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19-3160; Rev 1; 3/04
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers
General Description
The MAX9703/MAX9704 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 15W while offering up to 78% efficiency. Proprietary and patent-protected modulation and switching schemes render the traditional class D output filter unnecessary. The MAX9703/MAX9704 offer two modulation schemes: a fixed-frequency mode (FFM), and a spread-spectrum mode (SSM) that reduces EMI-radiated emissions due to the modulation frequency. The device utilizes a fully differential architecture, a full bridged output, and comprehensive click-and-pop suppression. The MAX9703/MAX9704 feature high 80dB PSRR, low 0.07% THD+N, and SNR in excess of 100dB. Short-circuit and thermal-overload protection prevent the devices from being damaged during a fault condition. The MAX9703 is available in a 32-pin TQFN (5mm x 5mm x 0.8mm) package. The MAX9704 is available in a 32-pin TQFN (7mm x 7mm x 0.8mm) package. Both devices are specified over the extended -40C to +85C temperature range.
Features
Filterless Class D Amplifier Unique Spread-Spectrum Mode Offers 5dB Emissions Improvement Over Conventional Methods Up to 78% Efficient 15W Output Power into 8 Up to 20W Peak Power Low 0.07% THD+N High PSRR (80dB at 1kHz) 10V to 25V Single-Supply Operation Differential Inputs Minimize Common-Mode Noise Pin-Selectable Gain Reduces Component Count Industry-Leading Click-and-Pop Suppression Low Quiescent Current (24mA) Low-Power Shutdown Mode (0.2A) Short-Circuit and Thermal-Overload Protection Available in Thermally Efficient, Space-Saving Packages 32-Pin TQFN (5mm x 5mm x 0.8mm)-MAX9703 32-Pin TQFN (7mm x 7mm x 0.8mm)-MAX9704
MAX9703/MAX9704
Applications
LCD TVs LCD Monitors Desktop PCs LCD Projectors Hands-Free Car Phone Adaptors Automotive
PART MAX9703ETJ MAX9704ETJ
o
Ordering Information
TEMP RANGE -40 C to +85 C -40oC to +85oC
o
PIN-PACKAGE 32 TQFN-EP* 32 TQFN-EP*
AMP Mono Stereo
*EP = Exposed paddle.
Block Diagrams
0.47F
INL+ H-BRIDGE INL-
MAX9704
OUTL+
MAX9703
0.47F IN+ H-BRIDGE INOUTOUT+
0.47F
OUTL-
0.47F
0.47F
INR+ H-BRIDGE INR-
OUTR+
0.47F
OUTR-
Pin Configurations appear 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.
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.) VDD to PGND, AGND .............................................................30V OUTR_, OUTL_, C1N..................................-0.3V to (VDD + 0.3V) C1P............................................(VDD - 0.3V) to (CHOLD + 0.3V) CHOLD ........................................................(VDD - 0.3V) to +40V All Other Pins to GND.............................................-0.3V to +12V Duration of OUTR_/OUTL_ Short Circuit to GND, VDD ..................................................10s Continuous Input Current (VDD, PGND) ...............................1.6A Continuous Input Current......................................................0.8A Continuous Input Current (all other pins)..........................20mA Continuous Power Dissipation (TA = +70C) MAX9703 32-Pin TQFN (derate 21.3mW/C above +70C)..........................................................1702.1mW MAX9704 32-Pin TQFN (derate 33.3mW/C above +70C)..........................................................2666.7mW Junction Temperature ......................................................