19-3597; Rev 6; 3/09 KIT ATION EVALU E L B AVAILA 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown The MAX9724A/MAX9724B stereo headphone amplifiers are designed for portable equipment where board space is at a premium. These devices use a unique, patented † DirectDrive ® architecture to produce a ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors, saving cost, board space, and component height. The MAX9724 suppresses RF radiation received by input and supply traces acting as antennas and prevents the amplifier from demodulating the coupled noise. The MAX9724A offers an externally adjustable gain while the MAX9724B has an internally preset gain of -1.5V/V. The MAX9724A/MAX9724B deliver up to 60mW per channel into a 32Ω load and have low 0.02% THD+N. An 80dB at 1kHz power-supply rejection ratio (PSRR) allows these devices to operate from noisy digital supplies without an additional linear regulator. Comprehensive click-and-pop circuitry suppresses audible clicks and pops on startup and shutdown. The MAX9724A/MAX9724B operate from a single 2.7V to 5.5V supply, consume only 3.5mA of supply current, feature short-circuit and thermal-overload protection, and are specified over the extended -40°C to +85°C temperature range. The devices are available in tiny 12bump UCSP™ (1.5mm x 2mm) and 12-pin thin QFN (3mm x 3mm x 0.8mm) packages. Applications Cellular Phones MP3 Players Notebook PCs Handheld Gaming Consoles DVD Players Smart Phones PDAs DirectDrive is a registered trademark of Maxim Integrated Products, Inc. Features o Improved RF Noise Rejection (Up to 67dB Over Typical Amplifiers) o No Bulky DC-Blocking Capacitors Required o Low-Power Shutdown Mode, < 0.1µA o Adjustable Gain (MAX9724A) or Fixed -1.5V/V Gain (MAX9724B) o Low 0.02% THD+N o High PSRR (80dB at 1kHz) Eliminates LDO o Integrated Click-and-Pop Suppression o 2.7V to 5.5V Single-Supply Operation o Low Quiescent Current (3.5mA) o Available in Space-Saving Packages 12-Bump UCSP (1.5mm x 2mm) 12-Pin Thin QFN (3mm x 3mm x 0.8mm) Ordering Information PART GAIN (V/V) PINPACKAGE TOP MARK MAX9724AEBC+TG45 Adj. 12 UCSP +ADH MAX9724AETC+ Adj. 12 TQFN-EP* +AAT MAX9724BEBC+TG45 -1.5 12 UCSP +ADI MAX9724BETC+ -1.5 12 TQFN-EP* +AAU Note: All devices specified over the -40°C to +85°C operating range. +Denotes lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed paddle. Pin Configurations appear at end of data sheet. †U.S. Patent# 7,061,327 UCSP is a trademark of Maxim Integrated Products, Inc. Block Diagrams MAX9724B MAX9724A LEFT AUDIO INPUT SHDN RIGHT AUDIO INPUT DirectDrive OUTPUTS ELIMINATE DC-BLOCKING CAPACITORS LEFT AUDIO INPUT DirectDrive OUTPUTS ELIMINATE DC-BLOCKING CAPACITORS SHDN RIGHT AUDIO INPUT FIXED GAIN ELIMINATES EXTERNAL RESISTOR NETWORK ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX9724A/MAX9724B General Description MAX9724A/MAX9724B 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown ABSOLUTE MAXIMUM RATINGS VDD to GND ..............................................................-0.3V to +6V Continuous Input Current into PVSS ..................................260mA PVSS to SVSS .........................................................-0.3V to +0.3V Continuous Input Current (any other pin) .........................±20mA PGND to SGND .....................................................-0.3V to +0.3V Continuous Power Dissipation (TA = +70°C, Multilayer board) 12-Bump UCSP (derate 6.5mW/°C above +70°C) ........519mW C1P to PGND..............................................-0.3V to (VDD + 0.3V) C1N to PGND............................................(PVSS - 0.3V) to +0.3V θJA ................................................................................154 C/W PVSS and SVSS to PGND..........................................-6V to +0.3V 12-Pin TQFN (derate 16.7mW/°C above +70°C) .........1333mW IN_ to SGND (MAX9724A)..........................-0.3V to (VDD + 0.3V) θJA ..................................................................................60°C/W IN_ to SGND (MAX9724B) .............(SVSS - 0.3V) to (VDD + 0.3V) θJC ..................................................................................11°C/W OUT_ to SVSS (Note 1) ....-0.3V to Min (VDD - SVSS + 0.3V, +9V) Operating Temperature Range ...........................-40°C to +85°C OUT_ to VDD (Note 2) ......+0.3V to Max (SVSS - VDD - 0.3V, -9V) Storage Temperature Range .............................-65°C to +150°C SHDN to _GND.........................................................-0.3V to +6V Junction Temperature ......................................................+150°C OUT_ Short Circuit to GND ........................................Continuous Lead Temperature (soldering, 10s) .................................+300°C Short Circuit between OUTL and OUTR ....................Continuous Bump Temperature (soldering) Reflow............................