19-3882; Rev 0; 10/05 2.2W Stereo Audio Power Amplifier with Analog Volume Control Features The MAX9787 combines a stereo, 2.2W audio power amplifier with an analog volume control in a single device. A high 90dB PSRR and low 0.01% THD+N ensures clean, low-distortion amplification of the audio signal. The analog volume control can be driven with a potentiometer, an RC-filtered PWM source, or a DAC output. A BEEP input allows the addition of alert signals from the controller to the audio path. Industry-leading, click-and-pop suppression eliminates audible transients during power and shutdown cycles. Other features include single-supply voltage, a shutdown mode, logic-selectable gain, thermal-overload, and output short-circuit protection. ♦ Class AB, 2.2W, Stereo BTL Speaker Amplifiers The MAX9787 is offered in a space-saving, thermally efficient, 28-pin, thin QFN (5mm x 5mm x 0.8mm) package, and is specified over the extended -40°C to +85°C temperature range. ♦ Space-Saving 28-Pin TQFN (5mm x 5mm x 0.8mm) Applications Ordering Information Notebook PCs Portable DVD Players Flat-Panel TVs LCD Projectors Tablet PCs Multimedia Monitors PC Displays ♦ Analog Volume Control ♦ BEEP Input with Glitch Filter ♦ 5V Single-Supply Operation ♦ High 90dB PSRR ♦ Low-Power Shutdown Mode ♦ Industry-Leading Click-and-Pop Suppression ♦ Low 0.01% THD+N at 1kHz ♦ Short-Circuit and Thermal Protection ♦ Selectable-Gain Settings PART PIN-PACKAGE MAX9787ETI+ 28 TQFN-EP* Pin Configuration GND PGND OUTR+ OUTR- PVDD PVDD 20 19 18 17 16 15 SHDN 22 14 N.C. GAIN2 23 13 N.C. GAIN1 24 12 VSS 11 CPVSS MAX9787 VDD 25 GND 26 10 C1N INR 27 9 CPGND VOL 28 8 C1P *EXPOSED PAD. 3 4 5 6 7 OUTL- PVDD CPVDD 2 OUTL+ 1 PGND + *EP BEEP MAX9787 VOLUME 21 INL BEEP BIAS TOP VIEW +5V Σ T2855N-1 Note: This device is specified for -40°C to +85°C operation. +Denotes lead-free package. *EP = Exposed paddle. Typical Operating Circuit Σ PKG CODE THIN QFN ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX9787 General Description MAX9787 2.2W Stereo Audio Power Amplifier with Analog Volume Control ABSOLUTE MAXIMUM RATINGS Supply Voltage (VDD, PVDD, CPVDD to GND) .......................+6V GND to PGND.....................................................................±0.3V CPVSS, C1N, VSS to GND .........................-6.0V to (GND + 0.3V) Any Other Pin .............................................-0.3V to (VDD + 0.3V) Duration of OUT_ Short Circuit to GND or PVDD ........Continuous Duration of OUT_+ Short Circuit to OUT_- .................Continuous Continuous Current (PVDD, OUT_, PGND) ...........................1.7A Continuous Current (CPVDD, C1N, C1P, CPVSS, VSS)......850mA Continuous Input Current (all other pins) .........................±20mA Continuous Power Dissipation (TA = +70°C) 28-Pin Thin QFN (derate 23.8mW/°C above +70°C) .......1.9W Junction Temperature ......................................................+150°C Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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 (V DD = PV DD = CPV DD = 5V, GND = PGND = CPGND = 0V, SHDN = V DD , C BIAS = 1µF, C1 = C2 = 1µF, speaker load terminated between OUT_+ and OUT_-, GAIN1 = GAIN2 = VOL = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V GENERAL Supply Voltage Range VDD, PVDD Quiescent Supply Current IDD Shutdown Supply Current ISHDN Bias Voltage VBIAS Inferred from PSRR test SHDN = GND 1.7 Switching Time tSW Gain or input switching Input Resistance RIN Amplifier inputs (Note 2) Turn-On Time tSON Output Offset Voltage VOS Power-Supply Rejection Ratio (Note 3) Output Power (Note 4) Total Harmonic Distortion Plus Noise 2 POUT THD+N 14 29 mA 0.2 5 µA 1.8 1.9 V 30 kΩ 10 10 20 µs 25 Measured between OUT_+ and OUT_-, TA = +25°C PVDD or VDD = 4.5V to 5.5V (TA = +25°C) PSRR 4.5 ±0.4 75 80 f = 10kHz, VRIPPLE = 200mVP-P 55 RL = 8Ω 0.65 0.8 RL = 4Ω 1.2 1.5 RL = 3Ω ±6 mV 90 f = 1kHz, VRIPPLE = 200mVP-P THD+N = 1%, f = 1kHz, TA = +25°C ms dB W 2.2 RL = 8Ω, POUT = 500mW, f = 1kHz 0.01 RL = 4Ω, POUT = 1W, f = 1kHz 0.02 _______________________________________________________________________________________ % 2.2W Stereo Audio Power Amplifier with Analog Volume Control (V DD = PV DD = CPV DD = 5V, GND = PGND = CPGND = 0V, SHDN = V DD , C BIAS = 1µF, C1 = C2 = 1µF, speaker load terminated between OUT_+ and OUT_-, GAIN1 = GAIN2 = VOL = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Signal-to-Noise Ratio SYMBOL SNR CONDITIONS MIN RL = 8Ω, POUT = 500mW, BW = 22Hz to 22kHz TYP MAX UNITS 90 dB Noise Vn BW = 22Hz to 22kHz, A-weighted 80 µVRMS Capacitive-Load Drive CL No sustained oscillations 200 pF Crosstalk L to R, R to L, f = 10kHz Slew Rate SR Gain (Maximum Volume Setting) AVMAX(SPKR) 75 dB 1.4 V/µs GAIN1 = 0, GAIN2 = 0 6 GAIN1 = 1, GAIN2 = 0 7.5 GAIN1 = 0, GAIN2 = 1 9 GAIN1 = 1, GAIN2 = 1 10.5 dB CHARGE PUMP Charge-Pump Frequency fOSC 500 550 600 kHz VOLUME CONTROL VOL Input Impedance RVOL VOL Input Hysteresis 100 MΩ 10 mV Full-Mute Input Voltage (Note 5) 4.29 V Channel Matching AV = -25dB to +13.5dB ±0.2 dB BEEP INPUT Beep Signal Minimum Amplitude VBEEP Beep Signal Minimum Frequency fBEEP RB = 33kΩ (Note 6) 0.3 VP-P 300 Hz LOGIC INPUT (SHDN, GAIN1, GAIN2, VOL) Logic Input High Voltage VIH Logic Input Low Voltage VIL 0.8 V Logic Input Current IIN ±1 µA Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: 2 V All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design. Guaranteed by design. Not production tested. PSRR is specified with the amplifier input connected to GND through CIN. Output power levels are measured with the thin QFN’s exposed paddle soldered to the ground plane. See Table 3 for details of the mute levels. The value of RB dictates the minimum beep signal amplitude (see the BEEP Input section). _______________________________________________________________________________________ 3 MAX9787 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.) 0.01 OUTPUT POWER = 1.25W 0.01 0.001 0.0001 10k 0.0001 10 100k 100 1k 10k 100k FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER fIN = 10kHz 0.1 0.01 1 fIN = 10kHz 0.1 100 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 0.2 0.4 0.6 0.8 OUTPUT POWER (W) 5 MAX9787 toc07 2.0 THD+N = 10% 1.5 1.0 0 2.0 POWER DISSIPATION vs. OUTPUT POWER POWER DISSIPATION (W) OUTPUT POWER (W) 2.5 fIN = 1kHz fIN = 20Hz 1.0 1.5 OUTPUT POWER (W) OUTPUT POWER vs. LOAD RESISTANCE VCC = 5V f = 1kHz AV = 10.5dB fIN = 10kHz 0.1 0.001 OUTPUT POWER (W) 3.0 1 fIN = 1kHz 0.001 0 THD+N = 1% VDD = 5V f = 1kHz POUT = POUTL + POUTR 4 RL = 4Ω 3 2 RL = 8Ω 1 0.5 0 0 1 10 LOAD RESISTANCE (Ω) 100k 0.01 fIN = 20Hz 0.001 10k VCC = 5V RL = 8Ω AV = 10.5dB 10 0.01 fIN = 1kHz fIN = 20Hz 1k TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT POWER THD+N (%) 1 100 FREQUENCY (Hz) VCC = 5V RL = 4Ω AV = 10.5dB 10 THD+N (%) VCC = 5V RL = 3Ω AV = 10.5dB 10 100 MAX9787 toc04 100 10 MAX9787 toc05 FREQUENCY (Hz) MAX9787 toc08 0.0001 1k 0.01 OUTPUT POWER = 600mW 0.001 100 OUTPUT POWER = 100mW 0.1 OUTPUT POWER = 500mW 0.001 4 1 0.1 OUTPUT POWER = 500mW 10 VCC = 5V RL = 8Ω AV = 10.5dB MAX9787 toc06 OUTPUT POWER = 1.5W 0.1 10 MAX9787 toc02 1 THD+N (%) THD+N (%) VCC = 5V RL = 4Ω AV = 10.5dB THD+N (%) VCC = 5V RL = 3Ω AV = 10.5dB 1 10 MAX9787 toc01 10 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX9787 toc03 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY THD+N (%) MAX9787 2.2W Stereo Audio Power Amplifier with Analog Volume Control 100 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 