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| ASAHI KASEI [AK7841] Monaural Audio Class-D Amp with Power Booster for PiezoSpeaker GENERAL DESCRIPTION The AK7841 is a Monaural Class-D amplifier for driving Piezo-Electric Speakers. Its built-in power boost DCDC converter generates adequate high voltage for driving Piezo Speaker from a Li-Ion battery. Output filter-less solution eliminates post LC-filters, which are normally required at Class-D outputs, and contributes to total space savings. Class-D operation ensures higher power efficiency. The AK7841 is the most appropriate for Cellular Phones with a piezo speaker. FEATURES Class-D Amplifier : * Piezo-Electric Speaker Driver * Analog Monaural signal input for both single and Differential-ended * Monaural BTL output * Output voltage = 12Vpp @VDD1=8.75V * Filter-less solution * Pop noise free architecture during power up or down. * Output short protection Boost DCDC Converter * Input voltage = 2.7V 4.5V * Over-current protection * Over-voltage protection Output voltage = 8.75V AK7841 Control function * Pre-gain amplifier -3dB +18dB, 3dB step. * Power-own control * Over-temperature protection Controlled by pin setting. Operational voltage VBAT=2.7V 4.5VDVDDI=1.65V 4.5V Operational temperature -30C 85C Package 24pin WL-CSP (2.5mm x 2.5mm, 0.5mm pitch) Rev.08 -1- 2008/3 ASAHI KASEI [AK7841] BLOCK DIAGRAM DVDDI PDN VBAT PD C ont Pow er Booster VCO IL VFB ERRO VSS2 PG 0 PG 1 PG 2 Gain C ontrol VDD1 INN INP Pre AM P -3dB +18dB 3dB step C lass-D AM P VCN VCP VSS1 SDSEL +16dB VC VSS3 VREF Figure. 1 Block Diagram Rev.08 -2- 2008/3 ASAHI KASEI [AK7841] PIN ASSIGNMENT 5 4 3 2 1 E D C B A < Top View > E D C B A 5 NC VCOIL ERRO PG2 NC 4 VFB VSS2 VBAT PG0 PG1 3 2 VDD1 VCP SDSEL VCN NC VSS3 PDN INN DVDDI 1 NC VSS1 VC INP NC Rev.08 -3- 2008/3 ASAHI KASEI [AK7841] Pin / FUNCTION No. A1 A2 A3 A4 A5 B1 B2 B3 B4 B5 C1 C2 C3 C4 C5 D1 D2 D3 D4 D5 E1 E2 E3 E4 E5 Pin Name NC DVDDI PG1 NC INP INN PDN PG0 PG2 VC VSS3 NC VBAT ERRO VSS1 VCN SDSEL VSS2 VCOIL NC VCP VDD1 VFB NC I/O I I I I I I O O O I O O I Function No Connection pin. * Must be connected to VSS level. Note 1. Digital input pins (PDN, PG0, PG1, PG2, TEST1, TEST2) and NC pins must not be open. Un-used Pins Un-used pin must be configured as follows. Pin Name INP Configuration OPEN Analog Rev.08 -4- 2008/3 ASAHI KASEI [AK7841] ABSOLUTE MAXIMUM RATINGS (VSS1=VSS2=VSS3=0V; Note 2) Parameter Power Supplies Battery Class-D Amp Digital I/F |VSS2-VSS1| (Note 3) |VSS2-VSS3| (Note 3) Input Current (any pins except for supplies) Analog Input Voltage(Note 4) (Note 6) Digital Input Voltage (Note 5) (Note 6) Ambient Temperature Storage Temperature Symbol VBAT VDD1 DVDDI GND1 GND2 IIN VINA VIND Ta Tstg Min. -0.3 -0.3 -0.3 -0.3 -0.3 -30 -65 Max. 6.5 10 6.5 0.3 0.3 10 VBAT+0.3 DVDDI+0.3 85 150 Units V V V V V mA V V C C Note 2. All voltages are with respect to ground. Note 3. VSS1, VSS2, VSS3 pins must be connected to the same analog ground plane. Note 4. IPN and INN pin. Note 5. PDN, PG0, PG1, PG2, SDSEL pin. Note 6. Maximum value must not exceed 6.5V even if VBAT or DVDDI are more than 6.2V. WARNING: Operation at or beyond these limits may result in permanent damage to the device. Normal operation is not guaranteed at these extremes. RECOMMENDED OPERATING CONDITIONS (VSS1=VSS2=VSS3=0V;Note 2) Parameter Power