+150C Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +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 = 15V, GND = PGND = 0V, SHDN VIH, AV = 16dB, CSS = CIN = CREG = 0.47F, C1 = 100nF, C2 = 1F, FS1 = FS2 = GND (fS = 660kHz), RL connected between OUTL+ and OUTL- and OUTR+ and OUTR-, T A = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER GENERAL Supply Voltage Range Quiescent Current Shutdown Current Turn-On Time Amplifier Output Resistance in Shutdown VDD IDD ISHDN tON CSS = 470nF CSS = 180nF SHDN = GND AV = 13dB Input Impedance RIN AV = 16dB AV = 19.1dB AV = 29.6dB G1 = L, G2 = L Voltage Gain AV G1 = L, G2 = H G1 = H, G2 = L G1 = H, G2 = H Gain Matching Output Offset Voltage Common-Mode Rejection Ratio Power-Supply Rejection Ratio (Note 3) VOS CMRR PSRR fIN = 1kHz, input referred VDD = 10V to 25V 200mVP-P ripple THD+N = 10%, f = 1kHz, TA = +25C fRIPPLE = 1kHz fRIPPLE = 20kHz RL = 4 RL = 8, VDD = 20V 54 Between channels (MAX9704) 150 35 30 23 10 29.4 18.9 12.8 15.9 Inferred from PSRR test RL = OPEN MAX9703 MAX9704 10 14 24 0.2 100 50 330 58 48 39 15 29.6 19.1 13 16 0.5 6 60 80 80 66 7.5 W 20 dB 30 80 65 55 22 29.8 19.3 13.2 16.3 % mV dB dB k 25 22 34 1.5 V mA A ms k SYMBOL CONDITIONS MIN TYP MAX UNITS
Output Power
POUT
2
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15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 15V, GND = PGND = 0V, SHDN VIH, AV = 16dB, CSS = CIN = CREG = 0.47F, C1 = 100nF, C2 = 1F, FS1 = FS2 = GND (fS = 660kHz), RL connected between OUTL+ and OUTL- and OUTR+ and OUTR-, T A = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER Total Harmonic Distortion Plus Noise SYMBOL THD+N CONDITIONS fIN = 1kHz, either FFM or SSM, RL = 8, POUT = 4W RL = 8, POUT = 10W, f = 1kHz BW = 22Hz to 22kHz A-weighted Crosstalk FFM SSM FFM SSM 560 MIN TYP 0.07 94 88 97 91 65 670 940 470 670 7% 78 6 VIH VIL 2.5 0.8 1 % V kHz 800 dB dB MAX UNITS %
MAX9703/MAX9704
Signal-to-Noise Ratio
SNR
Left to right, right to left, 8 load, fIN = 10kHz FS1 = L, FS2 = L FS1 = L, FS2 = H
Oscillator Frequency
fOSC
FS1 = H, FS2 = L FS1 = H, FS2 = H (spread-spectrum mode)
Efficiency Regulator Output
VREG
POUT = 15W, f = 1kHz, RL = 8
DIGITAL INPUTS (SHDN, FS_, G_) (Note 4) Input Thresholds Input Leakage Current V A
Note 1: All devices are 100% production tested at +25C. 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 = 8, L = 68H. For RL = 4, L = 33H. Note 3: PSRR is specified with the amplifier inputs connected to GND through CIN. Note 4: Do not apply more than 8V to any logic pin.
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3
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
Typical Operating Characteristics
(33H with 4, 68H with 8, part in SSM mode, 136H with 16, measurement BW = 22Hz to 22kHz, unless otherwise noted.)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX9703/04 toc01
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX9703/04 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VDD = 20V RL = 8 AV = 16dB
MAX9703/04 toc03
10
VDD = 15V RL = 4 AV = 16dB
10
VDD = 15V RL = 8 AV = 16dB
10
1 THD+N (%) THD+N (%) POUT = 4W 0.1
1 THD+N (%) POUT = 8W
1 POUT = 8W
0.1
0.1
POUT = 500mW 0.01 10 100 1k FREQUENCY (Hz) 10k 100k 0.01 10 100
POUT = 500mW 0.01 1k FREQUENCY (Hz) 10k 100k 10 100
POUT = 500mW
1k FREQUENCY (Hz)
