10 4.5 TYP MAX 28 UNITS V V mA A V V V pF V dB mV V/s MHz
AMPLIFIER DC CHARACTERISTICS
INPUT AMPLIFIER CHARACTERISTICS
2
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Mono 7W Class D Amplifier MAX9737
ELECTRICAL CHARACTERISTICS (continued)
(VPVDD = 12V, VAGND = VPGND = 0, VSHDN = VMUTE = 5V, C1 = 0.1F, CIN = 0.47F, C2 = CCOM = CREG = 1F, RIN = RFB = 20k, RL = , AC measurement bandwidth 22Hz to 22kHz, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 3)
PARAMETER Output Amplifier Gain Output Current Limit Output Offset Power-Supply Rejection Ratio Output Power THD + Noise Signal-to-Noise Ratio Noise Efficiency VOS PSRR POUT THD+N SNR VN OUT+ to OUT-, TA = +25C VPVDD = 8V to 28V, TA = +25C f = 1kHz, 100mVP-P ripple THD+N = 10%, RL = 8 (Note 5) THD+N = 10%, RL = 4 (Note 6) POUT = 2W, f = 1kHz, RL = 8 (Note 5) A-weighted, POUT = THD+N at 1%, fIN = 1kHz A-weighted (Note 4) POUT = 4W Peak voltage, 32 samples/second, A-weighted (Notes 4, 5, 8) Into shutdown Out of shutdown Into mute Out of mute 270 6 65 SYMBOL AV CONDITIONS Preamplifier gain = 0dB (Note 7) MIN 13.1 3 TYP 13.6 4.6 2 80 88 7.4 13 0.06 97 100 85 38 38 38 38 300 4 +160 30 tON VINH VINL 50 TA = +25C 10 From shutdown to full operation 2 0.8 9 10 330 kHz kHz C C ms V V mV A dBV 10 MAX 14.1 UNITS dB A mV dB W % dB VRMS %
OUTPUT AMPLIFIER CHARACTERISTICS
Click-and-Pop Level
KCP
Switching Frequency Spread-Spectrum Bandwidth Thermal-Shutdown Level Thermal-Shutdown Hysteresis Turn-On Time DIGITAL INTERFACE (SHDN, MUTE) Input-Voltage High Input-Voltage Low Input-Voltage Hysteresis Input Leakage Current
Note 3: Note 4: Note 5: Note 6: Note 7:
All devices are 100% production tested at TA = +25C, and all temperature limits are guaranteed by design. Amplifier inputs AC-coupled to GND. 8 resistive load in series with 68mH inductive load connected across OUT+ and OUT- outputs. 4 resistive load in series with 33H inductive load connected across OUT+ and OUT- outputs for VPVDD 12V. Output amplifier gain is defined as:
| (V ) - (VOUT - ) | 20 x log OUT + | VPRE |
Note 8: Mode transition controlled by SHDN and MUTE.
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3
Mono 7W Class D Amplifier MAX9737
Typical Operating Characteristics
(VPVDD = 12V, VGND = VPGND = 0, V SHDN = V MUTE = 5V, RIN = RFB = 20k, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX9737 toc01
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX9737 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
PVDD = 12V, 8 LOAD
MAX9737 toc03
1 PVDD = 12V, 8 LOAD
1 PVDD = 12V, 4 LOAD
10
1 THD+N (%) 0.1 0.1 THD+N (%) 4W THD+N (%) POUT = 4W 6kHz 0.1 2W POUT = 2W 20Hz 0.01 10 100 1k FREQUENCY (Hz) 10k 100k 0.01 10 100 1k FREQUENCY (Hz) 10k 100k 0.01 0 1 2 3 4 5 6 7 8 OUTPUT POWER (W)
1kHz
