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19-0710; Rev 0; 12/06
KIT ATION EVALU BLE AVAILA
14VP-P, Class G Ceramic Speaker Driver
General Description
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 -40C to +85C extended temperature range and is available in small lead-free 28-pin TQFN (4mm x 4mm) or 20-bump UCSPTM (2mm x 2.5mm) packages.
Features
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
MAX9788
Ordering Information
PART MAX9788EBP+T* MAX9788ETI+ TEMP RANGE -40C to +85C -40C to +85C PINPACKAGE 20 UCSP-20 28 TQFN-EP** PKG CODE B20-7 T2844-1
+Denotes lead-free package. *Future product--contact factory for availability. **EP = Exposed pad.
Applications
Cell Phones Smartphones MP3 Players Personal Media Players Handheld Gaming Consoles Notebook Computers
Typical Application Circuit/Functional Diagram and Pin Configurations appear at end of data sheet.
UCSP is a trademark of Maxim Integrated Products, Inc.
Simplified Block Diagram
2.7V TO 5.5V
VCC FB+
CPVDD
MAX9788
CIN RIN+ RFB+ IN+ INCIN RINRFBFBGND CHARGE PUMP CPGND + CLASS G OUTPUT STAGE OUT+ OUT-
________________________________________________________________ Maxim Integrated Products
1
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.
14VP-P, Class G Ceramic Speaker Driver MAX9788
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 Duration of OUT+, OUT- Short Circuit to VCC, GND, CPVDD, CPGND ..................................Continuous Continuous Power Dissipation (TA = +70C) 20-Bump UCSP (derate 10.3mW/C above +70C) .....827mW 28-Pin TQFN (derate 20.8mW/C above +70C) ........1667mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) ................................+300C Bump Temperature (soldering) Reflow............................+235C
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- = 10k, RFB+ = RFB- = 10k, RFS = 100k, C1 = 4.7F, C2 = 10F; load connected between OUT+ and OUT-, ZLOAD = 10 + 1F, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER GENERAL Supply Voltage Range Quiescent Current Shutdown Current Turn-On Time Input DC Bias Voltage Charge-Pump Oscillator Frequency SHDN Input Threshold (Note 4) SHDN Input Leakage Current SPEAKER AMPLIFIER Output Offset Voltage VOS TA = +25C TMIN TA TMAX Peak voltage into/out of shutdown A-weighted, 32 samples per second (Notes 5, 6) (Notes 3, 7) VCC = 5V Output Voltage VOUT f = 1kHz, 1% THD+N VCC = 4.2V VCC = 3.6V VCC = 3.0V 11.5 -67 12 7.1 5.9 5.1 4.2 VRMS 12.5 3 15 20 mV VCC ICC ISHDN tON VBIAS SHDN = GND Time from shutdown or power-on to full operation IN_ inputs (Note 3) ILOAD = 0mA (slow mode) fOSC ILOAD > 100mA (normal mode) VIH VIL 230 1.4 0.4 1 330 470 V A 1.1 55 Inferred from PSRR test 2.7 8 0.3 50 1.24 83 1.4 110 kHz 5.5 12 5 V mA A ms V SYMBOL CONDITIONS MIN TYP MAX UNITS
Click-and-Pop Level Voltage Gain
VCP AV
dBV dB
2
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14VP-P, Class G Ceramic Speaker Driver
ELECTRICAL CHARACTERISTICS (continued)
(VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10k, RFB+ = RFB- = 10k, RFS = 100k, C1 = 4.7F, C2 = 10F; load connected between OUT+ and OUT-, ZLOAD = 10 + 1F, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER SYMBOL CONDITIONS VCC = 5V Output Voltage VOUT f = 10kHz, 1% THD+N, ZL = 1F + 10, no load VCC = 4.2V VCC = 3.6V VCC = 3.0V VCC = 5V Continuous Output Power POUT 1% THD+N, f = 1kHz, RL = 8 VCC = 2.7V to 5.5V Power-Supply Rejection Ratio (Note 3) PSRR f = 217Hz, 200mVP-P ripple f = 1kHz, 200mVP-P ripple f = 20kHz, 200mVP-P ripple Total Harmonic Distortion Plus Noise Signal-to-Noise Ratio Common-Mode Rejection Ratio Dynamic Range THD+N SNR CMRR DR ZL = 1F + 10, VOUT = 1kHz / 1.9VRMS ZL = 1F + 10, VOUT = 1kHz / 4.0VRMS VOUT = 5.1VRMS, A-weighted fIN = 1kHz (Note 8) A-weighted (Note 9) VCC = 5V VCC = 3.6V VCC = 4.2V VCC = 3.6V VCC = 3.0V 63 MIN TYP 6.5 5.4 4.7 3.3 2.4 1.67 1.25 0.8 77 77 77 58 0.002 0.08 108 68 106 105 % dB dB dB dB W VRMS MAX UNITS
MAX9788
Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: Note 9:
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 = 1F + 10. 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 10 resistive load in series with 1F 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.