OUTPUT POWER (W) _______________________________________________________________________________________ 4.0 1.0 1.2 2.2W Stereo Audio Power Amplifier with Analog Volume Control POWER-SUPPLY REJECTION RATIO vs. FREQUENCY VRIPPLE = 200mVP-P AV = 10.5dB OUTPUT REFERRED -10 -20 -40 -50 -60 VCC = 5V VRIPPLE = 200mVP-P RL = 4Ω -10 -20 -30 -40 -50 CROSSTALK (dB) PSRR (dB) -30 -60 -70 -80 -70 LEFT TO RIGHT -90 -100 -110 -80 -90 -100 MAX9787 toc10 CROSSTALK vs. FREQUENCY 0 MAX9787 toc09 0 RIGHT TO LEFT -120 100 10 1k 10k 100k 10 100 FREQUENCY (Hz) 1k 10k 100k FREQUENCY (Hz) TURN-ON RESPONSE TURN-OFF RESPONSE MAX9787 toc11 MAX9787 toc12 5V/div 5V/div SHDN SHDN OUT_+ AND OUT_- 2V/div OUT_+ - OUT_- 100mV/div OUT_+ AND OUT_- 2V/div OUT_+ - OUT_- 20mV/div RL = 8Ω RL = 8Ω 20ms/div 20ms/div SUPPLY CURRENT vs. SUPPLY VOLTAGE SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE 0.30 SUPPLY CURRENT (µA) 14 12 10 8 6 MAX9787 toc14 16 SUPPLY CURRENT (mA) 0.35 MAX9787 toc13 18 0.25 0.20 0.15 0.10 4 0.05 2 0 0 4.50 4.75 5.00 5.25 SUPPLY VOLTAGE (V) 5.50 4.50 4.75 5.00 5.25 5.50 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5 MAX9787 Typical Operating Characteristics (continued) (Measurement BW = 22Hz to 22kHz, TA = +25°C, unless otherwise noted.) 2.2W Stereo Audio Power Amplifier with Analog Volume Control MAX9787 Pin Description 6 PIN NAME 1 INL Left-Channel Audio Input FUNCTION Audible Alert Beep Input 2 BEEP 3, 19 PGND Power Ground 4 OUTL+ Left-Channel Positive Speaker Output 5 OUTL- Left-Channel Negative Speaker Output 6, 15, 16 PVDD Speaker Amplifier Power Supply 7 CPVDD 8 C1P 9 CPGND 10 C1N 11 CPVSS 12 VSS Charge-Pump Power Supply Charge-Pump Flying-Capacitor Positive Terminal Charge-Pump Ground Charge-Pump Flying-Capacitor Negative Terminal Charge-Pump Output. Connect to VSS. Amplifier Negative Power Supply 13, 14 N.C. No Connection. Not internally connected. 17 OUTR- Right-Channel Negative Speaker Output 18 OUTR+ Right-Channel Positive Speaker Output 20, 26 GND Ground 21 BIAS Common-Mode Bias Voltage. Bypass with a 1µF capacitor to GND. 22 SHDN Shutdown. Drive SHDN low to disable the device. Connect SHDN to VDD for normal operation. 23 GAIN2 Gain Control Input 2 24 GAIN1 25 VDD Power Supply 27 INR Right-Channel Audio Input 28 VOL EP EP Gain Control Input 1 Analog Volume Control Input Exposed Pad. Connect to GND. _______________________________________________________________________________________ 2.2W Stereo Audio Power Amplifier with Analog Volume Control The MAX9787 combines a 2.2W bridge-tied load (BTL) speaker amplifier and an analog volume control, BEEP input, and four-level gain control. The MAX9787 features high 90dB, low 0.01% THD+N, industry-leading clickpop performance, and a low-power shutdown mode. Each signal path consists of an input amplifier that sets the gain of the signal path, and feeds the speaker amplifier (Figure 1). The speaker amplifier uses a BTL architecture, doubling the voltage drive to the speakers and eliminating the need for DC-blocking capacitors. The output consists of two signals, identical in magnitude, but 180o out of phase. An analog volume control varies the gain of the amplifiers based on the DC voltage applied at VOL. An undervoltage lockout prevents operation from an insufficient power supply. Click-and-pop suppression eliminates audible transients on startup and shutdown. The amplifiers include thermal-overload and short-circuit protection. An additional feature of the speaker amplifiers is that there is no phase inversion from input to output. Charge Pump The MAX9787 features a low-noise charge pump. The 550kHz switching frequency is well beyond the audio range, and does not interfere with the audio