MAX9776ETJ+,MAX9776EBX+TG45,MAX9775EBX+TG45,MAX9776ETJ+T,MAX9776EVKIT+, 规格书,Datasheet 资料

General Description

The MAX9775/MAX9776 combine a high-efficiency Class D, stereo/mono audio power amplifier with a mono DirectDrive ?receiver amplifier and a stereo DirectDrive headphone amplifier.

Maxim’s 3rd-generation, ultra-low-EMI, Class D audio power amplifiers provide Class AB performance with Class D efficiency. The MAX9775/MAX9776 deliver 1.5W per channel into a 4Ωload from a 5V supply and offer efficiencies up to 79%. Active emissions limiting circuitry and spread-spectrum modulation greatly reduce EMI, eliminating the need for output filtering found in traditional Class D devices.

The MAX9775/MAX9776 utilize a fully differential archi-tecture, a full-bridged output, and comprehensive click-and-pop suppression. A 3D stereo enhancement function allows the MAX9775 to widen the stereo sound field immersing the listener in a cleaner, richer sound experience than typically found in portable applications.The devices utilize a flexible, user-defined mixer archi-tecture that includes an input mixer, volume control, and output mixer. All control is done through I 2C.

The mono receiver amplifier and stereo headphone amplifier use Maxim’s DirectDrive architecture that pro-duces a ground-referenced output from a single supply,eliminating the need for large DC-blocking capacitors,saving cost, space, and component height.

The MAX9775 is available in a 36-bump WLP (3mm x 3mm) package. The MAX9776 is available in a 32-pin TQFN (5mm x 5mm) or a 36-bump WLP (3mm x 3mm)package. Both devices are specified over the extended -40°C to +85°C temperature range.

Applications

Cell Phones

Portable Multimedia Players Handheld Gaming Consoles

Features

?Unique Spread-Spectrum Modulation and Active Emissions Limiting Significantly Reduces EMI ?3D Stereo Enhancement (MAX9775 Only)?Up to 3 Stereo Inputs

?1.5W Stereo Speaker Output (4Ω, V DD = 5V)

?50mW Mono Receiver/Stereo Headphone Outputs (32Ω, V DD = 3.3V)

?High PSRR (68dB at 217Hz)

?79% Efficiency (V DD = 3.3V, R L = 8Ω, P OUT =470mW)

?I 2C Control—Input Configuration, Volume Control,Output Mode

?Click-and-Pop Suppression

?Low Total Harmonic Distortion (0.03% at 1kHz)?Current-Limit and Thermal Protection

?Available in Space-Saving, 36-Bump WLP (3mm x 3mm) and 32-Pin TQFN (5mm x 5mm) Packages

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

________________________________________________________________Maxim Integrated Products 1

Ordering Information

I C

INTERFACE I C INTERFACE

Simplified Block Diagrams

19-0746; Rev 4; 8/08

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,or visit Maxim’s website at https://www.wendangku.net/doc/9b9547365.html,.

Pin Configurations appear at end of data sheet.

ating temperature range.

+Denotes a lead-free/RoHS-compliant package.*Four center bumps depopulated.**EP = Exposed pad.

DirectDrive is a registered trademark of Maxim Integrated Products, Inc.

M A X 9775/M A X 9776

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V DD = PV DD = CPV DD = 3.3V, V GND = V PGND = V CPGND = 0V, SHDN = V DD , I 2C settings (INA gain = +20dB, INB gain = INC gain =0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise noted. C1 = C2 = C3 = 1μF. T A = T MIN to 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.

V DD to GND..............................................................................6V PV DD to PGND.........................................................................6V CPV DD to CPGND....................................................................6V CPV SS to CPGND.....................................................-6V to +0.3V V SS to CPGND..........................................................-6V to +0.3V C1N.......................................(CPV SS - 0.3V) to (CPGND + 0.3V)C1P.......................................(CPGND - 0.3V) to (CPV DD + 0.3V)HPL, HPR to GND...................(CPV SS - 0.3V) to (CPV DD + 0.3V)GND to PGND and CPGND................................................±0.3V V DD to PV DD and CPV DD ....................................................±0.3V SDA, SCL to GND.....................................................-0.3V to +6V All other pins to GND..................................-0.3V to (V DD + 0.3V)Continuous Current In/Out of PV DD , PGND, CPV DD , CPGND,OUT__, HPR, and HPL..................................................±800mA Continuous Input Current CPV SS ......................................260mA Continuous Input Current (all other pins).........................±20mA