Supplies Battery (Note 7) Class-D Amp (Note 8) Digital I/F (Note 7) Symbol VBAT VDD1 DVDDI Min. 2.7 1.65 Typ. 3.6 8.75 2.8 Max. 4.5 4.5 Unit V V V Note 7. Have to be "VBAT DVDDI" Note 8. Supply with boosted voltage (typ. 8.75V) by the Power Booster. * AKEMD assumes no responsibility for usage beyond the conditions in this datasheet. Rev.08 -5- 2008/3 ASAHI KASEI [AK7841] DC CHARACTERISTICS (Ta=25C; VBAT=2.7V 4.5V, DVDDI=1.65V 4.5V, VSS1=VSS2=VSS3=0V) Parameter Symbol Min. Typ. High-Level Input Voltage 1 (Note 9) VIH1 70%DVDDI Low-Level Input Voltage 1 (Note 9) VIL1 High-Level Input Voltage 2 (Note 10) VIH2 80%DVDDI Low-Level Input Voltage 2 (Note 10) VIL2 Hysterisys Voltage DVDDI=2.8V VHS1 0.5 (Note 10) DVDDI=1.65V VHS2 0.3 Input Leakage Current Iin Max. 30%DVDDI 20%DVDDI 10 Units V V V V V V A Note 9. Applied to PG0, PG1, PG2, and SDSEL pin. Note 10. Applied to PDN pin (Summit trigger input. These specifications are guaranteed by design and characterization and are not tested in production.) Rev.08 -6- 2008/3 ASAHI KASEI AKM CONFIDENTIAL ANALOG CHARACTERISTICS [AK7840] (Typ.) value is measured at Ta=25 and VBAT=3.6,. The worst value was measured at the worst point between VBAT=2.74.5V and Ta=-30+85, and written on (Min.) or (Max.) column. Unless otherwise specified, Ta=25, VBAT=3.6V, DVDDI=2.8V, VSS1=VSS2=VSS3=0V;input signal frequency =1kHz; measurement band width=20Hz 20kHz; pre gain=0dB; Class-D amp load capacitance is 1.0uF. Parameter Conditions Min. Typ. Max. Units No input signal Idd 17.3 26.0 mA With output load. Shutdown Current PDN pin = "Low" 1.0 10 A INN pin 25 50 75 k Input Impedance INP pin 25 50 75 k Pre Gain -3.0 +18.0 dB Control Range PG2="L", PG1 = "L" , PG0 = "L" -4.0 -3.0 -2.0 dB PG2="L", PG1 = "L" , PG0 = "H" -1.0 0.0 +1.0 dB PG2="L", PG1 = "H" , PG0 = "L" +2.0 +3.0 +4.0 dB Pre Gain PG2="L", PG1 = "H" , PG0 = "H" +5.0 +6.0 +7.0 dB Step Size PG2="H", PG1 = "L" , PG0 = "L" +8.0 +9.0 +10.0 dB PG2="H", PG1 = "L" , PG0 = "H" +11.0 +12.0 +13.0 dB PG2="H", PG1 = "H" , PG0 = "L" +14.0 +15.0 +16.0 dB PG2="H", PG1 = "H" , PG0 = "H" +17.0 +18.0 +19.0 dB VCN/VCP pins Output Voltage 3.82. 4.24 4.66 Vrms Input signal level=0.70Vrms THD=10% VCN/VCP pins Output Offset Voltage 250 mV No input signal VCN/VCP pins dB THD+N -40 Input signal level=0.50Vrms VCN/VCP pins SNR Input signal level=0.70Vrms, 70 80 dB using A-weighting filter PSRR VCN/VCP pins (Note 12)(Note 1Note Vripple=200mVpp @1kHz Sine-wave, 65 dB 15) VBAT=3.6V, all temperature CMRR INP=1.2V0.5V @Sine-wave, 65 dB (Note 12)(Note 1Note VBAT=3.6V, all temperature 15) VREF VC pin 2.4 V Output Voltage (Note 12) (Note 13) Class-D Amp 225 250 275 kHz Switching Frequency Power Booster 900 1000 1100 kHz Start-up Time VBAT=2.7V 28 31 ms (Note 14) Note 11. Measure between VCN and VCP pin through Low-Pass-Filter (fc=20kHz). Note 12. These specifications are guaranteed by design and characterization and are not tested in production. Note 13. Analog ground in the AK7841 is 1.2V(typ.). Note 14. Time period that is required to be stable output after PDN is "High". Note 15. These specifications are guaranteed by design and characterization and are not tested in production. Rev.08 -7- 2008/3 ASAHI KASEI AKM CONFIDENTIAL OPERATION OVERVIEW [AK7840] Power Control The AK7841 enters shutdown mode by setting "PDN" pin to Logic "Low" level. And resumes normal operation mode (Stability Operation) by setting "PDN" pin to Logic "High" level. Power-Up Control VBAT and DVDDI must be turned on as (1) or (2) below. (1) VBAT=DVDDI="ON" simultaneously. (2) VBAT="ON" first, then DVDDI="ON". Set PDN pin to "High" when driving AK7841. Then, 1s wait after VBAT=DVDDI="High" is necessary before setting PDN="High". Do not do them simultaneously. VBAT "ON" DVDDI "ON" PDN pin 0V 0V 0V > 1us Figure. 