EVALUATION KIT AVAILABLE MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier General Description The MAX9708 mono/stereo, Class D audio power amplifier delivers up to 2 x 21W into an 8Ω stereo mode and 1 x 42W into a 4Ω load in mono mode while offering up to 87% efficiency. The MAX9708 provides Class AB amplifier performance with the benefits of Class D efficiency, eliminating the need for a bulky heatsink and conserving power. The MAX9708 operates from a single +10V to +18V supply, driving the load in a BTL configuration. The MAX9708 offers two modulation schemes: a fixedfrequency modulation (FFM) mode, and a spread-spectrum modulation (SSM) mode that reduces EMI-radiated emissions. The MAX9708 can be synchronized to an external clock from 600kHz to 1.2MHz. A synchronized output allows multiple units to be cascaded in the system. Features include fully differential inputs, comprehensive click-and-pop suppression, and four selectable-gain settings (22dB, 25dB, 29.5dB, and 36dB). A pin-programmable thermal flag provides seven different thermal warning thresholds. Short-circuit and thermal-overload protection prevent the device from being damaged during a fault condition. The MAX9708 is available in a 56-pin TQFN (8mm x 8mm x 0.8mm) package and is specified over the extended -40°C to +85°C temperature range. Features o 2 x 21W Output Power in Stereo Mode (8Ω, THD = 10%) o 1 x 42W Output Power in Mono Mode (4Ω, THD = 10%) o High Efficiency: Up to 87% o Filterless Class D Amplifier o Unique Spread-Spectrum Mode o Programmable Gain (+22dB, +25dB, +29.5dB, +36dB) o High PSRR (90dB at 1kHz) o Differential Inputs Suppress Common-Mode Noise o Shutdown and Mute Control o Integrated Click-and-Pop Suppression o Low 0.1% THD+N o Current Limit and Thermal Protection o Programmable Thermal Flag o SYNC Input/Output o Available in Thermally Efficient, Space-Saving 56-Pin TQFN Package Ordering Information TEMP RANGE PINPACKAGE -40°C to +85°C 56 TQFN-EP* T5688-3 MAX9708ETN/V+ -40°C to +85°C 56 TQFN-EP* T5688-3 Applications LCD TVs PDP TVs Automotive PC/HiFi Audio Solutions PART MAX9708ETN+ PKG CODE +Denotes lead-free package. /V denotes an automotive qualified part. *EP = Exposed pad. Pin Configurations appear at end of data sheet. Simplified Block Diagram MAX9708 2 FS1, FS2 SYNC SYNCOUT RIGHT CHANNEL GAIN CONTROL MONO G1, G2 TH0, TH1, TH2 AUDIO INPUT CLASS D MODULATOR LEFT CHANNEL MONO 2 3 TEMP STEREO MODE G1, G2 TH0, TH1, TH2 SYNCOUT CLASS D MODULATOR VDIGITAL OUTPUT PROTECTION MAX9708 2 FS1, FS2 SYNC GAIN CONTROL OUTPUT PROTECTION 2 3 TEMP MONO MODE For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com. 19-3678; Rev 3; 4/13 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier ABSOLUTE MAXIMUM RATINGS PVDD, VDD to PGND, GND .......................................-0.3 to +30V PVDD to VDD ..........................................................-0.3V to +0.3V OUTR+, OUTR-, OUTL+, OUTL- to PGND, GND...........................-0.3V to (PVDD + 0.3V) C1N to GND .............................................-0.3V to (PVDD + 0.3V) C1P to GND..............................(PVDD - 0.3V) to (CPVDD + 0.3V) CPVDD to GND ..........................................(PVDD - 0.3V) to +40V All Other Pins to GND.............................................-0.3V to +12V Continuous Input Current (except PVDD, VDD, OUTR+, OUTR-, OUTL+, and OUTL-) ...........................................20mA Continuous Power Dissipation (TA = +70°C) 56-Pin TQFN (derate 47.6mW/°C above +70°C) ............3.81W Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Junction Temperature ......................................................+150°C Thermal Resistance (θJC) 56-Pin TQFN… .............................................................0.6°C/W Lead Temperature (soldering, 10s) .................................+300°C 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 (PVDD = VDD = +18V, PGND = GND = 0V, CSS = 0.47µF, CREG = 0.01µF, C1 = 0.1µF, C2 = 1µF, RLOAD = ∞, MONO = low (stereo mode), SHDN = MUTE = high, G1 = low, G2 = high (AV = 22dB), FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are connected between OUT_+ and OUT_-, unless otherwise stated. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Supply Voltage Range Shutdown Current SYMBOL VDD ISHDN CONDITIONS Inferred from PSRR test MIN TYP 10 SHDN = low 0.1 Shutdown to Full Operation tSON 100 Mute to Full Operation tMUTE 100 Input Impedance RIN Switch On-Resistance Switching Frequency CMRR RDS fSW 40 63 90 G1 = 1, G2 = 0 25 43 60 G1= 0, G2 = 0 12 21 30 600 200mVP-P ripple (Note 2) 68 90 50 50 dB 70 dB f = 20Hz to 20kHz, input referred 70 One power switch 0.3 0.75 200 220 FS1 FS2 0 0 1 1 (SSM) 200 1 0 160 0 1 250 FS1 = FS2 = high (SSM) SYNCIN Lock Range Equal to fSW x 4 180 Ω kHz ±2 600 mV 90 fRIPPLE = 20kHz DC, input referred kΩ kΩ ±30 fRIPPLE = 1kHz Oscillator Spread Bandwidth 2 ms G1 = 1, G2 = 1 PVDD = 10V to 18V Common-Mode Rejection Ratio ms 125 Output Offset Voltage PSRR µA 85 SHDN = GND Power-Supply Rejection Ratio V 1 50 AC-coupled input, measured between OUT_+ and OUT_- UNITS 18 G1 = 0, G2 = 1 Output Pulldown Resistance VOS MAX % 1200 kHz Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier ELECTRICAL CHARACTERISTICS (continued) (PVDD = VDD = +18V, PGND = GND = 0V, CSS = 0.47µF, CREG = 0.01µF, C1 = 0.1µF, C2 = 1µF, RLOAD = ∞, MONO = low (stereo mode), SHDN = MUTE = high, G1 = low, G2 = high (AV = 22dB), FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are connected between OUT_+ and OUT_-, unless otherwise stated. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Gain SYMBOL AV MIN TYP MAX G1 = 0, G2 = 1 CONDITIONS 21.6 22.0 22.3 G1 = 1, G2 = 1 24.9 25.0 25.6 G1 = 1, G2 = 0 29.2 29.5 29.9 35.9 36.0 36.6 G1 = 0, G2 = 0 TEMP Flag Threshold TFLAG TEMP Flag Accuracy TH2 TH1 TH0 0 0 0 0 0 1 +90 0 1 0 +100 0 1 1 +110 1 0 0 +120 1 0 1 +129 1 1 0 +139 1 1 1 +150 UNITS dB +80 From +80°C to +140°C °C ±6 TEMP Flag Hysteresis 2 °C °C STEREO MODE (RLOAD = 8Ω) Quiescent Current Output Power Total Harmonic Distortion Plus Noise Signal-to-Noise Ratio Efficiency Left-Right Channel Gain Matching Maxim Integrated POUT THD+N SNR η MUTE = 1, RLOAD = ∞ 20 30 MUTE = 0 5 11 f = 1kHz, THD = 10%, TA = +25°C, RLOAD = 8Ω, PVDD = 18V f = 1kHz, BW = 22Hz to 22kHz, RLOAD = 8Ω, POUT = 8W RLOAD = 8Ω, POUT = 10W 21 W 0.1 % 22Hz to 22kHz 91 A-weighted 96 RLOAD = 8Ω, L > 60µH, POUT = 15W + 15W, f = 1kHz POUT = 10W 20 mA dB 87 % 0.02 dB 3 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier ELECTRICAL CHARACTERISTICS (continued) (PVDD = VDD = +18V, PGND = GND = 0V, CSS = 0.47µF, CREG = 0.01µF, C1 = 0.1µF, C2 = 1µF, RLOAD = ∞, MONO = low (stereo mode), SHDN = MUTE = high, G1 = low, G2 = high (AV = 22dB), FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are connected between OUT_+ and OUT_-, unless otherwise stated. TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS Output Short-Circuit Current Threshold ISC RLOAD = 0Ω Click-and-Pop Level KCP Peak voltage, 32 samples/second, A-weighted (Notes 2, 4) MIN TYP MAX 2.4 Into shutdown -63 Out of shutdown -55 UNITS A dBV MONO MODE (RLOAD = 4Ω, MONO = High) Quiescent Current Output Power POUT Total Harmonic Distortion Plus Noise Signal-to-Noise Ratio Efficiency MUTE = 1, RLOAD = ∞ 20 MUTE = 0 5 f = 1kHz, THD = 10% RLOAD = 8Ω 23 RLOAD = 4Ω 42 f = 1kHz, BW = 22Hz to 22kHz, RLOAD = 4Ω, POUT = 17W SNR η RLOAD = 4Ω, POUT = 10W 0.12 20Hz to 20kHz 91 A-weighted 95 4.8 A Click-and-Pop Level KCP Peak voltage, 32 samples/second, A-weighted (Notes 2, 4) Into shutdown -60 Out of shutdown -63 dBV DIGITAL INPUTS (SHDN, MUTE, G1, G2, FS1, FS2, TH0, TH1, TH2, SYNCIN, MONO) Logic-Input Current IIN 0 to 12V VIL dB % RLOAD = 0Ω VIH % 85 ISC Logic-Input Low Voltage W RLOAD = 4Ω, L > 40µH, POUT = 42W, f = 1kHz Output Short-Circuit Current Threshold Logic-Input High Voltage mA 1 µA 0.8 V 2.5 V OPEN-DRAIN OUTPUTS (TEMP, SYNCOUT) Open-Drain Output Low Voltage Leakage Current Note 1: Note 2: Note 3: Note 4: 4 VOL ILEAK ISINK = 3mA VPULLUP = 5.5V 0.4 0.2 V µA All devices are 100% production tested at +25°C. All temperature limits are guaranteed by design. Inputs AC-coupled to GND. The device is current limited. The maximum output power is obtained with an 8Ω load. Testing performed with an 8Ω resistive load in series with a 68µH inductive load connected across BTL outputs. Mode transitions are controlled by SHDN. Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Typical Operating Characteristics (PVDD = VDD = +18V, PGND = GND = 0V, CSS = 0.47µF, CREG = 0.01µF, C1 = 0.1µF, C2 = 1µF, RLOAD = ∞, SHDN = high, MONO = low, MUTE = high, G1 = low, G2 = high, FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are between OUT_+ and OUT_-, TA = +25°C, unless otherwise stated.) 10 RL = 8Ω THD+N (%) 1 1 PVDD = 18V, 8Ω STEREO MODE, POUT = 8.3W PER CHANNEL 0.01 0.01 5 10 15 20 25 0.01 0 30 5 15 10 10 1k 10k 100k OUTPUT POWER PER CHANNEL (W) FREQUENCY (Hz) EFFICIENCY vs. OUTPUT POWER OUTPUT POWER vs. SUPPLY VOLTAGE NO-LOAD SUPPLY CURRENT vs. SUPPLY VOLTAGE 70 60 50 40 30 PVDD = 18V, 8Ω STEREO MODE 20 RL = 8Ω STEREO MODE 25 20 24 10% THD+N 15 10 1% THD+N STEREO MODE 22 5 5 10 15 20 25 12 14 18 16 TA = -40°C 14 10 12 SHDN = 0 16 18 20 22 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 100 MAX9708 toc07 4.0 14 SUPPLY VOLTAGE (V) SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE PVDD = 18V, 4Ω MONO MODE, 1kHz 10 3.0 2.5 THD+N (%) SUPPLY CURRENT (nA) 16 SUPPLY VOLTAGE (V) OUTPUT POWER PER CHANNEL (W) 3.5 18 10 10 30 TA = +25°C TA = +85°C 20 12 0 10 MAX9708 toc06 80 30 MAX9708 toc08 90 SUPPLY CURRENT (mA) MAX9708 toc04 100 0 100 OUTPUT POWER PER CHANNEL (W) OUTPUT POWER PER CHANNEL (W) 0 0.1 RL = 4Ω 0.1 0.1 1 MAX9708 toc05 THD+N (%) 10 EFFICIENCY (%) PVDD = 12V, STEREO MODE, fIN = 1kHz THD+N (%) PVDD = 18V, 8Ω STEREO MODE, 1kHz TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX9708 toc02 100 MAX9708 toc01 100 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER MAX9708 toc03 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 2.0 1 1.5 0.1 1.0 0.5 0.01 0 10 12 14 16 18 SUPPLY VOLTAGE (V) Maxim Integrated 20 22 0 10 20 30 40 50 60 OUTPUT POWER (W) 5 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Typical Operating Characteristics (continued) (PVDD = VDD = +18V, PGND = GND = 0V, CSS = 0.47µF, CREG = 0.01µF, C1 = 0.1µF, C2 = 1µF, RLOAD = ∞, SHDN = high, MONO = low, MUTE = high, G1 = low, G2 = high, FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are between OUT_+ and OUT_-, TA = +25°C, unless otherwise stated.) 