signals. The switch drivers feature a controlled switching speed that minimizes noise generated by turn-on and turn-off transients. Limiting the switching speed of the charge pump minimizes the di/dt noise caused by the parasitic bond wire and trace inductance. Although not typically IN_ required, additional high-frequency ripple attenuation can be achieved by increasing the size of C2 (see the Typical Operating Circuit). BIAS The MAX9787 features an internally generated, powersupply independent, common-mode bias voltage of 1.8V referenced to GND. BIAS provides both click-and-pop suppression and sets the DC bias level for the amplifiers. Choose the value of the bypass capacitor as described in the BIAS Capacitor section. No external load should be applied to BIAS. Any load lowers the BIAS voltage, affecting the overall performance of the device. Gain Selection The GAIN1 and GAIN2 inputs set the maximum gain of the speaker and amplifiers (Table 1). The gain of the device can vary based upon the voltage at VOL (see the Analog Volume Control section). However, the maximum gain cannot be exceeded. Analog Volume Control (VOL) An analog volume control varies the gain of the device in 31 discrete steps based upon the DC voltage applied to VOL. The input range of VVOL is from 0 (full volume) to 0.858 x PVDD (full mute), with example step sizes shown in Table 2. Connect the reference of the device driving VOL (Figure 2) to PVDD. Since the volume control ADC is ratiometric to PVDD, any changes in Table 1. Gain Settings GAIN2 GAIN1 SPEAKER MODE GAIN (dB) 0 0 6 0 1 7.5 1 0 9 1 1 10.5 OUT_+ BIAS BIAS MAX9787 PVDD VOL VOLUME CONTROL OUT_ BIAS Figure 1. MAX9787 Signal Path VREF DAC VOL Figure 2. Volume Control Circuit _______________________________________________________________________________________ 7 MAX9787 Detailed Description MAX9787 2.2W Stereo Audio Power Amplifier with Analog Volume Control Table 2. Volume Levels VVOL (V) SPEAKER MODE GAIN (dB) VMIN* VTYP* VMAX* GAIN1 = 0, GAIN2 = 0 GAIN1 = 1, GAIN2 = 0 GAIN1 = 0, GAIN2 = 1 GAIN1 = 1, GAIN2 = 1 10.5 0 0.370 0.742 6 7.5 9 0.742 0.800 0.860 5 7 8.5 10 0.860 0.915 0.977 4 6 8 9.5 0.977 1.035 1.094 3 5 7.5 9 1.094 1.150 1.211 1 4 7 8.5 1.211 1.265 1.328 -1 3 6 8 1.328 1.385 1.446 -3 1 5 7.5 1.446 1.500 1.563 -5 -1 4 7 1.563 1.620 1.680 -7 -3 3 6 1.680 1.735 1.797 -9 -5 1 5 1.797 1.855 1.914 -11 -7 -1 4 1.914 1.970 2.032 -13 -9 -3 3 2.032 2.090 2.149 -15 -11 -5 1 2.149 2.205 2.266 -17 -13 -7 -1 2.266 2.320 2.383 -19 -15 -9 -3 2.383 2.440 2.500 -21 -17 -11 -5 2.500 2.555 2.617 -23 -19 -13 -7 2.617 2.675 2.735 -25 -21 -15 -9 2.735 2.790 2.852 -27 -23 -17 -11 2.852 2.910 2.969 -29 -25 -9 -13 2.969 3.025 3.086 -31 -27 -21 -15 3.086 3.140 3.203 -33 -29 -23 -17 3.203 3.260 3.321 -35 -31 -2 -19 3.321 3.375 3.438 -37 -3 -27 -21 3.438 3.495 3.555 -41 -35 -29 -23 3.555 3.610 3.672 -45 -37 -31 -25 3.672 3.730 3.789 -48 -41 -33 -27 3.789 3.845 3.907 -53 -45 -35 -29 3.907 3.965 4.024 -57 -49 -37 -31 4.024 4.080 4.141 -61 -53 -41 -33 4.141 4.195 4.258 -65 -57 -45 -35 4.258 4.290 5.000 MUTE MUTE MUTE MUTE *Based on PVDD = 5V 8 _______________________________________________________________________________________ 2.2W Stereo Audio Power Amplifier with Analog Volume Control roughly the amplitude of VBEEP(OUT) times the gain of the selected signal path. The input resistor (RB) sets the gain of the BEEP input amplifier, and thus the amplitude of V BEEP(OUT) . Choose RB based on: BEEP Input An audible alert beep input (BEEP) accepts a mono system alert signal and mixes it into the stereo audio path. When the amplitude of V BEEP(OUT) exceeds 800mVP-P (Figure 4) and the frequency of the beep signal is greater than 400Hz, the beep signal is mixed into the