Duration of Short Circuit Between

OUT_+ and OUT_-..................................................Continuous Duration of HP_, OUT_ Short Circuit to

GND or PV DD ..........................................................Continuous Continuous Power Dissipation (T A = +70°C)

36-Bump (3mm x 3mm) UCSP Multilayer Board

(derate 17.0mW/°C above +70°C)...........................1360.5mW 32-Pin (5mm x 5mm) TQFN Single-Layer Board

(derate 21.3mW/°C above +70°C)...........................1702.1mW 32-Pin TQFN Multilayer Board (derate 34.5mW/°C

above +70°C)...........................................................2758.6mW Junction Temperature......................................................+150°C Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range.............................-65°C to +150°C Lead Temperature (soldering, 10s).................................+300°C

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

_______________________________________________________________________________________3

ELECTRICAL CHARACTERISTICS (continued)

(V DD = PV DD = CPV DD = 3.3V, V GND = V PGND = V CPGND = 0V, SHDN = V DD , I 2C settings (INA gain = +20dB, INB gain = INC gain =0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise noted. C1 = C2 = C3 = 1μF. T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.) (Note 1)

M A X 9775/M A X 9776

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier 4_______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V DD = PV DD = CPV DD = 3.3V, V GND = V PGND = V CPGND = 0V, SHDN = V DD , I 2C settings (INA gain = +20dB, INB gain = INC gain =0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

_______________________________________________________________________________________5

ELECTRICAL CHARACTERISTICS (continued)

(V DD = PV DD = CPV DD = 3.3V, V GND = V PGND = V CPGND = 0V, SHDN = V DD , I 2C settings (INA gain = +20dB, INB gain = INC gain =0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise noted. C1 = C2 = C3 = 1μF. T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.) (Note 1)

M A X 9775/M A X 9776

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier 6_______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(V DD = PV DD = CPV DD = 3.3V, V GND = V PGND = V CPGND = 0V, SHDN = V DD , I 2C settings (INA gain = +20dB, INB gain = INC gain =0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise noted. C1 = C2 = C3 = 1μF. T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.) (Note 1)

Note 1:All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design.Note 2:Measured at headphone outputs.Note 3:Amplifier 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 R L = 8Ω, L = 68μH;for R L = 4Ω, L = 47μH.

Note 5:MAX9775 only.

Note 6:Testing performed at room temperature with an 8Ωresistive load in series with a 68μH inductive load connected across BTL

outputs for speaker amplifier. Testing performed with a 32Ωresistive load connected between OUT_ and GND for head-phone amplifier. Testing performed with 32Ωresistive load connected between OUTRx and GND for mono receiver amplifi-er. Mode transitions are controlled by I 2C.

Note 7:Guaranteed by design.

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

_______________________________________________________________________________________7

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

FREQUENCY (Hz)

T H D +N (%)

10k

1k 100

0.10.001

0.01

1

10

100k

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

FREQUENCY (Hz)

T H D +N (%)

10k

1k 100

0.10.001

0.01

1

10

100k

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

FREQUENCY (Hz)

T H D +N (%)

10k

1k 100

0.10.001

0.01

1

10

100k

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

FREQUENCY (Hz)

T H D +N (%)

10k

1k 100

0.10.001

0.01

1

10

100k

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

FREQUENCY (Hz)

T H D +N (%)

10k

1k 100

0.01

0.11

0.001

10

100k

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

OUTPUT POWER (W)

T H D +N (%)

1.6

1.2

0.8

0.4

0.01

0.1

1

10

100

0.001

2.0

Typical Operating Characteristics

(V DD = PV DD = CPV DD = 3.3V, GND = PGND = CPGND = 0V, SHDN = V DD , I 2C default gain settings (INA gain = +20dB, INB gain =INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise stated. C1 = C2 = C3 = 1μF. T A =+25°C, unless otherwise noted.)

M A X 9775/M A X 9776

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier 8_______________________________________________________________________________________

Typical Operating Characteristics (continued)

(V DD = PV DD = CPV DD = 3.3V, GND = PGND = CPGND = 0V, SHDN = V DD , I 2C default gain settings (INA gain = +20dB, INB gain =INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise stated. C1 = C2 = C3 = 1μF. T A =+25°C, unless otherwise noted.)

