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19-3589; Rev 1; 8/05
KIT ATION EVALU BLE AVAILA
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier
General Description Features
5V Single-Supply Operation Patented Spread-Spectrum Modulator Reduces EMI 2.8W, Class D, Stereo Speaker Amplifier (4) Filterless Class D Requires No LC Output Filter High PSRR (71dB at 1kHz) 86% Efficiency (RL = 8, POUT = 1W) Low-Power Shutdown Mode Integrated Click-and-Pop Suppression Low Total Harmonic Distortion: 0.06% at 1kHz Short-Circuit and Thermal Protection Internal Gain, +9.0dB or +10.5dB Available in Space-Saving Packages 16-Pin Thin QFN-EP (5mm x 5mm x 0.8mm) 16-Pin TSSOP
MAX9715
The MAX9715 high-efficiency, stereo, Class D audio power amplifier provides up to 2.8W per channel into a 4 speaker with a 5V supply. Maxim's second-generation Class D technology features robust output protection, high efficiency, and high power-supply rejection (PSRR) while eliminating the need for output filters. Selectable gain settings, +10.5dB or +9.0dB, adjust the amplifier gain to suit the audio input level and speaker load. The MAX9715 features high PSRR (71dB at 1kHz), allowing for operation from noisy supplies without additional regulation. Comprehensive click-and-pop suppression eliminates audible clicks and pops at startup and shutdown. The MAX9715 operates from a single 5V supply and consumes only 12mA of supply current. Integrated shutdown control reduces supply current to less than 100nA. The MAX9715 is fully specified over the extended -40C to +85C temperature range and is available in thermally enhanced 16-pin thin QFN-EP and 16-pin TSSOP packages.
Applications
High-End Notebook Audio LCD Projectors Portable Audio Multimedia Docking Stations
Typical Operating Circuit/Functional Diagram appears at end of data sheet.
PART MAX9715ETE+ MAX9715EUE+
Ordering Information
TEMP RANGE -40C to +85C -40C to +85C PIN-PACKAGE 16 TQFN-EP* 16 TSSOP
+Denotes lead-free package. *EP = Exposed paddle.
Pin Configurations
OUTR+ OUTR10 PGND
Block Diagram
TOP VIEW
4.5V TO 5.5V SUPPLY
12 BIAS 13 VDD 14
11
PVDD 9 8 7
OUTR+ INR OUTRGAIN CLASS D AMPLIFIER OUTL+ INL OUTL-
SHDN GND GAIN N.C.
MAX9715
INR 15 INL 16 6 5 1 PGND 2 OUTL+ 3 OUTL4 PVDD
MAX9715
TQFN Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier MAX9715
ABSOLUTE MAXIMUM RATINGS
VDD, PVDD, to GND ...............................................................+6V GND to PGND .......................................................-0.3V to +0.3V Any Other Pin to PGND ............................. -0.3V to (VDD + 0.3V) Duration of OUT__ Short Circuit to PGND or PVDD ....Continuous Duration of OUT_+ Short Circuit between OUT_- ......Continuous Continuous Current Into/Out of (PVDD, OUT__, PGND)........1.7A Continuous Input Current (All Other Pins) ....................... 20mA Continuous Power Dissipation (TA = +70C) 16-Pin TQFN-EP (derate 20.8mW/C above +70C)..1666mW 16-Pin TSSOP (derate 9.4mW/C above +70C) ......754.7mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Junction Temperature ......................................................+150C Lead Temperature (soldering, 10s) .................................+300C
