AKEMDAKEMD CONFIDENTIAL [AK7846] AK7846 Stereo Audio Class-D Amp with Power Booster for Piezo Speakers GENERAL DESCRIPTION THE AK7846 is Stereo Class-D amplifier for driving Piezo-Electric Speakers. Built-in Boost DCDC converter generates adequate high voltage for driving Piezo Speakers from Li-Ion battery. AKM state-of-the-art filter-less solution eliminates LC-filters, which are normally required at Class-D outputs. That contributes to total space saving. Class-D operation ensures higher power efficiency, and couple with Piezo Speaker that is low-power- consumption and low-profile figure. The AK7846 is very applicable for cellular phones with piezo speakers. FEATURES □ Class-D Amplifier ： • Piezo-Electric Speaker Driver • Single-ended analog Input • BTL output • Output voltage = 8Vrms @VDD1=13V • Filter-less solution • Stereo mode • Pop noise suppressor • Output short protection □ Boost DCDC Converter ： • Input voltage (Battery) = 2.7V ∼ 4.5V Æ Boosted voltage will be 13V • Over-current protection • Over-voltage protection □ Control function ： • Pre-gain amplifier −6dB ∼ +15dB, 3dB step * Adjustable by Pin (PG0, PG1 and PG2) control • Built-in Second order lowpass filter at Input. • Cutoff Frequency (4kHz,8kHz,16kHz) * Adjustable by Pin (PG0, PG1 and PG2) control • Power-on/off control • Over-temperature protection □ Operational voltage ： VBAT=2.7V ∼ 4.5V、DVDDI=1.65V ∼ 4.5V □ Operational temperature □ Package Rev.04.9 ： −30°C ∼ 85°C ： 31pin WL-CSP (3.0mm × 3.0mm, 0.5mm pitch) –1– 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] BLOCK DIAGRAM VBAT FC１ FC0 Power Booster PG2 VCOIL VFB PG1 PG 0 ERRO DVDDI VSS3 PDN VDD1 INL Pre GainL LPF L Fc: 4/8/16kHz Class-D AMP L VCLN VCLP VSS1 -6 ～ +15dB 3dB step VSS4 VDD2 INR VC Pre GainR LPF R Class-D AMP R VCRN VCRP VSS2 VREF Figure 1. BLOCK DIAGRAM Rev.04.9 –2– 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] PIN ASSIGNMENT A B D C E F 6 5 4 ３.0ｍｍ 3 2 1 0.25 0.25 0.5 <TOP 6 5 4 3 2 1 Rev.04.9 A NC VCRP ERRO PG2 VCOIL NC B VDD2 VCRN VSS2 VSS4 VSS3 <Index> VIEW> C D VFB NC NC NC － － － － PG1 FC1 PG0 DVDDI Figure 2. Pin Assighnment –3– E VDD1 VCLN VSS1 VBAT FC0 PDN F NC VCLP INL INR VC NC 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] Pin / FUNCTION No. Pin Name I/O Function A1 A2 A3 NC VCOIL PG2 － － I A4 ERRO A5 A6 B1 B2 B3 B4 B5 B6 C1 C2 C3 C4 C5 C6 D1 D2 D3 D4 D5 D6 VCRP NC － VSS3 VSS4 VSS2 VCRN VDD2 PG0 PG1 － － NC VFB DVDDI FC1 － － NC NC E1 PDN I E2 E3 E4 E5 E6 F1 F2 F3 F4 F5 F6 FC0 VBAT VSS1 VCLN VDD1 NC VC INR INL VCLP NC I － － O No Connection pin. Connect to ground. Inductor pin for Boost DCDC. Pre Gain setting pin2 (available when I2CEN=”L”) Phase compensation capacitor connection pin for Boost DCDC. Connect a 0.1µF capacitor between VC pin and ground. Right channel Class D amp plus output (+) No Connection pin. Connect to ground. <Index> Power Booster ground pin：VSS3=0V Internal analog circuit ground pin：VSS4=0V Right channel Class D amp ground pin：VSS2=0V Right channel Class D amp minus output (-) Right channel Class D amp power supply：VDD2=13V(typ.) Pre Gain setting pin0 Pre Gain setting pin1 － － No Connection pin. Connect to ground. Boosted voltege feedback pin. Digital interface power：DVDDI=1.65V～4.5V SCF cutoff frequency setting pin1 － － No Connection pin. Connect to ground. No