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12th Edition December 2009
Audio
Listen louder...
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Inside PageLow-power,ClassHheadphoneamps......................................................... 2Signal-processingcodecsandamps........................................................... 4Activenoise-cancellationsolution................................................................. 6Low-power,ClassDamps............................................................................ 8ReferencedesignforIntel®Atom™processor...........................................10High-power,low-EMI,filterlessClassDamps.............................................12Selectionguide............................................................................................14Applicationnotes..........................................................................................17ClassA–ClassHamplifiertutorial................................................................18
2
Provide outstanding audio performance
Class H headphone amplifiers offer higher efficiency…Class H amplifiers provide nearly 2x higher
efficiency than the closest competitive Class G headphone amplifiers. Class H amps modulate the supply voltage to minimize voltage drop across the output devices by using either multiple supply voltages or an infinitely adjustable power supply.
and longer battery life by using second-generation, dual-mode, DirectDrive® II technology
Based on Maxim’s proprietary DirectDrive technology, our dual-mode DirectDrive II Class H amplifiers save power by switching between two supply voltages. The dual-mode charge pump uses ±0.9V rails when the output signal is small, only switching to ±1.8V supply voltage when more output power is needed. This technology renders a continuous signal without the glitches seen in Class G amplifiers.
32ms+1.8V
+0.9V
VTH_H
VTH_L
-0.9V
-1.8V
HPVDD
HPVSS
OUTPUTVOLTAGE
32ms
TIME
DirectDrive is a registered trademark of Maxim Integrated Products, Inc.
Efficiency vs. output power (16Ω, noise)
OUTPUT POWER (mW/ch)0 5 10 15 20 25
45
40
35
30
25
20
15
5
10
0
EFFI
CIEN
CY (%
)
MAX97200
TPA6140
3
Class H DirectDrive II headphone amp provides best-in-class efficiency
Smallest solution size• Tiny, 1.27mm x 1.65mm x 0.4mm, 12-bump
WLP (vs. TPA6140/LM48824: 16-bump WLP)• No inductor needed
DirectDrive II technology• Low quiescent current:
1.06mA at 1.8V• Output power: 30mW
into 32Ω at 1.8V
CHARGEPUMP
MAX97200
AUDIOSOURCE
SHDN
Dynamic,Class H dual-mode
charge pump
No clicks or pops
0.05% THD+N performance
Highly efficient audio subsystem integrates best-in-class discrete parts
• Highly efficient Class H headphone amp
• Mono, low-EMI, 2W Class D amp• Analog DPST switch• Integrated distortion limiter for
better sounding speakers
24mm2
TPA6140/LM48824
36mm2
MAX97200
vs.
30% smaller solution sizethan the competition
STEREO/ MONOINPUT
STEREO/ MONOINPUT
POWER SUPPLY
BATTERY2.7V TO 5.5V
CONTROL
I2C
DISTORTIONLIMITER
MAX97000
VOLUME CLASS DAMPLIFIER
VOLUME CLASS HAMPLIFIER
CHARGEPUMP
SWITCH
4
Audio codecs and amplifiers with integrated signal processing
Equalization curve
FREQUENCY
AMPL
ITUD
E
Improve sound quality• Parametric equalizer Corrects for imperfections in the
acoustic frequency response.
• Distortion limiter Automatically reduces gain to prevent excessive distortion regardless of input signal level.
• Excursion limiter Balances loudness with sound quality by allowing more low-frequency output at low signal levels and less at high signal levels to prevent excessive speaker excursion.
-12LOW-LEVELTHRESHOLD
0
INPUT SIGNAL(dBFS)
OUTPUT SIGNAL(dBFS)
0
12dB GAINWITHOUT CLIPPING
NO NOISEAMPLIFICATION
Increase loudnessAutomatic level control increases the input signal by up
to 12dB without clipping to guarantee that the output signal always has the highest continuous power. The circuit also ensures that, when switching between various audio sources, the output signal level is continuously the same.
Protect speakersAll speakers can be destroyed if their power rating
is exceeded for too long. The power limiter tracks the approximate temperature of the loudspeaker voice coil by monitoring the output signal level over time. If the speaker is at risk of being destroyed, the power limiter reduces the output signal to protect the speaker.