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 = PVDD = 5.0V, GND = PGND = 0V, VSHDN = VDD, CBIAS = 1F, speaker impedance = 8 in series with 68H connected between OUT_+ and OUT_-, GAIN = +10.5dB, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER GENERAL Supply Voltage Range Quiescent Current Shutdown Supply Current Input Resistance Turn-On Time BIAS Voltage CLASS D SPEAKER AMPLIFIERS Output Offset Voltage Maximum Speaker Amplifier Gain (Note 3) VOS AV TA = +25C TA = TMIN to TMAX GAIN = 0 GAIN = 1 PVDD or VDD = 4.5V to 5.5V Power-Supply Rejection Ratio PSRR VIN_ = 0V f = 1kHz, 100mVP-P f = 20kHz, 100mVP-P THD+N = 1% Output Power POUT THD+N = 10% Total Harmonic Distortion Plus Noise Signal-to-Noise Ratio Maximum Capacitive Load Switching Frequency THD+N SNR CL_MAX fSW Average frequency in spread-spectrum operation 1.00 f = 1kHz RL = 8 RL = 4 RL = 8 RL = 4 RL = 8, POUT = 1.2W RL = 4, POUT = 2W 52.4 10.5 9.0 75 71 60 1.4 2.3 1.7 2.8 0.06 0.07 89 93 200 1.22 1.40 % dB pF MHz W dB 12.6 45 70 mV dB VDD IDD ISHDN RIN tON VBIAS Inferred from PSRR test No load VSHDN = 0V 6.5 4.5 12.8 0.1 10 25 1.8 5.5 16 2 13.5 V mA A k ms V SYMBOL CONDITIONS MIN TYP MAX UNITS
POUT = 1W, BW = 22Hz to 22kHz POUT = 1W, A-weighted
2
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2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(VDD = PVDD = 5.0V, GND = PGND = 0V, VSHDN = VDD, CBIAS = 1F, speaker impedance = 8 in series with 68H connected between OUT_+ and OUT_-, GAIN = +10.5dB, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER Spread-Spectrum Modulation Crosstalk Channel-to-channel, f = 10kHz, POUT = 1W, left to right or right to left Peak voltage, A-weighted, 32 samples per second (Note 4) Into shutdown Out of shutdown SYMBOL CONDITIONS MIN TYP 120 72 -64 dBV -46 86 % MAX UNITS kHz dB
MAX9715
Click-and-Pop Level
KCP
Efficiency DIGITAL INPUTS (GAIN and SHDN) Input High Voltage Input Low Voltage Input Leakage Current
RL = 8 in series with 68H, POUT = 1W per channel, f = 1kHz 2.0
VIH VIL ILEAK SHDN GAIN
V 0.8 1 1.5 V A
Note 1: All devices are 100% production tested at TA = +25C. All temperature limits are guaranteed by design. Note 2: Speaker amplifier gain is defined as AV = (VOUT_+ - VOUT_-) / VIN. Note 3: Click-and-pop level testing performed with an 8 resistive load in series with 68H inductive load connected across the Class D BTL outputs. Mode transitions are controlled by the SHDN pin. Inputs AC-coupled to GND. Note 4: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For RL = 4, L = 33H. For RL = 8, L = 68H.
Typical Operating Characteristics
(VDD = 5.0V, CVDD = 3 x 0.1F, CBIAS = 1F, CINL = CINR = 1F, AV = +10.5dB, TA = +25C, unless otherwise noted.) (See the Typical Operating Circuit/Functional Diagram)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX9715toc01
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VDD = 5V RL = 8 POUT = 0.5W 0.1 THD+N (%) THD+N (%) 1 0.1
MAX9715toc02
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX9715toc03
1 VDD = 5V RL = 4 POUT = 0.35W
1
100
10
fIN = 1kHz AND 20Hz
0.1 THD+N (%)
POUT = 2W
POUT = 1.25W
0.01
0.01 0.01
fIN = 10kHz VDD = 5V RL = 4
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 OUTPUT POWER (W)
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3
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier MAX9715
Typical Operating Characteristics (continued)
(VDD = 5.0V, CVDD = 3 x 0.1F, CBIAS = 1F, CINL = CINR = 1F, AV = +10.5dB, TA = +25C, unless otherwise noted.) (See the Typical Operating Circuit/Functional Diagram)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX9715toc04
EFFICIENCY vs. OUTPUT POWER
90 80 EFFICIENCY (%) 70 60 50 40 30 20 VDD = 5V fIN = 1kHz POUT = POUTL + POUTR OUTPUTS IN-PHASE 0 1 4 2 3 OUTPUT POWER (W) 5 6 RL = 4 RL = 8
MAX9715toc05
100 fIN = 1kHz 10 fIN = 20Hz THD+N (%) 1
100
0.1 fIN = 10kHz 0.01 VDD = 5V RL = 8 0.001 0 0.5 1.0 1.5 2.0 2.5 OUTPUT POWER (W)
10 0
EFFICIENCY vs. SUPPLY VOLTAGE
MAX9715 toc06
OUTPUT POWER vs. LOAD RESISTANCE
3.5 3.0 OUTPUT POWER (W) VDD = 5V fIN = 1kHz LLOAD = 33H
MAX9715toc07
