Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsLinear ICsLinear IC - Audio amplifier 2-channel (stereo) Class D TQFN 44 EP (7x7)

General Description

The MAX9744 20W stereo Class D audio power amplifi-

er provides Class AB amplifier performance with Class

D efficiency, conserving board space and eliminating

the need for a bulky heatsink. This device features sin-

gle-supply operation, adjustable gain, shutdown mode,

a SYNC output, speaker mute, and industry-leading

click-and-pop suppression.

The MAX9744 features a 64-step dual-mode (analog or

digital), programmable volume control and mute func-

tion. The MAX9744 operates from a 4.5V to 14V single

supply and can deliver up to 20W per channel into a

4Ω speaker with a 14V supply.

The MAX9744 offers two modulation schemes: a fixed-

frequency modulation mode that allows one of several

preset switching frequencies to be selected, and a

spread-spectrum modulation mode that helps to

reduce EMI-radiated emissions.

The MAX9744 features high 75dB PSRR, low 0.04%

THD+N, and SNR in excess of 90dB. Robust short-cir-

cuit and thermal-overload protection prevent device

damage during a fault condition. The MAX9744 is avail-

able in a 44-pin thin QFN-EP (7mm x 7mm x 0.8mm)

package and is specified over the extended -40°C to

+85°C temperature range.

Applications

Flat-Panel Televisions

PC Speaker Systems

Multimedia Docking Stations

Features

♦ Wide 4.5V to 14V Power-Supply Voltage Range

♦ Filterless Spread-Spectrum Modulation Lowers

Radiated RF Emissions from Speaker Cables

♦ 20W Stereo Output (4Ω, V

= 12V, THD+N = 10%)

♦ Integrated Volume Control (I

C or Analog)

♦ Low 0.04% THD+N

♦ High 75dB PSRR

♦ High 93% Efficiency

♦ Integrated Click-and-Pop Suppression

♦ Low-Power Shutdown Mode

♦ Short-Circuit and Thermal-Overload Protection

♦ Available in a 44-Pin Thin QFN-EP (7mm x 7mm x

0.8mm)

MAX9744

20W Stereo Class D Speaker Amplifier

with Volume Control

________________________________________________________________

Maxim Integrated Products

19-4078; Rev 1; 9/08

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

Pin Configuration appears at end of data sheet.

EVALUATION KIT

AVAILABLE

MAX9744

BIAS

SYNCOUTSYNC

VOLUME

CONTROL

CLASS D

MODULATOR

CLASS D

MODULATOR

MUTE

SHUTDOWN

CONTROL

ANALOG

CONTROL

OSCILLATOR

3V TO 3.6V 4.5V TO 14V

MAX9744 EMI WITH FERRITE BEAD FILTERS

= 12V, 1m CABLE, 8Ω LOAD)

FREQUENCY (MHz)

220

200

100

140

160

120

180

240

260

280

300

OUTPUT MAGNITUDE (dBV)

EN5022 B LIMIT

Simplified Block Diagram

Denotes a lead-free/RoHS-compliant package.

EP = Exposed pad.

PART TEMP RANGE PIN-PACKAGE

MAX9744ETH+ -40°C to +85°C 44 TQFN-EP*

Ordering Information

Summary of content (28 pages)