+235°C Note 1: OUTR and OUTL should be limited to no more than 9V above SVSS, or above VDD + 0.3V, whichever limits first. Note 2: OUTR and OUTL should be limited to no more than 9V below VDD, or below SVSS - 0.3V, whichever limits first. 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 = 5V, PGND = SGND, SHDN = 5V, C1 = C2 = 1µF, RL = ∞, resistive load reference to ground; for MAX9724A gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ); for MAX9724B gain = -1.5V/V (internally set), TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.) (Note 3) PARAMETER GENERAL SYMBOL Supply Voltage Range VDD Quiescent Current ICC Shutdown Current Shutdown to Full Operation ISHDN tSON CONDITIONS Guaranteed by PSRR test RIN MAX9724B, measured at IN_ Output Offset Voltage VOS (Note 4) PSRR VDD = 2.7V to 5.5V, TA = +25°C f = 1kHz, 100mVP-P (Note 4) 12 69 f = 20kHz, 100mVP-P (Note 4) Output Power (TQFN) POUT Output Power (UCSP) POUT Voltage Gain AV Channel-to-Channel Gain Tracking Total Harmonic Distortion Plus Noise (TQFN) (Note 6) THD+N Total Harmonic Distortion Plus Noise (UCSP) (Note 6) THD+N Signal-to-Noise Ratio 2 SNR RL = 32Ω, THD+N = 1% RL = 16Ω, THD+N = 1% RL = 32Ω, THD+N = 1% MAX UNITS 5.5 V 3.5 5.5 mA 0.1 180 1 µA µs 19 28 kΩ ±1.5 ±10 mV 86 80 dB 65 30 63 25 42 45 RL = 16Ω, THD+N = 1% MAX9724B (Note 5) TYP 2.7 SHDN = SGND = PGND Input Impedance Power-Supply Rejection Ratio MIN mW mW 35 -1.52 -1.5 MAX9724B ±0.15 RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz 0.003 RL = 32Ω, POUT = 50mW, fIN = 1kHz 0.02 RL = 16Ω, POUT = 35mW, fIN = 1kHz RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz 0.04 0.003 RL = 32Ω, POUT = 45mW, fIN = 1kHz 0.03 RL = 16Ω, POUT = 32mW, fIN = 1kHz 0.05 RL = 1kΩ, VOUT = 2VRMS BW = 22Hz to 22kHz A-weighted 102 105 RL = 32Ω, POUT = 50mW BW = 22Hz to 22kHz 98 A-weighted 101 _______________________________________________________________________________________ -1.48 V/V % % % dB 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown (VDD = 5V, PGND = SGND, SHDN = 5V, C1 = C2 = 1µF, RL = ∞, resistive load reference to ground; for MAX9724A gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ); for MAX9724B gain = -1.5V/V (internally set), TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.) (Note 3) PARAMETER SYMBOL Slew Rate SR Capacitive Drive CL Crosstalk CONDITIONS MIN TYP MAX UNITS 0.5 V/µs No sustained oscillations 100 pF L to R, R to L, f = 10kHz, RL = 16Ω, POUT = 15mW -70 dB Charge-Pump Oscillator Frequency fOSC Click-and-Pop Level KCP Into shutdown RL = 32Ω, peak voltage, A-weighted, 32 samples per Out of second (Notes 4, 7) shutdown VINH VINL VINH VINL (TQFN only) (TQFN only) (UCSP only) (UCSP only) 190 270 400 kHz -67 dB -64 DIGITAL INPUTS (SHDN) Input-Voltage High Input-Voltage Low Input-Voltage High Input-Voltage Low Input Leakage Current 2 0.8 1.4 0.9 ±1 V V V V µA ELECTRICAL CHARACTERISTICS (VDD = 3V, PGND = SGND, SHDN = 3V, C1 = C2 = 1µF, RL = ∞, resistive load reference to ground; for MAX9724A gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ); for MAX9724B gain = -1.5V/V (internally set), TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.) (Note 3) PARAMETER SYMBOL Quiescent Current ICC Shutdown Current ISHDN Power-Supply Rejection Ratio (Note 4) PSRR Output Power (TQFN) POUT Output Power (UCSP) POUT Total Harmonic Distortion Plus Noise (TQFN) (Note 6) Total Harmonic Distortion Plus Noise (UCSP) (Note 6) Note 3: Note 4: Note 5: Note 6: Note 7: THD+N THD+N CONDITIONS MIN TYP MAX UNITS 3.0 mA SHDN = SGND = PGND 0.1 µA f = 1kHz, 100mVP-P 80 f = 20kHz, 100mVP-P 65 RL = 32Ω, THD+N = 1% 20 RL = 16Ω, THD+N = 1% 14 RL = 32Ω, THD+N = 1% 17 RL = 16Ω, THD+N = 1% 12 RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz 0.05 RL = 32Ω, POUT = 15mW, fIN = 1kHz 0.03 RL = 16Ω, POUT = 10mW, fIN = 1kHz 0.06 RL = 1kΩ, VOUT = 2VRMS, fIN = 1kHz 0.003 RL = 32Ω, POUT = 15mW, fIN = 1kHz 0.04 RL = 16Ω, POUT = 10mW, fIN = 1kHz 0.06 dB mW mW % % All specifications are 100% tested at TA = +25°C; temperature limits are guaranteed by design. The amplifier inputs are AC-coupled to GND. Gain for the MAX9724A is adjustable. Measurement bandwidth is 22Hz to 22kHz. Test performed with a 32Ω resistive load connected to GND. Mode transitions are controlled by SHDN. KCP level is calculated as 20log[(peak voltage during mode transition, no input signal)/(peak voltage under normal operation at rated power level)]. Units are expressed in dB. _______________________________________________________________________________________ 3 MAX9724A/MAX9724B ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A), THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (TQFN) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (UCSP) VDD = 3V RL = 16Ω 10 100 MAX9724 toc02 10 MAX9724 toc01 100 VDD = 3V RL = 16Ω MAX9724toc03 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (TQFN) VDD = 3V RL = 32Ω 10 1 fIN = 1kHz 0.1 THD+N (%) THD+N (%) 0.1 fIN = 1kHz 0.1 fIN = 10kHz fIN = 10kHz 0.01 fIN = 10kHz fIN = 1kHz 0.01 0.01 fIN = 20Hz 0 10 20 30 40 0 5 10 15 20 25 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (USCP) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (TQFN) 20 30 40 50 TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (UCSP) 10 MAX9724 toc05 MAX9724toc04 100 VDD = 5V RL = 16Ω 10 1 10 OUTPUT POWER (mW) OUTPUT POWER (mW) VDD = 3V RL = 32Ω 0 30 OUTPUT POWER (mW) 10 fIN = 20Hz 0.001 0.001 0.001 MAX9724 toc06 fIN = 20Hz VDD = 5V RL = 16Ω 0.1 THD+N (%) 1 THD+N (%) THD+N (%) 1 1 fIN = 1kHz 0.1 fIN = 10kHz 0.01 fIN = 10kHz fIN = 1kHz fIN = 1kHz 0.1 fIN = 10kHz 0.01 0.01 fIN = 20Hz fIN = 20Hz 0.001 5 10 15 20 25 30 35 40 0.001 0 20 40 60 80 100 OUTPUT POWER (mW) OUTPUT POWER (mW) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (TQFN) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER (UCSP) VDD = 5V RL = 32Ω 10 10 20 30 40 50 60 70 80 OUTPUT POWER (mW) 10 MAX9724 toc07 100 0 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (TQFN) 1 MAX9724 toc08 0 fIN = 20Hz 0.001 VDD = 5V RL = 32Ω MAX9724 toc09 THD+N (%) 1 VDD = 3V RL = 16Ω 1 1 fIN = 1kHz 0.1 POUT = 5mW THD+N (%) THD+N (%) 0.1 THD+N (%) MAX9724A/MAX9724B 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown fIN = 1kHz 0.1 0.01 0.01 0.01 fIN = 10kHz fIN = 20Hz fIN = 20Hz 0.001 0.001 0 20 40 60 80 OUTPUT POWER (mW) 4 POUT = 10mW fIN = 10kHz 100 120 0.001 0 25 50 OUTPUT POWER (mW) 75 100 10 100 1k FREQUENCY (Hz) _______________________________________________________________________________________ 10k 100k 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown POUT = 5mW VDD = 3V RL = 32Ω 1 VDD = 3V RL = 32Ω 0.1 THD+N (%) THD+N (%) POUT = 10mW THD+N (%) 0.1 0.1 POUT = 8mW POUT = 8mW 0.01 0.01 0.01 MAX9724 toc12 1 MAX9724 toc11 VDD = 3V RL = 16Ω MAX9724 toc10 1 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (UCSP) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (TQFN) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (UCSP) POUT = 13mW POUT = 15mW 0.001 0.001 0.001 100 1k 10k 10 100k 100 10k 10 100k POUT = 20mW VDD = 5V RL = 16Ω VDD = 5V RL = 32Ω 0.1 POUT = 30mW THD+N (%) POUT = 20mW THD+N (%) THD+N (%) POUT = 37mW 0.01 0.01 POUT = 32mW POUT = 50mW 0.001 0.001 0.001 1k 10k 10 100k 100 POUT = 20mW 0.01 50 10% THD+N 40 30 20 10 FREQUENCY (Hz) fIN = 1kHz RL = 16Ω 60 10k 100k 100k 50 10% THD+N 40 30 20 1% THD+N 10 0 0.001 10k 70 1% THD+N POUT = 45mW 1k 1k OUTPUT POWER vs. SUPPLY VOLTAGE (UCSP) MAX9724 toc17 fIN = 1kHz RL = 16Ω 60 OUTPUT POWER (mW) VDD = 5V RL = 32Ω 100 100 FREQUENCY (Hz) 70 MAX9724 toc16 1 10 10 100k OUTPUT POWER vs. SUPPLY VOLTAGE (TQFN) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (UCSP) THD+N (%) 10k FREQUENCY (Hz) FREQUENCY (Hz) 0.1 1k MAX9724 toc18 100 OUTPUT POWER (mW) 10 100k 1 0.1 0.1 10k TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (TQFN) MAX9724 toc14 1 MAX9724 toc13 VDD = 5V RL = 16Ω 1k FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (UCSP) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY (TQFN) 0.01 100 FREQUENCY (Hz) FREQUENCY (Hz) 1 1k MAX9724 toc15 10 0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5 MAX9724A/MAX9724B Typical Operating Characteristics (continued) (VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A), THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A), THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.) 40 20 0 10% THD+N 60 40 1% THD+N 3.0 3.5 4.0 4.5 5.0 5.5 1% THD+N 10 0 2.5 3.0 3.5 4.0 4.5 5.0 10 5.5 100 1000 OUTPUT POWER vs. LOAD RESISTANCE (UCSP) OUTPUT POWER vs. LOAD RESISTANCE (TQFN) OUTPUT POWER vs. LOAD RESISTANCE (UCSP) THD+N = 1% 60 50 40 THD+N = 1% 30 80 VDD = 5V fIN = 1kHz 10 100 1000 60 50 40 THD+N = 1% 30 VDD = 5V fIN = 1kHz 10 0 0 10 70 20 20 0 THD+N = 10% 90 OUTPUT POWER (mW) 15 70 MAX9724 toc24 80 OUTPUT POWER (mW) 20 THD+N = 10% 90 100 MAX9724 toc23 100 MAX9724 toc22 VDD = 3V fIN = 1kHz 5 10 10 100 100 LOAD RESISTANCE (Ω) LOAD RESISTANCE (Ω) LOAD RESISTANCE (Ω) POWER DISSIPATION vs. OUTPUT POWER (TQFN) POWER DISSIPATION vs. OUTPUT POWER (UCSP) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY RL = 16Ω 150 RL = 32Ω 100 VDD = 3V fIN = 1kHz POUT = POUTL + POUTR OUTPUTS IN PHASE 50 120 -40 100 80 60 40 OUTPUT POWER (mW) 60 80 -60 VDD = 5V -80 VDD = 3V fIN = 1kHz POUT = POUTL + POUTR OUTPUTS IN PHASE 40 -100 0 20 RL = 32Ω -20 RL = 32Ω 20 0 MAX9724 toc27 RL = 16Ω PSRR (dB) POWER DISSIPATION (mW) 200 140 0 MAX9724t oc26 160 MAX9724t oc25 250 6 15 LOAD RESISTANCE (Ω) 25 0 20 SUPPLY VOLTAGE (V) THD+N = 10% 10 25 SUPPLY VOLTAGE (V) 35 30 VDD = 3V fIN = 1kHz 10% THD+N 5 0 2.5 OUTPUT POWER (mW) 80 20 1% THD+N 30 OUTPUT POWER (mW) 10% THD+N 60 fIN = 1kHz RL = 32Ω 100 OUTPUT POWER (mW) 80 35 MAX9724 toc20 fIN = 1kHz RL = 32Ω 100 OUTPUT POWER (mW) 120 MAX9724 toc19 120 OUTPUT POWER