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 4.5 4.8 5.0 5.3 fIN = 1kHz POUT = POUTL + POUTR OUTPUTS IN-PHASE THD+N = 1% RL = 4 RL = 8
4.0
2.5 2.0 1.5 1.0 0.5 0 THD+N = 1% THD+N = 10%
5.5
1
10
100
1k
SUPPLY VOLTAGE (V)
LOAD RESISTANCE ()
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX9715toc08
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX9715toc09
5.0 4.5 4.0 OUTPUT POWER (W) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 4.5 4.8 5.0 5.3 fIN = 1kHz RL = 4 THD+N = 1% THD+N = 10%
2.5 THD+N = 10% 2.0 OUTPUT POWER (W)
1.5 THD+N = 1% 1.0
0.5 fIN = 1kHz RL = 8 0 5.5 4.5 4.8 5.0 5.3 5.5 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V)
4
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2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier MAX9715
Typical Operating Characteristics (continued)
(VDD = 5.0V, CVDD = 3 x 0.1F, CBIAS = 1F, CINL = CINR = 1F, AV = +10.5dB, TA = +25C, unless otherwise noted.) (See the Typical Operating Circuit/Functional Diagram)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX9715toc10
CROSSTALK vs. FREQUENCY
MAX9715 toc11
OUTPUT SPECTRUM vs. FREQUENCY
-50 -60 AMPLITUDE (dBV) -70 -80 -90 -100 -110 -120 -130 RL = 8 VDD = 5V fIN = 1kHz
MAX9715toc12
0 -10 -20 -30 PSRR (dB) -40 -50 -60 -70 -80 -90 -100 0.01 0.1 1 FREQUENCY (Hz) 10 RL = 8
0 -20 CROSSTALK (dB) -40 -60 -80 -100 -120 POUT = 1W RL = 8 A = +10.5dB fIN = 10kHz
-40
RIGHT TO LEFT LEFT TO RIGHT
-140 0.01 0.1 1 FREQUENCY (kHz) 10 100 0 5 10 FREQUENCY (kHz) 15 20
100
OUTPUT SPECTRUM vs. FREQUENCY (A-WEIGHTED)
-50 -60 AMPLITUDE (dBV) -70 -80 -90 -100 -110 -120 -130 -140 0 5 10 FREQUENCY (kHz) 15 20 -120 1 RL = 8 VDD = 5V fIN = 1kHz
MAX9715toc13
WIDEBAND SPECTRUM
MAX9715 toc14
SUPPLY CURRENT vs. SUPPLY VOLTAGE
18 16 SUPPLY CURRENT (mA) 14 12 10 8 6 4 2 0 NO LOAD INPUTS AC GROUNDED
MAX9715toc15
-40
0 -20 AMPLITUDE (dBV) -40 -60 -80 -100 VDD = 5V INPUTS AC GROUNDED RL = 8 10 100
20
1000
4.5
4.8
5.0
5.3
5.5
FREQUENCY (MHz)
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier MAX9715
Typical Operating Characteristics (continued)
(VDD = 5.0V, CVDD = 3 x 0.1F, CBIAS = 1F, CINL = CINR = 1F, AV = +10.5dB, TA = +25C, unless otherwise noted.) (See the Typical Operating Circuit/Functional Diagram)
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
MAX9715 toc16
POWER-ON/OFF WAVEFORM
MAX9715 toc17
0.40 0.35 SHUTDOWN CURRENT (A) 0.30 0.25 0.20 0.15 0.10 0.05 0 4.5 4.8 5.0 5.3
SHDN 5V/div
IOUT 200mA/div
5.5
10ms/div
SUPPLY VOLTAGE (V)
Pin Description
PIN TQFN 1, 12 2 3 4, 9 5 6 7 8 10 11 13 14 15 16 EP TSSOP 4, 13 5 6 7, 10 -- 8 1, 14 9 11 12 15 16 2 3 -- NAME PGND OUTL+ OUTLPVDD N.C. GAIN GND SHDN OUTROUTR+ BIAS VDD INR INL EP Power Ground Left-Channel Positive Speaker Output Left-Channel Negative Speaker Output Positive Speaker Power-Supply Input. Power-supply input for speaker amplifier output stages. Connect to VDD and bypass with 0.1F to PGND. No connection. Not internally connected. Gain Select. Sets the internal amplifier gain. See the Gain Selection section. Ground Shutdown Control. Drive SHDN low to shut down the MAX9715. Right-Channel Negative Speaker Output Right-Channel Positive Speaker Output Bias Voltage Output. VBIAS = 1.8V, bypass BIAS to GND with a 1F ceramic capacitor. Positive Power-Supply Input. Bypass to GND with a 0.1F ceramic capacitor. Right-Channel Input Left-Channel Input Exposed Paddle. Connect EP to an electrically isolated copper pad or GND. FUNCTION
6
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2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier MAX9715
45 AMPLITUDE (dBV/m) 40 35 30 25 20 15 30 60 80 100 120 140 160 180 200 220 240 260 280 300 FREQUENCY (MHz)
MAX9715 fig01
50