PAGE 1
9-4078; Rev 1; 9/08 KIT ATION EVALU E L B AVAILA 20W Stereo Class D Speaker Amplifier with Volume Control Applications Features ♦ Wide 4.5V to 14V Power-Supply Voltage Range ♦ Filterless Spread-Spectrum Modulation Lowers Radiated RF Emissions from Speaker Cables ♦ 20W Stereo Output (4Ω, VDD = 12V, THD+N = 10%) ♦ Integrated Volume Control (I2C or Analog) ♦ Low 0.
PAGE 2
MAX9744 20W Stereo Class D Speaker Amplifier with Volume Control ABSOLUTE MAXIMUM RATINGS PVDD to PGND ....................................................................+16V VDD to GND ...........................................................................+4V FB_, SYNCOUT, SYNC, SDA/VOL, ADDR1, ADDR2 to GND........................................-0.3V to (VDD + 0.3V) BOOT_ to VDD ..........................................................-0.3V to +6V BOOT_ to OUT_......................................
PAGE 3
20W Stereo Class D Speaker Amplifier with Volume Control (VPVDD = 12V, VDD = 3.3V, VGND = VPGND = 0V, VMUTE = 0V; max volume setting; all speaker load resistors connected between OUT_+ and OUT_-, RL = ∞, unless otherwise stated, CBOOT_ = 0.1µF, CBIAS = 2.2µF, CIN = 0.47µF, RIN = 20kΩ, RF_ = 20kΩ, spreadspectrum mode, filterless modulation mode, see the Functional Diagrams/Typical Application Circuits. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 4
MAX9744 20W Stereo Class D Speaker Amplifier with Volume Control ELECTRICAL CHARACTERISTICS (continued) (VPVDD = 12V, VDD = 3.3V, VGND = VPGND = 0V, VMUTE = 0V; max volume setting; all speaker load resistors connected between OUT_+ and OUT_-, RL = ∞, unless otherwise stated, CBOOT_ = 0.1µF, CBIAS = 2.2µF, CIN = 0.47µF, RIN = 20kΩ, RF_ = 20kΩ, spreadspectrum mode, filterless modulation mode, see the Functional Diagrams/Typical Application Circuits. TA = TMIN to TMAX, unless otherwise noted.
PAGE 5
20W Stereo Class D Speaker Amplifier with Volume Control (VPVDD = 12V, VDD = 3.3V, VGND = VPGND = 0V, VMUTE = 0V; max volume setting; all speaker load resistors connected between OUT_+ and OUT_-, RL = ∞, unless otherwise stated, CBOOT_ = 0.1µF, CBIAS = 2.2µF, CIN = 0.47µF, RIN = 20kΩ, RF_ = 20kΩ, spreadspectrum mode, filterless modulation mode, see the Functional Diagrams/Typical Application Circuits. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
PAGE 6
Typical Operating Characteristics (VPVDD = 12V, VDD = 3.3V, VGND = VPGND = 0V, VMUTE = 0V; max volume setting; all speaker load resistors connected between OUT_+ and OUT_- with an inductor in series, 8Ω load, L = 68µH, 4Ω load, L= 33µH. RL = ∞, unless otherwise stated, CBIAS = 2.2µF, CIN = 0.47µF, RIN = 20kΩ, RF_ = 20kΩ, spread-spectrum mode, TA = +25°C, unless otherwise noted.) 0.1 fIN = 1kHz 0.01 1 0.1 fIN = 1kHz 0.01 fIN = 100Hz 4 6 8 10 12 14 16 18 20 MAX9744 toc03 fIN = 1kHz fIN = 100Hz 0.
PAGE 7
20W Stereo Class D Speaker Amplifier with Volume Control 0.01 MAX9744 toc10 OUTPUT POWER = 10W 0.1 OUTPUT POWER = 5W 0.01 0.001 8 12 16 PVDD = 12V RL = 4Ω PWM MODE 1 OUTPUT POWER = 10W 0.1 0.01 OUTPUT POWER = 5W 0.001 0.001 4 0 20 10 100 1k 10k 10 100k 100 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 1 OUTPUT POWER = 6W 0.1 0.