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3
14VP-P, Class G Ceramic Speaker Driver MAX9788
Typical Operating Characteristics
(VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10k, RFB+ = RFB- = 10k, RFS = 100k, C1 = 4.7F, C2 = 10F, ZL = 1F + 10; load terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX9788 toc01
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
MAX9788 toc02
TOTAL HARMONIC DISTORTION PLUS NOISE vs. FREQUENCY
VCC = 5V 1
MAX9788 toc03
10 VCC = 2.7V 1
10 VCC = 3.6V 1 THD+N (%)
10
THD+N (%)
0.1
0.1
THD+N (%)
VOUT = 3VRMS
VOUT = 4VRMS 0.1
VOUT = 5.9VRMS
0.01
VOUT = 1.25VRMS
0.01
VOUT = 1.9VRMS
0.01
VOUT = 3VRMS
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
0.001 10 100 1k FREQUENCY (Hz) 10k 100k
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE
MAX9788 toc04
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE
VCC = 3.6V fIN = 10kHz fIN = 1kHz 0.1
MAX9788 toc05
TOTAL HARMONIC DISTORTION PLUS NOISE vs. OUTPUT VOLTAGE
VCC = 5V 1 THD+N (%) fIN = 10kHz fIN = 1kHz 0.1
MAX9788 toc06
10 VCC = 2.7V 1 THD+N (%) fIN = 10kHz fIN = 1kHz 0.1
10
10
1 THD+N (%)
0.01 fIN = 20Hz 0.001 0 1 2 3 4 5 OUTPUT VOLTAGE (VRMS)
0.01 fIN = 20Hz 0.001 0 1 2 3 4 5 6 OUTPUT VOLTAGE (VRMS)
0.01 fIN = 20Hz 0.001 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE (VRMS)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX9788 toc07
POWER CONSUMPTION vs. OUTPUT VOLTAGE
MAX9788 toc08
POWER CONSUMPTION vs. OUTPUT VOLTAGE
175 POWER CONSUMPTION (mW) 150 125 100 75 50 25 0 4 0 1 VCC = 3.6V fIN = 1kHz 1% THD+N 2 3 4 OUTPUT VOLTAGE (VRMS) 5
MAX9788 toc09
0 -10 -20 -30 PSRR (dB) -40 -50 -60 -70 -80 -90 10 100 1k FREQUENCY (Hz) 10k VRIPPLE = 200mVP-P
100
200
POWER CONSUMPTION (mW)
75
50
25
VCC = 2.7V fIN = 1kHz 1% THD+N 0 1 2 3
0 100k OUTPUT VOLTAGE (VRMS)
4
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14VP-P, Class G Ceramic Speaker Driver
Typical Operating Characteristics (continued)
(VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10k, RFB+ = RFB- = 10k, RFS = 100k, C1 = 4.7F, C2 = 10F, ZL = 1F + 10; load terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
POWER CONSUMPTION vs. OUTPUT VOLTAGE
MAX9788 toc10
MAX9788
STARTUP WAVEFORM
MAX9788 toc11
SHUTDOWN WAVEFORM
MAX9788 toc12
350 300 POWER CONSUMPTION (mW) 250 200 150 100 50 0 0 1 2 3 4 5 6 7 VCC = 5V fIN = 1kHz 1% THD+N
SHDN 5V/div
SHDN 5V/div
OUT+ - OUT500mV/div
OUT+ - OUT500mV/div
10ms/div
10ms/div
OUTPUT VOLTAGE (VRMS)
CLASS G OUTPUT WAVEFORM
MAX9788 toc13
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX9788 toc14
12 10 SUPPLY CURRENT (mA) 8 6 4 2
OUT+ 5V/div
OUT5V/div
OUT+ - OUT10V/div 1% THD+N
0 200s/div 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 SUPPLY VOLTAGE (V)
SHUTDOWN CURRENT vs. SUPPLY VOLTAGE
MAX9788 toc15
SUPPLY CURRENT vs. OUTPUT VOLTAGE
MAX9788 toc16