Figure 1. MAX9715 Radiated Emissions with 75mm of Speaker Cable
Detailed Description
The MAX9715 2.8W, Class D speaker amplifier with gain control offers Class AB performance with Class D efficiency while occupying minimal board space. A unique modulation scheme and spread-spectrum switching allow filterless operation to create a compact, flexible, low-noise, efficient audio power amplifier. The MAX9715 features high 71dB at 1kHz PSRR, low 0.06% THD+N, industry-leading click-and-pop performance and a low-power shutdown mode. The MAX9715 features an undervoltage lockout that prevents operation from an insufficient power supply and click-and-pop suppression that eliminates audible transients at startup and shutdown. The speaker amplifier includes thermal-overload and short-circuit protection. The MAX9715 features unique, spread-spectrum operation that reduces the amplitude of spectral components at high frequencies, reducing EMI emissions that might otherwise be radiated by the speaker and cables. The switching frequency varies randomly by 120kHz around the center frequency (1.22MHz). The modulation scheme is consistent with Maxim's Class D amplifiers but the period of the triangle waveform changes from cycle to cycle. Audio reproduction is not affected by the spread-spectrum switching scheme. Instead of a large amount of spectral energy present at multiples of the switching frequency that energy is now spread over a range of frequencies. The spreading is increased with frequency so that above a few megahertz, the wideband spectrum looks like white noise for EMI purposes (Figure 1).
VIN = 0V
OUT-
OUT+
VOUT+ - VOUT- = 0V
Figure 2. MAX9715 Output without Input Signal Applied
Filterless Modulation/Common-Mode Idle The spread-spectrum modulation scheme eliminates the LC filter required by traditional Class D amplifiers, improving efficiency, reducing component count, conserving board space and system cost. Conventional Class D amplifiers output a 50% duty cycle square wave when no signal is present. With no filter, the output square wave appears across the load, resulting in finite load current, which increases power consumption. When no signal is present at the input, the MAX9715 outputs switch as shown in Figure 2. The two outputs cancel each other because the MAX9715 drives the speaker differently, minimizing power consumption as there is no net idlemode voltage across the speaker.
_______________________________________________________________________________________
7
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier MAX9715
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 output stage is mostly due to the I2R loss of the MOSFET on-resistance, switching losses, 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 or voice reproduction levels), efficiency falls below 30%. Under the same conditions, the MAX9715 still exhibits >80% efficiencies (Figure 3).
EFFICIENCY vs. OUTPUT POWER
90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0 OUTPUT POWER (W) VDD = 5V RL = 8 fIN = 1kHz 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 CLASS AB MAX9715
MAX9715 fig03
100
Gain Selection
Drive GAIN high to set the gain of the speaker amplifiers to +9dB, drive GAIN low to set the gain of the speaker amplifiers to +10.5dB (see Table 1). The gain of the MAX9715 is calculated by the following equation:
V - VOUT - 20 x log OUT + VIN
Figure 3. MAX9715 Class D Efficiency vs. Typical Class AB Efficiency
Table 1. MAX9715 Maximum Gain Settings
GAIN SPEAKER MODE GAIN (dB) +10.5 +9.0 0 1
Table 2 shows the speaker amplifier input voltage needed to attain maximum output power from a given gain setting and load.
