19-4666; Rev 0; 7/09 KIT ATION EVALU LE B A IL A AV DirectDrive Headphone Amplifier with External Gain Vista®-compliant 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. 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 Ordering Information 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. Applications PART TEMP RANGE MAX9820ETB+ -40°C to +85°C PINPACKAGE TOP MARK 10 TDFN-EP* AUU +Denotes a lead(Pb)-free/RoHS-compliant package. Cell Phones *EP = Exposed pad. MP3 Players Notebook PCs PDAs Pin Configuration Simplified Block Diagram TOP VIEW C1P 1 10 GND C1N 2 9 SHDN VSS 3 8 VDD OUTL 4 7 INL 6 INR OUTR 5 MAX9820 *EP TDFN MAX9820 LEFT AUDIO INPUT DirectDrive OUTPUTS ELIMINATE DC-BLOCKING CAPACITORS SHDN RIGHT AUDIO INPUT *EXPOSED PAD. Windows Vista is a registered trademark of Microsoft Corp. DirectDrive is a registered trademark of Maxim Integrated Products, Inc. ________________________________________________________________ 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 MAX9820 General Description MAX9820 DirectDrive Headphone Amplifier with External Gain 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 SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V GENERAL Supply Voltage Range VDD Undervoltage Lockout UVLO Guaranteed by PSRR test 2.7 2.2 V VDD = 3.3V 3.0 4.6 VDD = 5V 4.0 6.0 VSHDN = 0V, TA = +25°C < 0.1 1 Output Signal Attenuation in Shutdown VSHDN = 0V, VIN = 1VRMS, RLOAD = 10kΩ -110 dBV Output Impedance in Shutdown VSHDN = 0V 0.6 kΩ Quiescent Current IDD Shutdown Current ISHDN Turn-On Time tON Output Offset Voltage VOS 0.56 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) 2 ±0.1 Into shutdown -79 Out of shutdown -77 Into shutdown -62 Out of shutdown -58 mA µA ms ±0.5 mV dBV _______________________________________________________________________________________ DirectDrive Headphone Amplifier with External Gain (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 SYMBOL CONDITIONS VDD = 2.7V to 5.5V, TA = +25°C (Note 3) Power-Supply Rejection Ratio PSRR MIN TYP 75 90 f = 1kHz, 200mVP-P (Note 3) POUT Total Harmonic Distortion Plus Noise Signal-to-Noise Ratio Output Noise THD+N SNR VNOISE Crosstalk Capacitive Load Drive Oscillator Frequency CL fOSC 55 ZLOAD= 32Ω + 1µH, f = 1kHz, THD+N = 1% VDD = 3.6V 45 VDD = 5.0V 95 ZLOAD= 16Ω + 1µH, f = 1kHz, THD+N = 1% VDD = 3.6V 32 VDD = 5.0V 0.014 ZLOAD = 32Ω + 1µH, f = 1kHz, POUT = 20mW 0.005 ZLOAD = 10kΩ, f = 1kHz, VOUT = 1VRMS 0.001 ZLOAD = 32Ω + 1µH, POUT = 25mW, A-weighted A-weighted (Note 3) ZLOAD = 32Ω + 1µH FS = 0.300VRMS, VOUT = 30mVRMS % 105 dB 9 µV 73 dB ZLOAD = 10kΩ FS = 0.707VRMS, VOUT = 70.7mVRMS 73 No sustained oscillations TA = +25°C mW 75 ZLOAD = 16Ω + 1µH, f = 1kHz, POUT = 20mW L to R, R to L, BW = 20Hz to 15kHz UNITS dB 73 f = 20kHz, 200mVP-P (Note 3) Output Power MAX 200 300 500 pF 800 kHz Thermal Shutdown 145 °C Thermal Shutdown Hysteresis 15 °C DIGITAL INPUT (SHDN) Input Voltage High VINH Input Voltage Low VINL Input Leakage Current ILEAKAGE 1.2 TA = +25°C V 0.3 V ±1 µA 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 