5
MAX9888*• Integrated signal processing• Two digital audio interfaces• DirectDrive headphone amp• Stereo, low-EMI, 2W Class D
amps• Digital and analog microphone
inputs• Two stereo line inputs• 3.8mm x 3.3mm, 63-bump
WLP
Maxim’s newest codec and amplifier products with signal processing
Highly integrated multimedia codec
MAX97000• Integrated distortion limiter• Low quiescent power• Mono, low-EMI, 2W Class D amp• Class H, DirectDrive II headphone
amp• Two single-ended/differential
inputs• Analog DPST switch• 2mm x 2mm, 25-bump WLP
Mono speaker audio subsystem
FLEXSOUND is a trademark of Maxim Integrated Products, Inc. *Future product—contact factory for availability.
STEREO/ MONOINPUT
STEREO/MONO INPUT
CLASS HAMPLIFIER
CHARGEPUMP
VOLUME
POWER SUPPLY
BATTERY2.7V TO 5.5V
CONTROL
I2C
SWITCH
DISTORTIONLIMITER
MAX97000
VOLUME CLASS DAMPLIFIER
LINE INPUT
MIC/LINE INPUT
DIGITAL AUDIOINTERFACE
DIGITAL AUDIOINTERFACE
EARPIECEAMPLIFIER
BYPASS
CLASS DAMPLIFIER
CLASS DAMPLIFIER
CLASS ABAMPLIFIER
MIC INPUT
MIC INPUT
POWER SUPPLY
1.8V BATTERY I2S/PCM I2S/PCM I2S
CONTROL
MAX9888*
• FIVE-BAND PARAMETRIC EQ• DYNAMIC RANGE COMPRESSOR• LOUDSPEAKER SIGNAL PROCESSING • EXCURSION LIMITER • THD LIMITER • POWER LIMITER• MICROPHONE SIGNAL PROCESSING • AUTOMATIC GAIN CONTROL • NOISE GATE• ASYNCHRONOUS DIGITAL MIXING
FLEXSOUNDTM DSP
CHARGEPUMP
STEREODAC
STEREOADC
6
Silence is golden!Active noise-cancellation solution for stereo headphones and headsets—simple to design-in, provides excellent audio performance
Simple product designTypical active noise-cancellation (ANC) solutions
require many discrete components in a large PCB area and offer poor noise-cancellation performance. Maxim provides a one-chip solution accompanied by a step-by-step procedure that guides the customer from mechanical prototype through final product manufacturing.
FREQUENCY (Hz)
ATTE
NUAT
ION
(dB)
200 500 1k 2k 3k10050
10
15
0
5
-5
-10
-15
-20
-25
-3020
Typical noise-cancellation performanceusing Maxim ANC headphones
ANC OFF
ANC ON
High performance over a wider frequency range
Obtaining a desired level of noise reduction at certain frequencies can be a tedious task due to microphone and headphone variances. Maxim’s ANC solution offers a flexible input preamplifier followed by a processing block, both at the control of the system designer. The outcome is better noise-cancellation performance over a wider frequency range.
Output spectrum vs. frequency
FREQUENCY (kHz)
OUTP
UT S
PECT
RUM
(dBV
)
6 8 10 12 14 16 1842
-80
-120
-100
-20
-40
-60
0
-1400 20
VOUT = -60dBV Quiet the hissANC headphone solutions suffer from wideband noise present
in the system design. This noise is heard as a loud hiss by the consumer, especially in quieter environments. Maxim provides an ultra-low input-noise solution that completely eliminates ambient hiss from the output signal. Along with excellent headphone amplifier audio performance, the result is a much more pleasing user experience.
7
MAX9895A*• Up to 99% ambient noise reduction• Ultra-low-noise headphone amp• Ultra-low-noise microphone preamps • Stereo, capacitorless headphone amps
with very low (0.002%) THD+N• Microphone output path available for
speech transmission• 5mm x 5mm, 40-pin TQFN and 2.5mm
x 2.5mm, 36-bump WLP
*Future product—contact factory for availability.