vs. LOAD RESISTANCE (TQFN) OUTPUT POWER vs. SUPPLY VOLTAGE (UCSP) MAX9724 toc21 OUTPUT POWER vs. SUPPLY VOLTAGE (TQFN) POWER DISSIPATION (mW) MAX9724A/MAX9724B 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown VDD = 3V -120 0 5 10 15 20 25 30 35 40 45 OUTPUT POWER (mW) 50 10 100 1k FREQUENCY (Hz) _______________________________________________________________________________________ 10k 100k 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown OUTPUT POWER vs. LOAD RESISTANCE AND CHARGE-PUMP CAPACITOR SIZE (TQFN) CROSSTALK vs. FREQUENCY RIGHT TO LEFT -80 LEFT TO RIGHT -100 50 C1 = C2 = 0.47μF 40 VDD = 5V fIN = 1kHz THD+N = 1% 20 1k 100 10k 0 100k 50 OUTPUT POWER vs. LOAD RESISTANCE AND CHARGE-PUMP CAPACITOR SIZE (UCSP) C1 = C2 = 2.2μF OUTPUT SPECTRUM vs. FREQUENCY -60 AMPLITUDE (dBV) C1 = C2 = 1μF 40 C1 = C2 = 0.47μF 30 RL = 32Ω VDD = 3V fIN = 1kHz VOUT = -60dBV -50 60 50 150 -40 MAX9724 toc30 80 70 100 LOAD RESISTANCE (Ω) FREQUENCY (Hz) -70 MAX9724 toc31 10 OUTPUT POWER (mW) MAX9724 toc29 60 30 -120 -80 -90 -100 -110 20 -120 VDD = 5V fIN = 1kHz THD+N = 1% 10 -130 0 -140 0 50 100 150 0 5 10 15 20 LOAD RESISTANCE (Ω) FREQUENCY (kHz) SUPPLY CURRENT vs. SUPPLY VOLTAGE SHUTDOWN CURRENT vs. SUPPLY VOLTAGE (TQFN) 140 MAX9724 toc32 3.5 NO LOAD INPUTS GND 120 SHUTDOWN CURRENT (nA) 3.4 SUPPLY CURRENT (mA) C1 = C2 = 1μF 3.3 3.2 3.1 3.0 NO LOAD INPUTS GROUND 2.9 MAX9724 toc33 CROSSTALK (dB) -40 -60 C1 = C2 = 2.2μF 70 OUTPUT POWER (mW) POUT = 15mW RL = 16Ω -20 80 MAX9724 toc28 0 100 80 60 40 20 0 2.8 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 7 MAX9724A/MAX9724B Typical Operating Characteristics (continued) (VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A), THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VDD = 5V, PGND = SGND = 0V, SHDN = VDD, C1 = C2 = 1µF, RL = ∞, gain = -1.5V/V (RIN = 20kΩ, RF = 30kΩ for the MAX9724A), THD+N measurement bandwidth = 22Hz to 22kHz, both outputs driven in phase, TA = +25°C, unless otherwise noted.) EXITING SHUTDOWN VSHDN 5V/div MAX9724 toc35 ENTERING SHUTDOWN MAX9724 toc34 MAX9724A/MAX9724B 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown VSHDN 5V/div VIN_ 1V/div VIN_ 1V/div VOUT_ 500mV/div VOUT_ 500mV/div 40μs/div 20μs/div Pin Description PIN 8 NAME FUNCTION TQFN UCSP 1 C1 C1P 2 C2 PGND 3 C3 C1N Flying Capacitor Negative Terminal. Connect a 1µF ceramic capacitor from C1P to C1N. 4 C4 PVSS Charge-Pump Output. Connect to SVSS and bypass with a 1µF ceramic capacitor to PGND. 5 A2 SHDN 6 B3 INL 7 A1 SGND 8 B2 INR 9 B4 SVSS 10 A3 OUTR Right-Channel Output 11 A4 OUTL Left-Channel Output 12 B1 VDD EP — EP Flying Capacitor Positive Terminal. Connect a 1µF ceramic capacitor from C1P to C1N. Power Ground. Connect to SGND. Active-Low Shutdown Input Left-Channel Input Signal Ground. Connect to PGND. Right-Channel Input Amplifier Negative Supply. Connect to PVSS. Positive Power-Supply Input. Bypass with a 1µF capacitor to PGND. Exposed Paddle. Internally connected to SVSS. Connect to SVSS or leave unconnected. _______________________________________________________________________________________ 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown The MAX9724A/MAX9724B stereo headphone amplifiers feature Maxim’s patented DirectDrive architecture, eliminating the large output-coupling capacitors required by conventional single-supply headphone amplifiers. The device consists of two 60mW Class AB headphone amplifiers, undervoltage lockout (UVLO)/shutdown control, charge pump, and comprehensive click-and-pop suppression circuitry (see the Functional Diagram/Typical Operating Circuits). The charge pump inverts the positive supply (VDD), creating a negative supply (PVSS). The headphone amplifiers operate from these bipolar supplies with their outputs biased about PGND (Figure 1). The benefit of this PGND bias is that the amplifier outputs do not have a DC component. The large DC-blocking capacitors required with conventional headphone amplifiers are unnecessary, conserving board space, reducing system cost, and improving frequency response. The MAX9724A/MAX9724B feature an undervoltage lockout that prevents operation from an insufficient power supply and click-and-pop suppression that eliminates audible transients on startup and shutdown. The MAX9724A/MAX9724B also feature thermal-overload and short-circuit protection. DirectDrive Conventional single-supply headphone amplifiers have their outputs biased about a nominal DC voltage (typically half the supply) for maximum dynamic range. Large-coupling capacitors are needed to block this DC bias from the headphone. Without these capacitors, a significant amount of DC current flows to the headphone, resulting in unnecessary power dissipation and possible damage to both headphone and headphone amplifier. Maxim’s patented DirectDrive architecture uses a charge pump to create an internal negative supply