9-0866; Rev 0; 7/07 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers Features The MAX9796 combines a high-efficiency Class D, 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 MAX9796 delivers 2.3W into a 4Ω load from a 5V supply and offers efficiencies up to 80%.
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers ABSOLUTE MAXIMUM RATINGS VDD to GND ...........................................................................+6V PVDD to PGND .......................................................................+6V CPVDD to CPGND..................................................................+6V CPVSS to CPGND .....................................................-6V to +0.3V VSS to CPGND............................................
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers (VDD = PVDD = CPVDD = 3.3V, GND = PGND = CPGND = 0V, SHDN = VDD, I2C settings (INA gain = +20dB, INB gain = INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (RLSP) are terminated between OUT+ and OUT-, headphone load resistors are terminated to GND, unless otherwise noted. C1 = C2 = C3 = 1µF. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers ELECTRICAL CHARACTERISTICS (continued) (VDD = PVDD = CPVDD = 3.3V, GND = PGND = CPGND = 0V, SHDN = VDD, I2C settings (INA gain = +20dB, INB gain = INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (RLSP) are terminated between OUT+ and OUT-, headphone load resistors are terminated to GND, unless otherwise noted. C1 = C2 = C3 = 1µF.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers (VDD = PVDD = CPVDD = 3.3V, GND = PGND = CPGND = 0V, SHDN = VDD, I2C settings (INA gain = +20dB, INB gain = INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (RLSP) are terminated between OUT+ and OUT-, headphone load resistors are terminated to GND, unless otherwise noted. C1 = C2 = C3 = 1µF. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers ELECTRICAL CHARACTERISTICS (continued) (VDD = PVDD = CPVDD = 3.3V, GND = PGND = CPGND = 0V, SHDN = VDD, I2C settings (INA gain = +20dB, INB gain = INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). Speaker load resistors (RLSP) are terminated between OUT+ and OUT-, headphone load resistors are terminated to GND, unless otherwise noted. C1 = C2 = C3 = 1µF.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers (VDD = PVDD = CPVDD = 3.3V, GND = PGND = CPGND = 0V, SHDN = VDD, I2C settings (INA gain = +20dB, INB gain = INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). C1 = C2 = C3 = 1µF. Speaker load resistors (RLSP) are terminated between OUT+ and OUT-, headphone load resistors are terminated to GND, unless otherwise noted.) TOTAL HARMONIC DISTORTION PLUS NOISE vs.
Typical Operating Characteristics (continued) (VDD = PVDD = CPVDD = 3.3V, GND = PGND = CPGND = 0V, SHDN = VDD, I2C settings (INA gain = +20dB, INB gain = INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). C1 = C2 = C3 = 1µF. Speaker load resistors (RLSP) are terminated between OUT+ and OUT-, headphone load resistors are terminated to GND, unless otherwise noted.) EFFICIENCY vs. OUTPUT POWER RL = 4Ω 40 30 60 50 RL = 4Ω 40 30 20 VDD = 3.3V f = 1kHz 10 0 1 3 2 0 0 0.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers -20 -40 -60 -80 -100 -20 -40 -60 -80 -100 0 -120 0 5k 10k -40 -60 -80 -100 VDD = 5V RL = 8Ω INPUTS AC GROUNDED -140 0 20k 15k -20 -120 -140 -140 MAX9796 toc21 20 MAX9796 toc20 0 -120 5k 10k 20k 15k FREQUENCY (Hz) FREQUENCY (Hz) WIDEBAND OUTPUT SPECTRUM SPREAD-SPECTRUM MODE TURN-ON RESPONSE 0.
Typical Operating Characteristics (continued) (VDD = PVDD = CPVDD = 3.3V, GND = PGND = CPGND = 0V, SHDN = VDD, I2C settings (INA gain = +20dB, INB gain = INC gain = 0dB, volume setting = 0dB, mono path gain = 0dB, SHDN = 1, SSM = 1). C1 = C2 = C3 = 1µF. Speaker load resistors (RLSP) are terminated between OUT+ and OUT-, headphone load resistors are terminated to GND, unless otherwise noted.) VDD = 3.3V RL = 16Ω VDD = 3.3V RL = 32Ω 100 VDD = 5V RL = 32Ω 10 f = 1kHz 0.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers 140 120 100 THD+N = 10% 60 140 120 100 40 THD+N = 10% 80 60 40 VDD = 5V f = 1kHz THD+N = 1% 40 THD+N = 1% C1 = C2 = 0.68µF 0 100 1000 0 10 LOAD (Ω) 100 1000 POWER-SUPPLY REJECTION RATIO vs. FREQUENCY -30 -40 -50 HPR -60 -70 20 VDD = 3.3V f = 1kHz RL = 32Ω 0 OUTPUT MAGNITUDE (dBV) VDD = 3.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers MAX9796 Pin Description 12 BUMP NAME A1 CPVDD A2 C1P A3 CPGND A4 C1N A5 CPVSS FUNCTION Charge-Pump Power Supply Charge-Pump Flying Capacitor Positive Terminal Charge-Pump GND Charge-Pump Flying Capacitor Negative Terminal Charge-Pump Output. Connect to VSS. A6 HPL Left Headphone Output B1, F1, F5 PVDD Class D Power Supply B2, E6 I.C. B3 VBIAS Common-Mode Bias B4 INC1 Input C1.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers VDD C2 1µF CPVSS VSS A5 B5 VDD 1µF VDD 0.
