MAX9820

19-4666; Rev 0; 7/09 KIT ATION EVALU E AILABL AV DirectDrive Headphone Amplifier with External Gain General Description Features o Clickless/Popless Operation o High RF Noise Rejection o Windows Vista Premium Mobile Compliant o 2.7V to 5.5V Single-Supply Operation o 95mW Output Power (32Ω, VDD = 5V) o Low-Current Shutdown Mode, < 1µA o Low 3mA (VDD = 3.3V) Quiescent Current o Space-Saving, 3mm x 3mm, 10-Pin TDFN Package MAX9820 The MAX9820 Windows stereo headphone amplifier is designed for portable equipment where board space is at a premium. It features Maxim’s patented DirectDrive ® architecture to produce a ground-referenced output from a single supply, eliminating the large output-coupling capacitors required by conventional single-supply headphone amplifiers. The MAX9820 features an undervoltage lockout that prevents over discharging of the battery during brownout conditions, click-and-pop suppression that eliminates audible transients on startup, a low-power shutdown mode, and thermal-overload and short-circuit protection. Additionally, the MAX9820 suppresses RF radiation received by input and supply traces acting as antennas and prevents the amplifier from demodulating the coupled noise. The MAX9820 is available in a 10-pin TDFN package (3mm x 3mm x 0.8mm) and specified over the -40°C to +85°C extended temperature range. Vista®-compliant Ordering Information PART TEMP RANGE PINPACKAGE 10 TDFN-EP* TOP MARK AUU Applications Cell Phones MP3 Players Notebook PCs PDAs MAX9820ETB+ -40°C to +85°C +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. Pin Configuration TOP VIEW Simplified Block Diagram C1P C1N VSS OUTL OUTR 1 2 3 4 5 *EP 10 9 GND SHDN VDD INL INR MAX9820 LEFT AUDIO INPUT DirectDrive OUTPUTS ELIMINATE DC-BLOCKING CAPACITORS MAX9820 8 7 6 SHDN TDFN *EXPOSED PAD. RIGHT AUDIO INPUT Windows Vista is a registered trademark of Microsoft Corp. DirectDrive is a registered trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 1 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. DirectDrive Headphone Amplifier with External Gain MAX9820 ABSOLUTE MAXIMUM RATINGS VDD to GND ..............................................................-0.3V to +6V C1P to GND................................................-0.3V to (VDD + 0.3V) C1N to GND ................................................(VSS - 0.3V) to +0.3V VSS to GND...............................................................-6V to +0.3V OUTR, OUTL to GND.............................................................±3V SHDN to GND...........................................................-0.3V to +6V INR, INL to GND .........................................-0.3V to (VDD + 0.3V) OUTR, OUTL Short Circuit to GND, VDD ....................Continuous Short Circuit Between OUTL and OUTR ....................Continuous Continuous Input Current (Into All Other Pins) .................±20mA Continuous Power Dissipation (TA = +70°C) 10-Pin TDFN Single-Layer PCB (derate 18.5mW/°C above +70°C)........................................................1481.5mW Junction-to-Case Thermal Resistance (θJC) (Note 1) 10-Pin TDFN ................................................................8.5°C/W Junction-to-Ambient Thermal Resistance (θJA) (Note 1) 10-Pin TDFN ...............................................................41.0°C/W Continuous Power Dissipation (TA = +70°C) 10-Pin TDFN Multilayer PCB (derate 24.4mW/°C above +70°C)...........................................................1951mW Junction-to-Case Thermal Resistance (θJC) (Note 1) 10-Pin TDFN .................................................................9.0°C/W Junction-to-Ambient Thermal Resistance (θJA) (Note 1) 10-Pin TDFN ...............................................................41.0°C/W Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Junction Temperature ......................................................