Novel, ANC headphone amplifier solution
ANALOGSIGNAL PROCESSING
LINEIN LEFT
MICPREAMP
HEADPHONEAMP
HEADPHONELEFT
MICROPHONEINPUT LEFT
ANALOGSIGNAL PROCESSING
LINEIN RIGHT
MICPREAMP
HEADPHONEAMP
HEADPHONERIGHT
MICROPHONEINPUT RIGHT
MAX9895A*
8
Industry’s lowest supply currentThe MAX98300* and MAX98302* represent a substantial
advancement in Class D amplifier power consumption by achieving supply current as low as 600µA. Critical to maximizing battery life in today’s portable products, this low supply current has been achieved without sacrificing EMI suppression, clipping behavior, noise performance, and click-and-pop level. In fact, these have all been improved!
Overdrive is no problem—our amplifiers clip cleanly
In small consumer devices, both speakers and amplifiers are driven hard to yield the highest sound-pressure level (SPL) possible. As a result, the amplifier may be heavily clipped. Many amplifier designs, particularly Class D designs, contribute additional high-frequency distortion artifacts that are far more objectionable than a cleanly clipped signal. The MAX98300/MAX98302 have been carefully designed to ensure clean recovery from clipping events.
Low VOS for low click-and-pop noiseClick-and-pop performance becomes important as we
aggressively power-manage amplifiers with frequent turn-on and turn-off cycles. If a pop or click is heard each time, it is annoying for the user. The MAX98300 has a very low offset voltage, and carefully addresses other sources of click-and-pop noise to ensure the best performance.
Maxim’s newest Class D amplifier familyExtend battery life while reducing EMI, clipping, noise, and clicks/pops
*Future product—contact factory for availability.
Supply current vs. supply voltage
SUPPLY VOLTAGE (V)
SUPP
LY C
URRE
NT (m
A)
4.0 4.5 5.0 5.53.53.0
2.5
2.0
1.0
0.5
1.5
4.0
3.5
3.0
02.5
COMPETITION
MAX98300*
MAX98300 heavy clipping recovery
VOUT
SHDN
1mV (typ)
MAX98300 filtered output voltage vs. SHDN
9
EMI so low, you may not believe it’s Class D!Patented EMI reduction techniques† and careful circuit design allow the MAX98300*/MAX98302* to have
the industry’s lowest EMI emissions. Implementation of these devices not only makes it easy to pass FCC and CE EMI limits, but also avoids interference with other sensitive circuits. Additionally, using them saves significant board space, as no filtering components of any kind are required with speaker cable or trace lengths 24in and beyond.
MAX98300• < 750µA IQ at 3.3V• Low-current shutdown mode• 36µV output noise• 0.04% THD+N• WLP and TDFN packages
+
VDD
GND
Mono 2.7W amplifier
MAX98302• < 1.5mA IQ at 3.3V• 36µV output noise• 0.04% THD+N• Space-saving TDFN package
+
GND
+
VDD
Stereo 2.7W amplifier
†U.S. Patent #7,190,225.*Future product—contact factory for availability.
50.0
40.0
30.0
20.0
AMPL
ITUDE
(dBμ
V/m
)
10.0
0.0
-10.030.0 100.0 200.0 300.0 400.0 500.0
FREQUENCY (MHz)600.0 700.0 800.0 900.0 1000.0
MAX98300 EMI spectrum (24in cable)
MAX98300*
EN 55022B LIMIT
10
Complete audio + PMIC solution for mobile internet devicesHigh integration for Intel’s next-generation handheld platform
FlexibleFlexibility is one of the most important aspects of
integrated designs. Maxim’s compact stereo audio codec provides full audio integration through multiple digital interfaces; complete programmability; and an analog amplifier solution for microphones, headphones, and line amplifiers. All features comply with the required specifications for Intel’s next-generation handheld platform.
CompactToday’s consumer electronic products have very little PCB space
to spare. Maxim’s power-management integrated circuit (PMIC) and full-featured audio codec provide a complete solution for compact form-factor designs. This complete reference design ensures fast time-to-market for your highly integrated mobile internet devices (MIDs).
Form-factor layout (~1500mm2)15.0mm
32.8mm
18.5mm
43mm8.0mm
14.0mm
10.0
mm
2.5mm
OptimizedConsumer product designers face a formidable dilemma
when choosing integrated circuit solutions. Using multiple ICs for a design can be difficult due to size requirements. While using a one-chip solution typically results in less flexibility and poor performance, Maxim’s multichip, wafer-level package (WLP) MID solution is optimized for size, performance, and flexibility. Thus, it outperforms the competition in size and crucial specifications.