10k
100k
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VDD = 20V RL = 8 AV = 16dB POUT = 8W SSM
MAX9703/04 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
VDD = 15V RL = 4 AV = 16dB 10 THD+N (%) f = 10kHz 1
MAX9703/04 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
VDD = 15V RL = 8 AV = 16dB 1 THD+N (%) f = 1kHz 0.1 f = 10kHz
MAX9703/04 toc06
10
100
10
1 THD+N (%) 0.1
0.1 FFM f = 100Hz 0.01 10 100 1k FREQUENCY (Hz) 10k 100k 0.01 0 1 2 3 4 5 6 7 8 9 10 OUTPUT POWER (W) 0.01 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 OUTPUT POWER (W) f = 1kHz f = 100Hz
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
MAX9703/04 toc07
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER
VDD = 20V RL = 8 AV = 16dB f = 1kHz SSM
MAX9703/04 toc08
EFFICIENCY vs. OUTPUT POWER
90 80 EFFICIENCY (%) 70 60 50 40 30 RL = 4 RL = 8
MAX9703/04 toc09
100 VDD = 20V RL = 8 AV = 16dB
10
100
10 THD+N (%)
f = 10kHz
1 1 THD+N (%) 0.1 0.1 FFM (335kHz) f = 100Hz 0.01 0 2 4 6 8 10 12 14 16 18 20 OUTPUT POWER (W) 0.01 0 1 2 3 4 5 6 7 8 9 10111213141516171819 20 OUTPUT POWER (W)
f = 1kHz
20 10 0 0 1 2 3 4 5 6 7
VDD = 12V AV = 16dB f = 1kHz 8 9 10
OUTPUT POWER (W)
4
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15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
Typical Operating Characteristics (continued)
(33H with 4, 68H with 8, part in SSM mode, 136H with 16, measurement BW = 22Hz to 22kHz, unless otherwise noted.)
OUTPUT POWER vs. SUPPLY VOLTAGE
MAX9703/04 toc10 MAX9703/04 toc11
EFFICIENCY vs. OUTPUT POWER
100 90 80 EFFICIENCY (%) 70 60 50 40 30 20 10 0 0 2 4 6 8 10 12 14 16 18 20 OUTPUT POWER (W) VDD = 15V AV = 16dB f = 1kHz RL = 8 RL = 16 20 18 16 OUTPUT POWER (W) 14 12 10 8 6 4 2 0 10
OUTPUT POWER vs. LOAD RESISTANCE
18 16 OUTPUT POWER (W) 14 12 10 8 6 4 THD+N = 1% VDD = 15V RL = 8 AV = 16dB
MAX9703/04 toc12
20
THD+N = 10%
RL = 8 RL = 16
AV = 16dB THD+N = 10% 13 16 19 SUPPLY VOLTAGE (V) 22 25
2 0 1 10 LOAD RESISTANCE () 100
OUTPUT POWER vs. LOAD RESISTANCE
MAX9703/04 toc13
COMMON-MODE REJECTION RATIO vs. FREQUENCY
-10 -20 CMRR (dB) -30 -40 -50 VDD = 15V RL = 8 AV = 16dB
MAX9703/04 toc14
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
AV = 16dB RL = 8 200mVP-P INPUT VDD = 15V
MAX9703/04 toc15
24 22 20 18 16 14 12 10 8 6 4 2 0 1
VDD = 20V RL = 8 AV = 16dB
0
0 -20 -40 PSRR (dB) -60 -80 -100 -120
THD+N = 10%
OUTPUT POWER (W)
THD+N = 1%
-60 -70 -80
10 LOAD RESISTANCE ()
100
10
100
1k FREQUENCY (Hz)
10k
100k
10
100
1k FREQUENCY (Hz)
10k
100k
CROSSTALK vs. FREQUENCY
MAX9703/04 toc16
OUTPUT FREQUENCY SPECTRUM
MAX9703/04 toc17
OUTPUT FREQUENCY SPECTRUM
0 OUTPUT MAGNITUDE (dB) -20 -40 -60 -80 -100 -120 -140 0 2 4 6 8 10 12 14 16 18 20 SSM MODE AV = 16dB UNWEIGHTED fIN = 1kHz POUT = 5W RL = 8
MAX9703/04 toc18
0 -20 CROSSTALK (dB) -40
OUTPUT MAGNITUDE (dB)
AV = 16dB 1% THD+N VDD = 15V 8 LOAD LEFT TO RIGHT
20 0 -20 -40 -60 -80 -100 -120 -140
20
FFM MODE AV = 16dB UNWEIGHTED fIN = 1kHz POUT = 5W RL = 8
-60 -80 RIGHT TO LEFT -100 -120 10 100 1k FREQUENCY (Hz) 10k 100k
0
2
4
6
8
10 12 14 16 18 20
FREQUENCY (kHz)
FREQUENCY (kHz)
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5
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
Typical Operating Characteristics (continued)
(33H with 4, 68H with 8, part in SSM mode, 136H with 16, measurement BW = 22Hz to 22kHz, unless otherwise noted.)