+150°C Lead Temperature (soldering, 10s) .................................+300°C Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. 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 = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.) (Note 2) PARAMETER GENERAL Supply Voltage Range Undervoltage Lockout Quiescent Current Shutdown Current Output Signal Attenuation in Shutdown Output Impedance in Shutdown Turn-On Time Output Offset Voltage tON VOS TA = +25°C (Note 3) ZLOAD = 32Ω + 1µH, peak voltage, A-weighted, 32 samples per second (Notes 3, 4) Click-and-Pop Level KCP ZLOAD = 10kΩ, peak voltage, A-weighted, 32 samples per second (Notes 3, 4) Into shutdown Out of shutdown Into shutdown Out of shutdown VDD UVLO IDD ISHDN VDD = 3.3V VDD = 5V VSHDN = 0V, TA = +25°C VSHDN = 0V, VIN = 1VRMS, RLOAD = 10kΩ VSHDN = 0V Guaranteed by PSRR test 2.7 2.2 3.0 4.0 < 0.1 -110 0.6 0.56 ±0.1 -79 -77 dBV -62 -58 ±0.5 4.6 6.0 1 5.5 V V mA µA dBV kΩ ms mV SYMBOL CONDITIONS MIN TYP MAX UNITS 2 _______________________________________________________________________________________ DirectDrive Headphone Amplifier with External Gain ELECTRICAL CHARACTERISTICS (continued) (VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C, unless otherwise noted.) (Note 2) PARAMETER Power-Supply Rejection Ratio SYMBOL PSRR CONDITIONS VDD = 2.7V to 5.5V, TA = +25°C (Note 3) f = 1kHz, 200mVP-P (Note 3) f = 20kHz, 200mVP-P (Note 3) ZLOAD= 32Ω + 1µH, f = 1kHz, THD+N = 1% Output Power POUT ZLOAD= 16Ω + 1µH, f = 1kHz, THD+N = 1% VDD = 3.6V VDD = 5.0V VDD = 3.6V VDD = 5.0V MIN 75 TYP 90 73 55 45 95 32 75 0.014 0.005 0.001 105 9 ZLOAD = 32Ω + 1µH FS = 0.300VRMS, VOUT = 30mVRMS ZLOAD = 10kΩ FS = 0.707VRMS, VOUT = 70.7mVRMS 300 73 dB 73 200 500 145 15 VINH VINL ILEAKAGE TA = +25°C 1.2 0.3 ±1 800 pF kHz °C °C V V µA dB µV % mW dB MAX UNITS MAX9820 Total Harmonic Distortion Plus Noise Signal-to-Noise Ratio Output Noise ZLOAD = 16Ω + 1µH, f = 1kHz, POUT = 20mW THD+N SNR VNOISE ZLOAD = 32Ω + 1µH, f = 1kHz, POUT = 20mW ZLOAD = 10kΩ, f = 1kHz, VOUT = 1VRMS ZLOAD = 32Ω + 1µH, POUT = 25mW, A-weighted A-weighted (Note 3) Crosstalk L to R, R to L, BW = 20Hz to 15kHz Capacitive Load Drive Oscillator Frequency Thermal Shutdown Thermal Shutdown Hysteresis DIGITAL INPUT (SHDN) Input Voltage High Input Voltage Low Input Leakage Current CL fOSC No sustained oscillations TA = +25°C Note 2: All specifications are 100% tested at TA = +25°C; temperature limits are guaranteed by design. Note 3: The amplifier inputs are AC-coupled to GND. Note 4: Mode transitions are controlled by SHDN. _______________________________________________________________________________________ 3 DirectDrive Headphone Amplifier with External Gain MAX9820 Typical Operating Characteristics (VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞. Typical values are at TA = +25°C, unless otherwise noted.) THD+N vs. OUTPUT POWER MAX9820 toc01 THD+N vs. OUTPUT POWER VDD = 