voltage, allowing the MAX9724A/MAX9724B outputs to be biased about GND. With no DC component, there is no need for the large DC-blocking capacitors. The MAX9724A/MAX9724B charge pumps require two small ceramic capacitors, conserving board space, reducing cost, and improving the frequency response of the headphone amplifier. See the Output Power vs. Load Resistance and Charge-Pump Capacitor Size graph in the Typical Operating Characteristics for details of the possible capacitor sizes. There is a low DC voltage on the amplifier outputs due to amplifier offset. However, the offsets of the MAX9724A/MAX9724B are typically 1.5mV, which, when combined with a 32Ω load, results in less than 47µA of DC current flow to the headphones. MAX9724A/MAX9724B Detailed Description VOUT VDD VDD VDD/2 GND CONVENTIONAL DRIVER-BIASING SCHEME VOUT VDD GND 2VDD -VDD DirectDrive BIASING SCHEME Figure 1. Conventional Driver Output Waveform vs. MAX9724A/MAX9724B Output Waveform Charge Pump The MAX9724A/MAX9724B feature a low-noise charge pump. The 270kHz switching frequency is well beyond the audio range and does not interfere with audio signals. The switch drivers feature a controlled switching speed that minimizes noise generated by turn-on and turn-off transients. The di/dt noise caused by the parasitic bond wire and trace inductance is minimized by limiting the switching speed of the charge pump. Although not typically required, additional high-frequency noise attenuation can be achieved by increasing the value of C2 (see the Functional Diagram/Typical Operating Circuits). RF Susceptibility Modern audio systems are often subject to RF radiation from sources like wireless networks and cellular phone networks. Although the RF radiation is out of the audio band, many signals, in particular GSM signals, contain bursts or modulation at audible frequencies. Most analog amplifiers demodulate the low-frequency envelope, adding noise to the audio signal. The architecture of _______________________________________________________________________________________ 9 the MAX9724 addresses the problem of the RF susceptibility by rejecting RF noise and preventing it from coupling into the audio band. The RF susceptibility of an amplifier can be measured by placing the amplifier in an isolated chamber and subjecting it to an electric field of known strength. If the electric field is modulated with an audio band signal, a percentage of the modulated signal will be demodulated and amplified by the device in the chamber. Figure 2 shows the signal level at the outputs of an unoptimized amplifier and the MAX9724. The test conditions are shown in Table 1. Table 1. RF Susceptibility Test Conditions SETTING 50V/m RF Modulation Type Sine wave RF Modulation Index 100% RF Modulation Frequency 1kHz In conventional single-supply audio amplifiers, the output-coupling capacitor contributes significantly to audible clicks and pops. Upon startup, the amplifier charges the coupling capacitor to its bias voltage, typically half the supply. Likewise, on shutdown, the capacitor is discharged. This results in a DC shift across the capacitor, which appears as an audible transient at the speaker. Since the MAX9724A/ MAX9724B do not require outputcoupling capacitors, this problem does not arise. Additionally, the MAX9724A/MAX9724B feature extensive click-and-pop suppression that eliminates any audible transient sources internal to the device. 62dB IMPROVEMENT AT 850MHz RF SUSCEPTIBLE AMPLIFIER 20 0 Shutdown The MAX9724A/MAX9724B feature a < 0.1µA, lowpower shutdown mode that reduces quiescent current consumption and extends battery life for portable applications. Drive SHDN low to disable the amplifiers and the charge pump. In shutdown mode, the amplifier output impedance is set to 14kΩ||RF (RF is 30kΩ for the MAX9724B). The amplifiers and charge pump are enabled once SHDN is driven high. Applications Information Click-and-Pop Suppression 40 Typically, the output of the device driving the MAX9724A/MAX9724B has a DC bias of half the supply voltage. At startup, the input-coupling capacitor, CIN, is charged to the preamplifier’s DC bias voltage through the MAX9724A/MAX9724B input resistor, RIN, and a series 15kΩ resistor. This DC shift across the capacitor results in an audible click-and-pop. Delay the rise of SHDN 4 to 5 time constants based on RIN x 15kΩ x CIN to eliminate clicks-and-pops caused by the input filter. Power Dissipation Under normal operating conditions, linear power amplifiers can dissipate a significant amount of power. The maximum power dissipation for each package is given in the Absolute Maximum Ratings section under Continuous Power Dissipation or can be calculated by the following equation: PDISSPKG(MAX) = TJ(MAX) − TA θJA where TJ(MAX) is +150°C, TA is the ambient temperature, and θJA is the reciprocal of the derating factor in 39dB IMPROVEMENT