9-0854; Rev 0; 9/07 KIT ATION EVALU E L B AVAILA 10W Mono Class D Speaker Amplifier with Volume Control The MAX9768 mono 10W Class D speaker amplifier provides high-quality, efficient audio power with an integrated volume control function. The MAX9768 features a 64-step dual-mode (analog or digitally programmable) volume control and mute function. The audio amplifier operates from a 4.5V to 14V single supply and can deliver up to 10W into an 8Ω speaker with a 14V supply.
MAX9768 10W Mono Class D Speaker Amplifier with Volume Control ABSOLUTE MAXIMUM RATINGS PVDD to PGND........................................................-0.3V to +16V VDD to GND ..............................................................-0.3V to +4V SCLK, SDA/VOL to GND ..........................................-0.3V to +4V FB, SYNCOUT ............................................-0.3V to (VDD + 0.3V) BOOT_ to OUT_........................................................-0.3V to +4V OUT_ to GND .......
10W Mono Class D Speaker Amplifier with Volume Control (PVDD = 12V, VDD = 3.3V, GND = PGND = 0V, V SHDN = VDD, VMUTE = 0V; Max volume setting; speaker load resistor connected between OUT+ and OUT-, RL = ∞, unless otherwise noted. CBIAS = 2.2µF, C1 = C2 = 0.1µF, CIN = 0.47µF, RIN = 20kΩ, RF = 30kΩ, SSM mode. Filterless modulation mode (see the Functional Diagram/Typical Application Circuit). TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
MAX9768 10W Mono Class D Speaker Amplifier with Volume Control ELECTRICAL CHARACTERISTICS (continued) (PVDD = 12V, VDD = 3.3V, GND = PGND = 0V, V SHDN = VDD, VMUTE = 0V; Max volume setting; speaker load resistor connected between OUT+ and OUT-, RL = ∞, unless otherwise noted. CBIAS = 2.2µF, C1 = C2 = 0.1µF, CIN = 0.47µF, RIN = 20kΩ, RF = 30kΩ, SSM mode. Filterless modulation mode (see the Functional Diagram/Typical Application Circuit). TA = TMIN to TMAX, unless otherwise noted.
10W Mono Class D Speaker Amplifier with Volume Control (PVDD = 12V, VDD = 3.3V, GND = PGND = 0V, V SHDN = VDD, VMUTE = 0V; Max volume setting; speaker load resistor connected between OUT+ and OUT-, RL = ∞, unless otherwise noted. CBIAS = 2.2µF, C1 = C2 = 0.1µF, CIN = 0.47µF, RIN = 20kΩ, RF = 30kΩ, SSM mode. Filterless modulation mode (see the Functional Diagram/Typical Application Circuit). TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
ELECTRICAL CHARACTERISTICS (continued) (PVDD = 12V, VDD = 3.3V, GND = PGND = 0V, V SHDN = VDD, VMUTE = 0V; Max volume setting; speaker load resistor connected between OUT+ and OUT-, RL = ∞, unless otherwise noted. CBIAS = 2.2µF, C1 = C2 = 0.1µF, CIN = 0.47µF, RIN = 20kΩ, RF = 30kΩ, SSM mode. Filterless modulation mode (see the Functional Diagram/Typical Application Circuit). TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
10W Mono Class D Speaker Amplifier with Volume Control (PVDD = 12V, VDD = 3.3V = GND = PGND = 0V, VMUTE = 0V; 0dB volume setting; all speaker load resistors connected between OUT+ and OUT-, RL = 8Ω, unless otherwise noted. CBIAS = 2.2µF, C1 = C2 = 0.1µF, CIN = 0.47µF, RIN = 20kΩ, RFB = 30kΩ, spread-spectrum modulation mode.) 1 OUTPUT POWER = 300mW 0.1 0.01 SPREAD-SPECTRUM MODULATION 0.01 OUTPUT POWER = 800mW 0.001 100 1k 10k 100k 1k 10k 10 100k 0.
Typical Operating Characteristics (continued) (PVDD = 12V, VDD = 3.3V = GND = PGND = 0V, VMUTE = 0V; 0dB volume setting; all speaker load resistors connected between OUT+ and OUT-, RL = 8Ω, unless otherwise noted. CBIAS = 2.2µF, C1 = C2 = 0.1µF, CIN = 0.47µF, RIN = 20kΩ, RFB = 30kΩ, spread-spectrum modulation mode.) 80 EFFICIENCY (%) 70 60 50 40 FILTERLESS MODULATION 90 70 60 50 40 20 THD+N = 10% 89 86 0 4 6 0 8 0 10 0.5 OUTPUT POWER (W) 14 MAX9768 toc16 4.