active audio path (speaker or headphone). If the signal at VBEEP(OUT) is either < 800mVP-P or <400Hz, the BEEP signal is not mixed into the audio path. The amplitude of the BEEP signal at the device output is VOLUME CONTROL TRANSFER FUNCTION RB ≤ VIN x RINT 0.3 where RINT is the value of the BEEP amplifier feedback resistor (47kΩ) and VIN is the BEEP input amplitude. Note that the BEEP amplifier can be set up as either an attenuator, if the original alert signal amplitude is too large, or set to gain up the alert signal if it is below 800mVP-P. AC-couple the alert signal to BEEP. Choose the value of the coupling capacitor as described in the Input Filtering section. Multiple beep inputs can be summed (Figure 4). Shutdown 20 GAIN1 = GAIN2 = 0 10 0 AUDIO TAPER POT -10 GAIN (dB) The MAX9787 features a 0.2µA, low-power shutdown mode that reduces quiescent current consumption and extends battery life. Driving SHDN low disables the drive amplifiers, bias circuitry, and charge pump, and drives BIAS and all outputs to GND. Connect SHDN to VDD for normal operation. -20 -30 -40 MAX9787 Click-and-Pop Suppression -50 The MAX9787 speaker amplifiers feature Maxim’s comprehensive, industry-leading click-and-pop suppression. During startup, the click-and-pop suppression circuitry eliminates any audible transient sources internal to the device. When entering shutdown, both amplifier outputs ramp to GND quickly and simultaneously. -60 -70 -80 0 1 2 3 4 5 VVOL (V) Figure 3. Volume Control Transfer Function 0.47µF RS1 47kΩ RINT 47kΩ SOURCE 1 0.47µF RS2 47kΩ 0.47µF RS3 47kΩ SOURCE 2 BEEP SOURCE 3 VOUT(BEEP) SPEAKER AMPLIFIER INPUTS WINDOW DETECTOR (0.3VP-P THRESHOLD) BIAS FREQUENCY DETECTOR (300Hz THRESHOLD) MAX9787 Figure 4. Beep Input _______________________________________________________________________________________ 9 MAX9787 PVDD are negated. The gain step sizes are not constant; the step sizes are 0.5dB/step at the upper extreme, 2dB/step in the midrange, and 4dB/step at the lower extreme. Figure 3 shows the transfer function of the volume control for a 5V supply. Applications Information BTL Speaker Amplifiers The MAX9787 features speaker amplifiers designed to drive a load differentially, a configuration referred to as bridge-tied load (BTL). The BTL configuration (Figure 5) offers advantages over the single-ended configuration, where one side of the load is connected to ground. Driving the load differentially doubles the output voltage compared to a single-ended amplifier under similar conditions. Thus, the device’s differential gain is twice the closed-loop gain of the input amplifier. The effective gain is given by: A VD = 2 × RF RIN Substituting 2 X VOUT(P-P) into the following equation yields four times the output power due to double the output voltage: VRMS = VOUT(P−P) 2 2 2 V POUT = RMS RL Power Dissipation and Heat Sinking Under normal operating conditions, the MAX9787 can dissipate a significant amount of power. The maximum power dissipation for each package is given in the Absolute Maximum Ratings 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 oC/W as specified in the Absolute Maximum Ratings section. For example, θJA of the TQFN package is +42oC/W. For optimum power dissipation, the exposed paddle of the package should be connected to the ground plane (see the Layout and Grounding section). For 8Ω applications, the worst-case power dissipation occurs when the output power is 1.1W/channel, resulting in a power dissipation of about 1W. In this case, the TQFN packages can be used without violating the maximum power dissipation or exceeding the thermal protection threshold. Output Power Since the differential outputs are biased at midsupply, there is no net DC voltage