19-3405; Rev 0; 7/05 KIT ATION EVALU E L B A IL AVA 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier The MAX9705 offers two modulation schemes: a fixedfrequency (FFM) mode and a spread-spectrum (SSM) mode that further reduces EMI-radiated emissions due to the modulation frequency. The MAX9705 oscillator can be synchronized to an external clock through the SYNC input, allowing the switching frequency to be externally defined. The SYNC input also allows multiple MAX9705s to be cascaded and frequency locked, minimizing interference due to clock intermodulation. The device utilizes a fully differential architecture, a full-bridged output, and comprehensive click-and-pop suppression. The gain of the MAX9705 is set internally (MAX9705A: 6dB, MAX9705B: 12dB, MAX9705C: 15.6dB, MAX9705D: 20dB), further reducing external component count. The MAX9705 is available in 10-pin TDFN (3mm x 3mm x 0.8mm), 10-pin µMAX®, and 12-bump UCSP™ (1.5mm x 2mm x 0.6mm) packages. The MAX9705 is specified over the extended -40°C to +85°C temperature range. Applications Cellular Phones MP3 Players PDAs Portable Audio Selector Guide appears at end of data sheet. µMAX is a registered trademark and UCSP is a trademark of Maxim Integrated Products, Inc. ♦ Filterless Amplifier Passes FCC-Radiated Emissions Standards with 24in of Cable ♦ Unique Spread-Spectrum Mode and Active Emissions Limiting (AEL) Achieves Better than 20dB Margin Under FCC Limits ♦ Zero Dead Time (ZDT) H-Bridge Maintains Stateof-the-Art Efficiency and THD+N ♦ Simple Master-Slave Setup for Stereo Operation ♦ Up to 90% Efficiency ♦ 2.3W into 4Ω (1% THD+N) ♦ Low 0.02% THD+N (POUT = 1W, VDD = 5.0V) ♦ High PSRR (75dB at 217Hz) ♦ Integrated Click-and-Pop Suppression ♦ Low Quiescent Current (5.4mA) ♦ Low-Power Shutdown Mode (0.3µA) ♦ Short-Circuit and Thermal-Overload Protection ♦ Available in Thermally Efficient, Space-Saving Packages 10-Pin TDFN (3mm x 3mm x 0.8mm) 10-Pin µMAX 12-Bump UCSP (1.5mm x 2mm x 0.6mm) ♦ Pin-for-Pin Compatible with the MAX9700 and MAX9712 Ordering Information TEMP RANGE PINPACKAGE TOP MARK MAX9705AETB+T -40oC to +85oC 10 TDFN-10 ACY MAX9705AEUB+ -40oC to +85oC 10 µMAX PART o o — MAX9705AEBC+T -40 C to +85 C 12 UCSP-12 ACH MAX9705BETB+T -40oC to +85oC 10 TDFN-10 ACX o o MAX9705BEUB+ -40 C to +85 C 10 µMAX MAX9705BEBC+T -40oC to +85oC 12 UCSP-12 — ACG Ordering Information continued at end of data sheet. +Denotes lead-free package. EMI Spectrum Diagram 50.0 AMPLITUDE (dBµV/m) The MAX9705 3rd-generation, ultra-low EMI, mono, Class D audio power amplifier provides Class AB performance with Class D efficiency. The MAX9705 delivers 2.3W into a 4Ω load and offers efficiencies above 85%. Active emissions limiting (AEL) circuitry greatly reduces EMI by actively controlling the output FET gate transitions under all possible transient output-voltage conditions. AEL prevents high-frequency emissions resulting from conventional Class D free-wheeling behavior in the presence of an inductive load. Zero dead time (ZDT) technology maintains state-of-the-art efficiency and THD+N performance by allowing the output FETs to switch simultaneously without cross-conduction. A patented spreadspectrum modulation scheme eliminates the need for output filtering found in traditional Class D devices. These design concepts reduce an application’s component count and extend battery life. Features 45.0 40.0 FCC EMI LIMIT 35.0 30.0 25.0 20.0 15.0 10.0 5.0 MAXIM'S NEW ULTRA-LOW OUTPUT SPECTRUM 30.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0 200.0 220.0 240.0 260.0 280.0 300.0 FREQUENCY (MHz) ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX9705 General Description MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier ABSOLUTE MAXIMUM RATINGS Continuous Power Dissipation (TA = +70°C) 10-Pin TDFN (derate 24.4mW/°C above +70°C) .....1951.2mW 10-Pin µMAX (derate 5.6mW/oC above +70°C) .........444.4mW 12-Bump UCSP (derate 6.1mW/°C above +70°C)........484mW 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 Bump Temperature (soldering) Reflow ..........................................................................+235°C VDD to GND..............................................................................6V PVDD to PGND .........................................................................6V GND to PGND .......................................................-0.3V to +0.3V PVDD to VDD ..........................................................-0.3V to +0.3V All Other Pins to GND.................................-0.3V to (VDD + 0.3V) Continuous Current Into/Out of PVDD/PGND/OUT_........