Transcript
Audio 12th Edition
December 2009
Listen louder...
listen longer
Inside
Page
Low-power, Class H headphone amps.......................................................... 2 Signal-processing codecs and amps............................................................ 4 Active noise-cancellation solution.................................................................. 6 Low-power, Class D amps............................................................................. 8 Reference design for Intel® Atom™ processor............................................10 High-power, low-EMI, filterless Class D amps..............................................12 Selection guide.............................................................................................14 Application notes...........................................................................................17 Class A–Class H amplifier tutorial.................................................................18
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.
Efficiency vs. output power (16Ω, noise)
45 40
EFFICIENCY (%)
35 30
MAX97200
25
TPA6140
20 15 10 5 0
0
5
10
15
20
25
OUTPUT POWER (mW/ch)
and longer battery life by using second-generation, dual-mode, DirectDrive® II technology OUTPUT Based on Maxim’s proprietar y 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.
VOLTAGE
+1.8V +0.9V
TIME VTH_L
-1.8V
2
32ms
VTH_H
-0.9V
DirectDrive is a registered trademark of Maxim Integrated Products, Inc.
HPVDD
HPVSS
32ms
Class H DirectDrive II headphone amp provides best-in-class efficiency No clicks or pops
MAX97200 AUDIO SOURCE
DirectDrive II technology • Low quiescent current: 1.06mA at 1.8V • Output power: 30mW into 32Ω at 1.8V
SHDN
0.05% THD+N performance
Dynamic, Class H dual-mode charge pump
CHARGE PUMP
30% smaller solution size than the competition TPA6140/ LM48824
MAX97200
Smallest solution size • Tiny, 1.27mm x 1.65mm x 0.4mm, 12-bump WLP (vs. TPA6140/LM48824: 16-bump WLP) • No inductor needed
vs.
36mm2
24mm2
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
BATTERY 2.7V TO 5.5V
I2C
POWER SUPPLY
CONTROL
STEREO/ MONO INPUT
DISTORTION LIMITER
VOLUME
VOLUME STEREO/ MONO INPUT
MAX97000 CLASS D AMPLIFIER
CLASS H AMPLIFIER CHARGE PUMP
SWITCH
3
Audio codecs and amplifiers with integrated signal processing
Equalization curve
Improve sound quality • Parametric equalizer Corrects for imperfections in the acoustic frequency response.
AMPLITUDE
• 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.
FREQUENCY OUTPUT SIGNAL (dBFS)
Increase loudness
12dB GAIN WITHOUT CLIPPING
0
Automatic 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.
NO NOISE AMPLIFICATION INPUT SIGNAL (dBFS) LOW-LEVEL THRESHOLD
-12
0
Protect speakers All 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.
4
Maxim’s newest codec and amplifier products with signal processing Highly integrated multimedia codec 1.8V
BATTERY
POWER SUPPLY
I2S/PCM
I2S/PCM
I2S
DIGITAL AUDIO INTERFACE
DIGITAL AUDIO INTERFACE
CONTROL
FLEXSOUNDTM DSP MIC INPUT MIC INPUT STEREO ADC
MIC/LINE INPUT
EARPIECE AMPLIFIER BYPASS
• 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
CLASS D AMPLIFIER
STEREO DAC
CLASS D AMPLIFIER
CLASS AB AMPLIFIER
LINE INPUT
MAX9888*
CHARGE PUMP
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
Mono speaker audio subsystem BATTERY 2.7V TO 5.5V
I2C
POWER SUPPLY
CONTROL
STEREO/ MONO INPUT
MAX97000 DISTORTION LIMITER
VOLUME
VOLUME STEREO/ MONO INPUT
CLASS D AMPLIFIER
CLASS H AMPLIFIER CHARGE PUMP
SWITCH
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
FLEXSOUND is a trademark of Maxim Integrated Products, Inc. *Future product—contact factory for availability.
5
Silence is golden! Active noise-cancellation solution for stereo headphones and headsets— simple to design-in, provides excellent audio performance
Simple product design Typical 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-bystep procedure that guides the customer from mechanical prototype through final product manufacturing.
Typical noise-cancellation performance using Maxim ANC headphones
High performance over a wider frequency range
10 ATTENUATION (dB)
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 noisecancellation performance over a wider frequency range.