0.1 0.1 10kHz RBW 20 OUTPUT AMPLITUDE (dBV) PVDD = 18V, 4Ω MONO MODE, POUT = 18W THD+N (%) THD+N (%) 1 30 MAX9708 toc10 PVDD = 12V, MONO MODE, fIN = 1kHz RL = 4Ω 10 1 MAX9708 toc09 100 WIDEBAND OUTPUT SPECTRUM (SSM MODE) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY 10 MAX9708 toc11 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER 0 -10 -20 -30 -40 -50 -60 0.01 5 10 15 20 25 10 100 1k 10k 100k 100k 1M 100M 10M OUTPUT POWER (W) FREQUENCY (Hz) FREQUENCY (Hz) WIDEBAND OUTPUT SPECTRUM (FFM MODE) OUTPUT FREQUENCY SPECTRUM (SSM MODE) OUTPUT FREQUENCY SPECTRUM (FFM MODE) 0 -10 -20 -30 -40 -50 0 -40 -60 -80 MAX9708 toc14 -20 OUTPUT AMPLITUDE (dBV) 10 0 -20 OUTPUT AMPLITUDE (dBV) 10kHz RBW 20 MAX9708 toc13 30 MAX9708 toc12 0 OUTPUT AMPLITUDE (dBV) -70 0.01 -40 -60 -80 -100 -100 -60 -70 1M 10M FREQUENCY (Hz) 6 -120 -120 100k 100M 0 4 8 12 16 FREQUENCY (kHz) 20 24 0 4 8 12 16 20 24 FREQUENCY (kHz) Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Typical Operating Characteristics (continued) (PVDD = VDD = +18V, PGND = GND = 0V, CSS = 0.47µF, CREG = 0.01µF, C1 = 0.1µF, C2 = 1µF, RLOAD = ∞, SHDN = high, MONO = low, MUTE = high, G1 = low, G2 = high, FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are between OUT_+ and OUT_-, TA = +25°C, unless otherwise stated.) 70 60 50 40 40 30 20 MAX9708 toc17 MONO MODE, 10% THD+N, PVDD = 18V 50 OUTPUT POWER (W) OUTPUT POWER (W) 80 RL = 4Ω, MONO MODE, 10% THD+N 50 60 MAX9708 toc16 90 EFFICIENCY (%) 60 MAX9708 toc15 100 OUTPUT POWER vs. LOAD RESISTANCE OUTPUT POWER vs. SUPPLY VOLTAGE EFFICIENCY vs. OUTPUT POWER 40 30 20 30 10 PVDD = 18V, 4Ω MONO MODE 20 10 0 0 10 20 30 40 50 60 0 10 12 14 16 OUTPUT POWER (W) SUPPLY VOLTAGE (V) OUTPUT POWER vs. LOAD RESISTANCE MUTE RESPONSE 18 4 6 8 MAX9708 toc18 STEREO MODE, 10% THD+N, PVDD = 18V 25 10 12 LOAD RESISTANCE (Ω) SHUTDOWN RESPONSE MAX9708 toc20 MAX9708 toc19 30 OUTPUT POWER PER CHANNEL (W) 10 MUTE 5V/div SHDN 5V/div OUTPUT 50mV/div OUTPUT 50mV/div 20 15 10 5 0 7 8 9 10 11 12 40ms/div 40ms/div LOAD RESISTANCE (Ω) Maxim Integrated 7 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Typical Operating Characteristics (continued) (PVDD = VDD = +18V, PGND = GND = 0V, CSS = 0.47µF, CREG = 0.01µF, C1 = 0.1µF, C2 = 1µF, RLOAD = ∞, SHDN = high, MONO = low, MUTE = high, G1 = low, G2 = high, FS1 = FS2 = high (SSM), SYNCIN = low. All load resistors (RL) are between OUT_+ and OUT_-, TA = +25°C, unless otherwise stated.) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY -70 -40 -50 -60 -50 -80 -85 -90 CROSSTALK (dB) PSRR (dB) -75 CMRR (dB) -40 MAX9708 toc22 INPUT REFERRED -65 CROSSTALK vs. FREQUENCY -30 MAX9708 toc21 -60 -60 -70 -80 -95 MAX9708 toc23 COMMON-MODE REJECTION RATIO vs. FREQUENCY -70 -80 -90 -90 -100 -100 -110 -100 -120 -110 -110 10 100 1k 10 100k 10k 100 1k 25 20 15 10 MEASURED WITH THE EV KIT (TQFN PACKAGE), JUNCTION TEMPERATURE MAINTAINED AT +110°C 5 70 PVDD = 18V, 4Ω MONO MODE, 1kHz, FS1 = FS2 = 1 TH0 = TH1 = 1 TH2 = 0 60 OUTPUT POWER (W) PVDD = 18V, 8Ω STEREO MODE, 1kHz, FS1 = FS2 = 1 TH0 = TH1 = 1 TH2 = 0 50 100k 40 30 20 MEASURED WITH THE EV KIT (TQFN PACKAGE), JUNCTION TEMPERATURE MAINTAINED AT +110°C 10 0 10k MAXIMUM STEADY-STATE OUTPUT POWER vs. TEMPERATURE MAX9708 toc24 OUTPUT POWER PER CHANNEL (W) 40 1k FREQUENCY (Hz) MAXIMUM STEADY-STATE OUTPUT POWER vs. TEMPERATURE 30 100 FREQUENCY (Hz) FREQUENCY (Hz) 35 10 100k 10k MAX9708 toc25 -105 0 30 40 50 60 70 30 AMBIENT TEMPERATURE (°C) 40 50 60 70 AMBIENT TEMPERATURE (°C) Pin Description PIN NAME 1, 12, 42, 43, 44, 55, 56 N.C. 2, 3, 4, 39, 40, 41, 49, 50 PGND Power Ground 5, 6, 7, 36, 37, 38 PVDD Positive Power Supply. Bypass to PGND with a 0.1µF and a 47µF capacitor with the smallest capacitor placed as close to pins as possible. 8 FUNCTION No Connection. Not internally connected. Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Pin Description (continued) PIN NAME 8 C1N Charge-Pump Flying Capacitor C1, Negative Terminal FUNCTION 9 C1P Charge-Pump Flying Capacitor C1, Positive Terminal 10 CPVDD 11 SYNCOUT Charge-Pump Power Supply. Bypass to PVDD with a 1µF capacitor as close to the pin as possible. 