5.0V RLOAD = 32I LLOAD = 1FH f = 100Hz 0.1 f = 6kHz MAX9820 toc02 10 VDD = 5.0V RLOAD = 16I LLOAD = 1FH f = 6kHz 0.1 f = 100Hz 10 1 THD+N (%) 1 THD+N (%) 0.01 f = 1kHz 0.01 f = 1kHz 0.001 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 OUTPUT POWER (W) 0.001 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 OUTPUT POWER (W) THD+N vs. OUTPUT POWER MAX9820 toc03 THD+N vs. OUTPUT POWER VDD = 3.6V RLOAD = 32I LLOAD = 1FH MAX9820 toc04 10 VDD = 3.6V RLOAD = 16I LLOAD = 1FH f = 100Hz 0.1 f = 6kHz 10 1 THD+N (%) 1 THD+N (%) 0.1 f = 100Hz f = 6kHz 0.01 f = 1kHz 0.01 f = 1kHz 0.001 0 0.01 0.02 0.03 0.04 0.05 0.06 OUTPUT POWER (W) 0.001 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 OUTPUT POWER (W) THD+N vs. FREQUENCY MAX9820 toc05 THD+N vs. FREQUENCY VDD = 5.0V RLOAD = 32I LLOAD = 1FH MAX9820 toc06 10 VDD = 5.0V RLOAD = 16I LLOAD = 1FH 10 1 THD+N (%) 1 THD+N (%) 0.1 POUT = 60mW 0.1 POUT = 60mW 0.01 0.01 POUT = 20mW 0.001 10 100 1000 FREQUENCY (Hz) 10,000 100,000 0.001 10 POUT = 20mW 100 1000 FREQUENCY (Hz) 10,000 100,000 4 _______________________________________________________________________________________ DirectDrive Headphone Amplifier with External Gain Typical Operating Characteristics (VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞. Typical values are at TA = +25°C, unless otherwise noted.) THD+N vs. FREQUENCY MAX9820 toc07 MAX9820 THD+N vs. FREQUENCY VDD = 3.6V RLOAD = 32I LLOAD = 1FH MAX9820 toc08 10 VDD = 3.6V RLOAD = 16I LLOAD = 1FH 10 1 THD+N (%) 1 THD+N (%) 0.1 POUT = 20mW 0.01 POUT = 10mW 0.001 10 100 1000 FREQUENCY (Hz) 10,000 100,000 0.1 POUT = 30mW 0.01 POUT = 10mW 0.001 10 100 1000 FREQUENCY (Hz) 10,000 100,000 VISTA THD+N vs. FREQUENCY MAX9820 toc09 VISTA THD+N vs. FREQUENCY VDD = 5.0V RLOAD = 10kI LLOAD = 1µH VOUT = -3dBFS MAX9820 toc10 0 -20 -40 -60 -80 -100 FS = 1VRMS -120 10 100 1000 FREQUENCY (Hz) 10,000 VDD = 5.0V RLOAD = 32I LLOAD = 1FH VOUT = -3dBFS 0 -20 -40 -60 FS = 707mVRMS -80 -100 FS = 1VRMS -120 THD+N (dBFS) FS = 300mVRMS 100,000 THD+N (dBFS) 10 100 1000 FREQUENCY (Hz) 10,000 100,000 OUTPUT POWER vs. SUPPLY VOLTAGE MAX9820 toc11 OUTPUT POWER vs. SUPPLY VOLTAGE RLOAD = 32I LLOAD = 1µH MAX9820 toc12 180 150 120 POUT (mW) THD+N = 10% 90 60 30 0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 RLOAD = 16I LLOAD = 1µH 180 150 120 POUT (mW) 90 60 30 0 THD+N = 1% THD+N = 10% THD+N = 1% 5.5 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5 DirectDrive Headphone Amplifier with External Gain MAX9820 Typical Operating Characteristics (continued) (VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞. Typical values are at TA = +25°C, unless otherwise noted.) OUTPUT POWER vs. LOAD RESISTANCE MAX9820 toc13 OUTPUT POWER vs. LOAD RESISTANCE VDD = 3.6V LLOAD = 1µH 60 THD+N = 10% POUT (mW) 45 MAX9820 toc14 150 VDD = 5.0V LLOAD = 1µH 120 THD+N = 10% 75 POUT (mW) 90 60 THD+N = 1% 30 THD+N = 1% 15 30 0 1 10 100 1000 LOAD RESISTANCE (I) 0 1 10 100 1000 LOAD RESISTANCE (I) POWER DISSIPATION vs. OUTPUT POWER MAX9820 toc15 POWER DISSIPATION vs. OUTPUT POWER 350 POWER DISSIPATION (mW) 300 250 200 150 100 50 0 0 20 40 60 80 100 120 RLOAD = 32I VDD = 3.6V LLOAD = 1µH RLOAD = 16I MAX9820 toc16 600 500 POWER DISSIPATION (mW) 400 300 200 100 0 0 20 40 60 80 100 RLOAD = 32I VDD = 5.0V LLOAD = 1µH RLOAD = 16I 400 120 OUTPUT POWER PER CHANNEL (mW) OUTPUT POWER PER CHANNEL (mW) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY MAX9820 toc17 POWER-SUPPLY REJECTION RATIO vs. SUPPLY VOLTAGE VRIPPLE = 200mVP-P f = 1kHz -20 MAX9820 toc18 0 VRIPPLE = 200mVP-P -20 -40 PSRR (dB) -60 -80 -100 -120 10 100 1000 FREQUENCY (Hz) 10,000 0 RIGHT CHANNEL PSRR (dB) -40 -60 LEFT CHANNEL -80 LEFT CHANNEL -100 100,000 2.7 3.1 3.5 RIGHT CHANNEL 3.9 4.3 4.7 5.1 5.5 SUPPLY VOLTAGE (V) 6 _______________________________________________________________________________________ DirectDrive Headphone Amplifier with External Gain Typical Operating Characteristics (continued) (VDD = VSHDN = 5V, VGND = 0V, RIN = RFB = 40.2kΩ (gain = -1V/V), C1 = C2 = 1µF, C3 = 10µF, RLOAD = ∞. Typical values are at TA = +25°C, unless otherwise noted.) VISTA CROSSTALK vs. FREQUENCY MAX9820 toc19 MAX9820 VISTA CROSSTALK vs. FREQUENCY MAX9820 toc20 OUTPUT SPECTRUM -20 OUTPUT MAGNITUDE (dBV) -40 -60 -80 -100 -120 -140 f = 1kHz RLOAD = 32I LLOAD = 1µH MAX9820 toc21 0 -20 CROSSTALK (dB) -40 -60 -80 -100 -120 10 100 1000 FREQUENCY (Hz) 10,000 RIGHT TO LEFT RLOAD = 32I LLOAD = 1µH FS = 300mVRMS VOUT = -20dBFS 0 -20 CROSSTALK (dB) -40 -60 -80 -100 -120 -140 RIGHT TO LEFT RLOAD = 1kI LLOAD = 1µH FS = 707mVRMS VOUT = -20dBFS LEFT TO RIGHT 0 LEFT TO RIGHT 100,000 10 100 1000 FREQUENCY (Hz) 10,000 100,000 0 2 4 6 8 10 12 14 16 18 20 FREQUENCY (kHz) QUIESCENT CURRENT vs. SUPPLY VOLTAGE MAX9820 toc22 SHUTDOWN CURRENT vs. SUPPLY VOLTAGE 0.40 SHUTDOWN CURRENT (nA) 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 MAX9820 toc23 4.5 4.0 SUPPLY CURRENT (mA) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 0.45 5.5 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) EXITING SHUTDOWN MAX9820 toc24 ENTERING SHUTDOWN MAX9820 toc25 SHDN 2V/div SHDN 2V/div OUT_ 1V/div OUT_ 1V/div 100Fs/div 100Fs/div _______________________________________________________________________________________ 7 DirectDrive Headphone Amplifier with External Gain MAX9820 Pin Description PIN 1 2 3 4 5 6 7 8 9 10 — NAME C1P C1N VSS OUTL OUTR INR INL VDD SHDN GND EP FUNCTION Flying Capacitor Positive Terminal. Connect a 1µF ceramic capacitor from C1P to C1N. Flying Capacitor Negative Terminal. Connect a 1µF ceramic capacitor from C1N to C1P. Charge-Pump Output. Bypass with a 1µF capacitor to GND. Left-Channel Output Right-Channel Output Right-Channel Input Left-Channel Input Positive Power-Supply Input. Bypass with a 10µF capacitor to GND. Active-Low Shutdown Input Signal Ground Exposed Pad. Internally connected to GND. Connect to a large ground plane to maximize thermal performance. Not intended as an electrical connection point. Detailed Description The MAX9820 95mW stereo headphone amplifier features Maxim’s patented DirectDrive architecture, eliminating the large output-coupling capacitors required by conventional single-supply headphone amplifiers. The device features low RF susceptibility, extensive clickand-pop suppression, undervoltage lockout (UVLO) and shutdown control. The MAX9820 also features thermal-overload and short-circuit protection. The MAX9820 is Windows Vista Premium Mobile compliant (Table 1). 