15 ANC OFF
5 0 -5 -10 -15 -20
ANC ON
-25 -30 20
50
100
200 500 FREQUENCY (Hz)
1k
2k 3k
Output spectrum vs. frequency 0
VOUT = -60dBV
OUTPUT SPECTRUM (dBV)
-20
ANC 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.
-40 -60 -80 -100 -120 -140 0
6
Quiet the hiss
2
4
6
8 10 12 14 16 18 20 FREQUENCY (kHz)
Novel, ANC headphone amplifier solution
LINE IN LEFT MICROPHONE INPUT LEFT
MAX9895A*
HEADPHONE LEFT
ANALOG SIGNAL PROCESSING MIC PREAMP
HEADPHONE AMP HEADPHONE RIGHT ANALOG SIGNAL PROCESSING
MICROPHONE INPUT RIGHT
MIC PREAMP
HEADPHONE AMP
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
LINE IN RIGHT
*Future product—contact factory for availability.
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Maxim’s newest Class D amplifier family Extend battery life while reducing EMI, clipping, noise, and clicks/pops
Supply current vs. supply voltage 4.0
Industry’s lowest supply current
SUPPLY CURRENT (mA)
3.5 COMPETITION
3.0 2.5 2.0 1.5
MAX98300*
1.0 0.5 0
2.5
3.0
3.5 4.0 4.5 SUPPLY VOLTAGE (V)
5.0
5.5
The 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
MAX98300 heavy clipping recovery
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 highfrequency 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.
MAX98300 filtered output voltage vs. SHDN VOUT 1mV (typ)
SHDN
*Future product—contact factory for availability.
8
Low VOS for low click-and-pop noise
Click-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.
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 EMI spectrum (24in cable) 50.0
AMPLITUDE (dBμV/m)
40.0 EN 55022B LIMIT
30.0 20.0 10.0
MAX98300*
0.0 -10.0 30.0
100.0
200.0
300.0
400.0
500.0 600.0 FREQUENCY (MHz)
700.0
800.0
900.0
1000.0
Mono 2.7W amplifier VDD
+
GND
MAX98300 • < 750µA IQ at 3.3V • Low-current shutdown mode • 36µV output noise • 0.04% THD+N • WLP and TDFN packages
Stereo 2.7W amplifier VDD
+
+
MAX98302 • < 1.5mA IQ at 3.3V • 36µV output noise • 0.04% THD+N • Space-saving TDFN package
GND
†U.S. Patent #7,190,225.
*Future product—contact factory for availability.
9
Complete audio + PMIC solution for mobile internet devices High integration for Intel’s next-generation handheld platform CPU RAILS
Intel® SoC (INCLUDING Intel Atom™ PROCESSOR CORE)
SYSTEM RAILS
Intel I/O PLATFORM CONTROL HUB
MEMORY RAILS
MEMORY
COMMUNICATIONS
COMMUNICATIONS HDD/SSD, USB, ETC.
AUDIO INPUTS
AUDIO OUTPUTS
MAX9880A* AUDIO CODEC + MAX8920* MAIN PMIC + MAX8921* AUXILLIARY PMIC CODEC
Flexible Flexibility 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. Form-factor layout (~1500mm2) 15.0mm
Compact
2.5mm
Today’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-tomarket for your highly integrated mobile internet devices (MIDs).
8.0mm
18.5mm
10.0mm IC SIZE (mm2)
500 450 400 350 300 250 200 150 100 50 0
Smaller total solution size
COMPETITOR 1
COMPETITOR 2
Intel Atom is a trademark and Intel is a registered trademark of Intel Corporation. *Future product—contact factory for availability.
10
Optimized
43mm
14.0mm
32.8mm
Consumer 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.
Smart integration in a flexible, compact MID design
I2S/ PCM
I2S/ PCM
LEFT MIC AMP
MAX9880A* DIGITAL MICROPHONE INPUT
LINE OUTPUT MIX
ADC
DAC VOICE FILTERS
ADC
DIGITAL MIXING
LINE OUTPUT DAC
RIGHT MIC AMP MIX LEFT PREAMP
HEADPHONE AMP
RIGHT PREAMP
HEADPHONE AMP
LINEIN 1
LINEIN 2
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
• 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
*Future product—contact factory for availability.