±600mA Continuous Input Current (all other pins) .........................±20mA Duration of OUT_ Short Circuit to GND or PVDD ........Continuous Duration of Short Circuit Between OUT+ and OUT-.....Continuous 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. ELECTRICAL CHARACTERISTICS (VDD = PVDD = SHDN = 3.3V, GND = PGND = 0V, SYNC = GND (FFM), RL = ∞, RL connected between OUT+ and OUT-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS GENERAL Supply Voltage Range VDD 5.5 V Quiescent Current IDD Inferred from PSRR test 2.5 5.4 7 mA Shutdown Current 10 ISHDN 0.3 Turn-On Time tON 30 Input Resistance RIN Input Bias Voltage Voltage Gain Output Offset Voltage Common-Mode Rejection Ratio Power-Supply Rejection Ratio (Note 3) Output Power Total Harmonic Distortion Plus Noise Click/Pop Level 2 VBIAS AV VOS CMRR TA = +25°C MAX9705A 12 0.88 0.73 0.61 0.48 1.9 20 1.0 0.83 0.71 0.56 2.0 1.12 0.93 0.81 0.64 2.1 MAX9705B 3.8 4.0 4.2 MAX9705C 5.7 6.0 6.3 MAX9705D 9.5 10 10.5 TA = +25°C ±10 ±69 fIN = 1kHz, input referred 56 Either input MAX9705A MAX9705B MAX9705C MAX9705D VDD = 2.5V to 5.5V, TA = +25°C PSRR POUT THD+N KCP 200mVP-P ripple THD+N = 1%, fIN = 1kHz 75 fRIPPLE = 20kHz 60 RL = 8Ω 600 RL = 4Ω 950 Into shutdown kΩ V V/V mV dB 75 fRIPPLE = 217Hz RL = 8Ω, fIN = 1kHz, either FFM or POUT = 450mW SSM RL = 4Ω, POUT = 375mW Peak voltage, A-weighted (Notes 3, 4) 50 µA ms dB mW 0.02 % 0.025 -68 dB Out of shutdown -60.5 _______________________________________________________________________________________ 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier (VDD = PVDD = SHDN = 3.3V, GND = PGND = 0V, SYNC = GND (FFM), RL = ∞, RL connected between OUT+ and OUT-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) PARAMETER Output Slew Rate SYMBOL CONDITIONS MIN SR Rise/Fall Time tRISE, tFALL 10% to 90% Signal-to-Noise Ratio SNR BW = 22Hz to 22kHz VOUT = 2VRMS A-weighted Oscillator Frequency fOSC V/µs ns FFM 93 SSM 1100 1450 1220 1650 1220 ±120 800 η dB 91 980 1250 SYNC Frequency Lock Range UNITS 15 91 89 SYNC = GND SYNC = float MAX 176 FFM SSM SYNC = VDD (SSM mode) Efficiency TYP POUT = 800mW, fIN = 1kHz, RL = 8Ω 2000 89 kHz kHz % DIGITAL INPUTS (SHDN, SYNC) VIH Input Thresholds 2 VIL 0.8 SHDN Input Leakage Current SYNC Input Current (Note 5) V 0.1 ±10 µA -1.25 ±10 µA ELECTRICAL CHARACTERISTICS (VDD = PVDD = SHDN = 5V, GND = PGND = 0V, SYNC = GND (FFM), RL = ∞, RL connected between OUT+ and OUT-, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL Quiescent Current IDD Shutdown Current ISHDN Power-Supply Rejection Ratio Output Power Total Harmonic Distortion Plus Noise Signal-to-Noise Ratio CONDITIONS PSRR 200mVP-P ripple POUT THD+N = 1%, f = 1kHz THD+N SNR f = 1kHz, either FFM or SSM VOUT = 3VRMS MIN TYP 0.55 µA 75 f = 20kHz 60 RL = 16Ω 750 RL = 8Ω 1400 RL = 4Ω 2300 RL = 8Ω, POUT = 1.0W 0.02 RL = 4Ω, POUT = 1.75W 0.05 A-weighted UNITS mA f = 217Hz BW = 22Hz to 22kHz MAX 7 FFM 94 SSM 91 FFM 97 SSM 93 dB mW % dB Note 1: All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design. Note 2: Testing performed with a resistive load in series with an inductor to simulate an actual speaker load. For RL = 4Ω, L = 33µH. For RL = 8Ω, L = 68µH. For RL = 16Ω, L = 136µH. Note 3: Inputs AC-coupled to GND. Note 4: Testing performed with 8Ω resistive load in series with 68µH inductive load connected across BTL output. Mode transitions are controlled by SHDN pin. KCP level is calculated as 20 x log[(peak voltage under normal operation at rated power level)/(peak voltage during mode transition, no input signal)]. Units are expressed in dB. Note 5: SYNC has a 1MΩ resistor to VREF = 1.25V. _______________________________________________________________________________________ 3 MAX9705 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VDD = 3.3V, SYNC = VDD (SSM), differential input, TA = +25°C, unless otherwise noted.) 0.01 1 0.1 0.2 0.4 0.6 0.8 1.0 fIN = 1kHz 1.2 0.5 1.0 1.5 1 0.1 0.5 1.0 1.5 0.001 0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.2 0.4 0.6 0.8 1.0 OUTPUT POWER (W) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY VDD = 5.0V RL = 8Ω POUT = 100mW 1 POUT = 450mW POUT = 250mW 1 POUT = 1W 0.1 0.01 1k FREQUENCY (Hz) 10k 100k POUT = 50mW 1 POUT = 300mW 0.1 0.01 100 VDD = 2.5V RL = 4Ω 10 THD+N (%) 10 THD+N (%) 10 100 MAX9705toc08 MAX9705toc07 100 1.2 MAX9705toc09 OUTPUT POWER (W) VDD = 3.3V RL = 8Ω 10 FFM 0.1 OUTPUT POWER (W) 100 0.1 SSM VDD = 5.0V RL = 4Ω 0.001 0 1 0.01 fIN = 1kHz VDD = 3.3V RL = 4Ω 0.001 0.8 VDD = 3.3V RL = 8Ω fIN = 1kHz 10 THD+N (%) 10 0.01 fIN = 1kHz 0.6 100 