AT 900MHz 67dB IMPROVEMENT AT 1800MHz 49dB IMPROVEMENT AT 1900MHz MAX9724 fig02 TEST PARAMETER RF Field Strength AMPLIFIER OUTPUT AMPLITUDE (dBV) MAX9724A/MAX9724B 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown -20 -40 -60 MAX9724 -80 -100 100 600 1100 1600 2100 2600 RF CARRIER FREQUENCY (MHz) Figure 2. RF Susceptibility of the MAX9724 and a Typical Headphone Amplifier 10 ______________________________________________________________________________________ 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown The MAX9724A/MAX9724B have two power dissipation sources; a charge pump and the two output amplifiers. If power dissipation for a given application exceeds the maximum allowed for a particular package, reduce VDD, increase load impedance, decrease the ambient temperature, or add heatsinking to the device. Large output, supply, and ground traces decrease θJA, allowing more heat to be transferred from the package to the surrounding air. Thermal-overload protection limits total power dissipation in the MAX9724A/MAX9724B. When the junction temperature exceeds +150°C, the thermal protection circuitry disables the amplifier output stage. The amplifiers are enabled once the junction temperature cools by approximately 12°C. This results in a pulsing output under continuous thermal-overload conditions. Output Dynamic Range Dynamic range is the difference between the noise floor of the system and the output level at 1% THD+N. Determine the system’s dynamic range before setting the maximum output gain. Output clipping occurs if the output signal is greater than the dynamic range of the system. The DirectDrive architecture of the MAX9724A/ MAX9724B has increased the dynamic range compared to other single-supply amplifiers. Maximum Output Swing VDD < 4.35V If the output load impedance is greater than 1kΩ, the MAX9724A/MAX9724B can swing within a few millivolts of their supply rail. For example, with a 3.3V supply, the output swing is 2VRMS, or 2.83V peak while maintaining a low 0.003% THD+N. If the supply voltage drops to 3V, the same 2.83V peak has only 0.05% THD+N. VDD > 4.35V Internal device structures limit the maximum voltage swing of the MAX9724A/MAX9724B when operated at supply voltages greater than 4.35V. The output must not be driven such that the peak output voltage exceeds the opposite supply voltage by 9V. For example, if VDD = 5V, the charge pump sets PVSS = -5V. Therefore, the peak output swing must be less than ±4V to prevent exceeding the absolute maximum ratings. UVLO The MAX9724A/MAX9724B feature an undervoltage lockout (UVLO) function that prevents the device from operating if the supply voltage is less than 2.7V. This feature ensures proper operation during brownout conditions and prevents deep battery discharge. Once the supply voltage exceeds the UVLO threshold, the MAX9724A/MAX9724B charge pump is turned on and the amplifiers are powered, provided that SHDN is high. Component Selection Input-Coupling Capacitor The input capacitor (CIN), in conjunction with the input resistor (RIN), forms a highpass filter that removes the DC bias from an incoming signal (see the Functional Diagram/Typical Operating Circuits). The AC-coupling capacitor allows the device 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 2πRINCIN Choose the CIN such that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the device’s low-frequency response. Use capacitors whose dielectrics have low-voltage coefficients, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as ceramics, can result in increased distortion at low frequencies. Charge-Pump Capacitor Selection Use ceramic capacitors with a low ESR for optimum performance. For optimal performance over the extended temperature range, select capacitors with an X7R dielectric. Table 2 lists suggested manufacturers. Flying Capacitor (C1) The value of the flying capacitor (see the Functional Diagram/Typical Operating Circuits) affects the charge Table 2. Suggested Capacitor Manufacturers SUPPLIER WEBSITE PHONE FAX Taiyo Yuden 800-348-2496 847-925-0899 www.t-yuden.com TDK 847-803-6100 847-390-4405 www.component.tdk.com Murata 770-436-1300 770-436-3030 www.murata.com ______________________________________________________________________________________ 11 MAX9724A/MAX9724B °C/W as specified in the Absolute Maximum Ratings section. For example, θJA of the thin QFN package is +68°C/W, and 154.2°C/W for the UCSP package. MAX9724A/MAX9724B 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown pump’s load regulation and output resistance. A C1 value that is too small degrades the device’s ability to provide sufficient current drive, which leads to a loss of output voltage. Increasing the value of C1 improves load regulation and reduces the charge-pump output resistance to an extent. See the Output Power vs. Load Resistance and Charge-Pump Capacitor Size