13 SYNCIN 14 FS2 Frequency Select 2 15 FS1 Frequency Select 1 16 INL- Left-Channel Negative Input (Stereo Mode Only) 17 INL+ Left-Channel Positive Input (Stereo Mode Only) 18 MONO Open-Drain, Slew-Rate Limited Clock Output. Pullup with a 10kΩ resistor to REG. Clock Synchronization Input. Allows for synchronization of the internal oscillator with an external clock. SYNCIN is internally pulled up to VREG with a 100kΩ resistor. Mono/Stereo Mode Input. Drive logic-high for mono mode. Drive logic-low for stereo mode. 19, 20, 21 REG Internal Regulator Output Voltage (6V). Bypass with a 0.01µF capacitor to GND. 22, 23 GND Analog Ground 24 SS Soft-Start. Connect a 0.47µF capacitor to GND to utilize soft-start power-up sequence. 25 VDD Analog Power Supply. Bypass to GND with a 0.1µF capacitor as close to pin as possible. 26 INR- Right-Channel Negative Input. In mono mode, INR- is the negative input. 27 INR+ 28 G1 Gain Select Input 1 29 G2 Gain Select Input 2 30 SHDN Active-Low Shutdown Input. Drive SHDN high for normal operation. Drive SHDN low to place the device in shutdown mode. 31 MUTE Active-Low Mute Input. Drive logic-low to place the device in mute. In mute mode, Class D output stage is no longer switching. Drive high for normal operation. MUTE is internally pulled up to VREG with a 100kΩ resistor. 32 TEMP Thermal Flag Output, Open Drain. Pull up with a 10kΩ resistor to REG. 33 TH2 Temperature Flag Threshold Select Input 2 34 TH1 Temperature Flag Threshold Select Input 1 35 TH0 Temperature Flag Threshold Select Input 0 Right-Channel Positive Input. In mono mode, INR+ is the positive input. 45, 46 OUTR- 47, 48 OUTR+ Right-Channel Positive Output 51, 52 OUTL- Left-Channel Negative Output 53, 54 OUTL+ EP EP Maxim Integrated Right-Channel Negative Output Left-Channel Positive Output Exposed Paddle. Connect to GND with multiple vias for best heat dissipation. 9 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Typical Application Circuits/Functional Diagrams VDD PVDD 0.1μF 47μF* VDIGITAL 22, 23 VDIGITAL 25 GND 2–4, 39–41 49–50 5–7, 36–38 VDD PVDD PGND 10kΩ 15 FS1 14 FS2 SYNCOUT CONTROL 13 SYNCIN MAX9708 RF 1μF 17 INL+ + LEFT CHANNEL 1μF 16 INL- - PVDD VBIAS RIN 11 CLASS D MODULATOR AND H-BRIDGE RIN OUTL+ 53, 54 OUTL- 51, 52 OUTR+ 47, 48 OUTR- 45, 46 RF RF PVDD 1μF + RIGHT CHANNEL 1μF - 27 INR+ RIN MUX 26 INR- RIN CLASS D MODULATOR AND H-BRIDGE VBIAS VDIGITAL 30 CPVDD SHDN 31 MUTE 28 G2 RF CHARGE PUMP GAIN CONTROL 29 G1 18 MONO REGULATOR TH0 35 TH1 34 TH2 33 VDIGITAL PVDD 9 C1N 8 REG 19, 20, 21 C1 0.1μF CREG 0.01μF 32 10kΩ SS 24 10 C1P TEMP THERMAL SENSOR C2 1μF CSS 0.47μF VDIGITAL CONFIGURATION: TQFN STEREO MODE, SSM, INTERNAL OSCILLATOR, GAIN = 22dB, THERMAL SETTING = +120°C *ADDITIONAL BULK CAPACITANCE Figure 1. Typical Application and Functional Diagram in Stereo Mode 10 Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Typical Application Circuits/Functional Diagrams (continued) VDD PVDD 47μF* 0.1μF 0.1μF VDIGITAL 22, 23 VDIGITAL 25 GND 15 FS1 14 FS2 5–7, 36–38 VDD PVDD CONTROL + AUDIO INPUT 1μF - 16 INR- PVDD VBIAS RIN 11 MAX9708 RF 17 INR+ 10kΩ SYNCOUT 13 SYNCIN 1μF 2–4, 39–41 49–50 PGND CLASS D MODULATOR AND H-BRIDGE RIN OUTL+ 53, 54 OUTL- 51, 52 OUTR+ 47, 48 OUTR- 45, 46 CPVDD 10 PVDD RF MUX 30 VDIGITAL CLASS D MODULATOR AND H-BRIDGE SHDN 31 MUTE 28 G1 CHARGE PUMP GAIN CONTROL 29 G2 18 MONO VDIGITAL REGULATOR TH0 35 TH1 34 TH2 33 9 C1N 8 REG 19, 20, 21 C1 0.1μF CREG 0.01μF 32 10kΩ SS 24 PVDD C1P TEMP THERMAL SENSOR C2 1μF CSS 0.47μF VDIGITAL VDIGITAL CONFIGURATION: TQFN MONO MODE, SSM, INTERNAL OSCILLATOR, GAIN = 22dB, THERMAL SETTING = +120°C *ADDITIONAL BULK CAPACITANCE Figure 2. Typical Application and Functional Diagram in Mono Mode Maxim Integrated 11 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Detailed Description The MAX9708 filterless, Class D audio power amplifier features several improvements to switch-mode amplifier technology. The MAX9708 is a two-channel, stereo amplifier with 21W output power on each channel. The amplifier can be configured to output 42W output power in mono mode. The device offers Class AB performance with Class D efficiency, while occupying minimal board space. A unique filterless modulation scheme and spread-spectrum switching mode create a compact, flexible, low-noise, efficient audio power amplifier. The differential input architecture reduces common-mode noise pickup, and can be used without input-coupling capacitors. The device can also be configured as a single-ended input amplifier. Mono/Stereo Configuration The MAX9708 features a mono mode that allows the right and left channels to operate in parallel, achieving up to 42W of output power. The mono mode is enabled by applying logic-high to MONO. In this mode, an audio signal applied to the right channel (INR+/INR-) is routed to the H-bridge of both channels, while a signal applied to the left channel (INL+/INL-) is ignored. OUTL+ must be connected to OUTR+ and OUTL- must be connected to OUTR- using heavy PC board traces as close to the device as possible (see Figure 2). When the device is placed in