MAX9705toc05 MAX9705toc04 0.01 0.4 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 100 0.1 0.2 OUTPUT POWER (W) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 1 0 2.0 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER THD+N (%) THD+N (%) 0 OUTPUT POWER (W) 10 4 VDD = 2.5V RL = 4Ω 0.001 OUTPUT POWER (W) 100 fIN = 1kHz VDD = 5.0V RL = 8Ω 0.001 0 0.1 0.01 0.01 VDD = 3.3V RL = 8Ω 0.001 1 MAX9705toc06 0.1 10 THD+N (%) THD+N (%) 10 1 100 MAX9705toc02 fIN = 1kHz 10 THD+N (%) 100 MAX9705toc01 100 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER MAX9705toc03 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER THD+N (%) MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier 0.01 10 100 1k FREQUENCY (Hz) 10k 100k 10 100 1k FREQUENCY (Hz) _______________________________________________________________________________________ 10k 100k 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY VDD = 3.3V RL = 4Ω VDD = 5.0V RL = 4Ω POUT = 800mW 10 THD+N (%) POUT = 100mW 1 POUT = 250mW 1 0.1 0.01 100 10k 1k 0.01 100k 10 1k 100 10k 100k 10 10k FREQUENCY (Hz) FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. COMMON-MODE VOLTAGE EFFICIENCY vs. OUTPUT POWER EFFICIENCY vs. OUTPUT POWER 80 EFFICIENCY (%) 0.1 RL = 4Ω 50 40 0.5 1.0 1.5 2.0 0 2.5 40 0.2 0.4 0.6 0.8 VDD = 5.0V fIN = 1kHz 0 1.0 0 0.5 1.0 1.5 2.0 2.5 COMMON-MODE VOLTAGE (V) OUTPUT POWER (W) OUTPUT POWER (W) EFFICIENCY vs. SUPPLY VOLTAGE EFFICIENCY vs. SYNC FREQUENCY EFFICIENCY vs. SYNC FREQUENCY EFFICIENCY (%) 60 50 40 60 50 40 30 30 20 20 fIN = 1kHz THD+N = 1% 10 0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 RL = 8Ω 90 80 RL = 4Ω 70 60 50 40 30 VDD = 3.3V fIN = 1kHz THD+N = 1% 10 0 3.0 100 RL = 4Ω 70 3.0 MAX9705toc18 80 RL = 4Ω 70 RL = 8Ω EFFICIENCY (%) 80 90 MAX9705toc17 RL = 8Ω 90 100 MAX9705toc16 100 2.5 RL = 4Ω 50 10 0 0 60 20 VDD = 3.3V fIN = 1kHz 10 0.001 70 30 20 0.01 RL = 8Ω 90 70 60 MAX9705toc15 80 EFFICIENCY (%) 1 RL = 8Ω 90 100k 100 MAX9705toc14 100 MAX9705toc13 VDD = 3.3V to 5V fIN = 1kHz POUT = 500mW GAIN = 6dB RL = 8Ω 30 EFFICIENCY (%) 1k 100 FREQUENCY (Hz) 100 10 SSM 0.1 0.01 10 FFM 1 POUT = 1.75W 0.1 THD+N (%) VDD = 3.3V RL = 8Ω POUT = 450mW 10 THD+N (%) THD+N (%) 10 100 MAX9705toc11 100 MAX9705toc10 100 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX9705toc12 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 20 VDD = 5.0V fIN = 1kHz THD+N = 1% 10 0 800 1000 1200 1400 1600 SYNC FREQUENCY (kHz) 1800 2000 800 1000 1200 1400 1600 1800 2000 SYNC FREQUENCY (kHz) _______________________________________________________________________________________ 5 MAX9705 Typical Operating Characteristics (continued) (VDD = 3.3V, SYNC = VDD (SSM), differential input, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VDD = 3.3V, SYNC = VDD (SSM), differential input, TA = +25°C, unless otherwise noted.) OUTPUT POWER vs. SUPPLY VOLTAGE 1.6 THD+N = 10% 1.0 THD+N = 1% 0.6 THD+N = 10% 2.0 1.5 THD+N = 1% 1.0 0.5 fIN = 1kHz RL = 8Ω 0 fIN = 1kHz RL = 4Ω 3.0 3.5 4.0 4.5 5.0 3.0 SUPPLY VOLTAGE (V) 3.5 4.0 4.5 5.0 5.5 -20 -40 -50 -60 -70 -40 -60 -80 -100 -80 -120 -90 -140 -100 10 1k 100 10k 5 10 15 SPREAD-SPECTRUM-MODE OUTPUT SPECTRUM vs. FREQUENCY SPREAD-SPECTRUM-MODE OUTPUT SPECTRUM vs. FREQUENCY MAX9705 toc24 20 RL = 8Ω VDD = 5.0V fIN = 1kHz A-WEIGHTED 0 -20 AMPLITUDE (dBV) -20 0 FREQUENCY (kHz) RL = 8Ω VDD = 5.0V fIN = 1kHz BW = 22Hz to 22kHz 0 100k FREQUENCY (Hz) 20 AMPLITUDE (dBV) RL = 8Ω VDD = 5.0V fIN = 1kHz BW = 22Hz to 22kHz 0 AMPLITUDE (dBV) PSRR (dB) 20 MAX9705 toc22 VDD = 3.3V VIN = 200mVP-P RL = 8Ω -30 -40 -60 -80 20 -40 -60 -80 -100 -100 -120 -120 -140 -140 0 5 10 FREQUENCY (kHz) 6 100 LOAD RESISTANCE (Ω) FIXED-FREQUENCY-MODE OUTPUT SPECTRUM vs. FREQUENCY 0 -20 10 1 SUPPLY VOLTAGE (V) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY -10 3.3V 1.5 0 2.5 5.5 2.0 0.5 0 2.5 5.0V 2.5 1.0 0.4 0.2 3.0 MAX9705 toc23 0.8 2.5 fIN = 1kHz ZLOAD = 33µH IN SERIES WITH RL THD+N = 1% 3.5 MAX9705 toc25 1.2 3.0 OUTPUT POWER (W) 1.4 4.0 OUTPUT POWER (W) 1.8 MAX9705toc20 3.5 MAX9705toc19 2.0 OUTPUT POWER vs. LOAD RESISTANCE MAX9705 toc21 OUTPUT POWER vs. SUPPLY VOLTAGE OUTPUT POWER (W) MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier 15 20 0 5 10 15 FREQUENCY (kHz) _______________________________________________________________________________________ 20 1000 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier WIDEBAND OUTPUT SPECTRUM SPREAD-SPECTRUM MODE WIDEBAND OUTPUT SPECTRUM FIXED-FREQUENCY MODE -20 -40 AMPLITUDE (dBV) -40 -60 -80 MAX9705 toc27 -20 -60 -80 -100 -100 RL = 8Ω VDD = 5.0V INPUTS AC GROUNDED -120 RL = 8Ω