Smaller total solution size
050
100150200250300350
450400
500
COMPETITOR 1
IC S
IZE
(mm
2 )
COMPETITOR 2
Intel Atom is a trademark and Intel is a registered trademark of Intel Corporation. *Future product—contact factory for availability.
AUDIO OUTPUTS
Intel® SoC(INCLUDING Intel Atom™
PROCESSOR CORE)CPU RAILSAUDIO INPUTS
SYSTEM RAILS
MEMORY RAILS
COMMUNICATIONS
IntelI/O PLATFORM CONTROL HUB
MEMORY
COMMUNICATIONSHDD/SSD, USB, ETC.
MAX9880A*AUDIO CODEC
+MAX8920*MAIN PMIC
+MAX8921*
AUXILLIARY PMICCODEC
11
Smart integration in a flexible, compact MID design
MAX9880A*• 96dB dynamic range • Two independent I2S/PCM interfaces • Digital and analog mixing • 8kHz to 96kHz sample rates• Accepts any 10MHz to 60MHz master
clock
*Future product—contact factory for availability.
• Analog and digital microphone support• Voice-band filtering achieves > 70dB
stop-band attenuation• 2.7mm x 3.5mm, 48-bump WLP• Works with main PMIC (MAX8920*)
and auxilliary PMIC (MAX8921*) audio codecs
DAC
DAC
DIGITALMICROPHONE
INPUT
LEFT MIC AMP
LINE OUTPUT
LINE OUTPUT
HEADPHONE AMP
HEADPHONE AMP
RIGHT MIC AMP
LEFT PREAMP
LINEIN 1
LINEIN 2
RIGHT PREAMP
MAX9880A*
MIX
VOICEFILTERS
DIGITALMIXING
ADC
ADC
MIX
I2S/PCM
I2S/PCM
12
Turn it up!Filterless Class D amplifiers provide the output power you need with no EMI hassles
MAX9736• Wide, 8V to 28V supply voltage range• Passes CE EMI limits with low-cost
ferrite bead and capacitor on each output • Integrates input-filter op amps• Input resistors and capacitors select gain
and cutoff frequency
Versatile, high-efficiency, mono/stereo, 2 x 15W amplifier
SHDNMUTE
MONO
AUDIOINPUT
MAX9736
AUDIOINPUT
8Ω
8Ω
Emission-suppression technologies
Class D amplifiers of fer the high efficiencies needed to extend battery life, but they can contribute to EMI-related RF interference. While inductor- capacitor (LC) output filters may help reduce this interference, they are costly and bulky. Maxim’s Class D amplifiers use patented spread-spectrum modulation techniques* in conjunction with sophisticated edge-rate-control technology to minimize EMI emissions. With no need for LC filters to clean up RF interference, your design will be compact, perform well, and cost less.
*U.S. Patent #6,847,257
FREQUENCY (MHz)
AMPL
ITUD
E (d
BµV/
m)
400300200100
10
15
20
25
30
35
40
530 500 600 700 800 900 1000
EN 55022B LIMIT
MAX9736 EMI performance (1m speaker cable)
MAX9736
13
Direct-from-battery, high-efficiency, mono 7W amplifier
20W, stereo speaker amplifier with volume control
MAX9744• 4.5V to 14V power-supply range• Filterless, low-EMI modulation scheme • I2C or analog volume control • High 93% efficiency eliminates bulky heatsinks• High 75dB PSRR, low 0.04% THD+N
MAX9768• 4.5V to 14V power-supply range• Filterless, low-EMI modulation scheme • I2C or analog volume control• High 87% efficiency eliminates bulky heatsinks• High 77dB PSRR, low 0.08% THD+N
MAX9737• Wide, 8V to 28V supply voltage range• Passes CE EMI limits with low-cost
ferrite bead and small-value capacitor• Input-filter op amp• Input resistors and capacitors select gain
and cutoff frequency
10W, mono speaker amplifier with volume control
Class D amps reduce EMI emissions by using industry-leading technology
SHDN
8Ω
MUTE
AUDIOINPUT
MAX9737
BIAS VOLUMECONTROL
MUTE
SHUTDOWN
CLAS
S D
CLAS
S D
AUDIOINPUT
AUDIOINPUT
OSCILLATORSYNCOUTSYNC
ANALOG OR I2C VOLUMECONTROL MAX9744
AUDIOINPUT
BIAS
ANALOG OR I2CVOLUME CONTROL
SHUTDOWNMUTE
MAX9768
UCSP is a trademark of Maxim Integrated Products, Inc. Windows Vista is a registered trademark of Microsoft Corporation. *Future product—contact factory for availability.
