19-0710; Rev 1; 11/07 KIT ATION EVALU E L B AVAILA 14VP-P, Class G Ceramic Speaker Driver Features The MAX9788 features a mono Class G power amplifier with an integrated inverting charge-pump power supply specifically designed to drive the high capacitance of a ceramic loudspeaker. The charge pump can supply greater than 700mA of peak output current at 5.5VDC, guaranteeing an output of 14VP-P. The MAX9788 maximizes battery life by offering highperformance efficiency. Maxim’s proprietary Class G output stage provides efficiency levels greater than Class AB devices without the EMI penalties commonly associated with Class D amplifiers. The MAX9788 is ideally suited to deliver the high output-voltage swing required to drive ceramic/piezoelectric speakers. The device utilizes fully differential inputs and outputs, comprehensive click-and-pop suppression, shutdown control, and soft-start circuitry. The MAX9788 is fully specified over the -40°C to +85°C extended temperature range and is available in small lead-free 28-pin TQFN (4mm x 4mm) or 20-bump UCSP™ (2mm x 2.5mm) packages. o Integrated Charge-Pump Power Supply—No Inductor Required o 14VP-P Voltage Swing into Piezoelectric Speaker o 2.7V to 5.5V Single-Supply Operation o Clickless/Popless Operation o Small Thermally Efficient Packages 4mm x 4mm 28-Pin TQFN 2mm x 2.5mm 20-Bump UCSP Ordering Information PART MAX9788EBP+T* -40°C to +85°C 20 UCSP-20 MAX9788ETI+ -40°C to +85°C 28 TQFN-EP** PKG CODE B20-7 T2844-1 Typical Application Circuit/Functional Diagram and Pin Configurations appear at end of data sheet. Personal Media Players Handheld Gaming Consoles MP3 Players PINPACKAGE +Denotes lead-free package. T = Tape and reel. *Future product—contact factory for availability. **EP = Exposed pad. Applications Cell Phones Smartphones TEMP RANGE UCSP is a trademark of Maxim Integrated Products, Inc. Notebook Computers Simplified Block Diagram 2.7V TO 5.5V VCC CPVDD FB+ MAX9788 CIN RIN+ RFB+ IN+ IN- CIN RIN- CLASS G OUTPUT STAGE + - OUT+ OUT- RFBCHARGE PUMP FBGND CPGND ________________________________________________________________ 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 MAX9788 General Description MAX9788 14VP-P, Class G Ceramic Speaker Driver ABSOLUTE MAXIMUM RATINGS (Voltages with respect to GND.) VCC, CPVDD .............................................................-0.3V to +6V PVSS, SVSS ...............................................................-6V to +0.3V CPGND..................................................................-0.3V to +0.3V OUT+, OUT-...................................(SVSS - 0.3V) to (VCC + 0.3V) IN+, IN-, FB+, FB- ......................................-0.3V to (VCC + 0.3V) C1N .........................................(PVSS - 0.3V) to (CPGND + 0.3V) C1P ......................................(CPGND - 0.3V) to (CPVDD + 0.3V) FS, SHDN ...................................................-0.3V to (VCC + 0.3V) Continuous Current Into/Out of OUT+, OUT-, VCC, GND, SVSS .....................................800mA CPVDD, CPGND, C1P, C1N, PVSS .................................800mA Any Other Pin ..................................................................20mA Continuous Power Dissipation (TA = +70°C) 20-Bump UCSP (derate 10.3mW/°C above +70°C) .....827mW 28-Pin TQFN (derate 20.8mW/°C above +70°C) ........1667mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) ................................+300°C Bump Temperature (soldering) Reflow............................