across the load. This eliminates the need for DC-blocking capacitors required for single-ended amplifiers. These capacitors can be large and expensive, can consume board space, and can degrade low-frequency performance. The increase in power delivered by the BTL configuration directly results in an increase in internal power dissipation over the single-ended configuration. If the power dissipation for a given application exceeds the maximum allowed for a given package, either reduce VDD, increase load impedance, decrease the ambient temperature, or add heatsinking to the device. Large output, supply, and ground PC board traces improve the maximum power dissipation in the package. 1000 VDD = 5V RL = 16Ω AV = 3dB 100 +1 VOUT(P-P) 2 x VOUT(P-P) 10 THD+N (%) MAX9787 2.2W Stereo Audio Power Amplifier with Analog Volume Control OUTPUTS IN PHASE 1 0.1 -1 VOUT(P-P) 0.01 OUTPUTS 180° OUT OF PHASE 0.001 0 25 50 75 100 125 150 OUTPUT POWER (mW) Figure 5. Bridge-Tied Load Configuration 10 Figure 6. Total Harmonic Distortion Plus Noise vs. Output Power with Inputs In/Out of Phase ______________________________________________________________________________________ 2.2W Stereo Audio Power Amplifier with Analog Volume Control PHONE FAX Taiyo Yuden SUPPLIER 800-348-2496 847-925-0899 www.t-yuden.com TDK 807-803-6100 847-390-4405 www.component.tdk.com Thermal-overload protection limits total power dissipation in these devices. When the junction temperature exceeds +160°C, the thermal-protection circuitry disables the amplifier output stage. The amplifiers are enabled once the junction temperature cools by 15°C. This results in a pulsing output under continuous thermal-overload conditions as the device heats and cools. Power Supplies The MAX9787 speaker amplifiers are powered from PVDD. PVDD ranges from 4.5V to 5.5V. VSS is the negative supply of the amplifiers. Connect VSS to CPVSS. The charge pump is powered by CPVDD. CPVDD should be the same potential as PVDD. The charge pump inverts the voltage at CPV DD , and the resulting voltage appears at CPVSS. The remainder of the device is powered by VDD. Component Selection Input Filtering The input capacitor (CIN), in conjunction with the amplifier input resistance (RIN), forms a highpass filter that removes the DC bias from an incoming signal (see the Typical Operating Circuit). The AC-coupling capacitor allows the amplifier to bias the signal to an optimum DC level. Assuming zero source impedance, the -3dB point of the highpass filter is given by: f−3dB = 1 2πRINCIN R IN is the amplifier’s internal input resistance value given in the Electrical Characteristics. Choose CIN such that f-3dB is well below the lowest frequency of interest. Setting f-3dB too high affects the amplifier’s low-frequency response. Use capacitors with low-voltage coefficient dielectrics, such as tantalum or aluminum electrolytic. Capacitors with high-voltage coefficients, such as ceramics, may result in increased distortion at low frequencies. WEBSITE BIAS Capacitor BIAS is the output of the internally generated DC bias voltage. The BIAS bypass capacitor, CBIAS, improves PSRR and THD+N by reducing power supply and other noise sources at the common-mode bias node, and also generates the clickless/popless, startup/shutdown DC bias waveforms for the speaker amplifiers. Bypass BIAS with a 1µF capacitor to GND. Charge-Pump Capacitor Selection 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. Table 4 lists suggested manufacturers. Flying Capacitor (C1) The value of the flying capacitor (C1) affects the load regulation and output resistance of the charge pump. 