VDD = 5.0V INPUTS AC GROUNDED -120 -140 -140 100 10 0 1000 SUPPLY CURRENT vs. SUPPLY VOLTAGE 7.00 MAX9705 toc28 9 SYNC = VDD (SSM) 8 SYNC = FLOAT (FFM) 7 6 SYNC = GND (FFM) VDD = 3.3V NO LOAD INPUTS AC GROUNDED 6.75 SUPPLY CURRENT (mA) SUPPLY CURRENT (mA) 1000 SUPPLY CURRENT vs. TEMPERATURE 10 5 100 10 FREQUENCY (MHz) FREQUENCY (MHz) 6.50 SYNC = FLOAT (FFM) 6.25 6.00 SYNC = VDD (SSM) 5.75 5.50 SYNC = GND (FFM)) 5.25 NO LOAD INPUTS AC GROUNDED 4 MAX9705 toc29 0 5.00 2.5 3.5 4.5 5.5 -40 -15 10 60 TEMPERATURE (°C) SHUTDOWN CURRENT vs. SUPPLY VOLTAGE TURN-ON/TURN-OFF RESPONSE 0.80 3V SHDN TA = -40°C 0.70 85 MAX9705 toc31 MAX9705 toc30 0.90 0.60 35 SUPPLY VOLTAGE (V) 1.00 SHUTDOWN CURRENT (µA) AMPLITUDE (dBV) 0 MAX9705 toc26 0 TA = +85°C 0.50 0V TA = +25°C 0.40 0.30 0.20 MAX9705 OUTPUT NO LOAD INPUTS AC GROUNDED SHDN = GND 0.10 250mV/div 0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 f = 1kHz RL = 8Ω 10ms/div _______________________________________________________________________________________ 7 MAX9705 Typical Operating Characteristics (continued) (VDD = 3.3V, SYNC = VDD (SSM), differential input, TA = +25°C, unless otherwise noted.) 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier MAX9705 Functional Diagram 2.5V TO 5.5V 1µF 5 (B2) SHDN 1 (A1) 10 (B4) 6 (A3) VDD PVDD SYNC UVLO/POWER MANAGEMENT CLICK-AND-POP SUPPRESSION OSCILLATOR PVDD LOW-EMI DRIVER 1µF 2 (B1) IN+ 1µF 3 (C1) IN- 8 OUT+ (A4) PGND CLASS D MODULATOR PVDD OUT- 9 (C4) LOW-EMI DRIVER MAX9705 PGND PGND 7 (B3) GND 4 (C2) ( ) UCSP BUMP. FIGURE SHOWS MAX9705 CONFIGURED FOR SPREAD-SPECTRUM OPERATION. 8 _______________________________________________________________________________________ 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier PIN BUMP TDFN/µMAX UCSP 1 A1 VDD 2 B1 IN+ Noninverting Audio Input 3 C1 IN- Inverting Audio Input 4 C2 GND 5 B2 SHDN Active-Low Shutdown Input. Connect to VDD for normal operation. NAME FUNCTION Analog Power Supply Analog Ground 6 A3 SYNC Frequency Select and External Clock Input. SYNC = GND: Fixed-frequency mode with fS = 1100kHz. SYNC = Float: Fixed-frequency mode with fS = 1450kHz. SYNC = VDD: Spread-spectrum mode with fS = 1220kHz ±120kHz. SYNC = Clocked: Fixed-frequency mode with fS = external clock frequency. 7 B3 PGND Power Ground 8 A4 OUT+ Amplifier-Output Positive Phase 9 C4 OUT- Amplifier-Output Negative Phase 10 B4 PVDD H-Bridge Power Supply Detailed Description The MAX9705 ultra-low-EMI, filterless, Class D audio power amplifier features several improvements to switchmode amplifier technology. The MAX9705 features output driver 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 cross-conduction. A unique filterless modulation scheme, synchronizable switching frequency, and spread-spectrum mode create a compact, flexible, low-noise, efficient audio power amplifier while occupying minimal board space. The differential input architecture reduces common-mode noise pickup with or without the use of input-coupling capacitors. The MAX9705 can also be configured as a singleended input amplifier without performance degradation. Thermal-overload and short-circuit protection prevent the MAX9705 from being damaged during a fault condition. The amplifier is disabled if the die temperature reaches +150°C. The die must cool by 10°C before normal operation can continue. The output of the MAX9705 shuts down if the output current reaches approximately 2A. Each output FET has its own short-circuit protection. This protection scheme allows the amplifier to survive shorts to either supply rail. After a thermal overload or short circuit, the device remains disabled for a minimum of 50µs before attempting to return to normal operation. The amplifier will shut down immediately and wait another 50µs before turning on if the fault condition is still present. This operation will cause the output to pulse during a persistent fault. Comparators monitor the MAX9705 inputs and compare the complementary input voltages to the sawtooth waveform. The comparators trip when the input magnitude of the sawtooth exceeds their corresponding input voltage. Both comparators reset at a fixed time after the rising edge of the second comparator trip point, generating a minimum-width pulse tON(MIN) at the output of the second comparator (Figure 1). As the input voltage increases or decreases, the duration of the pulse at one output increases (the first comparator to trip), while the other output pulse duration remains at tON(MIN). This causes the net voltage across the speaker (VOUT+ VOUT-) to change. Operating Modes Fixed-Frequency