graph in the Typical Operating Characteristics. Above 1µF, the on-resistance of the switches and the ESR of C1 and C2 dominate. Hold Capacitor (C2) The hold capacitor value (see the Functional Diagram/Typical Operating Circuits) and ESR directly affect the ripple at PVSS. Increasing the value of C2 reduces output ripple. Likewise, decreasing the ESR of C2 reduces both ripple and output resistance. Lower capacitance values can be used in systems with low maximum output power levels. See the Output Power vs. Load Resistance and Charge-Pump Capacitor Size graph in the Typical Operating Characteristics. Power-Supply Bypass Capacitor (C3) The power-supply bypass capacitor (see the Functional Diagram/Typical Operating Circuits) lowers the output impedance of the power supply, and reduces the impact of the MAX9724A/MAX9724B’s charge-pump switching transients. Bypass VDD with C3, the same value as C1, and place it physically close to the VDD and PGND pins. AV = -RF/RIN (V/V) Choose feedback resistor values in the tens of kΩ range. Lower values may cause excessive power dissipation and require impractically small values of RIN for large gain settings. The high-impedance state of the outputs can also be degraded during shutdown mode if an inadequate feedback resistor is used since the equivalent output impedance during shutdown is 14kΩ||Rf (RF is equal to 30kΩ for the MAX9724B). The source resistance of the input device may also need to be taken into consideration. Since the effective value of RIN is equal to the sum of the source resistance of the input device and the value of the input resistor connected to the inverting terminal of the headphone amplifier (20kΩ for the MAX9724B), the overall closed-loop gain of the headphone amplifier can be reduced if the input resistor is not significantly larger than the source resistance of the input device. RF MAX9724A LEFT AUDIO INPUT RIN RIGHT AUDIO INPUT RIN INL OUTL Amplifier Gain The gain of the MAX9724B amplifier is internally set to -1.5V/V. All gain-setting resistors are integrated into the device, reducing external component count. The internally set gain, in combination with DirectDrive, results in a headphone amplifier that requires only five small capacitors to complete the amplifier circuit: two for the charge pump, two for audio input coupling, and one for power-supply bypassing (see the Functional Diagram/Typical Operating Circuits). The gain of the MAX9724A amplifier is set externally as shown in Figure 3, the gain is: 12 OUTR INR RF Figure 3. Gain Setting for the MAX9724A ______________________________________________________________________________________ 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown RMS OUTPUT VOLTAGE vs. SUPPLY VOLTAGE 3.5 RMS OUTPUT VOLTAGE (V) fIN = 1kHz RL = 10kΩ 1% THD+N 3.0 LIMITED BY ABS. MAXIMUM RATINGS 2.5 RL = 1kΩ 1% THD+N 2.0 1.5 2.5 3.0 3.5 4.0 4.5 5.0 sinusoidal signal equates to approximately 5.7VP-P, which means that the audio system designer cannot simply run the lineout stage from a (typically common) 5V supply—the resulting output swing would be inadequate. A common solution to this problem is to use op amps driven from split supplies (±5V typically), or to use a high-voltage supply rail (9V to 12V). This can mean adding extra cost and complexity to the system power supply to meet this output level requirement. Having the ability to derive 2VRMS from a 5V supply, or even 3.3V supply, can often simplify power-supply design in some systems. When the MAX9724A is used as a line driver to provide outputs that feed stereo equipment (receivers, STBs, notebooks, and desktops) with a digital-to-analog converter (DAC) used as an audio input source, it is often desirable to eliminate any high-frequency quantization noise produced by the DAC output before it reaches the load. This high-frequency noise can cause the input stages of the line-in equipment to exceed slew-rate limitations or create excessive EMI emissions on the cables between devices. 5.5 SUPPLY VOLTAGE (V) Figure 4. RMS Output Voltage vs. Supply Voltage 15kΩ 220pF LEFT AUDIO INPUT 1μF 7.5kΩ 7.5kΩ MAX9724A INL OUTL 1.2nF STEREO DAC LINE IN DEVICE 10kΩ 1.2nF RIGHT AUDIO INPUT 1μF OUTR 7.5kΩ 7.5kΩ INR 10kΩ 220pF 15kΩ Figure 5. MAX9724A Line Out Amplifier and Filter Block Configuration ______________________________________________________________________________________ 13 MAX9724A/MAX9724B Lineout Amplifier and Filter Block The MAX9724A can be used as an audio line driver capable of providing 2VRMS into 10kΩ loads with a single 5V supply (see Figure 4 for the RMS Output Voltage vs. Supply Voltage plot). 