Shutdown
The MAX9715 features a 0.1A low-power shutdown mode that reduces quiescent current consumption and extends battery life. Driving SHDN low disables the output amplifiers, bias circuitry, and drives BIAS to GND. Connect SHDN to logic 1 for normal operation.
Table 2. MAX9715 Input Voltage and Gain Settings for Maximum Output Power
GAIN (dB) 10.5 9.0 10.5 9.0 INPUT (VRMS) 0.90 1.08 1.00 1.19 RL () 4 4 8 8 POUT (W) 2.3 2.3 1.4 1.4
Click-and-Pop Suppression
The MAX9715 speaker amplifiers feature Maxim's comprehensive, industry-leading click-and-pop suppression that eliminates any audible transients at startup. The outputs are high-impedance while in shutdown. During startup or power-up, the modulator bias voltage is set to the correct level while the input amplifiers are muted. The input amplifiers are muted for 25ms allowing the input capacitors to charge to the bias voltage (VBIAS). The amplifiers are then unmuted, ensuring click-free startup.
Applications Information
Filterless Operation
Traditional Class D amplifiers require an output filter to recover the audio signal from the amplifier's PWM output. The filters add cost, increase the solution size of the
amplifier, and can decrease efficiency. The traditional PWM scheme uses large differential output swings (2 x VDD(P-P)), which causes large ripple currents. Any parasitic resistance in the filter components results in a loss of power, lowering the efficiency. The MAX9715 does not require an output filter. The device relies on the inherent inductance of the speaker coil and the natural filtering of both the speaker and the human ear to recover the audio component of the square-wave output. The elimination of the output filter results in a smaller, less costly, more efficient solution.
8
_______________________________________________________________________________________
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier
Voice coil movement due to the square-wave frequency is very small because the switching frequency of the MAX9715 is well beyond the bandwidth of most speakers. Although this movement is small, a speaker not designed to handle the additional power may be damaged. Use a speaker with a series inductance > 30H for optimum efficiency. Typical 8 speakers exhibit series inductances in the 30H to 100H range. The highest efficiency is achieved with speaker inductances > 60H. RIN is the amplifier's internal input resistance value given in the Electrical Characteristics table. Choose CIN so f -3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the amplifier's low-frequency response. Use capacitors with low-voltage coefficient dielectrics, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as ceramics, may result in increased distortion at low frequencies. The inability of small diaphragm speakers to reproduce low frequencies can be exploited to improve click-andpop performance. Set the cutoff frequency of the MAX9715's input highpass filter to match the speaker's frequency response. Doing so will allow for smaller CIN values and reduce click-and-pop. Output Filter The MAX9715 speaker amplifiers do not require output filters. However, output filtering can be used if a design is failing radiated emissions due to board layout, cable length, or the circuit is near EMI-sensitive devices. Use a ferrite bead filter or a common-mode choke when radiated frequencies above 10MHz are of concern. Use an LC filter when radiated frequencies below 10MHz are of concern, or when long cables (>75mm) connect the amplifier to the speaker. Figure 4 shows possible output filter connections.
MAX9715
Component Selection
Input Filter The input capacitor (CIN), in conjunction with the amplifier input resistance (R IN ), forms a highpass filter that removes the DC bias from an incoming signal (see the Typical Application Circuit). The AC-coupling capacitor allows the amplifier to bias the signal to an optimum DC level. Assuming zero source impedance, the -3dB point of the highpass filter is given by: f-3dB = 1 2 x RIN x CIN
OUTL+ OUTL-
OUTL+ OUTL-
OUTL+ OUTL-
MAX9715
MAX9715
MAX9715
OUTR+ OUTR-
OUTR+ OUTR-
OUTR+ OUTR-
(a) TYPICAL APPLICATION <75mm OF SPEAKER CABLE.
(b) COMMON-MODE CHOKE FOR APPLICATIONS USING CABLE LENGTHS GREATER THAN 150mm.
(c) LC FILTER WHEN USING LONG CABLE LENGTHS OR IN APPLICATIONS THAT ARE SENSITIVE TO EMI.