Modulation (FFM) Mode The MAX9705 features two FFM modes. The FFM modes are selected by setting SYNC = GND for a 1.1MHz switching frequency, and SYNC = FLOAT for a 1.45MHz switching frequency. In FFM mode, the frequency spectrum of the Class D output consists of the fundamental switching frequency and its associated harmonics (see the Wideband FFT graph in the Typical Operating Characteristics). The MAX9705 allows the switching frequency to be changed by +32%, should the frequency of one or more of the harmonics fall in a sensitive band. This can be done at any time and does not affect audio reproduction. Spread-Spectrum Modulation (SSM) Mode The MAX9705 features a unique, patented spread-spectrum mode that flattens the wideband spectral components, _______________________________________________________________________________________ 9 MAX9705 Pin Description MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier tSW VIN- VIN+ OUT- OUT+ tON(MIN) VOUT+ - VOUT- Figure 1. MAX9705 Outputs with an Input Signal Applied Table 1. Operating Modes SYNC INPUT MODE GND FFM with fS = 1100kHz FLOAT FFM with fS = 1450kHz VDD Clocked SSM with fS = 1220kHz ±120kHz FFM with fS = external clock frequency improving EMI emissions by 5dB. 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 SSM mode by setting SYNC = VDD. In SSM mode, the switching frequency varies randomly by ±120kHz around the center frequency (1.22MHz). The modulation scheme remains the same, but the period of the sawtooth waveform changes from cycle to cycle (Figure 2). Instead of a large amount of spectral energy present at multiples of 10 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 the EMI Spectrum Diagram). External Clock Mode The SYNC input allows the MAX9705 to be synchronized to a system clock moving the spectral components of the switching harmonics to insensitive frequency bands. Applying an external TTL clock of 800kHz to 2MHz to SYNC synchronizes the switching frequency of the MAX9705. The period of the SYNC clock can be randomized, enabling the MAX9705 to be synchronized to another MAX9705 operating in SSM mode. Filterless Modulation/Common-Mode Idle The MAX9705 uses Maxim’s unique, patented modulation scheme that eliminates the LC filter required by traditional Class D amplifiers, improving efficiency, reducing component count, and conserving board ______________________________________________________________________________________ 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier tSW tSW MAX9705 tSW tSW VIN- VIN+ OUT- OUT+ tON(MIN) VOUT+ - VOUT- Figure 2. MAX9705 Output with an Input Signal Applied (SSM Mode) space and system cost. Conventional Class D amplifiers output a 50% duty cycle square wave when no signal is present. With no filter, the square wave appears across the load as a DC voltage, resulting in a finite load current, increasing power consumption. When no signal is present at the input of the MAX9705, the outputs switch as shown in Figure 3. Because the MAX9705 drives the speaker differentially, the two outputs cancel each other, resulting in no net idle-mode voltage across the speaker, minimizing power consumption. power. Any power loss associated with the Class D output stage is mostly due to the I2R loss of the MOSFET on-resistance and quiescent-current overhead. The theoretical best efficiency of a linear amplifier is 78%; however, that efficiency is only exhibited at peak output powers. Under normal operating levels (typical music reproduction levels), efficiency falls below 30%, whereas the MAX9705 still exhibits >70% efficiencies under the same conditions (Figure 4). Efficiency The MAX9705 has a shutdown mode that reduces power consumption and extends battery life. Driving SHDN low places the MAX9705 in a low-power (0.3µA) shutdown mode. Connect SHDN to VDD for normal operation. Efficiency of a Class D amplifier is attributed to the region of operation of the output stage transistors. In a Class D amplifier, the output transistors act as currentsteering switches and consume negligible additional Shutdown ______________________________________________________________________________________ 11 MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier EFFICIENCY vs. OUTPUT POWER 100 VIN = 0V MAX9705 90 EFFICIENCY (%) 80 OUT- 70 60 50 CLASS AB 40 30 OUT+ 20 VDD = 3.3V fIN = 1kHz RL = 8Ω 10 0 0 0.4 0.6 0.8 1.0 OUTPUT POWER (W) VOUT+ - VOUT- = 0V Figure 3. MAX9705 Outputs with No Input Signal Click-and-Pop Suppression The MAX9705 features comprehensive click-and-pop suppression that eliminates audible