11
Turn it up! Filterless Class D amplifiers provide the output power you need with no EMI hassles
Emission-suppression technologies
MAX9736 EMI performance (1m speaker cable) 40
AMPLITUDE (dBµV/m)
35
EN 55022B LIMIT
30 25
MAX9736
20 15 10 5 30
100
200
300
400
500
600
700
800
FREQUENCY (MHz)
900
1000
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 edgerate-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.
Versatile, high-efficiency, mono/stereo, 2 x 15W amplifier AUDIO INPUT 8Ω
8Ω
AUDIO INPUT SHDN MUTE MONO
*U.S. Patent #6,847,257
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MAX9736
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
Class D amps reduce EMI emissions by using industry-leading technology Direct-from-battery, high-efficiency, mono 7W amplifier AUDIO INPUT 8Ω
SHDN MUTE
MAX9737
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
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
CLASS D
AUDIO INPUT BIAS
VOLUME CONTROL CLASS D
AUDIO INPUT MUTE SHUTDOWN ANALOG OR I2C VOLUME CONTROL SYNC
MAX9744 OSCILLATOR
SYNCOUT
10W, mono speaker amplifier with volume control AUDIO INPUT BIAS SHUTDOWN MUTE ANALOG OR I2C VOLUME CONTROL
MAX9768
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
13
Audio selector guide Capless, DirectDrive headphone amplifiers Part MAX4409 MAX4410/11 MAX9722 MAX9723 MAX9724 MAX9726
Supply Current (mA)
Output Offset (mV)
32Ω
16Ω
1.8 to 3.6
5.0
0.5
65
80
2.4 to 5.5 1.8 to 3.6
5.5 4.0 3.5 5.5
0.5 0.7 1.5 3.0
130 59 63 104
70 60 42 124
3.0
0.1
90
70
Windows Vista® Premium mobile compliant
10-TDFN (3 x 3)
1.15
0.1
30
40
Lowest quiescent current
12-WLP (1.7 x 1.3)
2.7 to 5.5
MAX9820 MAX97200
Output Power at 1% THD+N (mW)
Supply Voltage (V)
1.8
Package (mm x mm)
Features Ground noise rejection Ultra-low distortion Differential inputs Bass boost, I2C volume Lowest RF susceptibility Bass boost, I2C volume
20-TQFN (4 x 4) 16-UCSP™ (2 x 2), 20-TQFN (4 x 4) 16-TQFN (3 x 3) 16-TQFN (4 x 4), 16-UCSP (2 x 2) 12-TQFN (3 x 3), 12-UCSP (1.5 x 2) 20-TQFN (4 x 4), 20-UCSP (2 x 2.5)
Low-power, linear speaker amplifiers Part MAX9710 MAX9711 MAX9716/17 MAX9718 MAX9719 MAX9730 MAX9738 MAX9788
Supply Voltage (V) 4.5 to 5.5
2.7 to 5.5
Output Power at 1% THD+N (W)
Features
8Ω
4Ω
Gain
2 x 1.4 1.4 1.1 1.1 2 x 1.1 2.4
2 x 2.6 2.6 1.4 1.4 2 x 1.4 —
Package (mm x mm)
Other
Adj/fixed
Headphone sense
20-TQFN (5 x 5) 12-TQFN (4 x 4) 8-TDFN (3 x 3), 9-UCSP (1.5 x 1.5)
Adj/fixed
Differential inputs
10-TDFN (3 x 3), 9-UCSP (1.5 x 1.5)
Charge-pump-boosted amp for dynamic speakers DC-DC-boosted amp for ceramic speakers Charge-pump-boosted amp for ceramic speakers
28-TQFN (4 x 4), 20-UCSP (2 x 2.5) 20-UCSP (2 x 2.5) 28-TQFN (4 x 4), 20-UCSP (2 x 2.5)
Adj
16VP-P 20VP-P
Adj
Mute
Low-power, Class D speaker amplifiers (filterless) Output Power at 1% THD+N (W) Part
MAX9705 MAX9715 MAX9759 MAX9830 MAX98300* MAX98302* MAX98500*
Supply Voltage (V)
2.5 to 5.5 4.5 to 5.5 3.0 to 5.5 2.6 to 5.5 2.5 to 5.5
8Ω
4Ω
1.3 2 x 1.4 1.4 1.2 1.3 2x1 1.7
2.3 2 x 2.3 2.6 2.25 2.1 2x2 3.2
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
Features SpreadSpectrum/ Edge-Rate Control ✓/✓ ✓/— ✓/—
✓/✓