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers Detailed Description The MAX9796 ultra-low-EMI, filterless, Class D audio power amplifier features several improvements to switch-mode amplifier technology. The MAX9796 features 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 FETs to switch simultaneously without crossconduction.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers Fixed-Frequency Modulation The MAX9796 features a fixed-frequency modulation mode with a 1.1MHz switching frequency, set through the I2C interface (Table 2). In fixed-frequency 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 Fixed-Frequency Mode graph in the Typical Operating Characteristics).
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers 40 35 EN55022B LIMIT AMPLITUDE (dBµV/m) 30 25 20 15 10 5 30 60 80 100 120 140 160 180 200 220 240 260 280 300 FREQUENCY (MHz) Figure 3. EMI with 76mm of Speaker Cable VIN = 0V consumption, especially when idling. When no signal is present at the input of the MAX9796, the outputs switch as shown in Figure 4.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers VDD VDD / 2 VOUT GND CONVENTIONAL DRIVER-BIASING SCHEME +VDD 2) During an ESD strike, the driver’s ESD structures are the only path to system ground. Thus, the amplifier must be able to withstand the full ESD strike. 3) When using the headphone jack as a lineout to other equipment, the bias voltage on the sleeve may conflict with the ground potential from other equipment, resulting in possible damage to the amplifiers.
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers -75dB TO 0dB 12dB SPEAKER RVOL PREAMPLIFIER -75dB TO 0dB 3dB HEADPHONE INPUT MIXER INPUT OUTPUT MIXER LVOL INPUT A: 0dB, 6dB, 20dB INPUT B AND C: 0dB, 6dB 0dB OR 6dB -75dB TO 0dB 3dB RECEIVER MONO MONO+6dB MVOL Figure 6. Signal Path Current-Limit and Thermal Protection The MAX9796 features current limiting and thermal protection to protect the device from short circuits and overcurrent conditions.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers MAX9796 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 7. 2-Wire Serial-Interface Timing Diagram I2C Interface The MAX9796 features an I2C 2-wire serial interface consisting of a serial-data line (SDA) and a serial-clock line (SCL).
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers Early STOP Conditions The MAX9796 recognizes a STOP condition at any point during data transmission except if the STOP condition occurs in the same high pulse as a START condition. Slave Address The MAX9796 is available with one preset slave address (see Table 1). The address is defined as the seven most significant bits (MSBs) followed by the read/write (R/W) bit.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers MAX9796 Table 3.
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers Table 5b.
2.
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers Global Control Register The Global Control Register is used for global configurations, those affecting all inputs and outputs. The bits in the Control Register affect the inputs and outputs as shown in Table 11. Table 10. Global Control Register Global Control Register B7 B6 B5 B4 B3 B2 B1 B0 1 0 1 SHDN IN+6dB MUTE SSM MONO Table 11.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers DC-Coupled Input The input amplifier can accept DC-coupled inputs that are biased to the amplifier’s bias voltage. DC-coupling eliminates the input-coupling capacitors; reducing component count to potentially six external components (see the Typical Application Circuit). However, the highpass filtering effect of the capacitors is lost, allowing low-frequency signals to feed through to the load.
MAX9796 2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers Charge-Pump Capacitor Selection Use capacitors with an ESR less than 100mΩ for optimum performance. Low-ESR ceramic capacitors minimize the output resistance of the charge pump. Most surface-mount ceramic capacitors satisfy the ESR requirement. For best performance over the extended temperature range, select capacitors with an X7R dielectric or better. Table 12 lists suggested manufacturers.
2.3W, High-Power Class D Audio Subsystem with DirectDrive Headphone Amplifiers 36L,UCSP.EPS PACKAGE OUTLINE, 6x6 UCSP 21-0082 K 1 1 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.
