19-4327; Rev 0; 10/08 KIT ATION EVALU E L B AVAILA Mono 7W Class D Amplifier 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 -40°C to +85°C temperature range. 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 ♦ < 1µA Shutdown Mode ♦ Click-and-Pop Suppression ♦ < 10ms Turn-On Time ♦ Space-Saving, 4mm x 4mm x 0.8mm, 24-Pin TQFN Package Applications Ordering Information 2.1 Notebook PCs PART LCD/PDP/CRT Monitors MAX9737ETG+ TEMP RANGE PIN-PACKAGE -40°C to +85°C 24 TQFN-EP* PC Surround Speakers +Denotes a lead-free/RoHS-compliant package. MP3 Docking Stations *EP = Exposed pad. Simplified Diagram 8V TO 28V PRECHARGE AUDIO INPUT 8Ω SHDN MAX9737 MUTE INPUT RESISTORS AND CAPACITORS SELECT GAIN AND CUTOFF FREQUENCY Pin Configuration and Typical Application Circuit appear at end of data sheet. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX9737 General Description MAX9737 Mono 7W Class D Amplifier 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 = +70°C) 24-Pin TQFN Single-Layer PCB (derate 20.8mW/°C above +70°C)........................................................1666.7mW θJA ................................................................................48°C/W θJC ..................................................................................3°C/W Continuous Power Dissipation 24-Pin TQFN Multiple-Layer PCB (derate 27.8mW/°C above +70°C) ........................2222.2mW θJA ................................................................................36°C/W θJC ..................................................................................3°C/W 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 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 = 0.1µF, CIN = 0.47µF, C2 = CCOM = CREG = 1µF, RIN = RFB = 20kΩ, RL = ∞, AC measurement bandwidth 22Hz to 22kHz, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS AMPLIFIER DC CHARACTERISTICS Speaker-Supply Voltage Range PVDD Undervoltage Lockout UVLO Quiescent Supply Current IPVDD Shutdown Supply Current ISHDN REG Voltage VREG Preregulator Voltage COM Voltage Inferred from PSRR test 8 28 6.8 TA = +25°C 15 20 25 VSHDN = 0, TA = +25°C 4.0 VS 1.94 mA 1 10 µA 4.2 4.5 V 2.16 V 4.85 VCOM V V 2.06 V INPUT AMPLIFIER CHARACTERISTICS Capacitive Drive CL Output Swing Open-Loop Gain AVO Input Offset Voltage VOS No sustained oscillation 30 pF Sinking ±1mA (Note 4) 2.05 V 88 dB ±2 mV Input Amplifier Slew Rate 2.5 V/µs Input Amplifier Unity-Gain Bandwidth 3.5 MHz 2 IN to COM _______________________________________________________________________________________ Mono 7W Class D Amplifier (VPVDD = 12V, VAGND = VPGND = 0, VSHDN = VMUTE = 5V, C1 = 0.1µF, CIN = 0.47µF, C2 = CCOM = CREG = 1µF, RIN = RFB = 20kΩ, RL = ∞, AC measurement bandwidth 22Hz to 22kHz, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 3) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 13.1 13.6 14.1 dB 3 4.6 ±10 mV OUTPUT AMPLIFIER CHARACTERISTICS Output Amplifier Gain AV Preamplifier gain = 0dB (Note 7) Output Current Limit Output Offset VOS Power-Supply Rejection Ratio PSRR Output Power POUT THD + Noise THD+N Signal-to-Noise Ratio Noise SNR VN η Efficiency Click-and-Pop Level KCP OUT+ to OUT-, TA = +25°C VPVDD = 8V to 28V, TA = +25°C ±2 65 f = 1kHz, 100mVP-P ripple THD+N = 10%, RL = 8Ω (Note 5) 80 dB 88 6 THD+N = 10%, RL = 4Ω (Note 6) 7.4 W 13 POUT = 2W, f = 1kHz, RL = 8Ω (Note 5) 0.06 % A-weighted, POUT = THD+N at 1%, fIN = 1kHz 97 dB A-weighted (Note 4) 100 µVRMS POUT = 4W 85 % Peak voltage, 32 samples/second, A-weighted (Notes 4, 5, 8) Into shutdown 38 Out of shutdown 38 Into mute 38 Out of mute