10W Mono Class D Speaker Amplifier with Volume Control (PVDD = 12V, VDD = 3.3V = GND = PGND = 0V, VMUTE = 0V; 0dB volume setting; all speaker load resistors connected between OUT+ and OUT-, RL = 8Ω, unless otherwise noted. CBIAS = 2.2µF, C1 = C2 = 0.1µF, CIN = 0.47µF, RIN = 20kΩ, RFB = 30kΩ, spread-spectrum modulation mode.) POWER-SUPPLY REJECTION RATIO (VDD) vs. FREQUENCY POWER-SUPPLY REJECTION RATIO (PVDD) vs.
Typical Operating Characteristics (continued) (PVDD = 12V, VDD = 3.3V = GND = PGND = 0V, VMUTE = 0V; 0dB volume setting; all speaker load resistors connected between OUT+ and OUT-, RL = 8Ω, unless otherwise noted. CBIAS = 2.2µF, C1 = C2 = 0.1µF, CIN = 0.47µF, RIN = 20kΩ, RFB = 30kΩ, spread-spectrum modulation mode.
10W Mono Class D Speaker Amplifier with Volume Control PIN NAME 1, 2 OUT+ Positive Speaker Output FUNCTION 3, 16 PVDD Speaker Amplifier Power-Supply Input. Bypass with a 1µF capacitor to ground. 4 BOOT+ 5 SCLK 6 SDA/VOL 7 FB Feedback. Connect feedback resistor between FB and IN to set amplifier gain. See the Adjustable Gain section. Audio Input Positive Speaker Output Boost Flying-Capacitor Connection. Connect a 0.1µF ceramic capacitor between BOOT+ and OUT+.
10W Mono Class D Speaker Amplifier with Volume Control MAX9768 Functional Diagram/Typical Application Circuit 2.7V to 3.6V 4.5V to 14V 1μF 1μF VDD PVDD 3, 16 14 RF 30kΩ FB 7 4 BOOT+ IN 8 CLASS D CIN RIN 0.47μF 20kΩ MAX9768 VOLUME CONTROL 1, 2 OUT+ C1 0.1μF 17, 18 OUT15 BOOT- C2 0.1μF MUTE 20 SHDN 19 SDA/VOL 6 SCLK 5 VDD ADDR1 24 ADDR2 23 MUTE SHUTDOWN CONTROL 10 BIAS BIAS CBIAS 2.
10W Mono Class D Speaker Amplifier with Volume Control frequency bands. Applying a clock signal between 1MHz and 1.6MHz to SYNC synchronizes the MAX9768. The Class D switching frequency is equal to one-fourth the SYNC input frequency. SYNCOUT is equal to the SYNC input frequency and allows several Maxim amplifiers to be cascaded. The synchronized output minimizes interference due to clock intermodulation caused by the switching spread between single devices.
Soft Current Limit When the output current exceeds the soft current limit, 2A (typ), the MAX9768 enters a cycle-by-cycle currentlimit mode. In soft current-limit mode, the output is clipped at 2A. When the output decreases so the output current falls below 2A, normal operation resumes. The effect of soft current limiting is a slight increase in distortion. Most applications will not enter soft currentlimit mode unless the speaker or filter creates impedance nulls below 8Ω.
10W Mono Class D Speaker Amplifier with Volume Control Thermal Shutdown When the die temperature exceeds the thermal shutdown threshold, +150°C (typ), the MAX9768 outputs are disabled. When the die temperature decreases below +135°C (typ), normal operation resumes. The effect of thermal shutdown is an output signal turning off for approximately 3s in most applications, depending on the thermal time constant of the audio system. Most applications should never enter thermal shutdown.
MAX9768 10W Mono Class D Speaker Amplifier with Volume Control SDA tBUF tSU,STA tSU,DAT tHD,STA tHD,DAT tLOW tSP tSU,STO SCL tHIGH tHD,STA tR tF REPEATED START CONDITION START CONDITION STOP CONDITION START CONDITION Figure 3. 2-Wire Serial-Interface Timing Diagram Bit Transfer One data bit is transferred during each SCL cycle. The data on SDA must remain stable during the high period of the SCL pulse.