3 Power-Up Sequence (1) VBAT "ON" DVDDI "ON" PDN pin 0V 0V 0V 0V >0 > 1us Figure. 4 Power -Up Sequence (2) Attention: The performance of the device will not be guaranteed after the below sequence. (3) DVDDI="ON" first, then VBAT="ON". Rev.08 -8- 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] Power-Down Control VBAT and DVDDI must be turned off as (4) or (5) below. (4) VBAT=DVDDI="OFF" at the same time. (5) DVDDI="OFF" first, then VBAT="OFF". Set PDN pin to "Low" when shutting down. Then, 1s wait is necessary before pulling down VBAT and DVDDI. Do not do them simultaneously. When PDN pin is "High" and VBAT/DVDDI supply is suddenly cut off due to unexpected event, pop noise may be detected while sound signal is being output. Even under such cases LSI will not be harmed. VBAT "OFF" DVDDI "OFF" PDN pin > 1us 0V 0V 0V Figure. 5 Power-Down Sequence (4) ///VBAT "OFF" DVDDI "OFF" PDN pin >0 0V 0V > 1us 0V Figure. 6 Power -Down Sequence (5) Attention: The performance of the device will not be guaranteed after the below sequence. (6) VBAT="OFF" first, then DVDDI="OFF" Analog inputs The AK7841 correspond to both single and differential-ended input. Use ac coupling capacitors as described below. Avoid the change from 0.1uF of the recommended value as much as possible because these change of capacitance may influence not only HPF (High Pass Filter) at input but also the operation of the pop noise prevention circuit. When single-ended input Connect SDSEL pin to ground. Input t analog signal to INN pin through a 0.1uF capacitor. Then, INP pin should be open. ( Figure. 16) When differential-ended input Connect SDSEL pin to DVDDI. Input t analog signal to between INN and INP pins through ac-coupling 0.1uF capacitors ( Figure. 17). If two conditions are fulfilled as below, ac-coupling capacitors are not needed ( Figure. 18). 1. The voltage of INP and INN are VSS while shutting down. 2. The common level of INP and INN pin is between 0.8V and 1.6V, and input signals are within common level0.5V for each pin (2Vpp). Rev.08 -9- 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] Pre AMP Users can change Pre Gain value by setting PG0, PG1, PG2 pins as following Table.1. For fixed gain application, these pins should be fixed to either VSS3 or DVDDI. PG2 "Low" "Low" "Low" "Low" "High" "High" "High" "High" PG1 PG0 Pre Gain Setting Value -3.0 dB 0.0 dB +3.0 dB +6.0 dB +9.0 dB +12.0 dB +15.0 dB +18.0 dB "Low" "Low" "Low" "High" "High" "Low" "High" "High" "Low" "Low" "Low" "High" "High" "Low" "High" "High" Table.1 Pre Gain setting Class-D amplifier. The AK7841, a monaural Class-D audio amplifier, has higher efficiency compared to Class-AB amplifier. AK7841 would eliminate much external equipment especially output filter, which is normally equipped to cut high frequency spectrum in class-D output, by using a unique circuit composition. Pop Noise Suppressor The AK7841 