Switching Frequency dBV 38 270 Spread-Spectrum Bandwidth 300 330 ±4 Thermal-Shutdown Level Thermal-Shutdown Hysteresis Turn-On Time A tON From shutdown to full operation kHz kHz +160 °C 30 °C 9 10 ms DIGITAL INTERFACE (SHDN, MUTE) Input-Voltage High VINH Input-Voltage Low VINL 2 Input-Voltage Hysteresis Input Leakage Current Note 3: Note 4: Note 5: Note 6: Note 7: V 0.8 50 TA = +25°C V mV ±10 µA All devices are 100% production tested at TA = +25°C, and all temperature limits are guaranteed by design. Amplifier inputs AC-coupled to GND. 8Ω resistive load in series with 68mH inductive load connected across OUT+ and OUT- outputs. 4Ω resistive load in series with 33µH inductive load connected across OUT+ and OUT- outputs for VPVDD ≤ 12V. Output amplifier gain is defined as: ⎛ | (V ) − (VOUT − ) | ⎞ 20 × log⎜ OUT + ⎟ | VPRE | ⎝ ⎠ Note 8: Mode transition controlled by SHDN and MUTE. _______________________________________________________________________________________ 3 MAX9737 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VPVDD = 12V, VGND = VPGND = 0, V SHDN = V MUTE = 5V, RIN = RFB = 20kΩ, unless otherwise noted.) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY PVDD = 12V, 8Ω LOAD 10 MAX9737 toc02 1 MAX9737 toc01 1 PVDD = 12V, 4Ω LOAD MAX9737 toc03 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY PVDD = 12V, 8Ω LOAD 0.1 POUT = 4W THD+N (%) THD+N (%) THD+N (%) 1 4W 0.1 6kHz 1kHz 0.1 POUT = 2W 2W 20Hz 0.01 0.01 10 100 1k 10k 100k 0.01 10 100 1k 10k 100k 2 3 4 5 6 7 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER PVDD = 24V, 8Ω LOAD 1 1kHz 0.1 THD+N (%) 1kHz 0.1 0.1 20Hz 20Hz 20Hz 0.01 0.01 0.01 1 2 3 4 5 6 7 8 1 0 2 OUTPUT POWER (W) 3 4 5 6 7 4 6 8 EFFICIENCY vs. TOTAL OUTPUT POWER MAX9737 toc07 PVDD = 12V, 8Ω LOAD 10 80 70 7 60 6 50 5 40 4 30 3 POWER DISSIPATION EFFICEINCY (%) 80 8 POWER DISSIPATION (W) 90 EFFICIENCY MAX9737 toc08 100 9 PVDD = 18V, 8Ω LOAD 10 9 8 7 70 EFFICIENCY 60 6 50 5 40 4 30 3 POWER DISSIPATION 2 20 2 10 1 10 1 0 0 0 20 0 1 2 3 4 5 6 TOTAL OUTPUT POWER (W) 10 OUTPUT POWER (W) OUTPUT POWER (W) 100 EFFICEINCY (%) 2 0 8 EFFICIENCY vs. TOTAL OUTPUT POWER 90 1kHz 6kHz 7 8 0 0 1 2 3 4 5 6 7 8 TOTAL OUTPUT POWER (W) _______________________________________________________________________________________ POWER DISSIPATION (W) 6kHz PVDD = 12V, 4Ω LOAD 1 6kHz THD+N (%) 1 10 MAX9737 toc05 MAX9737 toc04 10 8 MAX9737 toc06 OUTPUT POWER (W) PVDD = 18V, 8Ω LOAD 0 1 FREQUENCY (Hz) 10 4 0 FREQUENCY (Hz) THD+N (%) MAX9737 Mono 7W Class D Amplifier 12 14 16 Mono 7W Class D Amplifier EFFICIENCY vs. TOTAL OUTPUT POWER 9 90 8 80 7 60 EFFICIENCY 6 50 5 40 4 POWER DISSIPATION 30 3 8 7 70 EFFICIENCY 60 5 4 40 POWER DISSIPATION 30 20 2 10 1 10 1 0 0 0 1 2 3 4 5 6 7 8 0 0 2 4 6 1% THD+N 5 4 3 2 14 MAX9737 toc12 PVDD = 12V 12 14 16 12 10 8 10% THD+N 6 4 11 9 8 7 6 5 10% THD+N 4 3 2 2 1% THD+N 1 0 0 12 14 16 18 20 22 24 26 28 PVDD = 8V 10 1% THD+N 0 0 5 10 15 20 25 0 30 5 10 15 20 25 SUPPLY VOLTAGE (V) LOAD RESISTANCE (Ω) LOAD RESISTANCE (Ω) INBAND OUTPUT SPECTRUM WIDEBAND OUTPUT SPECTRUM SUPPLY CURRENT vs. PVDD SUPPLY VOLTAGE -20 -40 -60 -80 -100 -120 -20 -30 -40 -50 -60 -70 10k 15k FREQUENCY (Hz) 20k 18 16 14 12 10 8 6 -80 4 -90 2 -100 5k 20 30 MAX9737 toc16 8Ω LOAD SUPPLY CURRENT (mA) OUTPUT AMPLITUDE (dBV) 0 0 -10 MAX9737 toc15 8Ω LOAD MAX9737 toc14 20 OUTPUT AMPLITUDE (dBV) 10 TOTAL OUTPUT POWER vs. LOAD RESISTANCE 16 8Ω LOAD f = 1kHz 0 8 TOTAL OUTPUT POWER (W) 18 TOTAL OUTPUT POWER (W) TOTAL OUTPUT POWER (W) 10% THD+N 6 TOTAL OUTPUT POWER vs. LOAD RESISTANCE MAX9737 toc11 9 8 10 3 2 TOTAL OUTPUT POWER vs. PVDD 