PAGE 8
20W Stereo Class D Speaker Amplifier with Volume Control MAX9744 Typical Operating Characteristics (continued) (VPVDD = 12V, VDD = 3.3V, VGND = VPGND = 0V, VMUTE = 0V; max volume setting; all speaker load resistors connected between OUT_+ and OUT_- with an inductor in series, 8Ω load, L = 68µH, 4Ω load, L= 33µH. RL = ∞, unless otherwise stated, CBIAS = 2.2µF, CIN = 0.47µF, RIN = 20kΩ, RF_ = 20kΩ, spread-spectrum mode, TA = +25°C, unless otherwise noted.
PAGE 9
20W Stereo Class D Speaker Amplifier with Volume Control THD+N = 10% 8 4 THD+N = 1% 3 THD+N = 10% 12 8 THD+N = 1% 0 0 8 12 10 10 15 20 0 30 25 10 15 20 25 30 SUPPLY VOLTAGE (V) LOAD RESISTANCE (Ω) CASE TEMPERATURE vs. OUTPUT POWER CASE TEMPERATURE vs. OUTPUT POWER POWER-SUPPLY REJECTION RATIO (PVDD) vs.
PAGE 10
20W Stereo Class D Speaker Amplifier with Volume Control MAX9744 Typical Operating Characteristics (continued) (VPVDD = 12V, VDD = 3.3V, VGND = VPGND = 0V, VMUTE = 0V; max volume setting; all speaker load resistors connected between OUT_+ and OUT_- with an inductor in series, 8Ω load, L = 68µH, 4Ω load, L= 33µH. RL = ∞, unless otherwise stated, CBIAS = 2.2µF, CIN = 0.47µF, RIN = 20kΩ, RF_ = 20kΩ, spread-spectrum mode, TA = +25°C, unless otherwise noted.
PAGE 11
20W Stereo Class D Speaker Amplifier with Volume Control CROSSTALK vs. FREQUENCY CROSSTALK vs. AMPLITUDE RL = 8Ω f = 1kHz -10 -20 CROSSTALK (dB) -40 -60 LEFT TO RIGHT -80 SHDN 2V/div -30 -40 -50 RIGHT TO LEFT LEFT TO RIGHT -60 -70 -100 OUTPUT -80 RIGHT TO LEFT -90 -120 -100 100 1k 100k 10k -60 FREQUENCY (Hz) -50 -40 -30 -20 -10 0 20 10 100ms/div AMPLITUDE (dBV) VOLUME CONTROL LEVEL vs.
PAGE 12
20W Stereo Class D Speaker Amplifier with Volume Control MAX9744 Pin Description PIN NAME 1 BOOTL+ 2, 3 OUTL+ 4, 5, 29, 30 PVDD 6, 10, 21, 28 VDD Power-Supply Input. Bypass each with a 1µF capacitor to GND. 7, 11, 12, 15, 27 GND Ground 8 SDA/VOL 9 Left-Channel Positive Speaker Output Boost Flying-Capacitor Connection. Connect a 0.1µF ceramic capacitor between BOOTL+ and OUTL+. Left-Channel Speaker Output, Positive Phase Speaker Amplifier Power-Supply Input.
PAGE 13
20W Stereo Class D Speaker Amplifier with Volume Control PIN NAME 26 SYNCOUT 31, 32 OUTR+ 33 BOOTR+ 34, 35, 39, 43, 44 PGND 36, 37 OUTR- FUNCTION SYNC Signal Output Right-Channel Positive Speaker Output Right-Channel Positive Speaker Output Boost Flying-Capacitor Connection. Connect a 0.1µF ceramic capacitor between BOOTR+ and OUTR+. Power Ground Right-Channel Negative Speaker Output 38 BOOTR- Right-Channel Negative Speaker Output Boost Flying-Capacitor Connection. Connect a 0.
PAGE 14
MAX9744 20W Stereo Class D Speaker Amplifier with Volume Control Spread-Spectrum Modulation Mode The MAX9744 features a unique 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 SYNC = VDD (Table 1). In spread-spectrum mode, the switching frequency varies randomly by ±7.5kHz around the center frequency (300kHz).
PAGE 15