+235°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 (VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 = 10µF; load connected between OUT+ and OUT-, ZLOAD = 10Ω + 1µF, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 5.5 V GENERAL Supply Voltage Range VCC Quiescent Current ICC Shutdown Current ISHDN Turn-On Time tON Input DC Bias Voltage VBIAS Charge-Pump Oscillator Frequency fOSC SHDN Input Threshold (Note 4) Inferred from PSRR test 2.7 8 12 mA SHDN = GND 0.3 5 µA Time from shutdown or power-on to full operation 50 ms IN_ inputs (Note 3) 1.1 1.24 1.4 ILOAD = 0mA (slow mode) 55 83 110 ILOAD > 100mA (normal mode) 230 330 470 VIH 1.4 V kHz VIL 0.4 SHDN Input Leakage Current ±1 V µA SPEAKER AMPLIFIER TA = +25°C ±3 Output Offset Voltage VOS Click-and-Pop Level VCP Peak voltage into/out of shutdown A-weighted, 32 samples per second (Notes 5, 6) Voltage Gain AV (Notes 3, 7) Output Voltage 2 VOUT TMIN ≤ TA ≤ TMAX f = 1kHz, 1% THD+N ±15 ±20 -67 11.5 12 VCC = 5V 7.1 VCC = 4.2V 5.9 VCC = 3.6V 5.1 VCC = 3.0V 4.2 _______________________________________________________________________________________ mV dBV 12.5 dB VRMS 14VP-P, Class G Ceramic Speaker Driver (VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 = 10µF; load connected between OUT+ and OUT-, ZLOAD = 10Ω + 1µF, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) PARAMETER Output Voltage SYMBOL VOUT Continuous Output Power POUT CONDITIONS f = 10kHz, 1% THD+N, ZL = 1µF + 10Ω, no load 1% THD+N, f = 1kHz, RL = 8Ω PSRR 6.5 VCC = 4.2V 5.4 VCC = 3.6V 4.7 VCC = 3.0V 3.3 VCC = 5V 2.4 VCC = 4.2V 1.67 VCC = 3.6V 1.25 VCC = 3.0V 0.8 63 Signal-to-Noise Ratio Common-Mode Rejection Ratio Dynamic Range Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: Note 9: THD+N SNR CMRR DR MAX UNITS VRMS W 77 f = 217Hz, 200mVP-P ripple 77 f = 1kHz, 200mVP-P ripple 77 f = 20kHz, 200mVP-P ripple Total Harmonic Distortion Plus Noise TYP VCC = 5V VCC = 2.7V to 5.5V Power-Supply Rejection Ratio (Note 3) MIN dB 58 ZL = 1µF + 10Ω, VOUT = 1kHz / 1.9VRMS 0.002 ZL = 1µF + 10Ω, VOUT = 1kHz / 4.0VRMS 0.08 VOUT = 5.1VRMS, A-weighted 108 dB 68 dB fIN = 1kHz (Note 8) A-weighted (Note 9) VCC = 5V 106 VCC = 3.6V 105 % dB All devices are 100% production tested at room temperature. All temperature limits are guaranteed by design. Testing performed with resistive and capacitive loads to simulate an actual ceramic/piezoelectric speaker load, ZL = 1µF + 10Ω. Input DC bias voltage determines the maximum voltage swing of the input signal. Inputing a signal with a peak voltage of greater than the input DC bias voltage results in clipping. 1.8V logic compatible. Amplifier/inputs AC-coupled to GND. Testing performed at room temperature with 10Ω resistive load in series with 1µF capacitive load connected across the BTL output for speaker amplifier. Mode transitions are controlled by SHDN. VCP is the peak output transient expressed in dBV. Voltage gain is defined as: [VOUT+ - VOUT-] / [VIN+ - VIN-]. PVSS is forced to -3.6V to simulate boosted rail. Dynamic range is calculated by measuring the RMS voltage difference between a -60dBFS output signal and the noise floor, then adding 60dB. Full scale is defined as the output signal needed to achieve 1% THD+N. RIN_ and RFB_ have 0.5% tolerance. The Class G output stage has 12dB of gain. Any gain or attenuation at the input stage will add to or subtract from the gain of the Class G output. _______________________________________________________________________________________ 3 MAX9788 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 = 10µF, ZL = 1µF + 10Ω; load terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY VCC = 2.7V VCC = 3.6V 0.1 VOUT = 1.25VRMS THD+N (%) THD+N (%) 0.1 VOUT = 1.9VRMS 0.01 0.001 0.001 100 1k 10k 100 1k 10k 100k 10 1k 10k 100k FREQUENCY (Hz) TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE fIN = 10kHz THD+N (%) 1 fIN = 1kHz 0.1 0.01 10 VCC = 5V 0.1 fIN = 20Hz fIN = 20Hz 0.001 0.001 3 0.1 fIN = 20Hz 0.001 2 fIN = 1kHz 0.01 0.01 1 fIN = 10kHz 1 fIN = 1kHz MAX9788 toc06 VCC = 3.6V THD+N (%) MAX9788 toc04 10 fIN = 10kHz 4 5 0 1 2 3 4 5 0 6 1 2 3 4 5 6 OUTPUT VOLTAGE (VRMS) OUTPUT VOLTAGE (VRMS) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY POWER CONSUMPTION vs. OUTPUT VOLTAGE POWER CONSUMPTION vs. OUTPUT VOLTAGE -30 -40 -50 -60 -70 75 50 25 VCC = 2.7V fIN = 1kHz 1% THD+N -80 -90 1k FREQUENCY (Hz) 10k 100k 8 200 175 150 125 100 75 50 VCC = 3.6V fIN = 1kHz 1% THD+N 25 0 100 7 MAX9788 toc09 -20 MAX9788 toc08 -10 100 POWER CONSUMPTION (mW) VRIPPLE = 