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. Charge-Pump Capacitance and Load Resistance graph in the Typical Operating Characteristics. Above 2.2µF, the on-resistance of the switches and the ESR of C1 and C2 dominate. Output Capacitor (C2) The output capacitor value and ESR directly affect the ripple at CPVSS. 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. Charge-Pump Capacitance and Load Resistance graph in the Typical Operating Characteristics. ______________________________________________________________________________________ 11 MAX9787 Table 3. Suggested Capacitor Manufacturers MAX9787 2.2W Stereo Audio Power Amplifier with Analog Volume Control CPVDD Bypass Capacitor The CPVDD bypass capacitor (C3) lowers the output impedance of the power supply and reduces the impact of the MAX9787’s charge-pump switching transients. Bypass CPVDD with C3, the same value as C1, and place it physically close to the CPVDD and PGND (refer to the MAX9750 Evaluation Kit for a suggested layout). Powering Other Circuits from a Negative Supply An additional benefit of the MAX9787 is the internally generated negative supply voltage (CPVSS). CPVSS provides the negative supply for the amplifiers. It can also be used to power other devices within a design. Current draw from CPV SS should be limited to 5mA; exceeding this affects the operation of the amplifier. A typical application is a negative supply to adjust the contrast of LCD modules. When considering the use of CPVSS in this manner, note that the charge-pump voltage of CPVSS is roughly proportional to PVDD and is not a regulated voltage. The charge-pump output impedance plot appears in the Typical Operating Characteristics. Layout and Grounding Proper layout and grounding are essential for optimum performance. Use large traces for the power-supply inputs and amplifier outputs to minimize losses due to parasitic trace resistance, as well as route head away from the device. Good grounding improves audio performance, minimizes crosstalk between channels, and prevents any switching noise from coupling into the 12 audio signal. Connect CPGND, PGND, and GND together at a single point on the PC board. Route CPGND and all traces that carry switching transients away from GND, PGND, and the traces and components in the audio signal path. Connect all components associated with the charge pump (C2 and C3) to the CPGND plane. Connect VSS and CPVSS together at the device. Place the chargepump capacitors (C1, C2, and C3) as close to the device as possible. Bypass PVDD with a 0.1µF capacitor to GND. Place the bypass capacitors as close to the device as possible. Use large, low-resistance output traces. As load impedance decreases, the current drawn from the device outputs increase. At higher current, the resistance of the output traces decrease the power delivered to the load. For example, when compared to a 0Ω trace, a 100mΩ trace reduces the power delivered to a 4Ω load from 2.1W to 2W. Large output, supply, and GND traces also improve the power dissipation of the device. The MAX9787 thin QFN features and exposed thermal pad on its underside. This pad lowers the package’s thermal resistance by providing a direct heat conduction path from the die to the PC board. Connect the exposed thermal pad to GND by using a large pad and multiple vias to the GND plane. Chip Information TRANSISTOR COUNT: 9591 PROCESS: BiCMOS ______________________________________________________________________________________ 2.2W Stereo Audio Power Amplifier with Analog Volume Control 4.5V TO 5.5V 0.1µF VDD 25 6, 15, 16 PVDD MAX9787 CIN 1µF LEFT-CHANNEL AUDIO INPUT CIN 1µF RIGHT-CHANNEL AUDIO INPUT INL 1 INR 27 4.5V TO 5.5V 0.1µF 4 OUTL+ GAIN/ VOLUME CONTROL BTL AMPLIFIER GAIN/ VOLUME CONTROL BTL AMPLIFIER 5 OUTL- 18 OUTR+ 17 OUTR- BIAS 21 CBIAS 1µF VOL 28 VDD GAIN1 