transients on startup and shutdown. While in shutdown, the H-bridge is in a high-impedance state. During startup or power-up, the input amplifiers are muted and an internal loop sets the modulator bias voltages to the correct levels, preventing clicks and pops when the H-bridge is subsequently enabled. For 30ms following startup, a soft-start function gradually unmutes the input amplifiers. Applications Information Filterless Operation Traditional Class D amplifiers require an output filter to recover the audio signal from the amplifier’s output. The filters add cost, increase the solution size of the amplifier, and can decrease efficiency and THD+N performance. The traditional PWM scheme uses large differential output swings (2 x VDD peak-to-peak) and causes large ripple currents. Any parasitic resistance in the filter components results in a loss of power, lowering the efficiency. The MAX9705 does not require an output filter. The device relies on the inherent inductance of the speaker coil and the natural filtering of both the speaker and the human ear to recover the audio component of the square-wave output. Eliminating the output filter results in a smaller, less costly, more efficient solution. Because the frequency of the MAX9705 output is well beyond the bandwidth of most speakers, voice coil movement due to the square-wave frequency is very small. Although this movement is small, a speaker not 12 0.2 Figure 4. MAX9705 Efficiency vs. Class AB Efficiency designed to handle the additional power can be damaged. For optimum results, use a speaker with a series inductance >10µH. Typical 8Ω speakers exhibit series inductances in the 20µH to 100µH range. Power-Conversion Efficiency Unlike a class AB amplifier, the output offset voltage of a Class D amplifier does not noticeably increase quiescent-current draw when a load is applied. This is due to the power conversion of the Class D amplifier. For example, an 8mV DC offset across an 8Ω load results in 1mA extra current consumption in a Class AB device. In the Class D case, an 8mV offset into 8Ω equates to an additional power drain of 8µW. Due to the high efficiency of the Class D amplifier, this represents an additional quiescent-current draw of 8µW/(VDD/100η), which is on the order of a few microamps. Input Amplifier Differential Input The MAX9705 features a differential input structure, making it compatible with many CODECs, and offering improved noise immunity over a single-ended input amplifier. In devices such as cellular phones, high-frequency signals from the RF transmitter can be picked up by the amplifier’s input traces. The signals appear at the amplifier’s inputs as common-mode noise. A differential input amplifier amplifies the difference of the two inputs; any signal common to both inputs is canceled. Single-Ended Input The MAX9705 can be configured as a single-ended input amplifier by capacitively coupling either input to GND and driving the other input (Figure 5). ______________________________________________________________________________________ 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier DC-Coupled Input The input amplifier can accept DC-coupled inputs that are biased within the amplifier’s common-mode range (see the Typical Operating Characteristics). DC coupling eliminates the input-coupling capacitors, reducing component count to potentially one external component (see the System Diagram). However, the low-frequency rejection of the capacitors is lost, allowing low-frequency signals to feed through to the load. Component Selection Input Filter An input capacitor, CIN, in conjunction with the input resistance of the MAX9705 forms a highpass filter that removes the DC bias from an incoming signal. The ACcoupling capacitor allows the amplifier to bias the signal to an optimum DC level. Assuming zero source impedance, the -3dB point of the highpass filter is given by: f −3dB = 1 2π RIN CIN Choose CIN so f-3dB is well below the lowest frequency of interest. Setting f -3dB too high affects the lowfrequency response of the amplifier. Use capacitors whose dielectrics have low-voltage coefficients, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as ceramics, may result in increased distortion at low frequencies. Other considerations when designing the input filter include the constraints of the overall system and the actual frequency band of interest. Although high-fidelity audio calls for a flat gain response between 20Hz and 20kHz, portable voice-reproduction devices such as cellular phones and two-way radios need only concentrate on the frequency range of the spoken human voice (typically 300Hz to 3.5kHz). In addition, speakers used in portable devices typically have a poor response below 150Hz. Taking these two factors into consideration, the input filter may not need to be designed for a 20Hz to 20kHz response, saving both board space and cost due to the use of smaller capacitors. MAX9705 Note that the single-ended voltage range of the MAX9705A is 3VP-P. This limits the achievable output power for this device. Use higher gain versions (MAX9705B, MAX9705C, MAX9705D) if higher output power is desired in a single-ended application. 