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

OUTPUT POWER (W)

T H D +N (%)

1.2

0.9

0.6

0.3

0.01

0.1

1

10100

0.001

1.5

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

OUTPUT POWER (W)

T H D +N (%)

0.6

0.4

0.2

0.01

0.1

1

10100

0.001

0.8

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

OUTPUT POWER (W)

T H D +N (%)

0.4

0.2

0.01

0.1

1

10

100

0.001

0.6

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

OUTPUT POWER (W)

T H D +N (%)

1.2

0.9

0.6

0.3

0.01

0.1

1

10

1000.001

1.5

EFFICIENCY vs. OUTPUT POWER

OUTPUT POWER (W)

E F F I C I E N C Y (%)

3.2

2.4

1.6

0.8

10

2030

4050607080901000

4.0

EFFICIENCY vs. OUTPUT POWER

OUTPUT POWER (W)

E F F I C I E N C Y (%)

1.6

1.2

0.8

0.4

102030

405060708090100

00

2.0

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

_______________________________________________________________________________________9

Typical Operating Characteristics (continued)

(V DD = PV DD = CPV DD = 3.3V, GND = PGND = CPGND = 0V, SHDN = V DD , I 2C default gain settings (INA gain = +20dB, INB gain =INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise stated. C1 = C2 = C3 = 1μF. T A =+25°C, unless otherwise noted.)

OUTPUT POWER vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

O U T P U T P O W E R (m W )

5.2

4.7

4.2

3.7

3.2

200400600800100012001400160018002000220002.7

OUTPUT POWER vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

O U T P U T P O W E R (m W ) 5.2

4.7

3.2

3.7

4.2

200400

60080010001200140016000

2.7

OUTPUT POWER vs. LOAD

LOAD (Ω)

O U T P U T P O W E R (W )

100.5

1.0

1.5

2.02.5

01

100

OUTPUT POWER vs. LOAD

LOAD (Ω)

O U T P U T P O W E R (W )

10200

400

600

8001000

01

100

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

FREQUENCY (Hz)

P O W E R -S U P P L Y R E J E C T I O N R A T I O (d B )

10k 1k 100-90-80-70-60-50-40

-30-20-100-100

10

100k CROSSTALK vs. FREQUENCY

FREQUENCY (Hz)

C R O S S T A L K (d B )

-120-110-100-90-80-70-60-50-40-30-20-10010100

1k 10k 100k

M A X 9775/M A X 9776

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier 10______________________________________________________________________________________

Typical Operating Characteristics (continued)

(V DD = PV DD = CPV DD = 3.3V, GND = PGND = CPGND = 0V, SHDN = V DD , I 2C default gain settings (INA gain = +20dB, INB gain =INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise stated. C1 = C2 = C3 = 1μF. T A =+25°C, unless otherwise noted.)

CROSSTALK vs. INPUT AMPLITUDE

INPUT AMPLITUDE (V RMS )

C R O S S T A L K (d B )

0.1

0.20.30.40.50.6

-120

-110-100-90-80-70-60-50-40-30-20-100IN-BAND OUTPUT SPECTRUM

FREQUENCY (Hz)

O U T P U T M A G N I T U D E (d B V )

15k 10k 5k -120-100-80-60-40-20020-140

20k

IN-BAND OUTPUT SPECTRUM

FREQUENCY (Hz)

O U T P U T M A G N I T U D E (d B V )

15k 10k 5k -120-100-80-60-40-20020

-140

020k

WIDEBAND OUTPUT SPECTRUM FIXED-FREQUENCY MODE

FREQUENCY (MHz)

O U T P U T M A G N I T U D E (d B V )

-140

-120-100-80-60-40-200200.1

1

10100

1000

WIDEBAND OUTPUT SPECTRUM SPREAD-SPECTRUM MODE

FREQUENCY (MHz)

O U T P U T M A G N I T U D E (d B V )

-140

-120-100-80-60-40-200

200.1

1

10100

1000

MAX9775 SUPPLY CURRENT vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

S U P P L Y C U R R E N T (m A )

5.2

4.7

4.2

3.7

3.2

15

20

25

102.7

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

______________________________________________________________________________________11

Typical Operating Characteristics (continued)

(V DD = PV DD = CPV DD = 3.3V, GND = PGND = CPGND = 0V, SHDN = V DD , I 2C default gain settings (INA gain = +20dB, INB gain =INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise stated. C1 = C2 = C3 = 1μF. T A =+25°C, unless otherwise noted.)