mono mode on a PC board with outputs wired together, ensure that the MONO pin can never be driven low when the device is enabled. Driving the MONO pin low (stereo mode) while the outputs are wired together in mono mode may trigger the short circuit or thermal protection or both, and may even damage the device. Efficiency 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 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 12 powers. Under normal operating levels (typical music reproduction levels), efficiency falls below 30%, whereas the MAX9708 still exhibits 87% efficiency under the same conditions. Shutdown The MAX9708 features a shutdown mode that reduces power consumption and extends battery life. Driving SHDN low places the device in low-power (0.1µA) shutdown mode. Connect SHDN to digital high for normal operation. Mute Function The MAX9708 features a clickless/popless mute mode. When the device is muted, the outputs stop switching, muting the speaker. Mute only affects the output stage and does not shut down the device. To mute the MAX9708, drive MUTE to logic-low. Driving MUTE low during the power-up/down or shutdown/turn-on cycle optimizes click-and-pop suppression. Click-and-Pop Suppression The MAX9708 features comprehensive click-and-pop suppression that eliminates audible transients on startup and shutdown. While in shutdown, the H-bridge is pulled to GND through a 330kΩ resistor. 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 Hbridge is subsequently enabled. Following startup, a soft-start function gradually un-mutes the input amplifiers. The value of the soft-start capacitor has an impact on the click-and-pop levels as well as startup time. Thermal Sensor The MAX9708 features an on-chip temperature sensor that monitors the die temperature. When the junction temperature exceeds a programmed level, TEMP is pulled low. This flags the user to reduce power or shut down the device. TEMP may be connected to SS or MUTE for automatic shutdown during overheating. If TEMP is connected to MUTE, during thermal-protection mode, the audio is muted and the device is in mute mode. If TEMP is connected to SS, during thermal-protection mode, the device is shut down but the thermal sensor is still active. Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier TEMP returns high once the junction temperature cools below the set threshold minus the thermal hysteresis. If TEMP is connected to either MUTE or SS, the audio output resumes. The temperature threshold is set by the TH0, TH1, and TH2 inputs as shown in Table 1. An RC filter may be used to eliminate any transient at the TEMP output as shown in Figure 3. Gain Selection The MAX9708 features four pin-selectable gain settings; see Table 2. VDIGITAL 10kΩ 10kΩ TO DIGITAL INPUT TEMP 0.1μF Figure 3. An RC Filter Eliminates Transient During Switching Table 1. MAX9708 Junction Temperature Threshold Setting JUNCTION TEMPERATURE (°C) TH2 TH1 TH0 80 Low Low Low High 90 Low Low 100 Low High Low 110 Low High High 120 High Low Low 129 High Low High 139 High High Low 150 High High High Synchronous Switching Mode The MAX9708 SYNCIN input allows the Class D amplifier to switch at a frequency defined by an external clock frequency. Synchronizing the amplifier with an external clock source may confine the switching frequency to a less sensitive band. The external clock frequency range is from 600kHz to 1.2MHz and can have any duty cycle, but the minimum pulse must be greater than 100ns. SYNCOUT is an open-drain clock output for synchronizing external circuitry. Its frequency is four times the amplifier’s switching frequency, and it is active in either internal or external oscillator mode. FS1 FS2 SYNCOUT FREQUENCY (kHz) MODULATION 22 0 0 200 Fixed-Frequency High 25 0 1 250 Fixed-Frequency Low 29.5 1 0 160 Fixed-Frequency 36 1 1 200 ±4 Spread-Spectrum G1 G2 GAIN (dB) Low High High High Maxim Integrated Spread-Spectrum Modulation (SSM) Mode The MAX9708 features a unique spread-spectrum (SSM) 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 FS1 = FS2 = high. In SSM mode, the switching frequency varies randomly by ±4% around the center frequency (200kHz). The modulation scheme remains the same, but the period of the triangle waveform changes from cycle to cycle. 