MAX9820 ELECTRICAL CHARACTERISTICS (continued) 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 THD+N vs. OUTPUT POWER f = 100Hz THD+N (%) THD+N (%) 0.1 VDD = 5.0V RLOAD = 32I LLOAD = 1FH 1 f = 6kHz f = 100Hz f = 6kHz 0.1 f = 1kHz 0.01 MAX9820 toc02 VDD = 5.0V RLOAD = 16I LLOAD = 1FH 1 10 MAX9820 toc01 10 0.01 f = 1kHz 0.001 0.001 0.02 0.04 0.06 0.08 0.10 0.14 0.12 0 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 OUTPUT POWER (W) OUTPUT POWER (W) THD+N vs. OUTPUT POWER THD+N vs. OUTPUT POWER VDD = 3.6V RLOAD = 16I LLOAD = 1FH 1 VDD = 3.6V RLOAD = 32I LLOAD = 1FH 1 0.1 THD+N (%) f = 100Hz THD+N (%) 10 MAX9820 toc03 10 f = 6kHz 0.01 MAX9820 toc04 0 f = 100Hz 0.1 f = 6kHz 0.01 f = 1kHz f = 1kHz 0.001 0.001 0.01 0.02 0.03 0.04 0.05 0.06 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 OUTPUT POWER (W) OUTPUT POWER (W) THD+N vs. FREQUENCY THD+N vs. FREQUENCY VDD = 5.0V RLOAD = 16I LLOAD = 1FH VDD = 5.0V RLOAD = 32I LLOAD = 1FH 1 THD+N (%) 1 10 MAX9820 toc05 10 POUT = 60mW 0.1 0.1 POUT = 60mW 0.01 0.01 POUT = 20mW POUT = 20mW 0.001 0.001 10 100 1000 FREQUENCY (Hz) 4 MAX9820 toc06 0 THD+N (%) MAX9820 DirectDrive Headphone Amplifier with External Gain 10,000 100,000 10 100 1000 10,000 FREQUENCY (Hz) _______________________________________________________________________________________ 100,000 DirectDrive Headphone Amplifier with External Gain THD+N vs. FREQUENCY THD+N vs. FREQUENCY THD+N (%) THD+N (%) VDD = 3.6V RLOAD = 32I LLOAD = 1FH 1 0.1 POUT = 20mW MAX9820 toc08 VDD = 3.6V RLOAD = 16I LLOAD = 1FH 1 10 MAX9820 toc07 10 0.1 POUT = 30mW 0.01 0.01 POUT = 10mW POUT = 10mW 0.001 0.001 100 1000 10,000 100,000 10 100 FREQUENCY (Hz) VISTA THD+N vs. FREQUENCY FS = 300mVRMS VDD = 5.0V RLOAD = 10kI LLOAD = 1µH VOUT = -3dBFS -20 THD+N (dBFS) -80 -40 -60 FS = 707mVRMS -80 -100 -100 FS = 1VRMS FS = 1VRMS -120 -120 10 100 1000 100,000 10,000 10 100 FREQUENCY (Hz) MAX9820 toc11 180 RLOAD = 16I LLOAD = 1µH RLOAD = 32I LLOAD = 1µH 150 120 POUT (mW) 120 POUT (mW) 100,000 10,000 OUTPUT POWER vs. SUPPLY VOLTAGE OUTPUT POWER vs. SUPPLY VOLTAGE 180 150 1000 FREQUENCY (Hz) THD+N = 10% 90 MAX9820 toc12 THD+N (dBFS) -60 100,000 0 MAX9820 toc09 VDD = 5.0V RLOAD = 32I LLOAD = 1FH VOUT = -3dBFS -40 10,000 VISTA THD+N vs. FREQUENCY 0 -20 1000 FREQUENCY (Hz) MAX9820 toc10 10 THD+N = 10% 90 60 60 30 THD+N = 1% 30 THD+N = 1% 0 0 2.7 3.1 3.5 3.9 4.3 4.7 SUPPLY VOLTAGE (V) 5.1 5.5 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5 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.) 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 60 THD+N = 10% POUT (mW) 90 60 45 30 THD+N = 1% THD+N = 1% 15 0 0 1 10 1000 100 10 POWER DISSIPATION vs. OUTPUT POWER POWER DISSIPATION vs. OUTPUT POWER 300 RLOAD = 32I 200 VDD = 3.6V LLOAD = 1µH 350 POWER DISSIPATION (mW) RLOAD = 16I 400 100 MAX9820 toc16 400 MAX9820 toc15 VDD = 5.0V LLOAD = 1µH 1000 100 LOAD RESISTANCE (I) 600 500 1 LOAD RESISTANCE (I) 300 RLOAD = 16I 250 200 RLOAD = 32I 150 100 50 0 0 0 20 40 60 80 0 120 100 20 40 60 80 100 OUTPUT POWER PER CHANNEL (mW) OUTPUT POWER PER CHANNEL (mW) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY POWER-SUPPLY REJECTION RATIO vs. SUPPLY VOLTAGE 0 MAX9820 toc17 0 VRIPPLE = 200mVP-P -20 120 MAX9820 toc18 POUT (mW) VDD = 3.6V LLOAD = 1µH THD+N = 10% 30 POWER DISSIPATION (mW) MAX9820 toc14 VDD = 5.0V LLOAD = 1µH 120 OUTPUT POWER vs. LOAD RESISTANCE 75 MAX9820 toc13 150 VRIPPLE = 200mVP-P f = 1kHz -20 -60 PSRR (dB) -40 PSRR (dB) MAX9820 DirectDrive Headphone Amplifier with External Gain RIGHT CHANNEL -40 -60 LEFT CHANNEL -80 -80 -100 RIGHT CHANNEL LEFT CHANNEL -100 -120 10 100 1000 FREQUENCY (Hz) 6 10,000 100,000 2.7 3.1 3.5 3.9 4.3 4.7 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5.1 5.5 DirectDrive Headphone Amplifier with External Gain -80 -40 OUTPUT SPECTRUM MAX9820 toc20 0 LEFT TO RIGHT -60 -80 -100 -100 RIGHT TO LEFT RIGHT TO LEFT -120 -120 100 1000 100,000 10,000 -40 -60 -80 -100 -120 -140 10 f = 1kHz RLOAD = 32I LLOAD = 1µH -20 OUTPUT MAGNITUDE (dBV) LEFT TO RIGHT -60 RLOAD = 1kI LLOAD = 1µH FS = 707mVRMS VOUT = -20dBFS -20 CROSSTALK (dB) -40 -140 10 FREQUENCY (Hz) 100 1000 10,000 100,000 0 2 4 FREQUENCY (Hz) 6 10 12 14 16 18 20 8 FREQUENCY (kHz) QUIESCENT CURRENT vs. SUPPLY VOLTAGE SHUTDOWN CURRENT vs. SUPPLY VOLTAGE 4.0 MAX9820 toc23 0.45 MAX9820 toc22 4.5 0.40 3.5 SHUTDOWN CURRENT (nA) SUPPLY CURRENT (mA) CROSSTALK (dB) MAX9820 toc19 RLOAD = 32I LLOAD = 1µH FS = 300mVRMS VOUT = -20dBFS -20 VISTA CROSSTALK vs. FREQUENCY 0 MAX9820 toc21 VISTA CROSSTALK vs. FREQUENCY 0 3.0 2.5 2.0 1.5 1.0 0.5 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0 0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 2.7 SUPPLY VOLTAGE (V) 3.1 3.5 3.9 4.3 5.1 5.5 ENTERING SHUTDOWN EXITING SHUTDOWN MAX9820 toc25 MAX9820 toc24 100Fs/div 4.7 SUPPLY VOLTAGE (V) SHDN 2V/div SHDN 2V/div OUT_ 1V/div OUT_ 1V/div 100Fs/div _______________________________________________________________________________________ 7 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.) DirectDrive Headphone Amplifier with External Gain MAX9820 Pin Description PIN NAME 1 C1P Flying Capacitor Positive Terminal. Connect a 1µF ceramic capacitor from C1P to C1N. FUNCTION 2 C1N Flying Capacitor Negative Terminal. Connect a 1µF ceramic capacitor from C1N to C1P. 3 VSS Charge-Pump Output. Bypass with a 1µF capacitor to GND. 4 OUTL Left-Channel Output 5 OUTR Right-Channel Output 6 INR Right-Channel Input 7 INL Left-Channel Input 8 VDD Positive Power-Supply Input. Bypass with a 10µF capacitor to GND. 9 SHDN Active-Low Shutdown Input 10 GND Signal Ground — EP 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 Analog Line Output Jack (RL = 10kΩ, FS = 0.707VRMS) Analog Headphone Out Jack (RL = 32Ω, FS = 0.300VRMS) REQUIREMENT WINDOWS VISTA PREMIUM MOBILE SPECIFICATIONS MAX9820 TYPICAL PERFORMANCE THD+N ≤ -65dB FS (100Hz, 20kHz) -83dBFS (100Hz, 20kHz) Dynamic range with signal present ≤ -80dBV, A-weighted (20Hz, 20kHz) -101dB A-weighted (20Hz, 20kHz) Line output crosstalk ≤ -50dB (20Hz, 15kHz) -73dB (20Hz, 15kHz) THD+N ≤ -45dB FS (100Hz, 20kHz) -85dBFS (100Hz, 20kHz) Dynamic range with signal present ≤ -60dBV, A-weighted (20Hz, 20kHz) -94dB A-weighted (20Hz, 20kHz) Headphone output crosstalk ≤ -50dB (20Hz, 15kHz) -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 RF IMMUNITY vs. FREQUENCY VDD -20 VDD RF IMMUNITY (dBV) VDD/2 GND MAX9820 fig02 0 -40 LEFT CHANNEL -60 -80 CONVENTIONAL DRIVER OUTPUT WAVEFORMS -100 VOUT RIGHT CHANNEL -120 0.8 VDD 1.35 1.90 2.45 3.00 FREQUENCY (GHz) Figure 2. MAX9820 RF Susceptibility GND 2VDD Click-and-Pop Suppression -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. 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. 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. 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. _______________________________________________________________________________________ 9 MAX9820 DirectDrive Headphone Amplifier with External Gain Shutdown Undervoltage Lockout (UVLO) 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. 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 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. 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 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 10 SUPPLIER PHONE FAX WEBSITE 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 ______________________________________________________________________________________ DirectDrive Headphone Amplifier with External Gain 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. R A V = − FB (V/ V) RIN Choose feedback resistor values in the tens of kΩ range. Functional Diagram/Typical Operating Circuit CIN 1.0µF RIN 40.2kΩ RFB 40.2kΩ 7 INL TO VDD ON 9 SHDN UVLO/SHUTDOWN CONTROL OFF 2.7V TO 5.5V HEADPHONE JACK VDD C3 10µF OUTR -1 C1 1.0µF 4 TO VSS CLICK-AND-POP SUPPRESSION 8 OUTL -1 1 C1P 2 C1N 5 CHARGE PUMP TO VDD 10 INR VSS GND 3 C2 1.0µF CIN 1.0µF RIN 40.2kΩ 6 RFB 40.2kΩ Chip Information PROCESS: BiCMOS ______________________________________________________________________________________ 11 MAX9820 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: Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 10 TDFN-EP T1033+1 21-0137 6, 8, &10L, DFN THIN.EPS MAX9820 DirectDrive Headphone Amplifier with External Gain 12 ______________________________________________________________________________________ DirectDrive Headphone Amplifier with External Gain COMMON DIMENSIONS PACKAGE VARIATIONS SYMBOL MIN. MAX. PKG. CODE N D2 E2 e JEDEC SPEC b [(N/2)-1] x e A 0.70 0.80 T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF D 2.90 3.10 T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF E 2.90 3.10 T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF A1 0.00 0.05 T1033-1 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF L 0.20 0.40 T1033-2 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF k 0.25 MIN. T1433-1 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF A2 0.20 REF. T1433-2 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 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. MAX9820 Package Information (continued) For the latest package outline information and land patterns, go to www.maxim-ic.com/packages.