Gain Fixed Pin programmable Pin programmable Fixed
Differential Input ✓
✓ Pin programmable
Package (mm x mm)
10-TDFN (3 x 3), 12-UCSP (1.5 x 2) 16-TQFN (5 x 5) 16-TQFN (4 x 4) 8-TDFN (2 x 2), 9-WLP (1.2 x 1.2) 9-WLP (2 x 2) 14-TDFN (3 x 3) 16-WLP (2 x 2)
Audio selector guide (cont.) High-power, Class D speaker amplifiers Part MAX9708 MAX9709 MAX9736A MAX9736B MAX9737 MAX9742 MAX9744 MAX9768 MAX98400A* MAX98400B*
Output Power at 10% THD+N (W)
Supply Voltage (V) 10 to 18 10 to 22 8 to 28 20 to 40 4.5 to 14 4.5 to 14 8 to 28 8 to 28
8Ω
4Ω
2 x 20 2 x 25 2 x 15 2x6 7.4 2 x 20 2 x 13 10 2 x 15 2x6
40 50 30 12 13 2 x 16 2 x 20 9.5 1 x 30 —
Features Gain
Other
Pin programmable Pin programmable
Programmable thermal flag Programmable thermal flag Mute function
Set by external resistors
Pin programmable Pin programmable
Single-ended output I2C/analog volume control I2C/analog volume control Clipping limiter Clipping limiter
Package (mm x mm) 56-TQFN (8 x 8) 56-TQFN (8 x 8) 32-TQFN (7 x 7) 32-TQFN (7 x 7) 24-TQFN (4 x 4) 36-TQFN (6 x 6) 44-TQFN (7 x 7) 24-TQFN (4 x 4) 36-TQFN (6 x 6) 24-TQFN (4 x 4)
Integrated audio subsystems Part
Supply Voltage (V)
Output Power at 1% THD+N**
Features
HP 32Ω (mW)
HP 16Ω (mW)
SP 8Ω (W)
SP 4Ω (W)
Gain/Volume Control
Speaker Amplifier
4.5 to 5.5
50 —
95 —
3 x 1.4
3 x 2.3
Pin programmable
Triple Class D
2 x 1.1
2 x 1.5
2.7 to 5.5
50
60
4.5 to 5.5
55
100
2.7 to 5.5
180
100
MAX9796
2.7 to 5.5
50
MAX9877
2.7 to 5.25
MAX9879
MAX9706 MAX9707 MAX9775 MAX9776
Stereo Class D I2C
Other Integrated 2.1 crossover
Package (mm x mm) 36-TQFN (6 x 6) 36-UCSP (3 x 3)
6 single-ended or 3 differential audio inputs, 3D sound
36-UCSP (3 x 3), 32-TQFN (5 x 5)
Stereo Class AB
Integrated LDO
32-TQFN (5 x 5)
Stereo Class D
Wake-on-beep, ground sense, integrated LDO
28-TQFN (4 x 4)
1.1
1.5
2x1
2x2
2 x 1.2
2 x 1.7
1.5
2.5
60
1.3
2.3
Mono Class D
6 single-ended or 3 differential audio inputs, 3D sound
32-TQFN (5 x 5)
27
53
0.725
0.825
Mono Class D
2 stereo or 2 mono differential audio inputs
20-WLP (2 x 2.5)
2.7 to 5.5
54
58
2 x 0.715
2 x 0.825
Stereo Class D
2 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)
MAX9789 MAX9791 MAX9792
Pin programmable Adj
I2C
Mono Class D
Mono Class D
*Future product—contact factory for availability. **HP = headphone, SP = speaker
15
Audio selector guide (cont.) Audio data converters Supply Voltage (V) Part
48kHz DAC Playback Power Consumption (mW)
Playback Dynamic Range (dB)
Analog I/O
Digital Audio Interface
MCLK Range (MHz)
Supported Sample Rates (kHz)
Package (mm x mm)
91
2 line inputs, 2 line outputs, 2 headphone amps
I2S
8.5 to 40
8 to 48
28-TQFN (5 x 5)
9
91
3 line inputs, 3 microphone inputs, 2 line outputs, 2 headphone amps
8 to 96
40-TQFN (6 x 6)
4.5
90
2 microphone inputs, 1 headphone amp
8 to 48
24-TQFN (4 x 4)
1.65 to 1.95
5.5
92
2 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)
1.65 to 1.95
10.6
96
2 line inputs, 2 microphone inputs, 2 line outputs, 2 headphone amps, 1 aux ADC
100
Dual 4 line inputs, 2 microphone I2S/TDM inputs, 2 speaker amps, (MAX9888), 2 headphone amps, single I2S/TDM 1 earpiece amp (MAX9889)
Core
I/O
MAX9850 (DAC)
1.8 to 3.6
1.8 to 3.6
10.1
MAX9856 (codec)