20W Stereo Class D Speaker Amplifier with Volume Control ADDR2 ADDR1 SDA/VOL SCLK/PWM 0 0 Analog volume control 0 Filterless modulation FUNCTION 0 0 Analog volume control 1 Classic PWM (50% duty cycle) Efficiency Thermal Shutdown The high efficiency of a Class D amplifier is due to the switching operation of the output stage transistors. In a Class D amplifier, the output transistors act as currentsteering switches and consume negligible additional power.
PAGE 16
MAX9744 20W Stereo Class D Speaker Amplifier with Volume Control Volume Control For maximum flexibility, the MAX9744 features volume control operation using an analog voltage input or through the I2C interface. To set the device to analog mode, connect ADDR1 and ADDR2 to GND. In analog mode, SDA/VOL is an analog input for volume control. The analog input range is ratiometric between 0.9 x VDD and 0.1 x VDD where 0.9 x VDD = full mute and 0.1 x VDD = full volume (Table 7).
PAGE 17
20W Stereo Class D Speaker Amplifier with Volume Control START and STOP Conditions A master device initiates communication by issuing a START condition. A START condition is a high to low transition on SDA with SCL high. A STOP condition is a low to high transition on SDA while SCL is high (Figure 4). A START (S) condition from the master signals the beginning of a transmission to the MAX9744. The master terminates transmission, and frees the bus, by issuing a STOP (P) condition.
PAGE 18
MAX9744 20W Stereo Class D Speaker Amplifier with Volume Control Write Byte A write to the MAX9744 includes transmission of a START condition, the slave address with the R/W bit set to 0 (see Table 3), one byte of data to the command register, and a STOP condition. Figure 6 illustrates the proper format for one frame. A write to the MAX9744 consists of a 6-step sequence as seen below: 1) The master sends a START condition. 2) The master sends the 7 bits slave ID plus a write bit (low).
PAGE 19
20W Stereo Class D Speaker Amplifier with Volume Control MAX9744 Table 7. Speaker Volume Levels V5 V4 V3 V2 V1 V0 VOLUME POSITION SDA/VOL VOLUME VOLUME INPUT VOLTAGE (V) ATTENUATION (dB) 1 1 1 1 1 1 63 0.100 x VDD 9.5 1 1 1 1 1 0 62 0.113 x VDD 8.8 1 1 1 1 0 1 61 0.125 x VDD 8.2 1 1 1 1 0 0 60 0.138 x VDD 7.6 1 1 1 0 1 1 59 0.151 x VDD 7.0 1 1 1 0 1 0 58 0.163 x VDD 6.5 1 1 1 0 0 1 57 0.176 x VDD 5.9 1 1 1 0 0 0 56 0.
PAGE 20
MAX9744 20W Stereo Class D Speaker Amplifier with Volume Control Table 7. Speaker Volume Levels (continued) 20 V5 V4 V3 V2 V1 V0 VOLUME POSITION SDA/VOL VOLUME VOLUME INPUT VOLTAGE (V) ATTENUATION (dB) 0 1 1 1 1 1 31 0.506 x VDD -17.5 0 1 1 1 1 0 30 0.519 x VDD -19.7 0 1 1 1 0 1 29 0.532 x VDD -21.6 0 1 1 1 0 0 28 0.544 x VDD -23.5 0 1 1 0 1 1 27 0.557 x VDD -25.2 0 1 1 0 1 0 26 0.570 x VDD -27.2 0 1 1 0 0 1 25 0.583 x VDD -29.
PAGE 21
20W Stereo Class D Speaker Amplifier with Volume Control Filterless Class D Operation The MAX9744 meets common EMC radiation limits without a filter when the speaker leads are less than approximately 10cm. Using lengths beyond 10cm is possible verifying against the appropriate EMC standard. For longer speaker wire lengths, up to approximately 1m, use a simple ferrite bead and capacitor filter to meet EMC limits. Select a ferrite bead with 100Ω to 600Ω impedance, and rated for at least 3A.