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX9737 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX9737 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
PVDD = 12V, 4 LOAD
MAX9737 toc06
10 PVDD = 18V, 8 LOAD
10 PVDD = 24V, 8 LOAD
10
1 THD+N (%) THD+N (%)
1
1kHz
THD+N (%)
6kHz
1 6kHz 0.1 1kHz
6kHz 0.1
1kHz
0.1
20Hz 0.01 0 1 2 3 4 5 6 7 8 OUTPUT POWER (W) 0.01 0 1 2 3 4 5 6
20Hz 0.01 7 8 0 2 4 6 8 10
20Hz 12 14 16
OUTPUT POWER (W)
OUTPUT POWER (W)
EFFICIENCY vs. TOTAL OUTPUT POWER
100 90 80 EFFICEINCY (%) 70 60 50 40 30 20 10 0 0 1 2 3 4 5 6 7 8 TOTAL OUTPUT POWER (W) POWER DISSIPATION EFFICIENCY PVDD = 12V, 8 LOAD
MAX9737 toc07
EFFICIENCY vs. TOTAL OUTPUT POWER
10 9 8 POWER DISSIPATION (W) 7 6 5 4 3 2 1 0 EFFICEINCY (%) 100 90 80 70 60 50 40 30 20 10 0 0 1 2 3 4 5 6 7 8 TOTAL OUTPUT POWER (W) POWER DISSIPATION EFFICIENCY PVDD = 18V, 8 LOAD
MAX9737 toc08
10 9 8 7 6 5 4 3 2 1 0 POWER DISSIPATION (W)
4
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Mono 7W Class D Amplifier
Typical Operating Characteristics (continued)
(VPVDD = 12V, VGND = VPGND = 0, V SHDN = V MUTE = 5V, RIN = RFB = 20k, unless otherwise noted.)
EFFICIENCY vs. TOTAL OUTPUT POWER
90 80 70 EFFICEINCY (%) 60 50 40 30 20 10 0 0 1 2 3 4 5 6 7 8 TOTAL OUTPUT POWER (W) POWER DISSIPATION EFFICIENCY
MAX9737 toc09
MAX9737
EFFICIENCY vs. TOTAL OUTPUT POWER
10 9 8 POWER DISSIPATION (W) 7 6 5 4 3 2 1 0 EFFICEINCY (%) 100 90 80 70 60 50 40 30 20 10 0 0 2 4 6 8 10 12 14 16 TOTAL OUTPUT POWER (W) POWER DISSIPATION EFFICIENCY PVDD = 12V, 4 LOAD
MAX9737 toc10
10 9 8 7 6 5 4 3 2 1 0 POWER DISSIPATION (W)
PVDD = 24V, 8 LOAD
TOTAL OUTPUT POWER vs. PVDD
MAX9737 toc11
TOTAL OUTPUT POWER vs. LOAD RESISTANCE
PVDD = 12V 16 TOTAL OUTPUT POWER (W) 14 12 10 8 6 4 1% THD+N 2 0 0 5 10 15 20 25 30 10% THD+N
MAX9737 toc12
TOTAL OUTPUT POWER vs. LOAD RESISTANCE
10 TOTAL OUTPUT POWER (W) 9 8 7 6 5 4 3 2 1 0 0 5 10 15 20 25 30 1% THD+N 10% THD+N PVDD = 8V
MAX9737 toc13
9 8 TOTAL OUTPUT POWER (W) 7 6 5 4 3 2 1 0 8 10 8 LOAD f = 1kHz 10% THD+N 1% THD+N
18
11
12 14 16 18 20 22 24 26 28 SUPPLY VOLTAGE (V)
LOAD RESISTANCE ()
LOAD RESISTANCE ()
INBAND OUTPUT SPECTRUM
MAX9737 toc14
WIDEBAND OUTPUT SPECTRUM
-10 OUTPUT AMPLITUDE (dBV) -20 -30 -40 -50 -60 -70 -80 8 LOAD
MAX9737 toc15
SUPPLY CURRENT vs. PVDD SUPPLY VOLTAGE
18 16 SUPPLY CURRENT (mA) 14 12 10 8 6 4 2 0
MAX9737 toc16
20 8 LOAD 0 OUTPUT AMPLITUDE (dBV) -20 -40 -60 -80 -100 -120 0 5k 10k 15k FREQUENCY (Hz)
0
20
-90 -100 20k 100k 1M 10M 100M FREQUENCY (Hz)
8
10 12 14 16 18 20 22 24 26 28 SUPPLY VOLTAGE (V)
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5
Mono 7W Class D Amplifier MAX9737
Typical Operating Characteristics (continued)
(VPVDD = 12V, VGND = VPGND = 0, V SHDN = V MUTE = 5V, RIN = RFB = 20k, unless otherwise noted.)