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. SSM mode reduces EMI compared to fixedfrequency mode. This can also help to randomize visual artifacts caused by radiated or supply-borne interference in displays. Table 3. Switching Frequencies Table 2. MAX9708 Gain Setting Low Operating Modes Fixed-Frequency Modulation (FFM) Mode The MAX9708 features three switching frequencies in the FFM mode (Table 3). In this mode, the frequency spectrum of the Class D output consists of the fundamental switching frequency and its associated harmonics (see the Wideband Output Spectrum graph in the Typical Operating Characteristics). Select one of the three fixed switching frequencies such that the harmonics do not fall in a sensitive band. The switching frequency can be changed at any time without affecting audio reproduction. Low 13 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Linear Regulator (REG) The supply voltage range for the MAX9708 is from 10V to 18V to achieve high-output power. An internal linear regulator reduces this voltage to 6.3V for use with small-signal and digital circuitry that does not require a high-voltage supply. Bypass a 0.01µF capacitor from REG to GND. 1μF INR+ MAX9708 Applications Information INR- Logic Inputs All of the digital logic inputs and output have an absolute maximum rating of +12V. If the MAX9708 is operating with a supply voltage between 10V and 12V, digital inputs can be connected to PV DD or V DD. If PVDD and VDD are greater than 12V, digital inputs and outputs must connected to a digital system supply lower than 12V. Input Amplifier Differential Input The MAX9708 features a differential input structure, making them compatible with many CODECs, and offering improved noise immunity over a single-ended input amplifier. In devices such as flat-panel displays, noisy digital signals can be picked up by the amplifier’s inputs. These signals appear at the amplifiers’ inputs as common-mode noise. A differential input amplifier amplifies only the difference of the two inputs, while any signal common to both inputs is attenuated. Single-Ended Input The MAX9708 can be configured as a single-ended input amplifier by capacitively coupling either input to GND and driving the other input (Figure 4). Component Selection Input Filter An input capacitor, CIN, in conjunction with the input impedance of the MAX9708, 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 = 14 1 2π RIN CIN 1μF Figure 4. Single-Ended Input Connections Choose CIN so that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the low-frequency response of the amplifier. Use capacitors with dielectrics that 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. Output Filter The MAX9708 does not require an output filter. However, output filtering can be used if a design is failing radiated emissions due to board layout or cable length, or the circuit is near EMI-sensitive devices. Refer to the MAX9708 Evaluation Kit for suggested filter topologies. The tuning and component selection of the filter should be optimized for the load. A purely resistor load (8Ω) used for lab testing will require different components than a real, complex load-speaker load. Charge-Pump Capacitor Selection The MAX9708 has an internal charge-pump converter that produces a voltage level for internal circuitry. It requires a flying capacitor (C1) and a holding capacitor (C2). Use capacitors with an ESR less than 100mΩ for optimum performance. Low-ESR ceramic capacitors minimize the output resistance of the charge pump. For best performance over the extended temperature range, select capacitors with an X7R dielectric. The capacitors’ voltage rating must be greater than 36V. Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Sharing Input Sources In certain systems, a single audio source can be shared by multiple devices (speaker and headphone amplifiers). When sharing inputs, it is common to mute the unused device, rather than completely shutting it down, preventing the unused device inputs from distorting the input signal. Mute the MAX9708 by driving MUTE low. Driving MUTE low turns off the Class D output stage, but does not affect the input bias levels of the MAX9708. Frequency Synchronization The MAX9708 outputs up to 21W on each channel in stereo mode. If higher output power or a 2.1 solution is needed, two MAX9708s can be used. Each MAX9708 is synchronized by connecting SYNCOUT from the first MAX9708 to SYNCIN of the second MAX9708 (see Figure 5). Supply Bypassing/Layout Proper power-supply bypassing ensures low-distortion operation. For optimum performance, bypass PVDD to PGND with a 0.1µF capacitor as close to each PVDD pin as possible. A low-impedance, high-current powersupply connection to PVDD is assumed. Additional bulk capacitance should be added as required depending on the application and power-supply characteristics. GND and PGND should be star-connected to system ground. For the TQFN package, solder the exposed paddle (EP) to the ground plane using multiple-plated through-hole vias. The exposed paddle must be soldered to the ground plane for rated power dissipation and good ground return. Use wider PC board traces to lower the parasitic resistance for the high-power output pins (OUTR+, OUTR-, OUTL+, OUTL-). Refer to the MAX9708 Evaluation Kit for layout guidance. Thermal Considerations Class D amplifiers provide much better efficiency and thermal performance than a comparable Class AB amplifier. However, the system’s thermal performance must be considered with realistic expectations along with its many parameters. Maxim Integrated