PAGE 22
Component Selection Gain-Setting Resistors External feedback resistors set the gain of the MAX9744. The output stage has an internal 20dB gain in addition to the externally set input stage gain. Set the maximum gain by using resistors RF and RIN (Figure 9) as follows: ⎛R ⎞ A V = −30 ⎜ F ⎟ V / V ⎝ RIN ⎠ Choose R F between 10kΩ and 50kΩ. Note that the actual gain of the amplifier is dependent on the volume level setting. For example, with the volume set to +9.5dB, the amplifier gain would be 9.
PAGE 23
20W Stereo Class D Speaker Amplifier with Volume Control Use large, low-resistance output traces. Current drawn from the outputs increase as load impedance decreases. High output trace resistance decreases the power delivered to the load. Large output, supply, and GND traces allow more heat to move from the MAX9744 to the air, decreasing the thermal impedance of the circuit. The MAX9744 thin QFN package features an exposed thermal pad on its underside.
PAGE 24
20W Stereo Class D Speaker Amplifier with Volume Control MAX9744 Functional Diagrams/Typical Application Circuits I2C MODE 3V TO 3.6V 4.5V TO 14V VDD PVDD 1μF 6, 10, 21, 28 RF 20kΩ RIN 20kΩ 4, 5, 29, 30 1 BOOTL+ FBL 17 MAX9744 CLASS D CIN 0.47μF 100μF 1μF INL 16 CBOOT 0.1μF 2, 3 OUTL+ 41, 42 OUTL- CBOOT 0.1μF 40 BOOTLBIAS CIN 0.47μF RIN 20kΩ VOLUME CONTROL INR 19 PVDD 33 BOOTR+ RF 20kΩ MUTE 24 SHDN 22 SDA/VOL 8 TO μC VDD VDD CLASS D FBR 18 MUTE CBOOT 0.
PAGE 25
20W Stereo Class D Speaker Amplifier with Volume Control ANALOG MODE 3V TO 3.6V 4.5V TO 14V VDD PVDD 1μF 6, 10, 21, 28 RF 20kΩ RIN 20kΩ 4, 5, 29, 30 1 BOOTL+ FBL 17 MAX9744 CLASS D CIN 0.47μF INL 16 2, 3 OUTL+ BIAS RIN 20kΩ VOLUME CONTROL INR 19 CBOOT 0.1μF 41, 42 OUTL40 BOOTL- CIN 0.47μF 100μF 1μF CBOOT 0.1μF PVDD 33 BOOTR+ RF 20kΩ MUTE 24 SHDN 22 VDD SDA/VOL 8 SCLK/PWM 9 ADDR1 13 ADDR2 14 VDD SYNC 25 N.C. CLASS D FBR 18 MUTE SHUTDOWN CONTROL 31, 32 OUTR+ CBOOT 0.
PAGE 26
Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. E DETAIL A 32, 44, 48L QFN.EPS MAX9744 20W Stereo Class D Speaker Amplifier with Volume Control (NE-1) X e E/2 k e D/2 C L (ND-1) X e D D2 D2/2 b L E2/2 C L k E2 C L C L L L e A1 A2 e A PACKAGE OUTLINE, 32, 44, 48, 56L THIN QFN, 7x7x0.
PAGE 27
20W Stereo Class D Speaker Amplifier with Volume Control PACKAGE OUTLINE, 32, 44, 48, 56L THIN QFN, 7x7x0.8mm 21-0144 Chip Information PROCESS: BICMOS G 2 2 PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 44 TQFN-EP T4477-3 21-0144 ______________________________________________________________________________________ 27 MAX9744 Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.
PAGE 28
MAX9744 20W Stereo Class D Speaker Amplifier with Volume Control Revision History REVISION NUMBER REVISION DATE 0 3/08 Initial release 1 9/08 Updated EC table for single pass flow DESCRIPTION PAGES CHANGED — 2, 4, 5 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.