14
Audio selector guide
Part Supply Voltage (V)
Supply Current
(mA)
Output Offset (mV)
Output Power at 1% THD+N (mW)
Features Package (mm x mm)
32Ω 16Ω
MAX4409 1.8 to 3.6 5.0 0.5 65 80
Ground noise rejection 20-TQFN (4 x 4)MAX4410/11 Ultra-low distortion 16-UCSP™ (2 x 2), 20-TQFN (4 x 4)MAX9722 2.4 to 5.5 5.5 0.5 130 70 Differential inputs 16-TQFN (3 x 3)MAX9723 1.8 to 3.6 4.0 0.7 59 60 Bass boost, I2C volume 16-TQFN (4 x 4), 16-UCSP (2 x 2)MAX9724
2.7 to 5.5
3.5 1.5 63 42 Lowest RF susceptibility 12-TQFN (3 x 3), 12-UCSP (1.5 x 2)MAX9726 5.5 3.0 104 124 Bass boost, I2C volume 20-TQFN (4 x 4), 20-UCSP (2 x 2.5)
MAX9820 3.0 0.1 90 70 Windows Vista® Premium mobile compliant 10-TDFN (3 x 3)
MAX97200 1.8 1.15 0.1 30 40 Lowest quiescent current 12-WLP (1.7 x 1.3)
Capless, DirectDrive headphone amplifiers
Part Supply Voltage (V)
Output Power at 1% THD+N (W) Features
Package (mm x mm)
8Ω 4Ω Gain Other
MAX97104.5 to 5.5
2 x 1.4 2 x 2.6Adj Mute
20-TQFN (5 x 5)MAX9711 1.4 2.6 12-TQFN (4 x 4)MAX9716/17
2.7 to 5.5
1.1 1.4 Adj/fixed Headphone sense 8-TDFN (3 x 3), 9-UCSP (1.5 x 1.5)MAX9718 1.1 1.4
Adj/fixed Differential inputs 10-TDFN (3 x 3), 9-UCSP (1.5 x 1.5)MAX9719 2 x 1.1 2 x 1.4MAX9730 2.4 —
AdjCharge-pump-boosted amp for dynamic speakers 28-TQFN (4 x 4), 20-UCSP (2 x 2.5)
MAX9738 16VP-P DC-DC-boosted amp for ceramic speakers 20-UCSP (2 x 2.5)MAX9788 20VP-P Charge-pump-boosted amp for ceramic speakers 28-TQFN (4 x 4), 20-UCSP (2 x 2.5)
Low-power, linear speaker amplifiers
Part Supply Voltage (V)
Output Power at 1% THD+N (W) Features
Package (mm x mm)
8Ω 4Ω
Spread-Spectrum/Edge-Rate
Control
Gain Differential Input
MAX9705 2.5 to 5.5 1.3 2.3 / Fixed 10-TDFN (3 x 3), 12-UCSP (1.5 x 2)MAX9715 4.5 to 5.5 2 x 1.4 2 x 2.3 /— Pin programmable 16-TQFN (5 x 5)MAX9759 3.0 to 5.5 1.4 2.6 /— Pin programmable
16-TQFN (4 x 4)MAX9830
2.6 to 5.51.2 2.25
/
Fixed 8-TDFN (2 x 2), 9-WLP (1.2 x 1.2)MAX98300* 1.3 2.1
Pin programmable9-WLP (2 x 2)
MAX98302* 2 x 1 2 x 2 14-TDFN (3 x 3)MAX98500* 2.5 to 5.5 1.7 3.2 16-WLP (2 x 2)
Low-power, Class D speaker amplifiers (filterless)
15
Audio selector guide (cont.)