WIDEBAND OUTPUT SPECTRUM (FFM MODE)
MAX9703/04 toc19 MAX9703/04 toc20
OUTPUT FREQUENCY SPECTRUM
20 0 OUTPUT MAGNITUDE (dB) -20 -40 -60 -80 -100 -120 -140 0 2 4 6 8 10 12 14 16 18 20 FREQUENCY (kHz) SSM MODE AV = 16dB A-WEIGHTED fIN = 1kHz POUT = 5W RL = 8 0 -20 OUTPUT AMPLITUDE (dBV) -40 -60 -80 -100 -120 100k
WIDEBAND OUTPUT SPECTRUM (SSM MODE)
RBW = 10kHz VDD = 15V
MAX9703/04 toc21
0 -20 OUTPUT AMPLITUDE (dBV) -40 -60 -80 -100 -120
RBW = 10kHz VDD = 15V
1M
10M
100M
100k
1M
10M
100M
FREQUENCY (Hz)
FREQUENCY (Hz)
TURN-ON/TURN-OFF RESPONSE
MAX9703/04 toc22
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX9703/04 toc23
SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX97703/04 toc24
CSS = 180pF
35 30 SUPPLY CURRENT (mA)
0.35 0.30 SUPPLY CURRENT (A) 0.25 0.20 0.15 0.10 0.05 0
SHDN
5V/div
25 20 15 10 5 0
1V/div OUTPUT f = 1kHz RL = 8 20ms/div
10
13
16
19
22
25
10
12
14
16
18
20
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
6
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15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers
Pin Description
PIN NAME MAX9703 1, 2, 23, 24 3, 4, 21, 22 5 6 7 8, 17, 20, 25, 26, 31, 32 9 10 11 12 13 14 15 16 18 19 27, 28 29, 30 -- -- -- -- -- -- -- -- -- MAX9704 1, 2, 23, 24 3, 4, 21, 22 5 6 7 8 14 13 -- -- 12 11 17 18 19 20 -- -- 9 10 15 16 25, 26 27, 28 29, 30 31, 32 -- PGND VDD C1N C1P CHOLD N.C. REG AGND ININ+ SS SHDN G1 G2 FS1 FS2 OUTOUT+ INLINL+ INRINR+ OUTROUTR+ OUTLOUTL+ EP Power Ground Power-Supply Input Charge-Pump Flying Capacitor Negative Terminal Charge-Pump Flying Capacitor Positive Terminal Charge-Pump Hold Capacitor. Connect a 1F capacitor from CHOLD to VDD. No Connection. Not internally connected. Internal Regulator Output. Bypass with a 0.47F capacitor to PGND. Analog Ground Negative Input Positive Input Soft-Start. Connect a 0.47F capacitor from SS to GND to enable soft-start feature. Active-Low Shutdown. Connect SHDN to GND to disable the device. Connect to VDD for normal operation. Gain-Select Input 1 Gain-Select Input 2 Frequency-Select Input 1 Frequency-Select Input 2 Negative Audio Output Positive Audio Output Left-Channel Negative Input Left-Channel Positive Input Right-Channel Negative Input Right-Channel Positive Input Right-Channel Negative Audio Output Right-Channel Positive Audio Output Left-Channel Negative Audio Output Left-Channel Positive Audio Output Exposed Paddle. Connect to GND. FUNCTION
MAX9703/MAX9704
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7
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
Detailed Description
The MAX9703/MAX9704 filterless, class D audio power amplifiers feature several improvements to switchmode amplifier technology. The MAX9703 is a mono amplifier, the MAX9704 is a stereo amplifier. These devices offer class AB performance with class D efficiency, while occupying minimal board space. A unique filterless modulation scheme and spread-spectrum switching mode create a compact, flexible, lownoise, efficient audio power amplifier. The differential input architecture reduces common-mode noise pickup, and can be used without input-coupling capacitors. The devices can also be configured as a single-ended input amplifier. Comparators monitor the device inputs and compare the complementary input voltages to the triangle waveform. The comparators trip when the input magnitude of the triangle exceeds their corresponding input voltage.