1µF SINGLE-ENDED AUDIO INPUT IN+ MAX9705 IN1µF Figure 5. Single-Ended Input Output Filter The MAX9705 does not require an output filter. The device passes FCC emissions standards with 24in of unshielded twisted-pair speaker cables. However, an output filter can be used if a design is failing radiated emissions due to board layout or excessive cable length, or the circuit is near EMI-sensitive devices. Supply Bypassing/Layout Proper power-supply bypassing ensures low-distortion operation. For optimum performance, bypass VDD to GND and PVDD to PGND with separate 1µF capacitors as close to each pin as possible. A low-impedance, high-current power-supply connection to PV DD is assumed. Additional bulk capacitance should be added as required depending on the application and powersupply characteristics. GND and PGND should be star connected to system ground. Refer to the MAX9705 evaluation kit for layout guidance. Stereo Configuration Two MAX9705s can be configured as a stereo amplifier (Figure 6). Device U1 is the master amplifier; its unfiltered output drives the SYNC input of the slave device (U2), synchronizing the switching frequencies of the two devices. Synchronizing two MAX9705s ensures that no beat frequencies occur within the audio spectrum. This configuration works when the master device is in either FFM or SSM mode. There is excellent THD+N performance and minimal crosstalk between devices due to the SYNC connection (Figures 7 and 8). U2 locks onto only the frequency present at SYNC, not the pulse width. The internal feedback loop of device U2 ensures that the audio component of U1’s output is rejected. ______________________________________________________________________________________ 13 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier MAX9705 Designing with Volume Control The MAX9705 can easily be driven by single-ended sources (Figure 5), but extra care is needed if the source impedance “seen” by each differential input is unbalanced, such as the case in Figure 9a, where the MAX9705 is used with an audio taper potentiometer acting as a volume control. Functionally, this configuration works well, but can suffer from click-pop transients at power-up (or coming out of SHDN) depending on the volume-control setting. As shown, the click-pop performance is fine for either max or min volume, but worsens at other settings. One solution is the configuration shown in Figure 9b. The potentiometer is connected between the differential inputs, and these “see” identical RC paths when the device powers up. The variable resistive element appears between the two inputs, meaning the setting affects both inputs the same way. The potentiometer is audio taper, as in Figure 9a. This significantly improves transient performance on power-up or release from SHDN. A similar approach can be applied when the MAX9705 is driven differentially and a volume control is required. VDD 1µF RIGHT-CHANNEL DIFFERENTIAL AUDIO INPUT VDD PVDD IN+ MAX9705 OUT+ IN- OUTSYNC 1µF LEFT-CHANNEL DIFFERENTIAL AUDIO INPUT VDD PVDD IN+ MAX9705 OUT+ IN- OUT- UCSP Applications Information For the latest application details on UCSP construction, dimensions, tape carrier information, PC board techniques, bump-pad layout, and recommended reflow temperature profile, as well as the latest information on reliability testing results, refer to Application Note: UCSP—A Wafer-Level Chip-Scale Package available on Maxim’s website at www.maxim-ic.com/ucsp. SYNC Figure 6. Master-Slave Stereo Configuration TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER VDD = 3.3V SLAVE DEVICE fIN = 1kHz SYNC = GND (FFM) RL = 8Ω VDD = 3.3V VIN = 500mVP-P fIN = 1kHz SYNC = GND (FFM) RL = 8Ω -10 -20 -30 CROSSTALK (dB) 10 THD+N (%) CROSSTALK vs. FREQUENCY 0 100 1 0.1 -40 -50 -60 MASTER TO SLAVE -70 -80 0.01 -90 SLAVE TO MASTER -100 -110 0.001 0 0.2 0.4 OUTPUT POWER (W) Figure 7. Master-Slave THD+N 14 0.6 0.8 10 100 1k 10k FREQUENCY (Hz) Figure 8. Master-Slave