Connection pin. Connect to ground. Power down contorol：schmitt trigger input “High”：poewer up、”Low”：power down SCF cutoff frequency setting pin2 Battery voltage input：VBAT=2.7V～4.5V Left channel Class D amp ground pin：VSS1=0V Left channel Class D amp minus output (-) Left channel Class D amp power supply：VDD1=13V(typ.) No Connection pin. Connect to ground. Voltage reference output. Connect a 0.01µF capacitor between VC pin and ground. Right channel analog signal input Left channel analog signal input Left channel Class D amp plus output (+) No Connection pin. Connect to ground. O － － I O I I － － I － － I I O Note 1. Digital input pins (PDN, PG2, PG1, PG0, FC1, FC0) must not be open. Unused Pins Unused pins should be configured as below. Category NoConnection Rev.04.9 Pin Name Configuration NC VSS –4– 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] ABSOLUTE MAXIMUM RATINGS (VSS1=VSS2=VSS3=VSS4=0V;Note 3) Parameter Symbol min max Units Power Supplies: (Note.4) VBAT DVDDI VDD1,2 IIN VINA VIND Ta Tstg −0.3 −0.3 −0.3 -10 −0.3 −0.3 −30 −65 6.5 6.5 15 +10 VBAT+0.3 DVDDI+0.3 85 150 V V V mA V V °C °C Battery Digital I/F Class-D Amp Input Current, Any Pin Except Supplies Analog Input Voltage (Note 4) (Note 6) Digital Input Voltage (Note 5) (Note 6) Ambient Temperature (powered applied) Storage Temperature Note 2. All voltages are with respect to ground. Note 3. VSS1, VSS2, VSS3, VSS4 pin must be connected to the same analog ground plane. Note 4. INL,INR pin Note 5. PDN, PG2, PG1, PG0, FC1, FC0 pin Note 6. Maximum value must not exceed 6.5V even if VBAT or DVDDI is 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=VSS4=0V; Note 2) Parameter Symbol min typ max Units Power Supplies Battery (Note 7) VBAT VDD (Note 8) VDDx DigitalI/F(Note 7) DVDDI 2.7 12 1.65 3.6 13 2.8 4.5 14 4.5 V V V Note 2. All voltages are with respect to ground. Note 7. Should sustain “VBAT≧ DVDDI” condition Note 8. Supply with boosted voltage (typ. 13V) by the Power Booster. * AKM assumes no responsibility for usage beyond the conditions in this datasheet. DC CHARACTERISTICS (Ta=25°C; VBAT=2.7 ∼ 4.5V,DVDDI = 1.65～4.5V,VSS1=VSS2=VSS3=VSS4=0V) Parameter High-Level Input Voltage1 Low-Level Input Voltage1 High-Level Input Voltage2 Low-Level Input Voltage2 Input Leakage CurrentI (Note 9) (Note 9) (Note 10) (Note 10) Symbol min typ max Units VIH1 VIL1 VIH2 VIL2 70%DVDDI 80%DVDDI - - 30%DVDDI 20%DVDDI ±10 V V V V µA Note 9. Applied to PG0, PG1, PG2. Note 10. Applied to PDN, FC1, FC2 (Summit trigger input). Rev.04.9 –5– 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] ANALOG CHARACTERISTICS (Unless otherwise noted, Ta＝25℃、VBAT=3.6Ｖ、DVDDI=2.8V、VSS1,2,3,4＝0V, Input Signal Frequency =1kHz , Measurement Band Width =20～20kHz ,PreGain=0dB , Fc= 16kHz Class-D ampu Output Load Impedance ZL=150nF) Parameter Condition min typ max Units Idd No input signal. With output Load T.B.D ShutdownCurrent PDN pin = ”Low” 1.0 10 μA Input Impedance INL INR 50 50 75 75 kΩ kΩ +15 dB 25 25 PreGain Control Range PreGain Step Size (Note 11) Output Voltage Output Offset Voltage THD+N SNR PSRR (Note 13) Cross Talk Switching Frequency Startup Time (Note 14) -6 PG2=”Low”,PG1=” Low”,PG0=” Low” PG2=”Low”,PG1=” Low”,PG0=” High” PG2=”Low”,PG1=” High”,PG0=” Low” PG2=”Low”,PG1=” High”,PG0=” High” PG2=” High”,PG1=” Low”,PG0=” Low” PG2=” High”,PG1=” Low”,PG0=” High” PG2=” High”,PG1=” High”,PG0=” Low” PG2=” High”,PG1=” High”,PG0=” High” VCL(R)P/VCL(R)N