VIN = 0V
OUT-
OUT+
Operating Modes
Fixed-Frequency Modulation (FFM) Mode The MAX9703/MAX9704 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 FFT graph in the Typical Operating Characteristics). The MAX9703/ MAX9704 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 does not affect audio reproduction. Spread-Spectrum Modulation (SSM) Mode The MAX9703/MAX9704 feature a unique, patented spread-spectrum mode that flattens the wideband spectral components, improving EMI emissions that may be radiated by the speaker and cables. This mode is enabled by setting FS1 = FS2 = H. In SSM mode, the switching frequency varies randomly by 7% around the center frequency (670kHz). The modulation scheme remains the same, but the period of the triangle waveform changes from cycle to cycle. Instead of a large amount of spectral energy present at multiples of the switching frequency, the energy is now spread over a bandwidth that increases with frequency. Above a few megahertz, the wideband spectrum looks like white noise for EMI purposes.
Figure 1. MAX9704 Outputs with No Input Signal Applied
Table 1. Operating Modes
FS1 L L H H FS2 L H L H SWITCHING MODE (kHz) 670 940 470 670 7%
Efficiency
Efficiency of a class D amplifier is attributed to the region of operation of the output stage transistors. In a class D amplifier, the output transistors act as currentsteering switches and consume negligible additional power. Any power loss associated with the class D output stage is mostly due to the I*R 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 MAX9704 still exhibits >78% efficiency under the same conditions (Figure 2).
8
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15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers
EFFICIENCY vs. OUTPUT POWER
100 90 80 70 EFFICIENCY (%) 60 50 40 30 20 10 0 0 2 4 6 8 10 12 14 16 18 20 OUTPUT POWER (W) VDD = 15V f = 1kHz RL = 8 CLASS AB MAX9704
swings (2 VDD peak-to-peak) and causes large ripple currents. Any parasitic resistance in the filter components results in a loss of power, lowering the efficiency. The MAX9703/MAX9704 do not require an output filter. The devices rely on the inherent inductance of the speaker coil and the natural filtering of both the speaker and the human ear to recover the audio component of the square-wave output. Eliminating the output filter results in a smaller, less-costly, more-efficient solution. Because the frequency of the MAX9703/MAX9704 output is well beyond the bandwidth of most speakers, voice coil movement due to the square-wave frequency is very small. Although this movement is small, a speaker not designed to handle the additional power can be damaged. For optimum results, use a speaker with a series inductance > 30H. Typical 8 speakers exhibit series inductances in the range of 30H to 100H. Optimum efficiency is achieved with speaker inductances > 60H.
MAX9703/MAX9704
Figure 2. MAX9704 Efficiency vs. Class AB Efficiency
Shutdown
The MAX9703/MAX9704 have a shutdown mode that reduces power consumption and extends battery life. Driving SHDN low places the device in low-power (0.2A) shutdown mode. Connect SHDN to a logic high for normal operation.
Gain Selection
Table 2 shows the suggested gain settings to attain a maximum output power from a given peak input voltage and given load.
Output Offset
Unlike a class AB amplifier, the output offset voltage of class D amplifiers does not noticeably increase quiescent current draw when a load is applied. This is due to the power conversion of the class D amplifier. For example, an 8mVDC offset across an 8 load results in 1mA extra current consumption in a class AB device. In the class D case, an 8mV offset into 8 equates to an additional power drain of 8W. Due to the high efficiency of the class D amplifier, this represents an additional quiescent current draw of: 8W/(VDD/100 ), which is in the order of a few microamps.