Continuous Sine Wave vs. Music When a Class D amplifier is evaluated in the lab, often a continuous sine wave is used as the signal source. While this is convenient for measurement purposes, it represents a worst-case scenario for thermal loading on the amplifier. It is not uncommon for a Class D amplifier to enter thermal shutdown if driven near maximum output power with a continuous sine wave. The PC board must be optimized for best dissipation (see the PC Board Thermal Considerations section). Audio content, both music and voice, has a much lower RMS value relative to its peak output power. Therefore, while an audio signal may reach similar peaks as a continuous sine wave, the actual thermal impact on the Class D amplifier is highly reduced. If the thermal performance of a system is being evaluated, it is important to use actual audio signals instead of sine waves for testing. If sine waves must be used, the thermal performance will be less than the system’s actual capability for real music or voice. PC Board Thermal Considerations The exposed pad is the primary route for conducting heat away from the IC. With a bottom-side exposed pad, the PC board and its copper becomes the primary heatsink for the Class D amplifier. Solder the exposed pad to a copper polygon. Add as much copper as possible from this polygon to any adjacent pin on the Class D amplifier as well as to any adjacent components, provided these connections are at the same potential. These copper paths must be as wide as possible. Each of these paths contributes to the overall thermal capabilities of the system. The copper polygon to which the exposed pad is attached should have multiple vias to the opposite side of the PC board, where they connect to another copper polygon. Make this polygon as large as possible within the system’s constraints for signal routing. Additional improvements are possible if all the traces from the device are made as wide as possible. Although the IC pins are not the primary thermal path out of the package, they do provide a small amount. The total improvement would not exceed approximately 10%, but it could make the difference between acceptable performance and thermal problems. 15 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Auxiliary Heatsinking If operating in higher ambient temperatures, it is possible to improve the thermal performance of a PC board with the addition of an external heatsink. The thermal resistance to this heatsink must be kept as low as possible to maximize its performance. With a bottom-side exposed pad, the lowest resistance thermal path is on the bottom of the PC board. The topside of the IC is not a significant thermal path for the device, and therefore is not a costeffective location for a heatsink. If an LC filter is used in the design, placing the inductor in close proximity to the IC can help draw heat away from the MAX9708. Thermal Calculations The die temperature of a Class D amplifier can be estimated with some basic calculations. For example, the die temperature is calculated for the below conditions: • TA = +40°C • POUT = 16W • Efficiency (η) = 87% • θJA = 21°C/W First, the Class D amplifier’s power dissipation must be calculated: PDISS = 16W POUT − POUT = − 16W = 2.4W η 0.87 Then the power dissipation is used to calculate the die temperature, TC, as follows: TC = TA + PDISS × θJA = 40°C + 24W × 21°C / W = 90.4°C Load Impedance The on-resistance of the MOSFET output stage in Class D amplifiers affects both the efficiency and the peak-current capability. Reducing the peak current into the load reduces the I2R losses in the MOSFETs, which increases efficiency. To keep the peak currents lower, choose the highest impedance speaker that can still deliver the desired output power within the voltage swing limits of the Class D amplifier and its supply voltage. Although most loudspeakers fall either 4Ω or 8Ω, there are other impedances available that can provide a more thermally efficient solution. 16 Another consideration is the load impedance across the audio frequency band. A loudspeaker is a complex electro-mechanical system with a variety of resonance. In other words, an 8Ω speaker usually has 8Ω impedance within a very narrow range. This often extends well below 8Ω, reducing the thermal efficiency below what is expected. This lower-than-expected impedance can be further reduced when a crossover network is used in a multidriver audio system. Systems Application Circuit The MAX9708 can be configured into multiple amplifier systems. One concept is a 2.1 audio system (Figure 5) where a stereo audio source is split into three channels. The left- and right-channel inputs are highpass filtered to remove the bass content, and then amplified by the MAX9708 in stereo mode. Also, the left- and right-channel inputs are summed together and lowpass filtered to remove the high-frequency content, then amplified by a second MAX9708 