24 VDD GAIN2 23 1µF 47kΩ BEEP 2 VDD SHDN 22 GAIN/ VOLUME CONTROL HEADPHONE DETECTION BEEP DETECTION SHUTDOWN CONTROL CPVDD 7 3V TO 5.5V 1µF C1P 8 C1 1µF 10 CHARGE PUMP C1N CPGND 9 11 CPVSS 12 VSS C2 1µF 20, 26 GND 3, 19 PGND ______________________________________________________________________________________ 13 MAX9787 Block Diagram Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) QFN THIN.EPS MAX9787 2.2W Stereo Audio Power Amplifier with Analog Volume Control D2 D MARKING b CL 0.10 M C A B D2/2 D/2 k L AAAAA E/2 E2/2 CL (NE-1) X e E DETAIL A PIN # 1 I.D. E2 PIN # 1 I.D. 0.35x45° e/2 e (ND-1) X e DETAIL B e L1 L CL CL L L e e 0.10 C A C 0.08 C A1 A3 PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm -DRAWING NOT TO SCALE- 14 21-0140 ______________________________________________________________________________________ I 1 2 2.2W Stereo Audio Power Amplifier with Analog Volume Control COMMON DIMENSIONS EXPOSED PAD VARIATIONS PKG. 16L 5x5 20L 5x5 28L 5x5 32L 5x5 40L 5x5 SYMBOL MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. MIN. NOM. MAX. A A1 A3 b D E e 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0.70 0.75 0.80 0 0.02 0.05 0 0.02 0.05 0 0.02 0.05 0 0.02 0.05 0 0.02 0.05 0.20 REF. 0.20 REF. 0.20 REF. 0.20 REF. 0.20 REF. 0.25 0.30 0.35 0.25 0.30 0.35 0.20 0.25 0.30 0.20 0.25 0.30 0.15 0.20 0.25 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 4.90 5.00 5.10 0.65 BSC. 0.50 BSC. 0.50 BSC. 0.40 BSC. 0.80 BSC. - 0.25 - 0.25 - 0.25 0.35 0.45 0.25 - 0.25 0.30 0.40 0.50 0.45 0.55 0.65 0.45 0.55 0.65 0.30 0.40 0.50 0.40 0.50 0.60 L1 0.30 0.40 0.50 40 N 20 28 32 16 ND 10 5 7 8 4 10 5 7 8 4 NE ----WHHC WHHD-1 WHHD-2 WHHB JEDEC k L NOTES: 1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994. 2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES. 3. N IS THE TOTAL NUMBER OF TERMINALS. PKG. CODES E2 exceptions MIN. NOM. MAX. ±0.15 T1655-2 3.00 T1655-3 3.00 T1655N-1 3.00 T2055-3 3.00 3.00 T2055-4 T2055-5 3.15 T2855-3 3.15 T2855-4 2.60 T2855-5 2.60 3.15 T2855-6 T2855-7 2.60 T2855-8 3.15 T2855N-1 3.15 T3255-3 3.00 T3255-4 3.00 T3255-5 3.00 T3255N-1 3.00 T4055-1 3.20 4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE. L D2 MIN. NOM. MAX. 3.10 3.10 3.10 3.10 3.10 3.25 3.25 2.70 2.70 3.25 2.70 3.25 3.25 3.10 3.10 3.10 3.10 3.30 3.20 3.20 3.20 3.20 3.20 3.35 3.35 2.80 2.80 3.35 2.80 3.35 3.35 3.20 3.20 3.20 3.20 3.40 3.00 3.00 3.00 3.00 3.00 3.15 3.15 2.60 2.60 3.15 2.60 3.15 3.15 3 3.00 3 3.00 3.00 3.00 3.20 3.10 3.10 3.10 3.10 3.10 3.25 3.25 2.70 2.70 3.25 2.70 3.25 3.25 3.10 3.10 3.10 3.10 3.30 3.20 3.20 3.20 3.20 3.20 3.35 3.35 2.80 2.80 3.35 2.80 3.35 3.35 .20 .20 3.20 3.20 3.40 ** ** ** ** ** 0.40 ** ** ** ** ** 0.40 ** ** ** ** ** ** DOWN BONDS ALLOWED YES NO NO YES NO YES YES YES NO NO YES YES NO YES NO YES NO YES ** SEE COMMON DIMENSIONS TABLE 5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.25 mm AND 0.30 mm FROM TERMINAL TIP. 6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY. 7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION. 8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS. 9. DRAWING CONFORMS TO JEDEC MO220, EXCEPT EXPOSED PAD DIMENSION FOR T2855-3 AND T2855-6. 10. WARPAGE SHALL NOT EXCEED 0.10 mm. 11. MARKING IS FOR PACKAGE ORIENTATION REFERENCE ONLY. 12. NUMBER OF LEADS SHOWN ARE FOR REFERENCE ONLY. 13. LEAD CENTERLINES TO BE AT TRUE POSITION AS DEFINED BY BASIC DIMENSION "e", ±0.05. -DRAWING NOT TO SCALE- PACKAGE OUTLINE, 16, 20, 28, 32, 40L THIN QFN, 5x5x0.8mm 21-0140 I 2 2 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 ____________________ 15 © 2005 Maxim Integrated Products Heaney Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX9787 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)