1.0 0.9 SHUTDOWN CURRENT (A) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
70 60 SUPPLY CURRENT (mA) 50 40 30 20 10 0 VCC = 5V fIN = 1kHz 0 1 2 3 4 5 6 7
6.0
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE (VRMS)
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5
14VP-P, Class G Ceramic Speaker Driver MAX9788
Typical Operating Characteristics (continued)
(VCC = CPVDD = SHDN = 3.6V, GND = CPGND = 0V, RIN+ = RIN- = 10k, RFB+ = RFB- = 10k, RFS = 100k, C1 = 4.7F, C2 = 10F, ZL = 1F + 10; load terminated between OUT+ and OUT-, unless otherwise stated; TA = TMIN to TMAX, unless otherwise noted.
OUTPUT AMPLITUDE vs. FREQUENCY
MAX9788 toc17
FREQUENCY RESPONSE
18 16 14 GAIN (dB) 12 10 8 6 4 2 0 VOUT = 2VRMS
MAX9788 toc18
8 VCC = 5V 7 OUTPUT AMPLITUDE (VRMS) 6 5 4 3 2 1 0 10 100 1k FREQUENCY (Hz) 10k VCC = 2.7V VCC = 3.6V
20
100k
10
100
1k FREQUENCY (Hz)
10k
100k
Pin Description
PIN TQFN 1 2, 5, 6, 8, 11, 17, 19, 23, 25, 28 3 4 7 9 10 12 13 14, 22 15, 21 16 18 20 24 26 27 EP UCSP B2 -- A2 A3 A4 A5 B5 B4 C5 D1, D5 C2, C4 D4 D3 D2 C1 B1 A1 -- NAME SHDN N.C. C1P CPVDD FBININ+ FB+ FS VCC SVSS OUTGND OUT+ PVSS C1N CPGND EP Shutdown No Connection. No internal connection. Charge-Pump Flying Capacitor, Positive Terminal. Connect a 4.7F capacitor between C1P and C1N. Charge-Pump Positive Supply Negative Amplifier Feedback Negative Amplifier Input Positive Amplifier Input Positive Amplifier Feedback Charge-Pump Frequency Set. Connect a 100k resistor from FS to GND to set the charge-pump switching frequency. Supply Voltage. Bypass with a 10F capacitor to GND. Amplifier Negative Power Supply. Connect to PVSS. Negative Amplifier Output Ground Positive Amplifier Output Charge-Pump Output. Connect a 10F capacitor between PVSS and CPGND. Charge-Pump Flying Capacitor, Negative Terminal. Connect a 4.7F capacitor between C1N and C1P. Charge-Pump Ground. Connect to GND. Exposed Pad. Connect the TQFN EP to GND. FUNCTION
6
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14VP-P, Class G Ceramic Speaker Driver
Detailed Description
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. 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.
MAX9788
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 VCC
IP ON P ZL ON P
IP ZL ON P
IP ZL
IN1
N1
ON
IN1
N1
ON
N1
OFF
N2
OFF
IN2
N2
ON
IN2
N2
ON
SVSS LOW SUPPLY RANGE OPERATION IP = IN1
SVSS SUPPLY TRANSITION IP = IN1 + IN2
SVSS HIGH SUPPLY RANGE OPERATION IP = IN2
Figure 1. Class G Supply Transition
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14VP-P, Class G Ceramic Speaker Driver MAX9788
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. 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 CIN+ = CIN-
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 (0.3A) shutdown mode. Connect SHDN to V CC for normal operation.