Figure 4. Optional Speaker Amplifier Output Filter--Guidelines for FCC Compliance _______________________________________________________________________________________ 9
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier MAX9715
Supply Bypassing, Layout, and Grounding
Proper layout and grounding are essential for optimum performance. Use large traces for the power-supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance. Large traces also aid in moving heat away from the package. Proper grounding improves audio performance, minimizes crosstalk between channels, and prevents any switching noise from coupling into the audio signal. Route ground return paths that carry switching transients to power ground (PGND). Keep highcurrent return paths that connect to PGND short and route them away from analog ground (GND) and any traces or components in the audio input signal path. Use a star connection to connect GND and PGND together at one point on the PC board. Bypass each PVDD with a 0.1F capacitor to PGND. Bypass VDD to GND with a 0.1F capacitor. Place a bulk capacitor between VDD and PGND. Place the bypass capacitors as close to the MAX9715 as possible. Use large, low-resistance output traces. Current drawn from the output increases as load impedance decreases. High-output-trace resistance decreases the power delivered to the load. For example, when compared to a 0 trace, a 100m trace reduces the power delivered to a 4 load from 2.1W to 2.0W. Large output, supply, and GND traces decrease the thermal impedance of the circuit and allow more heat to be radiated from the MAX9715 to the air. The MAX9715 thin QFN-EP package features an exposed thermal pad on its underside. This pad lowers the package's thermal impedance by providing a directheat conduction path from the die to the PC board. Connect the exposed thermal pad to an electrically isolated pad of copper. A bigger pad area provides better thermal performance. Connect EP to GND if PC board layout rules do not allow for isolated pads of copper. If EP is connected to GND, ensure that high-current return paths do not flow through EP.
Biamp Configuration
The Typical Application Circuit shows the MAX9715 configured as a mid-/high-frequency amplifier and the MAX9713 is configured as a mono bass amplifier. Capacitors C1 and C2 set the highpass cutoff frequency according to the following equation: f= 1 2 x RIN x C1
where RIN is the input resistance of the MAX9715 and C1 = C2. The 10F capacitors on the output of the MAX9715 ensure a two-pole roll-off with the 5 load shown. The stereo signal is summed to a mono signal and then sent to a two-pole lowpass filter. The filtered signal is then amplified by the MAX9713. The passband gain of the lowpass filter, for coherent left and right signals is (-2 x R3) / R1, where R1 = R2. The cutoff frequency of the lowpass filter is set by the following equation: f= 1 x 2 1 C 3 x C4 x R 3 x R4
10
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2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier
Typical Application Circuit
5V C1 15nF LEFT IN 22F 8
MAX9715
C2 15nF RIGHT IN
MAX9715
22F 8
R3 7.5k C4 2.2nF R4 15k C6 1F R2 15k 1F C3 22nF 2.5V 12V
C5 1F
R1 15k
MAX4480
1F
MAX9713
______________________________________________________________________________________
11
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier MAX9715
Typical Operating Circuit/Functional Diagram
4.5V TO 5.5V
SHUTDOWN CONTROL
*
0.1F
0.1F
0.1F
VDD
PVDD
PVDD
SHDN SHDN CONTROL
MAX9715
1F LEFT AUDIO INL RIN VDD
CLASS D MODULATOR AND H-BRIDGE
OUTL+ OUTL-
GAIN-SELECT LOGIC 1F RIGHT AUDIO
GAIN
GAIN SELECT RIN VBIAS
VBIAS
VDD
OSCILLATOR OUTR+ OUTR-
INR
CLASS D MODULATOR AND H-BRIDGE
BIAS
BIAS GENERATOR GND PGND PGND
1F
*BULK PC BOARD DECOUPLING, TYPICALLY GREATER THAN 10F.
Pin Configurations (continued)
TOP VIEW
GND 1 INR 2 INL 3 PGND 4 OUTL+ 5 OUTL- 6 PVDD 7 GAIN 8 16 VDD 15 BIAS 14 GND
Chip Information
TRANSISTOR COUNT: 11,721 PROCESS: BiCMOS
MAX9715
13 PGND 12 OUTR+ 11 OUTR10 PVDD 9 SHDN
TSSOP 12 ______________________________________________________________________________________
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
QFN THIN.EPS
MAX9715
D2 D D/2 MARKING k L E/2 E2/2 E (NE-1) X e
C L C L
b D2/2
0.10 M C A B
XXXXX
E2
PIN # 1 I.D.