200mVP-P MAX9788 toc07 OUTPUT VOLTAGE (VRMS) 0 10 100 FREQUENCY (Hz) VCC = 2.7V 0 VOUT = 3VRMS FREQUENCY (Hz) 10 1 0.1 0.001 10 100k MAX9788 toc05 10 VOUT = 5.9VRMS 0.01 POWER CONSUMPTION (mW) THD+N (%) 1 VOUT = 4VRMS VOUT = 3VRMS 0.01 THD+N (%) VCC = 5V 1 1 4 10 MAX9788 toc02 10 MAX9788 toc01 10 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY MAX9788 toc03 TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY PSRR (dB) MAX9788 14VP-P, Class G Ceramic Speaker Driver 0 0 1 2 3 OUTPUT VOLTAGE (VRMS) 4 0 1 2 3 4 OUTPUT VOLTAGE (VRMS) _______________________________________________________________________________________ 5 14VP-P, Class G Ceramic Speaker Driver (VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 = 10µF, ZL = 1µF + 10Ω; load terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) POWER CONSUMPTION vs. OUTPUT VOLTAGE MAX9788 toc12 MAX9788 toc11 MAX9788 toc10 300 SHDN 5V/div SHDN 5V/div OUT+ - OUT500mV/div OUT+ - OUT500mV/div 250 200 150 100 VCC = 5V fIN = 1kHz 1% THD+N 50 0 1 2 3 4 5 7 6 10ms/div 10ms/div OUTPUT VOLTAGE (VRMS) SUPPLY CURRENT vs. SUPPLY VOLTAGE CLASS G OUTPUT WAVEFORM MAX9788 toc13 MAX9788 toc14 12 10 SUPPLY CURRENT (mA) OUT+ 5V/div OUT5V/div OUT+ - OUT10V/div 8 6 4 2 1% THD+N 0 2.5 200μs/div 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V) SHUTDOWN CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. OUTPUT VOLTAGE 0.9 70 60 SUPPLY CURRENT (mA) 0.8 0.7 0.6 0.5 0.4 0.3 MAX9788 toc16 1.0 MAX9788 toc15 0 SHUTDOWN CURRENT (μA) POWER CONSUMPTION (mW) SHUTDOWN WAVEFORM STARTUP WAVEFORM 350 50 40 30 20 0.2 VCC = 5V fIN = 1kHz 10 0.1 0 0 2.5 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) 5.5 6.0 0 1 2 3 4 5 6 7 OUTPUT VOLTAGE (VRMS) _______________________________________________________________________________________ 5 MAX9788 Typical Operating Characteristics (continued) Typical Operating Characteristics (continued) (VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10kΩ, RFB+ = RFB- = 10kΩ, RFS = 100kΩ, C1 = 4.7µF, C2 = 10µF, ZL = 1µF + 10Ω; load terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 2) OUTPUT AMPLITUDE vs. FREQUENCY MAX9788 toc17 VCC = 5V 7 VCC = 3.6V 6 20 VOUT = 2VRMS 18 16 MAX9788 toc18 FREQUENCY RESPONSE 8 14 5 GAIN (dB) OUTPUT AMPLITUDE (VRMS) MAX9788 14VP-P, Class G Ceramic Speaker Driver 4 3 12 10 VCC = 2.7V 8 6 2 4 1 2 0 0 10 100 1k 10k 10 100k 100 1k 10k 100k FREQUENCY (Hz) FREQUENCY (Hz) Pin Description PIN 6 NAME FUNCTION TQFN UCSP 1 B2 SHDN 2, 5, 6, 8, 11, 17, 19, 23, 25, 28 — N.C. No Connection. No internal connection. 3 A2 C1P Charge-Pump Flying Capacitor, Positive Terminal. Connect a 4.7µF capacitor between C1P and C1N. 4 A3 CPVDD Charge-Pump Positive Supply 7 A4 FB- Negative Amplifier Feedback 9 A5 IN- Negative Amplifier Input 10 B5 IN+ Positive Amplifier Input 12 B4 FB+ Shutdown Positive Amplifier Feedback Charge-Pump Frequency Set. Connect a 100kΩ resistor from FS to GND to set the charge-pump switching frequency. 13 C5 FS 14, 22 D1, D5 VCC Supply Voltage. Bypass with a 10µF capacitor to GND. 15, 21 C2, C4 SVSS Amplifier Negative Power Supply. Connect to PVSS. 16 D4 OUT- Negative Amplifier Output 18 D3 GND Ground 20 D2 OUT+ Positive Amplifier Output 24 C1 PVSS Charge-Pump Output. Connect a 10µF capacitor between PVSS and CPGND. 26 B1 C1N Charge-Pump Flying Capacitor, Negative Terminal. Connect a 4.7µF capacitor between C1N and C1P. 27 A1 CPGND EP — EP Charge-Pump Ground. Connect to GND. Exposed Pad. Connect the TQFN EP to GND. _______________________________________________________________________________________ 14VP-P, Class G Ceramic Speaker Driver As the output signal increases so a wider supply is needed, the device begins its transition to the higher supply range (VCC to SVSS) for the large signals. To ensure a seamless transition between the low and high supply ranges, both of the lower transistors are on so that: ILOAD = IN1 + IN2 As the output signal continues to increase, the transition to the high supply is complete. The device then operates in