Input Signal=0.7Vrms VCL(R)P/VCL(R)N No input signal VCL(R)P/VCL(R)N (Note 12) Input Signal=0.7Vrms VCL(R)P/VCL(R)N (Note 12) Input Signal=0.7Vrms using an A wating filter. VCL(R)P/VCL(R)N (Note 12) Vripple=200mVpp@1kHz sinwave INL：NoInput 、INR=2Vpp Lch：OutputPin monitoring. INR：NoInput 、INL=2Vpp Rch：OutputPin monitoring. Class-D Amp PowerBooster C3=0.01uF, C5=C6= 0.1uF(Note 15) VBAT=2.7V mA -7 -4 -1 +2 +5 +8 +11 +14 -6 -3 0 +3 +6 +9 +12 +15 -5 -2 +1 +4 +7 +10 +13 +16 dB dB dB dB dB dB dB dB 7.2 8.0 8.8 Vrms - - T.B.D. mV - - -30 dB 70 80 - dB 50 225 900 70 dB 70 dB 250 1000 28 275 1100 kHz ms Note 11. Setting accuracy of each setting is within ±1dB. Monotony is guaranteed. Note 12 . Measure signals between VCL(R)N and VC L(R)P through Low-Pass-Filter (fc=20kHz). Note 13. 200mVpp@1kHz superimposed signal at VBAT pin, and measured output. Note 14. Time period from “PDN” turns “High” to stability operation. Note 15. Refer to section “TYPICAL APPLICATION CIRCUIT”. Rev.04.9 –6– 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] OPERATION OVERVIEW Power Control The AK7848 enters SHUT-DOWN MODE by setting PDN pin to Logic “Low” level. Power-Up Control Power supply (VBAT pin, DVDDI pin) sequence must be either (1) or (2) as follows. (1) VBAT and DVDDI are simultaneously turned on. (2) First, VBAT pin is turned on. Next, DVDDI is turned on. z Simultaneous turn-on of DVDDI pin and PDN pin is prohibited. At least 1 us delay is needed before the transision (“L”→”H”) of PDN pin. VBAT “ON” 0V DVDDI “ON” 0V PDN pin 0V > 1us Power-Up Sequence (1) VBAT “ON” 0V DVDDI “ON” 0V 0V PDN pin 0V >0 > 1us Power –Up Sequence (2) CAUTION: The performance of the device will not be guaranteed after the sequence below. (3) First, DVDDI pin = ”H”, Next VBAT = ”H” Rev.04.9 –7– 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] Power-Down Control Power supply (VBAT, DVDDI) sequences must be either (4) or (5) as follows. (4) VBAT and DVDDI are simultaneously turned-off. (5) First DVDDI is turned-off, Next, VBAT is turned-on. * Simultaneous turn-off of PDN pin and DVDDI pin is prohibited. At least 1 us delay is needed before the transision (“L”→”H”) of DVDDI pin. z In case PDN pin is “High” and VBAT/DVDDI supply is suddenly cut off due to unexpected event, pop noise may be detected, however, LSI will not be harmed even under such a case. VBAT “OFF” 0V DVDDI “OFF” 0V > 1us PDN pin 0V Power-Down Sequence (4) ///VBAT “OFF” >0 DVDDI “OFF” > 1us PDN pin 0V 0V 0V Power –Down Sequence (5) CAUTION: The performance of the device will not be guaranteed after the sequence below. (5) First VBAT is turned-off, Next, DVDDI is turned-off. Rev.04.9 –8– 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] Analog inputs AC-coupling capacitor is required at analog inputs. Recommended capacitance is 0.1µF. This AC-coupling capacitance configures High-Pass-Filter, and used to configuration of POP NOISE SUPPRESSOR as well. Therefore, any variation of this capacitance affects both HPF cut-off frequency and POP NOISE SUPPRESSOR operation. Additional input filter is applicable. When using filter at analog input, place it before AC-coupling capacitors. Note 16. Cut