Click-and-Pop Suppression
The MAX9703/MAX9704 feature comprehensive clickand-pop suppression that eliminates audible transients on startup and shutdown. While in shutdown, the Hbridge is pulled to GND through 330k. During startup, 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 unmutes the input amplifiers. The value of the soft-start capacitor has an impact on the click/pop levels. For optimum performance, CSS should be at least 180nF with a voltage rating of at least 7V.
Table 2. Gain Settings
GAIN (dB) 13.0 16.0 19.1 29.6 13.0 16.0 19.1 29.6 INPUT DIFF (VRMS) 0.67 0.48 0.33 0.10 1.23 0.86 0.61 0.19 RL () 4 4 4 4 8 8 8 8 POUT AT 10% THD+N (W) 9 9 9 9 15 15 15 15
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
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9
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
Input Amplifier
Differential Input The MAX9703/MAX9704 feature a differential input structure, making them compatible with many CODECs, and offering improved noise immunity over a single-ended input amplifier. In devices such as PCs, noisy digital signals can be picked up by the amplifier's input traces. The signals appear at the amplifiers' inputs as commonmode noise. A differential input amplifier amplifies the difference of the two inputs, any signal common to both inputs is canceled. Single-Ended Input The MAX9703/MAX9704 can be configured as singleended input amplifiers by capacitively coupling either input to GND and driving the other input (Figure 3).
0.47F SINGLE-ENDED AUDIO INPUT IN+
MAX9703/
IN- MAX9704 0.47F
Figure 3. Single-Ended Input
C1 improves load regulation and reduces the chargepump output resistance to an extent. Above 1F, the onresistance of the switches and the ESR of C1 and C2 dominate. Hold Capacitor (C2) The output capacitor value and ESR directly affect the ripple at CHOLD. Increasing C2 reduces output ripple. Likewise, decreasing the ESR of C2 reduces both ripple and output resistance. Lower capacitance values can be used in systems with low maximum output power levels. Output Filter The MAX9703/MAX9704 do not require an output filter and can pass FCC emissions standards with unshielded speaker cables. However, output filtering can be used if a design is failing radiated emissions due to board layout or cable length, or the circuit is near EMIsensitive devices. Use a ferrite bead filter when radiated frequencies above 10MHz are of concern. Use an LC filter when radiated frequencies below 10MHz are of concern, or when long leads connect the amplifier to the speaker. Refer to the MAX9704 Evaluation Kit schematic for details of this filter.
Component Selection
Input Filter An input capacitor, CIN, in conjunction with the input impedance of the MAX9703/MAX9704, forms a highpass filter that removes the DC bias from an incoming signal. The AC-coupling capacitor allows the amplifier to bias the signal to an optimum DC level. Assuming zero-source impedance, the -3dB point of the highpass filter is given by: f -3dB = 1 2RINCIN
Choose CIN so f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the low-frequency response of the amplifier. Use capacitors with dielectrics that have low-voltage coefficients, such as tantalum or aluminum electrolytic. Capacitors with highvoltage coefficients, such as ceramics, may result in increased distortion at low frequencies.
Charge-Pump Capacitor Selection
Use capacitors with an ESR less than 100m for optimum performance. Low-ESR ceramic capacitors minimize the output resistance of the charge pump. For best performance over the extended temperature range, select capacitors with an X7R dielectric. 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
Sharing Input Sources
In certain systems, a single audio source can be shared by multiple devices (speaker and headphone amplifiers). When sharing inputs, it is common to mute the unused device, rather than completely shutting it down, preventing the unused device inputs from distorting the input signal. Mute the MAX9703/MAX9704 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 MAX9703/MAX9704. Be aware that during normal operation, the voltage at SS can be up to 7V, depending on the MAX9703/MAX9704 supply.