Crosstalk ______________________________________________________________________________________ 100k 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier MAX9705 1µF 22kΩ CW 1µF IN- 50kΩ IN- CW 50kΩ MAX9705 MAX9705 1µF IN+ IN+ 22kΩ 1µF Figure 9a. Single-Ended Drive of MAX9705 Plus Volume Figure 9b. Improved Single-Ended Drive of MAX9705 Plus Volume Pin Configurations Selector Guide PART TOP VIEW + VDD 1 10 PVDD PIN-PACKAGE GAIN (dB) MAX9705AETB+T 10 TDFN-10 6 10 µMAX 6 9 OUT- MAX9705AEUB+ 8 OUT+ MAX9705AEBC+T 12 UCSP-12 6 4 7 PGND MAX9705BETB+T 10 TDFN-10 12 5 6 SYNC 12 MAX9705BEUB+ 10 µMAX µMAX MAX9705BEBC+T 12 UCSP-12 12 MAX9705CETB+T 10 TDFN-10 15.6 MAX9705CEUB+ 10 µMAX 15.6 MAX9705CEBC+T 12 UCSP-12 15.6 MAX9705DETB+T 10 TDFN-10 20 MAX9705DEUB+ 10 µMAX 20 MAX9705DEBC+T 12 UCSP-12 20 SYNC SHDN PGND GND MAX9705 OUT+ 3 OUT- 2 IN- PVDD IN+ 10 9 8 7 6 MAX9705 4 5 SHDN IN+ 3 GND 2 IN- 1 VDD + Ordering Information (continued) PART TDFN TOP VIEW (BUMP SIDE DOWN) 1 MAX9705CETB+T MAX9705 2 3 VDD SYNC A IN+ SHDN IN- GND PGND PVDD B PINPACKAGE TOP MARK -40oC to +85oC 10 TDFN-10 ACZ o o MAX9705CEUB+ -40 C to +85 C 10 µMAX MAX9705CEBC+T -40oC to +85oC 12 UCSP-12 ACI MAX9705DETB+T -40oC to +85oC 10 TDFN-10 ADA 4 OUT+ TEMP RANGE o o MAX9705DEUB+ -40 C to +85 C 10 µMAX MAX9705DEBC+T -40oC to +85oC 12 UCSP-12 — — ACJ +Denotes lead-free package. OUT- C UCSP ______________________________________________________________________________________ 15 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier MAX9705 System Diagram VDD 1µF VDD VDD 0.1µF AUX_IN IN+ OUT 2.2kΩ OUT BIAS PVDD MAX9705 OUT+ IN- OUT- SHDN SYNC CODEC/ BASEBAND PROCESSOR 2.2kΩ MAX4063 0.1µF IN+ VDD IN0.1µF 1µF VDD SHDN 1µF INL OUTL 1µF MAX9722 INR µCONTROLLER OUTR PVSS SVSS C1P CIN 1µF 1µF Chip Information TRANSISTOR COUNT: 3595 PROCESS: BiCMOS 16 ______________________________________________________________________________________ 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier 12L, UCSP 4x3.EPS PACKAGE OUTLINE, 4x3 UCSP 21-0104 F 1 ______________________________________________________________________________________ 1 17 MAX9705 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.) Package Information (continued) (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.) 6, 8, &10L, DFN THIN.EPS MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier D2 D A2 PIN 1 ID N 0.35x0.35 b PIN 1 INDEX AREA E [(N/2)-1] x e REF. E2 DETAIL A e k A1 CL CL A L L e e PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm -DRAWING NOT TO SCALE- 18 21-0137 ______________________________________________________________________________________ G 1 2 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier COMMON DIMENSIONS MIN. MAX. D 0.70 2.90 0.80 3.10 E A1 2.90 0.00 3.10 0.05 L k 0.20 0.40 0.25 MIN. A2 0.20 REF. SYMBOL A PACKAGE VARIATIONS PKG. CODE N D2 E2 e JEDEC SPEC b [(N/2)-1] x e DOWNBONDS ALLOWED T633-1 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF NO T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF NO T833-1 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF NO T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF NO T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF YES T1033-1 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF NO T1433-1 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF YES T1433-2 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF NO PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm -DRAWING NOT TO SCALE- 21-0137 G 2 2 ______________________________________________________________________________________ 19 MAX9705 Package Information (continued) (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.) Package Information (continued) (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.) e 10LUMAX.EPS MAX9705 2.3W, Ultra-Low-EMI, Filterless, Class D Audio Amplifier 4X S 10 10 INCHES H Ø0.50±0.1 0.6±0.1 1 1 0.6±0.1 BOTTOM VIEW TOP VIEW D2 MILLIMETERS MAX DIM MIN 0.043 A 0.006 A1 0.002 A2 0.030 0.037 D1 0.120 0.116 0.118 D2 0.114 E1 0.116 0.120 0.118 E2 0.114 0.199 H 0.187 L 0.0157 0.0275 L1 0.037 REF b 0.007 0.0106 e 0.0197 BSC c 0.0035 0.0078 0.0196 REF S α 0° 6° MAX MIN 1.10 0.15 0.05 0.75 0.95 3.05 2.95 2.89 3.00 3.05 2.95 2.89 3.00 4.75 5.05 0.40 0.70 0.940 REF 0.177 0.270 0.500 BSC 0.090 0.200 0.498 REF 0° 6° E2 GAGE PLANE A2 c A b A1 α E1 L D1 L1 FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 10L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0061 REV. I 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. 20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.