SHUTDOWN CURRENT vs. PVDD SUPPLY VOLTAGE
35 SHUTDOWN CURRENT (nA) 30 25 20 15 10 5 0 8 10 12 14 16 18 20 22 24 26 28 PVDD SUPPLY VOLTAGE (V) 10ms/div OUTPUT 5V/div
MAX9737 toc17
SHDN ON/OFF RESPONSE
MAX9737 toc18
40
SHDN 1V/div
MUTE ON/OFF RESPONSE
MAX9737 toc19
PSRR
-10 MUTE 1V/div PSRR (dB) -20 -30 -40 -50 -60 -70 -80 -90 -100 PVDD = 12V + 100mVP-P 8 LOAD
MAX9737 toc20
0
OUTPUT 5V/div
10ms/div
10
100
1k FREQUENCY (Hz)
10k
100k
6
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Mono 7W Class D Amplifier
Pin Description
PIN 1, 17, 18 2 3, 10, 11 4 5 6 7 8 9 12 13, 14 15 16 19, 20 21, 22 23, 24 -- NAME PVDD CHOLD AGND MUTE SHDN PC IN PRE COM REG VS C1N C1P OUTPGND OUT+ EP FUNCTION Power Supply. Bypass PVDD to PGND with a 1F capacitor connected to pin 1 and a 1F capacitor connected to pins 17 and 18. Charge-Pump Output. Connect a 1F capacitor to PVDD. Analog Ground Mute Input. Drive MUTE low to place the device in mute mode. Shutdown Input. Drive SHDN low to place the part in shutdown mode. Input Capacitor Precharge Connection. Connect between input resistor, RIN, and input coupling capacitor, CIN. Op Amp Inverting Input. Op Amp Output. PRE is the output of the input operational amplifier. Internal 2.0V Bias. Bypass COM to AGND with a 1F capacitor. Internal 4.2V Bias. Bypass REG to AGND with a 1F capacitor. Internal 5.0V Bias. Bypass VS to AGND with a 1F capacitor. Charge-Pump, Flying-Capacitor Negative Terminal. Connect C1N to C1P through a 0.1F capacitor. Charge-Pump, Flying-Capacitor Positive Terminal. Connect C1P to C1N through a 0.1F capacitor. Negative Speaker Output Power Ground Positive Speaker Output Exposed Pad. Must be externally connected to PGND.
MAX9737
Detailed Description
The MAX9737 filterless, mono class D audio power amplifier offers Class AB audio performance and Class D efficiency with minimal board space. The device operates from an 8V to 28V supply range. The MAX9737 features filterless, spread-spectrum modulation, externally set gain and a low-power shutdown mode that reduces supply current to less than 1A. Comprehensive click-and-pop suppression and precharge circuitry reduce noise into and out of shutdown or mute within 10ms.
EMI purposes. A proprietary amplifier topology ensures this white noise does not corrupt the noise floor in the audio bandwidth.
Efficiency
The high efficiency of a Class D amplifier is due to the output transistors acting as switches and therefore consume negligible power. Power loss associated with the Class D output stage is due to the MOSFET I2R losses, switching losses, and quiescent current. Although the theoretical best efficiency of a linear amplifier is 78% at peak output power, under typical music reproduction levels, the efficiency falls to below 40%. The MAX9737 exhibits > 80% efficiency under the same conditions (Figure 1).
Spread-Spectrum Modulation
The MAX9737 features a unique, patented spreadspectrum switching modulation that flattens EMI wideband spectral components, reducing radiated emissions from the speaker and cables. The switching frequency of the Class D amplifier varies randomly by 4kHz around the 300kHz center frequency. Instead of a large amount of spectral energy present at multiples of the switching frequency, the energy is spread over a bandwidth that increases with frequency. Above a few MHz, the wideband spectrum looks like white noise for
Shutdown
The MAX9737 features a shutdown mode that reduces power consumption to less than 1A (typ), extending battery life in portable applications. Drive SHDN low to place the device in low-power shutdown mode. In shutdown mode, the outputs are high impedance and the common-mode voltage at the output decays to zero.