1.7 to 3.6
1.7 to 3.6
MAX9860 (codec)
1.7 to 1.9
1.7 to 3.6
MAX9867 (codec)
MAX9880A* (codec)
1.65 to 3.6
MAX9888*/89* (codecs)
Features
1.65 to 2.0
14
I2S/TDM
10 to 60
Dual I2S/TDM
48-WLP (2.7 x 3.5) 8 to 96 63-WLP (3.8 x 3.3)
Microphone amplifiers with integrated mic bias Part MAX4060 MAX4061 MAX4063 MAX4465/66 MAX9810 MAX9812/13L MAX9812/13H MAX9814
Features
Supply Voltage (V)
Supply Current (μA)
Input-Noise Voltage Density (nV/√Hz)
Single Ended
Differential
2.4 to 5.5
750
20
1
1
2.4 to 5.5 2.4 to 5.5 2.3 to 5.5 2.7 to 4.5 3.6 to 5.5 2.7 to 5.5
750 24 670
70 80 16
1 — 1
1 1
230
40
2
—
3100
30
1
Inputs
Shutdown Mode
Gain Adj 0dB, 20dB, 40dB Adj Adj 24dB, 27dB, 30dB
Package (mm x mm) 8-TQFN (3 x 5)
✓
16-TQFN (4 x 4) 5-SC70 (2 x 2), 5-SOT23 (3 x 3) 4-UCSP (1 x 1)
20dB
✓
6-SC70 (2 x 2.1) (MAX9812), 8-SOT23 (3 x 3) (MAX9813)
Automatic gain control
✓
14-TDFN (3 x 3)
Specialty audio devices Part MAX9890 MAX9892 MAX4744 MAX4764 MAX4993/94 MAX9895A*
Supply Voltage (V) 2.7 to 5.5 1.7 to 5.5 1.8 to 5.5 2.5 to 4.5
*Future product—contact factory for availability.
16
Description Headphone-amp click-pop suppressor Audio shunt-mode click-pop suppressor Dual SPDT audio switch Dual SPDT audio switch DPDT audio switch Active noise-cancellation solution for stereo headphones
Package (mm x mm) 8-TDFN (3 x 3), 9-UCSP (1.5 x 1.5) 6-UCSP (1 x 1.5), 6-μDFN (2 x 2) 10-µDFN (2 x 2) 10-TDFN (3 x 3), 10-UCSP (1.5 x 2) 10-UTQFN (1.4 x 1.8) 36-WLP (2.5 x 2.5 x 0.4), 40-TQFN (5 x 5)
Audio application notes How 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 Supply www.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
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Class A–Class H amplifier tutorial Class 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 B Class 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 AB A 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.
Class D
CLASS D MOSFET MODULATOR CLASS D MOSFETDRIVER MODULATOR DRIVER
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Class 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 lowpassfiltered average value of this waveform corresponds to the actual required audio waveform. These CLASS D MOSFETamplifiers are MODULATOR DRIVER because the highly efficient (often up to 90% or higher) output transistors are eitherCLASS fully D turned MOSFETon or off during MODULATOR DRIVER 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.
+V1 +V2
Class A–Class H amplifier tutorial (cont.) +V1 +V2
Class G
+V1 +V2
-V2
Class G amplifiers-V1are 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 -V1 -V2 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.
+V1 +V2 -V2 -V1
-V1 -V2
Class H
+V1
Class 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 +V1 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+V1required to predict and control the supply voltage.
+V1 -V1
-V1
-V1
Theoretical output power
-V1
The 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 100
4Ω BTL, 10% THD+N
4Ω BTL, 1% THD+N
8Ω BTL, 10% THD+N
OUTPUT POWER (W)
10 8Ω BTL, 1% THD+N
1
0.1 3
8
13
18
23
28
SUPPLY VOLTAGE (V)
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