Part Supply Voltage (V)
Output Power at 10% THD+N (W) Features
Package (mm x mm)
8Ω 4Ω Gain Other
MAX9708 10 to 18 2 x 20 40 Pin programmable Programmable thermal flag 56-TQFN (8 x 8)MAX9709 10 to 22 2 x 25 50 Pin programmable Programmable thermal flag 56-TQFN (8 x 8)MAX9736A
8 to 282 x 15 30
Set by external resistors
Mute function32-TQFN (7 x 7)
MAX9736B 2 x 6 12 32-TQFN (7 x 7)MAX9737 7.4 13 24-TQFN (4 x 4)MAX9742 20 to 40 2 x 20 2 x 16 Single-ended output 36-TQFN (6 x 6)MAX9744 4.5 to 14 2 x 13 2 x 20 I2C/analog volume control 44-TQFN (7 x 7)MAX9768 4.5 to 14 10 9.5 I2C/analog volume control 24-TQFN (4 x 4)MAX98400A* 8 to 28 2 x 15 1 x 30 Pin programmable Clipping limiter 36-TQFN (6 x 6)MAX98400B* 8 to 28 2 x 6 — Pin programmable Clipping limiter 24-TQFN (4 x 4)
High-power, Class D speaker amplifiers
Part Supply Voltage (V)
Output Power at 1% THD+N** FeaturesPackage
(mm x mm)HP 32Ω (mW)
HP 16Ω (mW)
SP 8Ω (W)
SP 4Ω (W)
Gain/Volume Control
Speaker Amplifier Other
MAX97064.5 to 5.5
50 953 x 1.4 3 x 2.3 Pin
programmable Triple Class D Integrated 2.1 crossover 36-TQFN (6 x 6)
MAX9707 — —MAX9775
2.7 to 5.5 50 602 x 1.1 2 x 1.5
I2CStereo Class D 6 single-ended or
3 differential audio inputs, 3D sound
36-UCSP (3 x 3)
MAX9776 1.1 1.5 Mono Class D 36-UCSP (3 x 3), 32-TQFN (5 x 5)
MAX9789 4.5 to 5.5 55 100 2 x 1 2 x 2 Pin programmable Stereo Class AB Integrated LDO 32-TQFN (5 x 5)
MAX97912.7 to 5.5 180 100
2 x 1.2 2 x 1.7Adj
Stereo Class D Wake-on-beep, ground sense, integrated LDO
28-TQFN (4 x 4)MAX9792 1.5 2.5 Mono Class D
MAX9796 2.7 to 5.5 50 60 1.3 2.3
I2C
Mono Class D6 single-ended or 3 differential audio inputs, 3D sound
32-TQFN (5 x 5)
MAX9877 2.7 to 5.25 27 53 0.725 0.825 Mono Class D2 stereo or 2 mono differential audio inputs
20-WLP (2 x 2.5)
MAX9879 2.7 to 5.5 54 58 2 x 0.715 2 x 0.825 Stereo Class D2 stereo or 2 mono differential audio inputs
30-UCSP (2.5 x 3)
MAX97000 2.7 to 5.5/ 1.7 to 2.0 23 40 0.930 — Mono Class D
Integrated LDO, bypass switch, THD limiter, Class H headphone amp
25-WLP (2 x 2 x 0.4)
MAX97001* 2.7 to 5.5/ 1.6 to 2.0 34 43 0.710 — Mono Class D
Bypass switch, THD limiter, Class H headphone amp
20-WLP (2 x 2.5)
Integrated audio subsystems
*Future product—contact factory for availability. **HP = headphone, SP = speaker
16
Audio selector guide (cont.)