the higher supply range, where the operation of the device is identical to a traditional dual-supply Class AB amplifier where: ILOAD = IN2 During operation, the output common-mode voltage of the MAX9788 adjusts dynamically as the device transitions between supply ranges. Utilizing a Class G output stage with an inverting charge pump allows the MAX9788 to realize a 20VP-P output swing with a 5V supply. The MAX9788 Class G power amplifier with inverting charge pump is the latest in linear amplifier technology. The Class G output stage offers improved performance over a Class AB amplifier while increasing efficiency to extend battery life. The integrated inverting charge pump generates a negative supply capable of delivering greater than 700mA. The Class G output stage and the inverting charge pump allow the MAX9788 to deliver a 14VP-P voltage swing, up to two times greater than a traditional singlesupply linear amplifier. Class G Operation The MAX9788 Class G amplifier is a linear amplifier that operates within a low (VCC to GND) and high (VCC to SVSS) supply range. Figure 1 illustrates the transition from the low to high supply range. For small signals, the device operates within the lower (VCC to GND) supply range. In this range, the operation of the device is identical to a traditional single-supply Class AB amplifier where: ILOAD = IN1 BTL CLASS G SUPPLY TRANSITION VCC VCC IP ON P VCC IP ON ZL IN1 N1 ON N2 OFF P IP ON ZL IN1 IN2 N1 ON N2 ON P ZL IN2 N1 OFF N2 ON SVSS SVSS SVSS LOW SUPPLY RANGE OPERATION IP = IN1 SUPPLY TRANSITION IP = IN1 + IN2 HIGH SUPPLY RANGE OPERATION IP = IN2 Figure 1. Class G Supply Transition _______________________________________________________________________________________ 7 MAX9788 Detailed Description MAX9788 14VP-P, Class G Ceramic Speaker Driver Inverting Charge Pump The MAX9788 features an integrated charge pump with an inverted supply rail that can supply greater than 700mA over the positive 2.7V to 5.5V supply range. In the case of the MAX9788, the charge pump generates the negative supply rail (PVSS) needed to create the higher supply range, which allows the output of the device to operate over a greater dynamic range as the battery supply collapses over time. Shutdown Mode The MAX9788 has a shutdown mode that reduces power consumption and extends battery life. Driving SHDN low places the MAX9788 in a low-power (0.3µA) shutdown mode. Connect SHDN to V CC for normal operation. Click-and-Pop Suppression where AV is the desired voltage gain in dB. RIN+ should be equal to RIN-, and RFB+ should be equal to RFB-. The Class G output stage has a fixed gain of 4V/V (12dB). Any gain or attenuation set by the external input stage resistors will add to or subtract from this fixed gain. See Figure 2. In differential input configurations, the common-mode rejection ratio (CMRR) is primarily limited by the external resistor and capacitor matching. Ideally, to achieve the highest possible CMRR, the following external components should be selected where: RFB + RFB − = RIN+ RIN− and The MAX9788 Class G amplifier features 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. CIN+ = CIN− Applications Information MAX9788 FB+ Differential Input Amplifier The MAX9788 features a differential input configuration, making the device compatible with many CODECs, and offering improved noise immunity over a single-ended input amplifier. In devices such as PCs, noisy digital signals can be picked up by the amplifier’s input traces. The signals appear at the amplifier’s inputs as common-mode noise. A differential input amplifier amplifies the difference of the two inputs and signals common to both inputs are canceled out. When configured for differential inputs, the voltage gain of the MAX9788 is set by: ⎡ ⎛ RFB _ ⎞ ⎤ A V = 20 log⎢4 × ⎜ ⎟ ⎥ (dB) ⎢⎣ ⎝ RIN _ ⎠ ⎥⎦ 8 RFB+ CIN+ RIN+ IN+ IN- CIN- + - RINRFB- FB- Figure 2. Gain Setting _______________________________________________________________________________________ CLASS G OUTPUT STAGE 