8 6 50 TOTAL OUTPUT POWER (W) 1 9 20 0 7 10 PVDD = 12V, 4Ω LOAD TOTAL OUTPUT POWER (W) EFFICEINCY (%) 70 MAX9737 toc10 100 MAX9737 toc13 80 10 POWER DISSIPATION (W) PVDD = 24V, 8Ω LOAD EFFICEINCY (%) 90 EFFICIENCY vs. TOTAL OUTPUT POWER POWER DISSIPATION (W) MAX9737 toc09 0 100k 1M 10M FREQUENCY (Hz) 100M 8 10 12 14 16 18 20 22 24 26 28 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5 MAX9737 Typical Operating Characteristics (continued) (VPVDD = 12V, VGND = VPGND = 0, V SHDN = V MUTE = 5V, RIN = RFB = 20kΩ, unless otherwise noted.) Typical Operating Characteristics (continued) (VPVDD = 12V, VGND = VPGND = 0, V SHDN = V MUTE = 5V, RIN = RFB = 20kΩ, unless otherwise noted.) SHUTDOWN CURRENT vs. PVDD SUPPLY VOLTAGE SHDN ON/OFF RESPONSE MAX9737 toc18 MAX9737 toc17 40 35 SHUTDOWN CURRENT (nA) SHDN 1V/div 30 25 20 15 OUTPUT 5V/div 10 5 0 8 10 12 14 16 18 20 22 24 26 28 10ms/div PVDD SUPPLY VOLTAGE (V) PSRR MUTE ON/OFF RESPONSE MAX9737 toc19 PVDD = 12V + 100mVP-P 8Ω LOAD -10 MUTE 1V/div OUTPUT 5V/div MAX9737 toc20 0 -20 -30 PSRR (dB) MAX9737 Mono 7W Class D Amplifier -40 -50 -60 -70 -80 -90 -100 10ms/div 10 100 1k 10k 100k FREQUENCY (Hz) 6 _______________________________________________________________________________________ Mono 7W Class D Amplifier PIN NAME FUNCTION 1, 17, 18 PVDD 2 CHOLD Charge-Pump Output. Connect a 1µF capacitor to PVDD. 3, 10, 11 AGND Analog Ground 4 MUTE Mute Input. Drive MUTE low to place the device in mute mode. 5 SHDN Shutdown Input. Drive SHDN low to place the part in shutdown mode. 6 PC Input Capacitor Precharge Connection. Connect between input resistor, RIN, and input coupling capacitor, CIN. 7 IN Op Amp Inverting Input. 8 PRE Power Supply. Bypass PVDD to PGND with a 1µF capacitor connected to pin 1 and a 1µF capacitor connected to pins 17 and 18. Op Amp Output. PRE is the output of the input operational amplifier. 9 COM Internal 2.0V Bias. Bypass COM to AGND with a 1µF capacitor. 12 REG Internal 4.2V Bias. Bypass REG to AGND with a 1µF capacitor. 13, 14 VS 15 C1N Charge-Pump, Flying-Capacitor Negative Terminal. Connect C1N to C1P through a 0.1µF capacitor. 16 C1P Charge-Pump, Flying-Capacitor Positive Terminal. Connect C1P to C1N through a 0.1µF capacitor. 19, 20 OUT- Negative Speaker Output 21, 22 PGND Power Ground 23, 24 OUT+ Positive Speaker Output — EP Internal 5.0V Bias. Bypass VS to AGND with a 1µF capacitor. Exposed Pad. Must be externally connected to PGND. 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 1µA. Comprehensive click-and-pop suppression and precharge circuitry reduce noise into and out of shutdown or mute within 10ms. 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 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). Shutdown The MAX9737 features a shutdown mode that reduces power consumption to less than 1µA (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. _______________________________________________________________________________________ 7 MAX9737 Pin Description Mute Function EFFICIENCY vs. OUTPUT POWER 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 Click-and-Pop Suppression 80 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 0.47µF input coupling capacitor (CIN). 70 EFFICIENCY (%) 90 50 CLASS AB 40 20 10 0 Current Limit When output current exceeds the current limit, 4.6A (typ), the MAX9737 disables the outputs and initiates a 450µs 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. MAX9737 60 30 0 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 100Ω to 600Ω 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. 