Part
Supply Voltage (V) 48kHz DAC Playback
Power Consumption
(mW)
Playback Dynamic
Range (dB)
Features
Package (mm x mm)Core I/O Analog I/O
Digital Audio
Interface
MCLK Range (MHz)
Supported Sample
Rates (kHz)
MAX9850 (DAC) 1.8 to 3.6 1.8 to 3.6 10.1 91 2 line inputs, 2 line outputs,
2 headphone amps I2S 8.5 to 40 8 to 48 28-TQFN (5 x 5)
MAX9856 (codec) 1.7 to 3.6 1.7 to 3.6 9 91
3 line inputs, 3 microphone inputs, 2 line outputs, 2 headphone amps
I2S/TDM
10 to 60
8 to 96 40-TQFN (6 x 6)
MAX9860 (codec) 1.7 to 1.9 1.7 to 3.6 4.5 90 2 microphone inputs,
1 headphone amp 8 to 48 24-TQFN (4 x 4)
MAX9867 (codec) 1.65 to 1.95
1.65 to 3.6
5.5 922 line inputs, 2 microphone inputs, 2 headphone amps, 1 aux ADC
8 to 48 30-WLP (2 x 2.5), 32-TQFN (5 x 5)
MAX9880A* (codec) 1.65 to 1.95 10.6 96
2 line inputs, 2 microphone inputs, 2 line outputs, 2 headphone amps, 1 aux ADC
Dual I2S/TDM
8 to 96
48-WLP (2.7 x 3.5)
MAX9888*/89* (codecs) 1.65 to 2.0 14 100
4 line inputs, 2 microphone inputs, 2 speaker amps, 2 headphone amps, 1 earpiece amp
Dual I2S/TDM
(MAX9888), single
I2S/TDM (MAX9889)
63-WLP (3.8 x 3.3)
Audio data converters
Part Supply Voltage (V)
Supply Current
(μA)
Input-Noise Voltage Density (nV/√Hz)
Features
Package (mm x mm)
InputsGain Shutdown
ModeSingle Ended Differential
MAX40602.4 to 5.5 750 20 1 1
Adj8-TQFN (3 x 5)
MAX4061 0dB, 20dB, 40dBMAX4063 2.4 to 5.5 750 70 1 1 Adj 16-TQFN (4 x 4)MAX4465/66 2.4 to 5.5 24 80 — 1 Adj 5-SC70 (2 x 2), 5-SOT23 (3 x 3)MAX9810 2.3 to 5.5 670 16 1
—
24dB, 27dB, 30dB 4-UCSP (1 x 1)MAX9812/13L 2.7 to 4.5
230 40 2 20dB 6-SC70 (2 x 2.1) (MAX9812), 8-SOT23 (3 x 3) (MAX9813)MAX9812/13H 3.6 to 5.5
MAX9814 2.7 to 5.5 3100 30 1 Automatic gain control 14-TDFN (3 x 3)
Microphone amplifiers with integrated mic bias
Part Supply Voltage (V) Description Package (mm x mm)MAX9890 2.7 to 5.5 Headphone-amp click-pop suppressor 8-TDFN (3 x 3), 9-UCSP (1.5 x 1.5)MAX9892 1.7 to 5.5 Audio shunt-mode click-pop suppressor 6-UCSP (1 x 1.5), 6-μDFN (2 x 2)MAX4744
1.8 to 5.5Dual SPDT audio switch 10-µDFN (2 x 2)
MAX4764 Dual SPDT audio switch 10-TDFN (3 x 3), 10-UCSP (1.5 x 2)MAX4993/94 DPDT audio switch 10-UTQFN (1.4 x 1.8)MAX9895A* 2.5 to 4.5 Active noise-cancellation solution for stereo headphones 36-WLP (2.5 x 2.5 x 0.4), 40-TQFN (5 x 5)
Specialty audio devices
*Future product—contact factory for availability.
17
Audio application notesHow to Pick a Click-and-Pop Suppressor www.maxim-ic.com/AN4449
Pots, Pans, Logs, and Linear Digital Pots Create Arbitrary Voltage Curves www.maxim-ic.com/AN4346
Capacitor Type Selection Optimizes PC Sound Quality for Windows Vista Audio Requirements www.maxim-ic.com/AN4333
Keep Power Consumption in Check with Low-Power Comparators that Autosense Plugged-In Accessories www.maxim-ic.com/AN4327
Reference Design for a Class D, 2.1 Channel Audio Amplifier for an MP3 Player Docking Station www.maxim-ic.com/AN4320
Amplifier Considerations in Ceramic Speaker Applications www.maxim-ic.com/AN4164
Class G and Charge-Pump Technologies Maximize Efficiency in Boosted Amplifiers with Minimal Support Components www.maxim-ic.com/AN4121
Minimize Noise in Audio Channels with Smart PCB Layout www.maxim-ic.com/AN4079
Overview of 2.1 (Satellite/Subwoofer) Speaker Systems www.maxim-ic.com/AN4046
Overview of DirectDrive Technology www.maxim-ic.com/AN3979
Class D Amplifiers: Fundamentals of Operation and Recent Developments www.maxim-ic.com/AN3977
Maxim’s Active-Emissions-Limiting Circuitry Demystified www.maxim-ic.com/AN3973
Spread-Spectrum-Modulation Mode Minimizes Electromagnetic Interference in Class D Amplifiers www.maxim-ic.com/AN3881
Minimizing RF Susceptibility in Cell-Phone Headphone Amplifiers www.maxim-ic.com/AN3880
Thermal Considerations for a Class D Amplifier www.maxim-ic.com/AN3879
Reduce EMI from Class D Amplifiers Using New Modulation Techniques and Filter Architectures www.maxim-ic.com/AN3878
Audio-DAC Performance Investigation www.maxim-ic.com/AN3735
Quantitative Analysis Yields Objective Measurement for Audio Amplifier Click and Pop www.maxim-ic.com/AN3687