14VP-P, Class G Ceramic Speaker Driver Component Selection Input-Coupling Capacitor The AC-coupling capacitors (CIN_) and input resistors (RIN_) form highpass filters that remove any DC bias from an input signal (see the Functional Diagram/ Typical Operating Circuit). CIN_ blocks DC voltages from the amplifier input. The -3dB point of the highpass filter, assuming zero source impedance due to the input signal source, is given by: The MAX9788 is ideal for driving a capacitive ceramic speaker. The high charge-pump current limit allows for a flat frequency response out to 20kHz while maintaining high output voltage swings. See the Frequency Response graph in the Typical Operating Characteristics. Figure 3 shows a typical circuit for driving a ceramic speaker. A 10Ω series resistance is recommended between the amplifier output and the ceramic speaker load to ensure the output of the amplifier sees some fixed resistance at high frequencies when the speaker is essentially an electrical short. MAX9788 OUT+ CLASS G OUTPUT STAGE OUT- RL f−3dB = 1 (Hz) 2π × RIN _ × CIN _ Ceramic speakers generally perform best at frequencies greater than 1kHz. Low frequencies can deflect the piezoelectric speaker element so that high frequencies cannot be properly reproduced. This can cause distortion in the speaker’s usable frequency band. Select a CIN so the f-3dB closely matches the low frequency response of the ceramic speaker. Use capacitors with low-voltage coefficient dielectrics. Aluminum electrolytic, tantalum, or film dielectric capacitors are good choices for AC-coupling capacitors. Capacitors with high-voltage coefficients, such as ceramics (nonC0G dielectrics), can result in increased distortion at low frequencies. Charge-Pump Capacitor Selection Use capacitors with an ESR less than 50mΩ 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. 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. Increasing the value of C1 improves load regulation and reduces the chargepump output resistance to an extent. Above 1µF, the onresistance of the switches and the ESR of C1 and C2 dominate. A 4.7µF capacitor is recommended. Figure 3. Driving a Ceramic Speaker _______________________________________________________________________________________ 9 MAX9788 Driving a Ceramic Speaker Applications that require thin cases, such as today’s mobile phones, demand that external components have a small form factor. Dynamic loudspeakers that use a cone and voice coil typically cannot conform to the height requirements. The option for these applications is to use a ceramic/piezoelectric loudspeaker. Ceramic speakers are much more capacitive than a conventional loudspeaker. Typical capacitance values for such a speaker can be greater than 1µF. High peak-topeak voltage drive is required to achieve acceptable sound pressure levels. The high output voltage requirement coupled with the capacitive nature of the speaker demand that the amplifier supply much more current at high frequencies than at lower frequencies. Above 10kHz, the typical speaker impedance can be less than 16Ω. Hold Capacitor (C2) The output capacitor value and ESR directly affect the ripple at PVSS. Increasing C2 reduces output ripple. Likewise, decreasing the ESR of C2 reduces both ripple and output resistance. A 10µF capacitor is recommended. Charge-Pump Frequency Set Resistor (RFS) The charge pump operates in two modes. When the charge pump is loaded below 100mA, it operates in a slow mode where the oscillation frequency is reduced to 1/4 of its normal operating frequency. Once loaded, the charge-pump oscillation frequency returns to normal operation. In applications where the design may be sensitive to the operating charge-pump oscillation frequency, the value of the external resistor RFS can be changed to adjust the charge-pump oscillation frequency shown in Figure 4. A 100kΩ resistor is recommended. Ceramic Speaker Impedance Characteristics A 1µF capacitor is a good model for the ceramic speaker as it best approximates