10
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15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers
Supply Bypassing/Layout Proper power-supply bypassing ensures low distortion operation. For optimum performance, bypass VDD to PGND with a 0.1F capacitor as close to each VDD pin as possible. A low-impedance, high-current power-supply connection to VDD is assumed. Additional bulk capacitance should be added as required depending on the application and power-supply characteristics. AGND and PGND should be star connected to system ground. Refer to the MAX9704 Evaluation Kit for layout guidance.
MAX9703/MAX9704
Pin Configurations
28 OUTR+ 27 OUTR+ 32 OUTL+ 31 OUTL+ 30 OUT+ 29 OUT+ 28 OUT27 OUT-
32 N.C.
31 N.C.
26 N.C.
25 N.C.
TOP VIEW
26 OUTR-
30 OUTL-
29 OUTL-
25 OUTR24 23 22 21
PGND PGND
VDD VDD
1 2 3 4 5 6 7 8 10 11 12 13 14 15 16 9
24 23 22 21
PGND PGND
VDD VDD
PGND PGND
VDD VDD
1 2 3 4 5 6 7 8 10 11 12 13 14 15 16 9
PGND PGND
VDD VDD
C1N C1P CHOLD N.C.
MAX9703
20 19 18 17
N.C. FS2
FS1
C1N C1P CHOLD N.C.
MAX9704
20 19 18 17
FS2 FS1
G2
N.C.
G1
INL-
INL+
SHDN
AGND
SHDN
TQFN (5mm x 5mm)
TQFN (7mm x 7mm)
Chip Information
MAX9703 TRANSISTOR COUNT: 3093 MAX9704 TRANSISTOR COUNT: 4630 PROCESS: BiCMOS
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AGND
INR+
REG
INR-
REG
SS
G1
IN+
IN-
G2
SS
11
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
Functional Diagrams
10V TO 25V 100F 25V 0.1F 25V 1 2 PGND 0.47F 3 4 VDD 21 22 VDD 0.1F 25V 23 24 PGND
11 IN+ MODULATOR 12 INH-BRIDGE
OUT+ 30 OUT+ 29 OUT- 28 OUT- 27
0.47F
VREG VREG VIH VREG VREG 0.18F 10V VREG 0.47F 10V
18 FS1 19 FS2 14 SHDN 15 G1 16 G2 13 SS 9 REG 10 AGND
OSCILLATOR
GAIN CONTROL SHUTDOWN CONTROL
MAX9703
C1P 6 CHARGE PUMP C1N CHOLD 7 C2 1F 25V 5
C1 0.1F 25V
LOGIC INPUTS SHOWN FOR AV = 16dB (SSM). VIN = LOGIC HIGH > 2.5V.
VDD
12
______________________________________________________________________________________
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers
Functional Diagrams (continued)
10V TO 25V 100F 25V 0.1F 25V 1 2 PGND 0.47F 3 4 VDD 21 22 VDD 0.1F 25V 23 24 PGND
MAX9703/MAX9704
10 INL+ MODULATOR 9 INLH-BRIDGE
OUTL+ 32 OUTL+ 31 OUTL- 30 OUTL- 29
0.47F
VREG VREG 0.47F
19 FS1 20 FS2
OSCILLATOR
15 INR+ MODULATOR 16 INRH-BRIDGE
OUTR+ 26 OUTR+ 25 OUTR- 28 OUTR- 27
0.47F
VIH VREG VREG 0.18F 10V VREG 0.47F 10V
11 SHDN 17 G1 18 G2 12 SS 14 REG 13 AGND
GAIN CONTROL SHUTDOWN CONTROL
MAX9704
C1P 6 CHARGE PUMP 5 C1N CHOLD 7 C2 1F 25V C1 0.1F 25V
VDD LOGIC INPUTS SHOWN FOR AV = 16dB (SSM). VIN = LOGIC HIGH > 2.5V.
______________________________________________________________________________________
13
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
System Diagram
VDD
100F
1F VDD INLSHDN OUTLOUTL+
0.47F
0.47F INL+ CODEC 0.47F INR+ 0.47F INRSS 100k 0.18F OUTR5V 1F
MAX9704
OUTR+
1F
SHDN INLVDD
1F
15k INL+
MAX9722B
OUTL
1F
15k INR+ OUTR PVSS SVSS CIN 1F
1F INR30k 30k C1P
1F
LOGIC INPUTS SHOWN FOR AV = 16dB (SSM).