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 MAX9820 outputs to be biased at Table 1. Windows Vista Premium Mobile Specifications vs. MAX9820 Specifications DEVICE TYPE REQUIREMENT THD+N Analog Line Output Jack (RL = 10kΩ, FS = 0.707VRMS) Dynamic range with signal present Line output crosstalk THD+N Analog Headphone Out Jack (RL = 32Ω, FS = 0.300VRMS) Dynamic range with signal present Headphone output crosstalk WINDOWS VISTA PREMIUM MOBILE SPECIFICATIONS ≤ -65dB FS (100Hz, 20kHz) ≤ -80dBV, A-weighted (20Hz, 20kHz) ≤ -50dB (20Hz, 15kHz) ≤ -45dB FS (100Hz, 20kHz) ≤ -60dBV, A-weighted (20Hz, 20kHz) ≤ -50dB (20Hz, 15kHz) MAX9820 TYPICAL PERFORMANCE -83dBFS (100Hz, 20kHz) -101dB A-weighted (20Hz, 20kHz) -73dB (20Hz, 15kHz) -85dBFS (100Hz, 20kHz) -94dB A-weighted (20Hz, 20kHz) -73dB (20Hz, 15kHz) Note: THD+N, dynamic range, and crosstalk are measured in accordance with AES-17 audio measurements standards. 8 _______________________________________________________________________________________ DirectDrive Headphone Amplifier with External Gain MAX9820 VOUT VDD/2 VDD -20 RF IMMUNITY (dBV) -40 -60 -80 -100 -120 RIGHT CHANNEL 0.8 1.35 1.90 FREQUENCY (GHz) 2.45 LEFT CHANNEL GND CONVENTIONAL DRIVER OUTPUT WAVEFORMS VOUT VDD 3.00 Figure 2. MAX9820 RF Susceptibility GND 2VDD Click-and-Pop Suppression 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 DirectDrive biases the outputs at ground, this problem does not arise. Additionally, the MAX9820 features extensive click-and-pop suppression that eliminates any audible transient sources internal to the device. -VDD MAX9820 OUTPUT WAVEFORMS Figure 1. Conventional Driver Output Waveform vs. MAX9820 Output Waveform GND (Figure 1). With no DC component, there is no need for the large DC-blocking capacitors. The MAX9820 charge pump requires two small ceramic capacitors, conserving board space, reducing cost, and improving the frequency response of the headphone amplifier. RF Susceptibility Modern audio systems are often subject to RF radiation from sources such as wireless and cellular phone networks. Although the RF radiation is out of the audio band, many signals, GSM signals in particular, contain bursts or modulation at audible frequencies. Most analog amplifiers demodulate the low-frequency envelope, adding noise to the audio signal. The MAX9820 architecture addresses the RF susceptibility problem by rejecting RF noise and preventing it from coupling into the audio band. Charge Pump The MAX9820 features a low-noise charge pump. The 500kHz (typ) charge pump switching frequency is well beyond the audio range and does not interfere with audio signals. _______________________________________________________________________________________ MAX9820 fig02 VDD RF IMMUNITY vs. FREQUENCY 0 9 DirectDrive Headphone Amplifier with External Gain MAX9820 Shutdown The MAX9820 features a low-power shutdown mode that reduces quiescent current consumption to less than 1µA, extending 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 600Ω || RFB. The amplifiers and charge pump are enabled once SHDN is driven high. Undervoltage Lockout (UVLO) The MAX9820 features a UVLO function that prevents the device from operating if the supply voltage falls below 2.2V (min). This feature ensures proper operation during brownout conditions and prevents deep battery discharge. Once the supply voltage reaches the minimum supply voltage range, the MAX9820 charge pump is turned on and the amplifiers are powered, provided that SHDN is high. Applications Information 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 or can be calculated by the following equation: PDISSPKG(MAX) = TJ(MAX) − TA θJA 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 Circuit). 