the impedance of a ceramic speaker over the audio band. When selecting a capacitor to simulate a ceramic speaker, the voltage rating or the capacitor must be equal to or higher than the expected output voltage swing. See Figure 5. Series Load Resistor The capacitive nature of the ceramic speaker results in very low impedances at high frequencies. To prevent the ceramic speaker from shorting the MAX9788 output at high frequencies, a series load resistor must be used. The output load resistor and the ceramic speaker create a lowpass filter. To set the rolloff frequency of the output filter, the approximate capacitance of the speaker must be known. This information can be obtained from bench testing or from the ceramic speaker manufacturer. A series load resistor greater than 10Ω is recommended. Set the lowpass filter cutoff frequency with the following equation: fLP = UCSP Applications Information IMPEDANCE (Ω) 500 450 400 350 300 10k 1k 100 CERAMIC SPEAKER 250 200 50 75 100 125 150 RFS (kΩ) Figure 4. Charge-Pump Oscillation Frequency vs. RFS 10 1μF CAPACITOR 100k MAX9788 fig05 ILOAD > 100mA 550 IMPEDANCE vs. FREQUENCY 1M MAX9788 fig04 600 1 (Hz) 2π × RL × CSPEAKER For the latest application details on UCSP construction, dimensions, tape carrier information, PCB techniques, bump-pad layout, and recommended reflow temperature profile, as well as the latest information on reliability testing results, go to the Maxim website at www.maximic.com/ucsp for the application note, UCSP—A WaferLevel Chip-Scale Package. CHARGE-PUMP OSCILLATION FREQUENCY vs. RFS CHARGE-PUMP OSCILLATION FREQUENCY (kHz) MAX9788 14VP-P, Class G Ceramic Speaker Driver 10 0.001 0.01 0.1 1 10 100 FREQUENCY (Hz) Figure 5. Ceramic Speaker and Capacitor Impedance ______________________________________________________________________________________ 14VP-P, Class G Ceramic Speaker Driver VDD 0.1μF 14, 22 (D1, D5) 4 (A3) 1 (B2) VCC SHDN * CPVDD 12 (B4) FB+ MAX9788 CIN 0.47μF RIN+ 10kΩ RFB+ 10kΩ OUT+ 20 (D2) 10 (B5) IN+ + 9 (A5) INCIN 0.47μF RIN10kΩ CLASS G OUTPUT STAGE - RL 10Ω OUT- 16 (D4) RFB10kΩ GND 18 (D3) ( ) UCSP PACKAGE FS 13 (C5) CHARGE PUMP 7 (A4) FBCPGND 27 (A1) C1P C1N 26 (B1) PVSS 3 (A2) 24 (C1) C1 4.7μF RFS 100kΩ SVSS 15, 21 (C2, C4) C2 10μF DEVICE SHOWN WITH AV = 12dB *SYSTEM-LEVEL REQUIREMENT TYPICALLY 10μF ______________________________________________________________________________________ 11 MAX9788 Typical Application Circuit/Functional Diagram 14VP-P, Class G Ceramic Speaker Driver MAX9788 Pin Configurations TOP VIEW (BUMP SIDE DOWN) N.C. CPGND C1N N.C. PVSS N.C. VCC 27 26 25 24 23 22 + 28 TOP VIEW MAX9788 SHDN 1 21 SVSS N.C. 2 20 OUT+ C1P 3 19 N.C. CPVDD 4 18 GND N.C. 5 17 N.C. N.C. 6 16 OUT- 15 SVSS 8 9 10 11 12 13 14 IN- IN+ N.C. FB+ FS VCC 7 EP* N.C. FB- MAX9788 1 2 3 4 5 CPGND C1P CPVDD FB- IN- C1N SHDN FB+ IN+ PVSS SVSS SVSS FS VCC OUT+ OUT- VCC A B C D GND UCSP THIN QFN *EXPOSED PAD. Chip Information PROCESS: BiCMOS 12 ______________________________________________________________________________________ 14VP-P, Class G Ceramic Speaker Driver 24L QFN THIN.EPS ______________________________________________________________________________________ 13 MAX9788 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.) MAX9788 14VP-P, Class G Ceramic Speaker Driver 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.) 14 ______________________________________________________________________________________ 14VP-P, Class G Ceramic Speaker Driver 5x4 UCSP.EPS ______________________________________________________________________________________ 15 MAX9788 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.) MAX9788 14VP-P, Class G Ceramic Speaker Driver Revision History REVISION NUMBER REVISION DATE 0 12/06 Initial release 11/07 Include tape and reel note, edit Absolute Maximum Ratings, update TQFN package outline 1 DESCRIPTION PAGES CHANGED — 1, 2,13, 14 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. 16 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.