2VRMS is a popular audio line level, first used in CD players, but now common in DVD and set-top box (STB) interfacing standards. A 2VRMS To suppress this noise, and to provide a 2VRMS standard audio output level from a single 5V supply, the MAX9724A can be configured as a line driver and active lowpass filter. Figure 5 shows the MAX9724A connected as 2-pole Rauch/multiple feedback filter with a passband gain of 6dB and a -3dB (below passband) cutoff frequency of approximately 27kHz (see Figure 6 for the Gain vs. Frequency plot). Layout and Grounding Proper layout and grounding are essential for optimum performance. Connect PGND and SGND together at a single point on the PC Board. Connect PVSS to SVSS and bypass with a 1µF capacitor. Place the power-supply bypass capacitor and the charge-pump hold capacitor as close to the MAX9724 as possible. Route PGND and all traces that carry switching transients away from SGND and the audio signal path. The thin QFN package features an exposed paddle that improves thermal efficiency. Ensure that the exposed paddle is electrically isolated from PGND, SGND, and VDD. Connect the exposed paddle to SVSS only when the board layout dictates that the exposed paddle cannot be left floating. MAX9724A ACTIVE FILTER GAIN vs. FREQUENCY 10 RL = 10kΩ 5 0 -5 GAIN (dB) MAX9724A/MAX9724B 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown -10 -15 -20 -25 -30 -35 1k 10k 100k Figure 6. Frequency Response of Active Filter of Figure 4 UCSP Applications Information For the latest application details on UCSP construction, dimensions, tape carrier information, printed circuit board techniques, bump-pad layout, and recommended reflow temperature profile, as well as the latest information on reliability testing results, refer to the Application Note UCSP—A Wafer-Level Chip-Scale Package available on Maxim’s website at www.maximic.com/ucsp. 14 1M FREQUENCY (Hz) ______________________________________________________________________________________ 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown VDD 0.1μF 15kΩ 1μF 15kΩ INR VDD PVDD BIAS OUTR+ OUTR- 1μF MAX9710 GND PGND MUTE 0.1μF 15kΩ OUTL- SHDN OUTL+ INL VDD 15kΩ μCONTROLLER 100kΩ 100kΩ 0.1μF STEREO DAC OUTL SHDN O.47μF MAX9724B OUTR INL SGND O.47μF INR PGND VDD PVSS 1μF SVSS C1P C1N VDD 1μF 1μF ______________________________________________________________________________________ 15 MAX9724A/MAX9724B System Diagram 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown MAX9724A/MAX9724B Functional Diagram/Typical Operating Circuits 2.7V TO 5.5V ON C3 1μF OFF CIN R IN* 0.47μF 20kΩ LEFT AUDIO INPUT RF* 30kΩ 12 (B1) 5 (A2) 6 (B3) VDD SHDN INL VDD 11 OUTL (A4) HEADPHONE JACK 1 (C1) C1P SVSS UVLO/ SHUTDOWN CONTROL CLICK-AND-POP SUPPRESSION CHARGE PUMP C1 1μF SGND VDD 3 (C3) C1N OUTR 10 (A3) MAX9724A PVSS 4 (C4) SVSS PGND 2 9 (B4) (C2) C2 1μF SVSS SGND 7 (A1) INR 8 (B2) RIGHT AUDIO INPUT CIN RIN* 0.47μF 20kΩ RF* 30kΩ *RIN AND RF VALUES ARE CHOSEN FOR A GAIN -1.5V/V. ( ) UCSP PACKAGE 16 ______________________________________________________________________________________ 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown 2.7V TO 5.5V ON C3 1μF OFF LEFT AUDIO INPUT CIN 0.47μF 12 (B1) 5 (A2) 6 (B3) VDD SHDN INL RIN* 20kΩ RF* 30kΩ VDD 11 OUTL (A4) HEADPHONE JACK 1 (C1) C1P VSS UVLO/ SHUTDOWN CONTROL CLICK-AND-POP SUPPRESSION CHARGE PUMP C1 1μF SGND VDD 3 (C3) C1N MAX9724B OUTR RIN 20kΩ 10 (A3) SVSS RF 30kΩ PVSS SVSS PGND SGND 4 (C4) C2 1μF 9 (B4) 2 (C2) 7 (A1) INR 8 (B2) CIN RIGHT 0.47μF AUDIO INPUT ( ) UCSP PACKAGE ______________________________________________________________________________________ 17 MAX9724A/MAX9724B Functional Diagram/Typical Operating Circuits (continued) 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown INR SGND TOP VIEW SVSS MAX9724A/MAX9724B Pin Configurations TOP VIEW (BUMPS ON BOTTOM) 9 8 7 1 2 3 4 MAX9724A/MAX9724B OUTR 10 MAX9724A MAX9724B OUTL 11 6 INL 5 SHDN 4 PVSS A SGND SHDN OUTR OUTL VDD INR INL SVSS C1P PGND C1N PVSS B VDD 12 + 3 C C1N 2 PGND C1P 1 TQFN UCSP Package Information Chip Information PROCESS: BiCMOS 18 For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 12 UCSP B12-1 21-0104 12 TQFN T1233-1 21-0136 ______________________________________________________________________________________ 60mW, DirectDrive, Stereo Headphone Amplifier with Low RF Susceptibility and Shutdown REVISION NUMBER REVISION DATE 0 5/05 Initial release 1 1/06 Added RF immunity to General Description, Features, and Detailed Description. 2 11/06 Added UCSP package. 3 3/07 Updated Electrical Characteristics table and Typical Operating Characteristics. 4 6/07 Corrected Pin Description, Pin Configuration, and Functional Diagrams/Typical Operating Circuits with new UCSP information. 5 3/08 Updated Absolute Maximum Ratings and Click-and-Pop Suppression section. 6 3/09 Updated Ordering Information, style changes DESCRIPTION PAGES CHANGED — 1, 7 1–3, 6, 9, 12, 14–16 1–6, 17, 18 1–6, 12, 14–16 2, 10 1, 10, 18, 19 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 19 © 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX9724A/MAX9724B Revision History