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 where TJ(MAX) is +150°C, TA is the ambient temperature, and θJA is the reciprocal of the derating factor in °C/W as specified in the Absolute Maximum Ratings section. The MAX9820 has two power dissipation sources: a charge pump and the two output amplifiers. If power dissipation for a given application exceeds the maximum allowed package power dissipation, 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 MAX9820. When the junction temperature exceeds 145°C (typ), the thermal protection circuitry disables the amplifier output stage. The amplifiers are enabled once the junction temperature cools by approximately 15°C. 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 or X5R dielectric. Table 2 lists suggested manufacturers. Table 2. Suggested Capacitor Vendors SUPPLIER Taiyo Yuden TDK Murata PHONE 800-348-2496 847-803-6100 770-436-1300 FAX 847-925-0899 847-390-4405 770-436-3030 WEBSITE www.t-yuden.com www.component.tdk.com www.murata.com 10 ______________________________________________________________________________________ DirectDrive Headphone Amplifier with External Gain Amplifier Gain The gain of the MAX9820 is set externally using input and feedback resistors (see the Functional Diagram/ Typical Operating Circuit ). The gain is: R A V = − FB (V/ V) RIN Choose feedback resistor values in the tens of k Ω range. Layout and Grounding Proper layout and grounding are essential for optimum performance. Connect EP and GND together at a single point on the PCB. Ensure ground return resistance is minimized for optimum crosstalk performance. Place the power-supply bypass capacitor, the charge-pump hold capacitor, and the charge-pump flying capacitor as close as possible to the MAX9820. Route all traces that carry switching transients away from the audio signal path. MAX9820 Functional Diagram/Typical Operating Circuit CIN 1.0µF RIN 40.2kΩ RFB 40.2kΩ 7 INL TO VDD ON OFF 9 SHDN UVLO/SHUTDOWN CONTROL -1 OUTL 4 HEADPHONE JACK TO VSS 2.7V TO 5.5V 8 C3 10µF 1 C1 1.0µF C1P CHARGE PUMP VDD CLICK-AND-POP SUPPRESSION -1 OUTR 5 2 C1N TO VDD GND 10 3 VSS C2 1.0µF CIN 1.0µF RIN 40.2kΩ 6 INR RFB 40.2kΩ Chip Information PROCESS: BiCMOS ______________________________________________________________________________________ 11 DirectDrive Headphone Amplifier with External Gain MAX9820 Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 10 TDFN-EP PACKAGE CODE T1033+1 DOCUMENT NO. 21-0137 6, 8, &10L, DFN THIN.EPS 12 ______________________________________________________________________________________ DirectDrive Headphone Amplifier with External Gain Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. MAX9820 COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40 PACKAGE VARIATIONS PKG. CODE T633-2 T833-2 T833-3 T1033-1 T1033-2 T1433-1 T1433-2 N 6 8 8 10 10 14 14 D2 1.50±0.10 1.50±0.10 1.50±0.10 1.50±0.10 1.50±0.10 1.70±0.10 1.70±0.10 E2 2.30±0.10 2.30±0.10 2.30±0.10 2.30±0.10 2.30±0.10 2.30±0.10 2.30±0.10 e 0.95 BSC 0.65 BSC 0.65 BSC 0.50 BSC 0.50 BSC 0.40 BSC 0.40 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEC MO229 / WEEC MO229 / WEED-3 MO229 / WEED-3 ------b 0.40±0.05 0.30±0.05 0.30±0.05 0.25±0.05 0.25±0.05 0.20±0.05 0.20±0.05 [(N/2)-1] x e 1.90 REF 1.95 REF 1.95 REF 2.00 REF 2.00 REF 2.40 REF 2.40 REF 0.25 MIN. 0.20 REF. 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 ____________________ 13 © 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.