MAX9776 SUPPLY CURRENT vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

S U P P L Y C U R R E N T (m A )

5.2

4.7

4.2

3.7

3.2

681012141642.7

SHUTDOWN SUPPLY CURRENT

vs. SUPPLY VOLTAGE

M A X 9775/76 t o c 26

SUPPLY VOLTAGE (V)

S U P P L Y C U R R E N T (n A )

5.2

4.7

4.2

3.7

3.2

10203040506070809010002.7

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

FREQUENCY (Hz)

T H D +N (%)

10k

1k 100

0.01

0.11

0.001

10

100k

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

FREQUENCY (Hz)

T H D +N (%)

10k

1k 100

0.01

0.11

0.00110

100k

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. FREQUENCY

FREQUENCY (Hz)

T H D +N (%)

10k

1k 100

0.01

0.1

1

0.001

10

100k

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

OUTPUT POWER (mW)

T H D +N (%)

60

40

20

0.01

0.1

1

10

100

0.001

80

M A X 9775/M A X 9776

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier 12______________________________________________________________________________________

Typical Operating Characteristics (continued)

(V DD = PV DD = CPV DD = 3.3V, GND = PGND = CPGND = 0V, SHDN = V DD , I 2C default gain settings (INA gain = +20dB, INB gain =INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise stated. C1 = C2 = C3 = 1μF. T A =+25°C, unless otherwise noted.)

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

OUTPUT POWER (mW)

T H D +N (%)

306090120

0.001

0.01

0.11

10100

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. OUTPUT POWER

OUTPUT POWER (mW)

T H D +N (%)

60

40

20

0.01

0.1

1

10

1000.0010

80

TOTAL HARMONIC DISTORTION PLUS NOISE

vs. COMMON-MODE VOLTAGE

COMMON-MODE VOLTAGE (V)

T H D +N (%)

0.5 1.0 1.5 2.0 2.5

0.001

0.01

0.1

1

10

100

POWER DISSIPATION vs. OUTPUT POWER

TOTAL OUTPUT POWER (mW)P O W E R D I S S I P A T I O N (m W )

80

40

5010015020025030035040045050000

120POWER DISSIPATION vs. OUTPUT POWER

TOTAL OUTPUT POWER (mW)P O W E R D I S S I P A T I O N (m W )

120

80

40

50100150200250300350400450

5000

160

OUTPUT POWER vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

O U T P U T P O W E R (m W )

5.2

4.7

4.2

3.7

3.2

35404550556065

30

2.7

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

______________________________________________________________________________________13

Typical Operating Characteristics (continued)

(V DD = PV DD = CPV DD = 3.3V, GND = PGND = CPGND = 0V, SHDN = V DD , I 2C default gain settings (INA gain = +20dB, INB gain =INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise stated. C1 = C2 = C3 = 1μF. T A =+25°C, unless otherwise noted.)

OUTPUT POWER vs. LOAD

LOAD (Ω)

O U T P U T P O W E R (m W )

10020406080100120140160180200010

1000

OUTPUT POWER

vs. LOAD

LOAD (Ω)

O U T P U T P O W E R (m W )

100204060801001201401601802000

10

1000

OUTPUT POWER vs. LOAD RESISTANCE AND CHARGE-PUMP CAPACITOR SIZE

LOAD (Ω)

O U T P U T P O W E R (m W )

20

40

60

80100

10

1001000

POWER-SUPPLY REJECTION RATIO

vs. FREQUENCY

FREQUENCY (Hz)

P O W E R

-S U P P L Y R E J E C T I O N R A T I O (d B )

-100

-90-80-70-60-50-40-30-20-10010

100

1k 10k 100k

OUTPUT FREQUENCY SPECTRUM

FREQUENCY (Hz)

O U T P U T M A G N I T U D E (d B V )

15k 10k 5k -120-100-80-60-40-20020-140

020k

CROSSTALK vs. FREQUENCY

FREQUENCY (Hz)

C R O S S T A L K (d B )

-120

-110-100-90-80-70-60-50-40-30-20-10010

100

1k 10k 100k

M A X 9775/M A X 9776

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier 14______________________________________________________________________________________

Typical Operating Characteristics (continued)

(V DD = PV DD = CPV DD = 3.3V, GND = PGND = CPGND = 0V, SHDN = V DD , I 2C default gain settings (INA gain = +20dB, INB gain =INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (R LSP ) are terminated between OUT_+ and OUT_-, headphone load resistors are terminated to GND, unless otherwise stated. C1 = C2 = C3 = 1μF. T A =+25°C, unless otherwise noted.)