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7
Mono 7W Class D Amplifier MAX9737
Mute Function
The MAX9737 features a mute mode where the signal is attenuated at the speaker and the outputs stop switching. To mute the MAX9737, drive MUTE low.
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0 1 2 3 4 5 6 7 8 OUTPUT POWER (W) CLASS AB MAX9737
EFFICIENCY vs. OUTPUT POWER
Click-and-Pop Suppression
The MAX9737 features comprehensive click-and-pop suppression and precharge circuitry that reduce audible transients on startup and shutdown. The precharge circuit enables the amplifier within 10ms without any clicks or pops. Connect PC between the input resistor (RIN) and the input capacitor (CIN). For optimal clickand-pop suppression, use a 0.47F input coupling capacitor (CIN).
Current Limit
When output current exceeds the current limit, 4.6A (typ), the MAX9737 disables the outputs and initiates a 450s startup sequence. The shutdown and startup sequence is repeated until the output fault is removed. Properly designed applications do not enter currentlimit mode unless the output is short circuited or connected incorrectly.
Figure 1. MAX9737 Efficiency vs. Class AB Efficiency
FB1
MAX9737
FB2 C1 330pF C2 330pF
Thermal Shutdown
When the die temperature exceeds the thermal-shutdown threshold, +160C (typ), the MAX9737 outputs are disabled. When the die temperature decreases by 30C, normal operation resumes. Some causes of thermal shutdown are excessively low load impedance, poor thermal contact between the MAX9737's exposed pad and the PCB, elevated ambient temperature, or poor PCB layout and assembly.
FB1 AND FB2: WURTH742792040
Figure 2. Ferrite Bead Filter Configuration
40 35 AMPLITUDE (dBV/m) 30 25 20 15 10 5 0 30 100 FREQUENCY (MHz) 1000 EN55022B LIMIT
Applications Information
Filterless Class D Operation
The MAX9737 meets EN55022B EMC radiation limits with an inexpensive ferrite bead and capacitor filter when the speaker leads are less than or equal to 1m (Figure 3). Select a ferrite bead with 100 to 600 impedance, and rated for 2A. The capacitor value varies based on the ferrite bead chosen and the speaker lead length. See Figure 2 for the correct connections of these components.
Figure 3. MAX9737 EMI Performance with 1m Twisted-Pair Speaker Cable
Table 1. Suggested Values for LC Filter
RL () 4 8 L1, L2 (H) 10 15 C1 (F) 0.47 0.15 C2, C3 (F) 0.10 0.15 C4, C5 (F) 0.22 0.15 R1, R2 () 10 15
8
_______________________________________________________________________________________
Mono 7W Class D Amplifier
When evaluating the MAX9737 with a ferrite bead filter and resistive load, include a series inductor (68H for 8 load and 33H for 4 load) to model typical loudspeaker's behavior. Omitting the series inductor reduces the efficiency, the THD+N performance and the output power of the MAX9737. When evaluating with a loudspeaker, no series inductor is required.
MAX9737
C2 L1
C4
R1
MAX9737
L2
C1
RL
Inductor-Based Output Filters
Some applications use the MAX9737 with a full inductor/capacitor-based (LC) output filter. See Figure 4 for the correct connections of these components. The load impedance of the speaker determines the filter component selection (see Table 1). Inductors L1 and L2 and capacitor C1 form the primary output filter. Capacitors C2 and C3 provide commonmode filtering to reduce radiated emissions. Capacitors C4 and C5, plus resistors R1 and R2, form a Zobel at the output. A Zobel corrects the output loading to compensate for the rising impedance of the loudspeaker. Without a Zobel, the filter exhibits peaking near the cutoff frequency.
C3
C5
R2
Figure 4. LC Filter Configuration
RF CIN AUDIO INPUT RIN
PRE IN COM OUT+ OUT-
CCOM PC
MAX9737
Component Selection
Gain-Setting Resistors The output stage provides a fixed internal gain in addition to the externally set input stage gain. The fixed-output stage gain is set at 13.6dB (4.8V/V). Set overall gain by using resistors RF and RIN (Figure 5) as follows:
R A V = -4.8 F V / V RIN where A V is the desired voltage gain. Choose R F between 10k and 50k. The PRE terminal is an operational amplifier output, allowing the MAX9737 to be configured as a filter or an equalizer.