features click-and-pop suppression circuit. Power Booster Built-in BOOST DCDC CONVERTER generates adequate high voltage for Piezo-Speaker (Typ.8.75V) from a Li-Ion battery voltage range (2.74.5V). Supply boosted voltage (VFB=8.75V) to VDD1 for class-D amp operation. Protection The AK7841 supports following protection circuits for protecting against any damages. Output Short-Circuit Protection In case detecting VCL(R)P and VCL(R)N short, the AK7841 clamps peak current of Class-D output circuit without shutting down the outputs. Over-Temperature Protection The AK7841 operation will stop at +150C. Note that the AK7841 DOES NOT support resume function from Over-Temperature Protection. Once it is activated, the AK7841 does not back in normal operation unless "PDN" is toggled ("L" "H"). Over-Current Protection Current-limiting protection clamps the output current without shutting down the outputs. Over-Voltage Protection AK7841 has a Voltage-limiting protection in DCDC converter to avoid destroying itself. Rev.08 - 10 - 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] Performance characteristics The following various characteristics are typical characteristic data in the typical condition. It is not the one necessarily to secure the characteristic of the description. Sinwave Single - ended , Total Gain=15.6dB, Output Load Impedance ZL=1uF, Measurement Band Width =2020kz, unless otherwise specified. 10 10 VBAT=4.5V VBAT=3.6 1 1 THD+N (%) Vout=4Vrms Vout=2Vrms THD+N (%) Vout=4Vrms Vout=2Vrms Vout=1Vrms 0.1 0.1 Vout=1Vrms 0.01 10 0.01 100 0.1 1k 1 Frequency (Hz) 10k 20k 10 100k 100 0.01 10 0.01 100 0.1 1k 1 Frequency (Hz) 10k 20k 10 100k 100 10 VBAT=2.7V 1 THD+N (%) Vout=4Vrms Vout=2Vrms Vout=1Vrms 0.1 0.01 10 0.01 100 0.1 1k 1 Frequency (Hz) 10k 20k 10 100k 100 Figure. 7 Total Harmonic Distortion Plus Noise vs Frequency Rev.08 - 11 - 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] 10 10 VBAT=4.5V VBAT=3.6V 1 1 THD+N (%) THD+N (%) Fin=10kHz Fin=4kHz Fin=10kHz Fin=4kHz Fin=1kHz 0.1 Fin=1kHz 0.1 0.01 0 1 2 3 4 5 0.01 0 1 2 3 4 5 Output Voltage (Vrms) Output Voltage (Vrms) 10 VBAT=2.7V 1 THD+N (%) Fin=10kHz Fin=4kHz Fin=1kHz 0.1 0.01 0 1 2 3 4 5 Output Voltage (Vrms) Figure. 8 Total Harmonic Distortion Plus Noise vs Output Voltage Rev.08 - 12 - 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] 5 Wave forms are overlapping. 20 VBAT=4.5V VBAT=3.6V Gain (dB) 15 Wave forms are overlapping. Vin=2Vpp 4 Vout=2Vrms VBAT=4.5V VBAT=3.6V VBAT=2.7V 10 Output Voltage (Vrms) 3 VBAT=2.7V 2 1 5 0 0.01 10 0.1 100 1 1k Frequency (Hz) 10 10k 20k 100 100k 0 10 0.01 100 0.1 1k 1 10k 20k 10 100k 100 Frequency (Hz) Figure. 9 Output Amplitude vs. Frequency Figure. 10 Frequency Response 150 Fin=1kHz VBAT=3.6V Supply Current @ Stereo (mA) VBAT=2.7V 100 50 VBAT=4.5V 0 0 1 2 3 4 5 Output Voltage (Vrms) Figure. 11 Supply Current vs Output Voltage Rev.08 - 13 - 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] 20 18 16 Shutdown Current (nA) 14 12 10 8 6 4 2 0 2.5 3 3.5 4 4.5 5 Supply Voltage (V) PDN 2V/div Output Waveform 10V/div 10ms/div Figure. 12 Shutdown Current vs Supply Voltage Figure. 13 Startup Waveform 70 Vin=1Vpp A-Weighted 60 VBAT=2.7V VBAT=3.6V CMRR (dB) 50 VBAT=4.5V Wave forms are overlapping. 40 30 20 0.01 0 0.1 100 1 1k Frequency (Hz) 10 20k 10k 100 100k Figure. 