2 3 4 5 6 7 8 Figure 1. MAX9737 Efficiency vs. Class AB Efficiency FB1 MAX9737 Thermal Shutdown When the die temperature exceeds the thermal-shutdown threshold, +160°C (typ), the MAX9737 outputs are disabled. When the die temperature decreases by 30°C, 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. 1 OUTPUT POWER (W) C1 330pF FB2 C2 330pF FB1 AND FB2: WURTH742792040 Figure 2. Ferrite Bead Filter Configuration 40 35 AMPLITUDE (dBμV/m) MAX9737 Mono 7W Class D Amplifier EN55022B LIMIT 30 25 20 15 10 5 0 30 100 1000 FREQUENCY (MHz) Figure 3. MAX9737 EMI Performance with 1m Twisted-Pair Speaker Cable Table 1. Suggested Values for LC Filter 8 RL (Ω) L1, L2 (µH) C1 (µF) C2, C3 (µF) C4, C5 (µF) R1, R2 (Ω) 4 10 0.47 0.10 0.22 10 8 15 0.15 0.15 0.15 15 _______________________________________________________________________________________ Mono 7W Class D Amplifier C2 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 10kΩ and 50kΩ. The PRE terminal is an operational amplifier output, allowing the MAX9737 to be configured as a filter or an equalizer. 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 2πRINCIN R1 L1 RL C1 MAX9737 L2 C3 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. C4 MAX9737 When evaluating the MAX9737 with a ferrite bead filter and resistive load, include a series inductor (68µH for 8Ω load and 33µH for 4Ω 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. C5 R2 Figure 4. LC Filter Configuration RF CIN AUDIO INPUT RIN PRE IN OUT+ COM OUT- CCOM PC MAX9737 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 0.47µF input capacitor. COM Capacitor COM is the output of the internally generated DC bias voltage. Bypass COM with a 1µF capacitor to AGND. Regulator Capacitor REG is the output of the internally generated DC bias voltage. Bypass REG with a 1µF capacitor to AGND. 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 1µF capacitor to AGND. _______________________________________________________________________________________ 9 Mono 7W Class D Amplifier MAX9737 Typical Application Circuit 8V TO 28V 1μF REG 12 1μF RFB 20kΩ RIN 20kΩ CCOM 1μF 1μF VS PVDD 13, 14 1, 17, 18 100μF C1 0.1μF 1μF CHARGE PUMP REGULATOR CREG PRE 8 IN 7 23, 24 OUT+ 9 19, 20 OUT- BIAS PC 6 PRECHARGE AUDIO INPUT MAX9737 CONTROL CIN 0.47μF 5 SHDN LOGIC INPUT SHDN 3, 10, 11 4 MUTE 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 1µF capacitors to PGND. Place the bypass capacitors as close as possible to the MAX9737. Place a 100µF capacitor between PVDD and PGND. Bypass VS, VCOM, and VREG with a 1µF capacitor to AGND. 10 2 CHOLD POWER STAGE COM C2 1μF C1N 15 C1P 16 AGND 21, 22 PGND VS 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. ______________________________________________________________________________________ Mono 7W Class D Amplifier Chip Information PVDD OUT+ OUT+ PGND PGND OUT- OUT- PROCESS: BiCMOS TOP VIEW 24 23 22 21 20 19 1 18 PVDD + CHOLD 2 17 PVDD AGND 3 16 C1P MUTE 4 15 C1N SHDN 5 14 VS PC 6 13 VS MAX9737 10 11 12 AGND REG PRE 9 AGND 8 COM 7 IN *EP TQFN 4mm x 4mm *EP = EXPOSED PAD, CONNECT TO PGND ______________________________________________________________________________________ 11 MAX9737 Pin Configuration Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 24 TQFN-EP T2444+4 21-0139 24L QFN THIN.EPS MAX9737 Mono 7W Class D Amplifier 12 ______________________________________________________________________________________ Mono 7W Class D Amplifier 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 © 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX9737 Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.