in mono mode. The conceptual drawing of Figure 5 can be applied to either single-ended or differential systems. Figure 6 illustrates the circuitry required to implement a fully differential filtering system. By maintaining a fully differential path, the signal-to-noise ratio remains uncompromised and noise pickup is kept very low. However, keeping a fully differential signal path results in almost twice the component count, and therefore performance must be weighed against cost and size. The highpass and lowpass filters should have different cutoff frequencies to ensure an equal power response at the crossover frequency. The filters should be at -6dB amplitude at the crossover frequency, which is known as a Linkwitz-Riley alignment. In the example circuit of Figure 6, the -3dB cutoff frequency for the highpass filters is 250Hz, and the -3dB cutoff frequency for the lowpass filter is 160Hz. Both the highpass filters and the lowpass filters are at a -6dB amplitude at approximately 200Hz. If the filters were to have the same -3dB cutoff frequency, a measurement of sound pressure level (SPL) vs. frequency would have a peak at the crossover frequency. The circuit in Figure 6 uses inverting amplifiers for their ease in biasing. Note the phase labeling at the outputs has been reversed. The resistors should be 1% or better in tolerance and the capacitors 5% tolerance or better. Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Mismatch in the components can cause discrepancies between the nominal transfer function and actual performance. Also, the mismatch of the input resistors (R15, R17, R19, and R21 in Figure 6) of the summing amplifier and lowpass filter will cause some high-frequency sound to be sent to the subwoofer. The circuit in Figure 6 drives a pair of MAX9708 devices similar to the circuit in Figure 5. The inputs to the MAX9708 still require AC-coupling to prevent compromising the click-and-pop performance of the MAX9708. INR+ INR- HIGHPASS FILTER RIGHT AUDIO The left and right drivers should be at an 8Ω to 12Ω impedance, whereas the subwoofer can be 4Ω to 12Ω depending on the desired output power, the available power-supply voltage, and the sensitivity of the individual speakers in the system. The four gain settings of the MAX9708 allow gain adjustments to match the sensitivity of the speakers. MONO 8Ω FULLRANGE SPEAKER OUTL+ OUTL- 8Ω FULLRANGE SPEAKER OUTR+ OUTR- 4Ω OR 8Ω WOOFER MAX9708 INL+ HIGHPASS FILTER LEFT AUDIO OUTR+ OUTR- INLSYNCOUT Σ SYNCIN INR+ INR- LOWPASS FILTER MAX9708 VDIGITAL MONO INL+ INL- OUTL+ OUTL- Figure 5. Multiple Amplifiers Implement a 2.1 Audio System Maxim Integrated 17 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier R1 56.2kΩ R2, 56.2kΩ R3 28kΩ C1 47nF C2 47nF 2 U1A MAX4478 R4 28kΩ RIGHT AUDIO INPUT R5 56.2kΩ BIAS 1 3 RIGHT AUDIO OUTPUT R6, 56.2kΩ R7 28kΩ C3 47nF C4 47nF 6 U1B MAX4478 R8 56.2kΩ BIAS 7 5 RIGHT AND LEFT OUTPUTS ARE AC-COUPLED TO A MAX9708 CONFIGURED AS A STEREO AMPLIFIER R9, 56.2kΩ R10 28kΩ C5 47nF C6 47nF 9 U1C MAX4478 R11 28kΩ LEFT AUDIO INPUT R12 56.2kΩ BIAS 8 10 LEFT AUDIO OUTPUT R13, 56.2kΩ R14 28kΩ C7 47nF C8 47nF 13 U1D MAX4478 R15 26.1kΩ R16 13kΩ BIAS 14 12 SUBWOOFER OUTPUT IS AC-COUPLED TO A MAX9708 CONFIGURED AS A MONO AMPLIFIER C9, 47nF R17 26.1kΩ R19 26.1kΩ R18 7.5kΩ C10 47nF 2 U2A MAX4478 R20 13kΩ BIAS 1 3 SUBWOOFER AUDIO OUTPUT C11, 47nF R21 28kΩ R22 7.5kΩ 6 U2B MAX4478 BIAS 7 5 NOTE: OP-AMP POWER PINS OMITTED FOR CLARITY. ALL RESISTORS ARE 1% OR BETTER. ALL CAPACITORS ARE 5% OR BETTER. Figure 6. Fully Differential Crossover Filters 18 Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Pin Configuration 35 34 33 G2 36 SHDN 37 TEMP 38 MUTE PVDD 39 TH1 PVDD 40 TH2 PGND 41 PVDD PGND 42 TH0 N.C. PGND TOP VIEW 32 31 30 29 N.C. 43 28 G1 N.C. 44 27 INR+ OUTR- 45 26 INR- OUTR- 46 25 VDD OUTR+ 47 24 SS OUTR+ 48 23 GND PGND 49 22 GND MAX9708 PGND 50 21 REG OUTL- 51 20 REG 6 7 8 9 10 11 12 13 14 FS2 5 SYNCIN 4 N.C. 3 SYNCOUT 2 C1P 1 CPVDD 15 FS1 C1N N.C. 56 PVDD INL- PVDD INL+ 16 PVDD 17 N.C. 55 PGND OUTL+ 54 PGND MONO N.C. 19 REG 18 PGND OUTL- 52 OUTL+ 53 THIN QFN Chip Information PROCESS: BiCMOS Maxim Integrated 19 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. 20 PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 56 TQFN-EP T5688-3 21-0135 90-0047 Maxim Integrated MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Package Information (continued) For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. Maxim Integrated 21 MAX9708 20W/40W, Filterless, Spread-Spectrum, Mono/Stereo, Class D Amplifier Revision History REVISION NUMBER REVISION DATE 3 4/13 DESCRIPTION Added automotive qualified part and removed TQFP package PAGES CHANGED 1, 2, 8–11, 20 Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. 22 ________________________________Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 © 2013 Maxim Integrated Products, Inc. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.