Figure 5. Preamplifier Gain Configuration
Choose CIN such that f-3dB is well below the lowest frequency of interest. To reduce low-frequency distortion, use capacitors whose dielectrics have low-voltage coefficients. Capacitors with high-voltage coefficients cause increased distortion close to f-3dB. For best clickand-pop suppression, use a 0.47F input capacitor.
COM Capacitor COM is the output of the internally generated DC bias voltage. Bypass COM with a 1F capacitor to AGND. Regulator Capacitor REG is the output of the internally generated DC bias voltage. Bypass REG with a 1F capacitor to AGND.
Input Capacitor An input capacitor, CIN, in conjunction with the input resistor, RIN, of the MAX9737 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 negligible source impedance, the -3dB point of the highpass filter is given by:
f -3dB = 1 2RINCIN
Power Supplies
The MAX9737 features separate supplies for signal and power portions of the device, allowing for the optimum combination of headroom, power dissipation and noise immunity. The speaker amplifiers are powered from PVDD and can range from 8V to 28V. The remainder of the device is powered by an internal 5V regulator, VS.
Internal Regulator The MAX9737 features an internal 5V regulator, VS, powered from PVDD. Bypass VS with a 1F capacitor to AGND.
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9
Mono 7W Class D Amplifier MAX9737
Typical Application Circuit
8V TO 28V
1F
1F
1F
100F C1 0.1F C2 1F
VS 13, 14 REG 12 1F CREG
PVDD 1, 17, 18
C1P 16
C1N 15
REGULATOR
CHARGE PUMP
2 CHOLD
RFB 20k RIN 20k
PRE IN
8 7 POWER STAGE 23, 24 OUT+ 19, 20 OUT-
CCOM 1F
COM
9
BIAS
PC 6 AUDIO INPUT CIN 0.47F 5 SHDN LOGIC INPUT
PRECHARGE
CONTROL
MAX9737
4 MUTE VS
3, 10, 11 AGND
21, 22 PGND
SHDN
Supply Bypassing, Layout, and Grounding
Proper layout and grounding are essential for optimum performance. Use wide traces for the power-supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance. Proper grounding improves audio performance, minimizes crosstalk between channels, and prevents switching noise from coupling into the audio signal. Connect PGND and AGND together at a single point on the PCB. Route all traces that carry switching transients away from AGND and the traces/components in the audio signal path. Bypass PVDD with two 1F capacitors to PGND. Place the bypass capacitors as close as possible to the MAX9737. Place a 100F capacitor between PVDD and PGND. Bypass VS, VCOM, and VREG with a 1F capacitor to AGND.
10
Use wide, low-resistance output traces. Current drawn from the outputs increases as load impedance decreases. High-output trace resistance decreases the power delivered to the load. The MAX9737 TQFN package features an exposed thermal pad on its underside. This pad lowers the package's thermal resistance by providing a heat conduction path from the die to the PCB. Connect the exposed thermal pad to PGND by using a large pad and multiple vias to the PGND plane.
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Mono 7W Class D Amplifier
Pin Configuration
PGND PGND OUT+ OUT+ OUTOUT-
Chip Information
PROCESS: BiCMOS
MAX9737
TOP VIEW
24 PVDD CHOLD AGND MUTE SHDN PC 1 + 2 3 4 5 6 7 IN
23
22
21
20
19 18 17 16 PVDD PVDD C1P C1N VS VS
MAX9737
*EP
15 14 13
8 PRE
9 COM
10 AGND
11 AGND
12 REG
TQFN 4mm x 4mm
*EP = EXPOSED PAD, CONNECT TO PGND
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11
Mono 7W Class D Amplifier MAX9737
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 24 TQFN-EP PACKAGE CODE T2444+4 DOCUMENT NO. 21-0139
12
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24L QFN THIN.EPS
Mono 7W Class D Amplifier
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
MAX9737
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13
(c) 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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