10W Mono Class D Speaker Amplifier with Volume Control SA7 (MSB) SA6 SA5 SA4 SA3 SA2 SA1 SA0 (LSB) 1 0 0 1 0 ADDR2 ADDR1 R/W Table 4. Slave Address ADDR2 ADDR1 CLOCK PULSE FOR ACKNOWLEDGMENT SLAVE ADDRESS 0 0 Disabled 0 1 1001001_ 1 0 1001010_ 1 1 1001011_ Write Data Format A write to the MAX9768 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.
MAX9768 10W Mono Class D Speaker Amplifier with Volume Control Table 5. Data Byte Format D7 (MSB) D6 D5 D4 D3 D2 D1 D0 (LSB) 0 0 V5 V4 V3 V2 V1 V0 Table 6. Speaker Volume Levels 18 V5 V4 V3 V2 V1 V0 VOLUME POSITION VOLUME LEVEL (dB) STEP SIZE (dB) 1 1 1 1 1 1 63 9.5 0.7 1 1 1 1 1 0 62 8.8 0.7 1 1 1 1 0 1 61 8.2 0.6 1 1 1 1 0 0 60 7.6 0.6 1 1 1 0 1 1 59 7.0 0.6 1 1 1 0 1 0 58 6.5 0.5 1 1 1 0 0 1 57 5.9 0.
10W Mono Class D Speaker Amplifier with Volume Control V5 V4 V3 V2 V1 V0 VOLUME POSITION VOLUME LEVEL (dB) STEP SIZE (dB) 0 1 1 1 1 1 31 -17.5 2.2 0 1 1 1 1 0 30 -19.7 1.9 0 1 1 1 0 1 29 -21.6 1.9 0 1 1 1 0 0 28 -23.5 1.7 0 1 1 0 1 1 27 -25.2 2.0 0 1 1 0 1 0 26 -27.2 2.6 0 1 1 0 0 1 25 -29.8 1.6 0 1 1 0 0 0 24 -31.5 2.0 0 1 0 1 1 1 23 -33.4 2.5 0 1 0 1 1 0 22 -36.0 1.6 0 1 0 1 0 1 21 -37.6 2.
MAX9768 10W Mono Class D Speaker Amplifier with Volume Control Applications Information limits. See Figure 7 for the correct connections of these components. Select a ferrite bead with 100Ω to 600Ω impedance, and rated for at least 1.5A. The capacitor value will vary based on the ferrite bead chosen and the actual speaker lead length. Select the capacitor value based on EMC performance.
10W Mono Class D Speaker Amplifier with Volume Control Adjustable Gain Gain-Setting Resistors External feedback resistors set the gain of the MAX9768. The output stage has an internal 20dB gain in addition to the externally set gain. Set the maximum gain by using resistors RF and RIN (Figure 9) as follows: ⎛R ⎞ AV = − 10⎜ F ⎟ V / V ⎝ RIN ⎠ The component selection is based on the load impedance of the speaker. Table 8 lists suggested values for a variety of load impedances.
MAX9768 10W Mono Class D Speaker Amplifier with Volume Control 12V BOOT+ AUDIO CIN INPUT RIN IN IN MAX9768 OUT+ OUT 3.3V SHDN RF FB OUT- BOOT- PVDD 1μF 1μF VDD MAX1726 MAX9768 GND GND Figure 10. Using a Linear Regulator to Produce 3.3V from a 12V Power Supply Figure 9. Setting Gain Power Supplies The MAX9768 has different supplies for each portion of the device, allowing for the optimum combination of headroom power dissipation and noise immunity.
10W Mono Class D Speaker Amplifier with Volume Control Chip Information OUT- OUT- PVDD BOOT- VDD SYNCOUT PROCESS: BICMOS 18 17 16 15 14 13 TOP VIEW SHDN 19 12 SYNC MUTE 20 11 GND 10 BIAS PGND 21 MAX9768 PGND 22 ADDR2 23 9 GND 8 IN 7 FB + 1 2 3 4 5 6 OUT+ OUT+ PVDD BOOT+ SCLK SDA/VOL ADDR1 24 TQFN (4mm × 4mm) ______________________________________________________________________________________ 23 MAX9768 Pin Configuration
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) 24L QFN THIN.
10W Mono Class D Speaker Amplifier with Volume Control 24L QFN THIN.EPS 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.