DirectDrive Technology Enables 2VRMS Audio Line Driver from a Single 3.3V Supplywww.maxim-ic.com/AN3354
A Beginner’s Guide to Filter Topologies www.maxim-ic.com/AN1762
See the complete list of audio application notes at:www.maxim-ic.com/Audio-Appnotes
Class ABA combination of Class A and Class B, the Class AB
amplifier has higher efficiency than Class A, but less distortion than Class B. This performance is achieved by biasing both transistors to conduct near zero signal output—the point where Class B amplifiers introduce nonlinearities. They then transition to Class B for large excursions. Thus, for small signals, both transistors are active, acting like a Class A amplifier. For large signal excursions, only one transistor is active for each half of the waveform, acting like a Class B amplifier.
18
Class A–Class H amplifier tutorialClass A
The simplest type of amplifiers, Class A amplifiers, are those in which the output transistors conduct (i.e., do not fully turn off), irrespective of the output signal waveform. This type of amplifier is typically associated with high linearity, but low efficiency.
CLASS DMODULATOR
MOSFETDRIVER
Class BClass B amplifiers are those in which the output transistors only
conduct during half (180°) of the signal waveform. To amplify the entire signal, they use two transistors, one conducting for positive output signals and the other conducting for negative outputs. Class B amplifiers are much more efficient than Class A amplifiers, but they have high distortion due to the crossover point at which the two transistors transition from on to off.
Class DClass D amplifiers are those that output a switching
waveform at a frequency far higher than the highest audio signal that needs to be reproduced. The lowpass-filtered average value of this waveform corresponds to the actual required audio waveform. These amplifiers are highly efficient (often up to 90% or higher) because the output transistors are either fully turned on or off during operation. This approach completely eliminates the use of the linear region of the transistor, which is responsible for the inefficiency of other amplifier types. Modern Class D amplifiers achieve fidelity comparable to Class AB.
CLASS DMODULATOR
MOSFETDRIVER
CLASS DMODULATOR
MOSFETDRIVER CLASS D
MODULATORMOSFETDRIVER
19
Class GClass G amplifiers are similar to Class AB amplifiers, except that
they use two or more supply voltages. When operating at low signal levels, the amplifier selects a low supply voltage. As the signal level increases, the amplifier automatically selects the appropriate supply voltage. Class G amplifiers are more efficient than Class AB amplifiers because they use the maximum supply voltage only when required, while a Class AB amplifier always uses the maximum supply voltage.
Class HClass H amplifiers modulate their supply voltage to minimize the
voltage drop across the output stage. Implementations range from using multiple discrete voltages to an infinitely adjustable supply. Though similar to the Class G technique of reducing dissipation across output devices, the Class H technique does not require multiple power supplies. Class H amplifiers are generally more complex than other designs, with extra control circuitry required to predict and control the supply voltage.
Theoretical output powerThe following figures show the theoretical output power possible from a range of supply voltages. Output
power is specified at 1% and 10% THD+N with 4Ω and 8Ω loads. Real amplifiers will always output less power than shown in these figures.
Output power vs. supply voltage
3
100
4Ω BTL, 10% THD+N
10
1
0.1
8 13 18 23 28
OUTP
UT P
OWER
(W)
SUPPLY VOLTAGE (V)
4Ω BTL, 1% THD+N
8Ω BTL, 1% THD+N
8Ω BTL, 10% THD+N
Class A–Class H amplifier tutorial (cont.)
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+V1
+V2
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+V1
+V1 +V2
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Audio-12 Rev 2 US 3/10
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