Click-and-Pop Suppression
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.
Applications Information
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 log4 x (dB) RIN _
RFB+ CIN+ RIN+ IN+ INCINRINRFB+ FB+
MAX9788
CLASS G OUTPUT STAGE
FB-
Figure 2. Gain Setting
8
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14VP-P, Class G Ceramic Speaker Driver
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 1F. 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 16. 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 10 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.
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:
f-3dB = 1 (Hz) 2 x RIN _ x CIN _
MAX9788
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.
MAX9788
Charge-Pump Capacitor Selection Use capacitors with an ESR less than 50m 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 1F, the onresistance of the switches and the ESR of C1 and C2 dominate. A 4.7F capacitor is recommended.
OUT+ CLASS G OUTPUT STAGE
RL
OUT-
Figure 3. Driving a Ceramic Speaker
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9
14VP-P, Class G Ceramic Speaker Driver MAX9788
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 10F 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 100k resistor is recommended.
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 10 is recommended. Set the lowpass filter cutoff frequency with the following equation: fLP = 1 (Hz) 2 x RL x CSPEAKER
Ceramic Speaker Impedance Characteristics
A 1F 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.
UCSP Applications Information
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) ILOAD > 100mA 550 500 450 400 350 300 250 200 50 75 100 RFS (k) 125 150 10 0.001 IMPEDANCE ()
MAX9788 fig04
IMPEDANCE vs. FREQUENCY
MAX9788 fig05
600
1M 1F CAPACITOR 100k
10k
1k CERAMIC SPEAKER
100
0.01
0.1
1
10
100
FREQUENCY (Hz)
Figure 4. Charge-Pump Oscillation Frequency vs. RFS
Figure 5. Ceramic Speaker and Capacitor Impedance
10
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14VP-P, Class G Ceramic Speaker Driver
Typical Application Circuit/Functional Diagram
VDD
MAX9788
0.1F 14, 22 (D1, D5) 4 (A3) VCC CPVDD
*
1 (B2) SHDN 12 (B4) FB+
MAX9788
CIN 0.47F RIN+ 10k RFB+ 10k 10 (B5) IN+ 9 (A5) INCIN 0.47F RIN10k RFB10k 7 (A4) FBGND 18 (D3) CPGND C1N 26 (B1) CHARGE PUMP C1P PVSS FS 13 (C5) RFS 100k + CLASS G OUTPUT STAGE OUT+ 20 (D2) OUT- 16 (D4) RL 10
SVSS 15, 21 (C2, C4) C2 10F
27 (A1)
3 (A2) 24 (C1)
( ) UCSP PACKAGE
C1 4.7F
DEVICE SHOWN WITH AV = 12dB *SYSTEM-LEVEL REQUIREMENT TYPICALLY 10F
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11
14VP-P, Class G Ceramic Speaker Driver MAX9788
Pin Configurations
TOP VIEW
CPGND PVSS N.C. C1N N.C. N.C. VCC
TOP VIEW (BUMP SIDE DOWN) MAX9788
1 2 3 4 5
28
27
26
25
24
23
+
SHDN N.C. C1P CPVDD N.C. N.C. FB-
22
1 2 3 4 5 6 7 EP* 10 11 12 13 14
21 20 19
SVSS OUT+ N.C. GND N.C. OUTSVSS
A CPGND B C1N C PVSS D VCC OUT+ GND OUTVCC SVSS SVSS FS SHDN FB+ IN+ C1P CPVDD FBIN-
MAX9788
18 17 16 15
8
N.C.
9
IN-
IN+
N.C.
FB+
FS
VCC
UCSP
THIN QFN
*EXPOSED PAD.
Chip Information
PROCESS: BiCMOS
12
______________________________________________________________________________________
14VP-P, Class G Ceramic Speaker Driver
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.) 24L QFN THIN.EPS
MAX9788
PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm
21-0139
E
1 2
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13
14VP-P, Class G Ceramic Speaker Driver 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.)
PACKAGE OUTLINE, 12, 16, 20, 24, 28L THIN QFN, 4x4x0.8mm
21-0139
E
2 2
14
______________________________________________________________________________________
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.)
5x4 UCSP.EPS
MAX9788
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
(c) 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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