14 Common-Mode Rejection Ratio vs Frequency Rev.08 - 14 - 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] LEVEL DIAGRAM Default gain of AK7841 is +15.6dB. Figure. 15.shows the level diagram of AK7841. Pre Gain value is adjustable by pin control as specified in Table.1. Pre Gain -3 to +18dB by3dB step [Vpp] 14.0 12.0 10.0 8.0 6.0 4.0 2.0 PG=+6dB PG=0dB Class-D Class-D amp gain=15.6dB 0.0 Figure. 15 Level Diagram Rev.08 - 15 - 2008/3 ASAHI KASEI AKM CONFIDENTIAL TYPICAL APPLICATION CIRCUIT [AK7840] Li-ion Battery C1: 10uF C6: 0.1uF DVDDI C2: 0.1uF SDSEL PDN Refer to "Pre AMP" section for details. C8: 0.1uF PG0 PG1 PG2 INN INP VC C7: 0.01uF VSS3 Figure. 16 External Components Examples : Single-ended Input Li-ion Battery C1: 10uF C6: 0.1uF DVDDI C2: 0.1uF SDSEL PDN Refer to "Pre AMP" section for details. C8: 0.1uF PG0 PG1 PG2 INN INP VC C7: 0.01uF VSS3 Figure. 17 External Components Examples : Differential Input with ac coupling capacitors at input PD Cont VDD1 Gain Cont Pre AMP VREF Class-D AMP VCN VCP VSS1 Power Booster C5: 2.2uF ERRO VFB L1: 1.0uH VBAT D1 VCOIL VSS2 C4: 10uF PD Cont Gain Cont Pre AMP VREF Class-D AMP VDD1 Power Booster C5: 2.2uF ERRO VFB L1: 1.0uH VBAT D1 VCOIL VSS2 C4: 10uF VCN VCP VSS1 Piezo Speaker C3: 0.1uF Piezo Speaker C3: 0.1uF Rev.08 - 16 - 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] Li-ion Battery C1: 10uF C6: 0.1uF DVDDI C2: 0.1uF SDSEL C5: 2.2uF ERRO VFB L1: 1.0uH VBAT D1 VCOIL VSS2 C4: 10uF Power Booster PDN PG0 PD Cont VDD1 Refer to "Pre AMP" PG1 PG2 section for details. C8: 0.1uF INN INP VC C7: 0.01uF VSS3 Gain Cont Pre AMP VREF Class-D AMP VCN VSS2 VCP VSS1 Piezo Speaker C3: 0.1uF Figure. 18 External Components Examples : Differential Input, direct Connection If two conditions are fulfilled as below, ac-coupling capacitors are not needed. 1. The voltage of INP and INN are VSS while shutting down. 2. The common level of INP and INN pin is between 0.8V and 1.6V, and input signals are within common level0.5V for each pin (2Vpp). Rev.08 - 17 - 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] 1. Grounding and Power Supply Decoupling The AK7841 requires careful attention to power supply and grounding arrangements. Supply VBAT with Battery Power. VDD1 must be supplied with boosted flat voltage. Connect VSS1, VSS2 and VSS3 to analog ground plane. System analog and digital ground should be isolated from each other and be connected nearby the power supply pin on the printed circuit board. Decoupling capacitors should be as close to the power supply pins as possible, with the small value ceramic capacitor nearby power supply. 2. Voltage Reference VC pin is the analog common voltage (ground for signals). Insert a 0.01F ceramic capacitor between VC and VSS3 to eliminate the effects of high frequency noise. This capacitor should be as close to the VC pin as possible. Do not take out load current from the VC pin. All signals, especially clocks, should be kept away from the VC pin in order to avoid unwanted coupling. 3. Class-D Outputs The Class-D outputs are in BTL signal format. Locate the outputs close to the speaker to minimize interconnect resistance and capacitance to suppress noise. Match the length and pattern of the plus and minus output interconnect. Keep AK7841 or Class-D outputs away as far away as possible from the devices such as antennas that are sensitive to high frequency noise. 