14
______________________________________________________________________________________
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers
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.)
MAX9703/MAX9704
D2 D D/2 k
C L
b D2/2
E/2 E2/2 E (NE-1) X e
C L
E2
k L DETAIL A e (ND-1) X e DETAIL B
e L
C L
C L
L1
L
L
e
e
A1
A2
A
TITLE:
SEMICONDUCTOR
PROPRIETARY INFORMATION
DALLAS
PACKAGE OUTLINE 32, 44, 48, 56L THIN QFN, 7x7x0.8mm
DOCUMENT CONTROL NO. REV.
APPROVAL
21-0144
D
1
2
______________________________________________________________________________________
15
32, 44, 48L QFN.EPS
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
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.)
SEMICONDUCTOR
PROPRIETARY INFORMATION TITLE:
DALLAS
PACKAGE OUTLINE 32, 44, 48, 56L THIN QFN, 7x7x0.8mm
DOCUMENT CONTROL NO. REV.
APPROVAL
21-0144
D
2
2
16
______________________________________________________________________________________
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
MAX9703/MAX9704
0.15 C A
D2
C L
D
b D2/2
0.10 M C A B
PIN # 1 I.D.
D/2
0.15 C B
k
PIN # 1 I.D. 0.35x45
E/2 E2/2 E (NE-1) X e
C L
E2
k L
DETAIL A
e (ND-1) X e
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
21-0140
E
1
2
______________________________________________________________________________________
17
QFN THIN.EPS
15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers MAX9703/MAX9704
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.)
COMMON DIMENSIONS PKG. 20L 5x5 28L 5x5 32L 5x5 40L 5x5 16L 5x5 SYMBOL MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. A A1 A3 b D E e k L L1 N ND NE JEDEC 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 0.20 REF. 0 0.02 0.05 0.20 REF. 0 0.02 0.05 0.20 REF. 0 0.02 0.05 0.20 REF. 0 0.05 0.20 REF. PKG. CODES T1655-1 T1655-2 T2055-2 T2055-3 T2055-4 T2855-1 T2855-2 T2855-3 T2855-4 T2855-5 T2855-6 T2855-7 T3255-2 T3255-3 T3255-4 T4055-1
EXPOSED PAD VARIATIONS
D2
MIN. NOM. MAX. MIN.
E2 3.10 3.20 3.10 3.20 3.10 3.20 3.10 3.20 3.10 3.25 2.70 3.25 2.70 2.70 3.25 2.70 3.10 3.10 3.10 3.20 3.35 2.80 3.35 2.80 2.80 3.35 2.80 3.20 3.20 3.20
NOM. MAX. ALLOWED
DOWN BONDS
3.00 3.00 3.00 3.00 3.00 3.15 2.60 3.15 2.60 2.60 3.15 2.60 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 3.25 2.70 3.25 2.70 2.70 3.25 2.70 3.10 3.10 3.10 3.20 3.35 2.80 3.35 2.80 2.80 3.35 2.80 3.20 3.20 3.20 3.00 3.15 2.60 3.15 2.60 2.60 3.15 2.60 3.00 3.00 3.00
0.25 0.30 0.35 0.25 0.30 0.35 0.20 0.25 0.30 0.20 0.25 0.30 0.15 0.20 0.25 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 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. 0.50 BSC. 0.50 BSC. 0.40 BSC. - 0.25 - 0.25 - 0.25 0.35 0.45 0.25 - 0.25 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 16 4 4 WHHB 20 5 5 WHHC 28 7 7 WHHD-1 32 8 8 WHHD-2 0.30 0.40 0.50 40 10 10 -
NO YES NO YES NO NO NO YES YES NO NO YES NO YES NO YES
3.30 3.40 3.20
3.30 3.40
NOTES: 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. PACKAGE OUTLINE 16, 20, 28, 32, 40L, THIN QFN, 5x5x0.8mm
21-0140
E
2
2
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 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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