DETAIL A
e (ND-1) X e
e/2
PIN # 1 I.D. 0.35x45 DETAIL B
e
L1
L
C L
C L
L
L
e 0.10 C A 0.08 C
e
C
A1 A3 PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
-DRAWING NOT TO SCALE-
21-0140
H
1
2
COMMON DIMENSIONS
PKG. 16L 5x5 20L 5x5 28L 5x5 32L 5x5 40L 5x5 SYMBOL MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX.
EXPOSED PAD VARIATIONS PKG. CODES T1655-1 T1655-2 T1655N-1 T2055-2 T2055-3 T2055-4 T2055-5 T2855-1 T2855-2 T2855-3 T2855-4 T2855-5 T2855-6 T2855-7 T2855-8 T2855N-1 T3255-2 T3255-3 T3255-4 T3255N-1 T4055-1
D2
MIN. NOM. MAX. MIN.
E2
NOM. MAX.
L
0.15
A A1 A3 b D E e k L L1 N ND NE JEDEC
NOTES:
DOWN BONDS ALLOWED
0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0 0.02 0.05 0 0.02 0.05 0 0.02 0.05 0 0.02 0.05 0 0.02 0.05 0.20 REF. 0.20 REF. 0.25 0.30 0.35 0.25 0.30 0.35 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 0.80 BSC. 0.65 BSC. 0.25 - 0.25 0.20 REF. 0.20 REF. 0.20 0.25 0.30 0.20 0.25 0.30 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 0.50 BSC. 0.50 BSC. - 0.25 0.25 0.20 REF. 0.15 0.20 0.25 4.90 5.00 5.10 4.90 5.00 5.10 0.40 BSC. 0.25 0.35 0.45
3.00 3.00 3.00 3.00 3.00 3.00 3.15 3.15 2.60 3.15 2.60 2.60 3.15 2.60 3.15 3.15 3.00 3.00 3.00 3.00 3.20
3.10 3.20 3.00 3.10 3.20 3.00 3.10 3.20 3.00 3.10 3.20 3.00 3.10 3.20 3.00 3.10 3.20 3.00 3.25 3.25 2.70 3.25 2.70 2.70 3.25 2.70 3.25 3.25 3.10 3.10 3.10 3.10 3.35 3.35 2.80 3.35 2.80 2.80 3.35 2.80 3.35 3.35 3.20 3.20 3.20 3.20 3.15 3.15 2.60 3.15 2.60 2.60 3.15 2.60 3.15 3.15 3.00 3.00 3.00 3.00
3.10 3.10 3.10 3.10 3.10 3.10 3.25 3.25 2.70 3.25 2.70 2.70 3.25 2.70 3.25 3.25 3.10 3.10 3.10 3.10 3.30
3.20 3.20 3.20 3.20 3.20 3.20 3.35 3.35 2.80 3.35 2.80 2.80 3.35 2.80 3.35 3.35 3.20 3.20 3.20 3.20 3.40
** ** ** ** ** ** 0.40 ** ** ** ** ** ** ** 0.40 ** ** ** ** ** **
NO YES NO NO YES NO YES NO NO YES YES NO NO YES YES NO NO YES NO NO YES
0.30 0.40 0.50 0.45 0.55 0.65 0.45 0.55 0.65 0.30 0.40 0.50 0.40 0.50 0.60 - 0.30 0.40 0.50 16 4 4 WHHB 20 5 5 WHHC 28 7 7 WHHD-1 32 8 8 WHHD-2 40 10 10 -----
1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. 2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. 3. N IS THE TOTAL NUMBER OF TERMINALS. 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. 5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm FROM TERMINAL TIP. 6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. 7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. 8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. 9. DRAWING CONFORMS TO JEDEC MO220, EXCEPT EXPOSED PAD DIMENSION FOR T2855-1, T2855-3, AND T2855-6. 10. WARPAGE SHALL NOT EXCEED 0.10 mm. 11. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY. 12. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY. 13. LEAD CENTERLINES TO BE AT TRUE POSITION AS DEFINED BY BASIC DIMENSION "e", 0.05.
3.30 3.40 3.20
** SEE COMMON DIMENSIONS TABLE
PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm
-DRAWING NOT TO SCALE-
21-0140
H
2
2
______________________________________________________________________________________
13
2.8W, Low-EMI, Stereo, Filterless Class D Audio Amplifier MAX9715
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.)
TSSOP4.40mm.EPS
PACKAGE OUTLINE, TSSOP 4.40mm BODY
21-0066
G
1
1
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

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