4. Effect on RF bands Power Booster or Class-D Outputs may affect high frequency signal while applying to some applications. Apply previous section (3. Class-D Outputs) in PCB layout. 5. Drivable Piezo Speakers AK7841 is designed to drive typical piezo speakers but in some cases electric characteristics of the speakers differ by manufacturers. Feel free to ask us whether your speakers can be driven or not before using them. Rev.08 - 18 - 2008/3 ASAHI KASEI AKM CONFIDENTIAL [AK7840] PACKAGE A 2.460.05 0.23 0.50 E B 2.460.05 0.50 D 0.23 0.250.05 S 0.600.02 INDEX MARK 1 2 3 4 5 C B A 0.300.05 0.05 M S AB 0.08 S Note: TheTerminal Pitch means the distances between the terminal centers. Figure. 19 Package Dimensions (AK7841) Rev.08 - 19 - 2008/3 ASAHI KASEI [AK7841] (a) (b) (c) MARKING Market number"7841" Date code(four digits) Y Last one digits of Christian year (ex. "2007" "7") WW Manufactured week L Wafer lot number, which manufactured in same week ("A", "B", "C", ) Index indication "A2" pin location (a) (b) (C) 7841 YWWL Figure. 20 Package Marking (AK7841) Rev.08 - 20 - 2008/3 ASAHI KASEI [AK7841] IMPORTANT NOTICE These products and their specifications are subject to change without notice. When you consider any use or application of these products, please make inquiries the sales office of Asahi Kasei EMD Corporation (AKEMD) or authorized distributors as to current status of the products. AKEMD assumes no liability for infringement of any patent, intellectual property, or other rights in the application or use of any information contained herein. Any export of these products, or devices or systems containing them, may require an export license or other official approval under the law and regulations of the country of export pertaining to customs and tariffs, currency exchange, or strategic materials. AKEMD products are neither intended nor authorized for use as critical componentsNote1) in any safety, life support, or other hazard related device or systemNote2), and AKEMD assumes no responsibility for such use, except for the use approved with the express written consent by Representative Director of AKEMD. As used here: Note1) A critical component is one whose failure to function or perform may reasonably be expected to result, whether directly or indirectly, in the loss of the safety or effectiveness of the device or system containing it, and which must therefore meet very high standards of performance and reliability. Note2) A hazard related device or system is one designed or intended for life support or maintenance of safety or for applications in medicine, aerospace, nuclear energy, or other fields, in which its failure to function or perform may reasonably be expected to result in loss of life or in significant injury or damage to person or property. It is the responsibility of the buyer or distributor of AKEMD products, who distributes, disposes of, or otherwise places the product with a third party, to notify such third party in advance of the above content and conditions, and the buyer or distributor agrees to assume any and all responsibility and liability for and hold AKEMD harmless from any and all claims arising from the use of said product in the absence of such notification. Rev.08 - 21 - 2008/3 |
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