CROSSTALK vs. INPUT AMPLITUDE

INPUT AMPLITUDE (V RMS )

C R O S S T A L K (d B )

0.40.8 1.2

-120

-110-100-90-80-70-60-50-40-30-20-100TURN-ON RESPONSE

MAX9775/76 toc44

10ms/div

SCL 2V/div SPEAKER OUTPUT 50mA/div HEADPHONE OUTPUT 2V/div

TURN-OFF RESPONSE

MAX9775/76 toc45

10ms/div

SCL 2V/div

SPEAKER OUTPUT 50mA/div HEADPHONE OUTPUT 2V/div

MUTE-ON RESPONSE

MAX9775/76 toc46

10ms/div

SCL 2V/div

SPEAKER OUTPUT 50mA/div HEADPHONE OUTPUT 2V/div

MUTE-OFF RESPONSE

MAX9775/76 toc47

10ms/div

SCL 2V/div

SPEAKER OUTPUT 50mA/div HEADPHONE OUTPUT 2V/div

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

______________________________________________________________________________________15

M A X 9775/M A X 9776

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier 16______________________________________________________________________________________

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

______________________________________________________________________________________17

Typical Application Circuits

M A X 9775/M A X 9776

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier 18______________________________________________________________________________________

Typical Application Circuits (continued)

MAX9775/MAX9776

2 x 1.5W, Stereo Class D Audio Subsystem

with DirectDrive Headphone Amplifier

______________________________________________________________________________________

19

Detailed Description

The MAX9775/MAX9776 ultra-low-EMI, filterless, Class D audio power amplifiers feature several improvements to switch-mode amplifier technology. The MAX9775/MAX9776 feature active emissions limiting circuitry to reduce EMI. Zero dead-time technology maintains state-of-the-art efficiency and THD+N performance by allowing the output F ETs to switch simultaneously without cross-conduction. A unique filterless modulation scheme and spread-spectrum modulation create compact, flexible,low-noise, efficient audio power amplifiers while occupying minimal board space. The differential input architecture reduces common-mode noise pickup with or without the use of input-coupling capacitors. The MAX9775/MAX9776 can also be configured as single-ended input amplifiers without performance degradation.The MAX9775/MAX9776 feature three fully differential input pairs (INA_, INB_, INC_) that can be configured as stereo single-ended or mono differential inputs. I 2C provides control for input configuration, volume level,and mixer configuration. The MAX9775’s 3D enhance-ment feature widens the stereo sound field to improve stereo imaging when stereo speakers are placed in close proximity.

DirectDrive allows the headphone and mono receiver amplifiers to output ground-referenced signals from a single supply, eliminating the need for large DC-block-ing capacitors. Comprehensive click-and-pop suppres-sion minimizes audible transients during the turn-on and turn-off of amplifiers.

Class D Speaker Amplifier

Comparators monitor the audio inputs and compare the complementary input voltages to a sawtooth waveform.The comparators trip when the input magnitude of the sawtooth exceeds their corresponding input voltage. The active emissions limiting circuitry slightly reduces the turn-on rate of the output H-bridge by slew-rate limiting the comparator output pulse. Both comparators reset at a fixed time after the rising edge of the second compara-tor trip point, generating a minimum-width pulse (t ON(MIN),100ns typ) at the output of the second com-parator (F igure 1). As the input voltage increases or decreases, the duration of the pulse at one output increases while the other output pulse duration remains the same. This causes the net voltage across the speak-er (V OUT+- V OUT-) to change. The minimum-width pulse helps the devices to achieve high levels of linearity.

Figure 1. Outputs with an Input Signal Applied

M A X 9775/M A X 9776

Operating Modes

Fixed-Frequency Modulation

The MAX9775/MAX9776 feature a fixed-frequency modulation mode with a 1.1MHz switching frequency,set through the I 2C interface (Table 2). In fixed-frequen-cy modulation mode, the frequency spectrum of the Class D output consists of the fundamental switching frequency and its associated harmonics (see the Wideband Output Spectrum F ixed-F requency Mode graph in the Typical Operating Characteristics ).Spread-Spectrum Modulation

The MAX9775/MAX9776 feature a unique spread-spec-trum modulation that flattens the wideband spectral com-ponents. Proprietary techniques ensure that the

cycle-to-cycle variation of the switching period does not degrade audio reproduction or efficiency (see the Typical Operating Characteristics ). Select spread-spec-trum modulation mode through the I 2C interface (Table 2). In spread-spectrum modulation mode, the switching frequency varies randomly by ±30kHz around the center frequency (1.16MHz). The modulation scheme remains the same, but the period of the sawtooth waveform changes from cycle to cycle (F igure 2). 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 (see Figure 3).

2 x 1.5W, Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier 20______________________________________________________________________________________

Figure 2. Output with an Input Signal Applied (Spread-Spectrum Modulation Mode)