off frequency (fc) of the High-pass filter, used as decoupling before input, is caluculated by an equation, 1 / (2 × π × R × C). For example, when Input impedance of INN and INP pins are 50kΩ(typ.) and AC coupling capacitors are 0.1µF, then the cut off frequency will be 31.8Hz. Pre AMP THE AK7846 has internal Pre-Amplifier, which supports from −6dB to +15dB(3dB/step) gain range. Pre-Amplifier gain is adjusted by PG0,PG1 and PG2 like as shown below. PG2 “Low” “Low” “Low” “Low” “High” “High” “High” “High” PG1 “Low” “Low” “High” “High” “Low” “Low” “High” “High” PG0 “Low” “High” “Low” “High” “Low” “High” “Low” “High” Pre Gain Setting Value −6dB -3dB 0dB +3dB +6dB +9dB +12dB +15dB Table. 1 Pre Gain Setting Class-D AMP Class-D architecture features higher efficiency and low power consumption operation. AKM filter-less solution offers Class-AB performance with Class-D efficiency and minimal board space. Pop Noise Suppressor The AK7846 features extensive pop noise suppression circuitry. Power Booster Built-in BOOST DCDC CONVERTER generates adequate high voltage for Piezo-Speaker. Input voltage range corresponds with Li-Ion battery voltage range (2.7V ~ 4.5V), and output voltage is 13V. Normally, output connected to and supply VDD1 and VDD2 for Class-D operation. Lowpass Filter The AK7846 has a built-in Lowpass Filter at the input side. Cutoff frequency can be adjusted by FC0 and FC1 as follows. FC0 and FC1 must be connected to either ground (VSS4) or DVDDI. FC1 FC0 CurOff Frequency “Low” “Low” 16kHz “Low” “High” 8kHz “High” “Low” 4kHz “High” “High” 4kHz Table. 2 Adjustable Cutoff Frequency of Lowpass filter Rev.04.9 –9– 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] Protection The AK7846 supports following protection circuits for protecting against any damages. Output Short-Circuit Protection In case of detecting VCL(R)P and VCL(R)N short, the AK7846 clamps peak current of Class-D output circuit without shutting down the outputs. Over-Temperature Protection The AK7846 is designed to shutdown at +150°C of inside temperature so that it can be protected from heat damage. Note that the AK7846 DOES NOT support resume function from Over-Temperature Protection. Once it is activated, the AK7846 does not back in normal operation unless “PDN” is toggled (“L” Æ “H”). Over-Current Protection Class-D amplifiers’ current-limiting protection clamps the output current without shutting down the outputs. Over-Voltage Protection Boost DCDC Converter has the voltage-limiting function to avoid destrying itself. Rev.04.9 – 10 – 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] 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. (TBD) Rev.04.9 – 11 – 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] LEVEL DIAGRAM The gain of AK7846 are determined by Pre-Amplifier, LPF and Class-D Amp, Total gain will be +21dB while Pre-Amplifier is default setting (PG=0). LPF gain and Class-D Amp gain are not changeable. Figure 3 shows level diagram of two example, PG=0dB and PG=+15dB. INx [dBV] 25 Pre AMP LPF Class-D AMP -3dB to +15dB 3dB step +6dB +15dB 0dBV = 1Vrms VCxN VCxP 1kHz Class-D AMP maximum output with 150nF load : 8.0Vrms 20 Output : 18.0dBV (8.0Vrms) 15 +15dB 10 5 0 +6.02dB Input (1) : -3.01dBV (0.70Vrms) *Pre Gain = 0dB Input path Limit : -3.01dBV 0dB -5 3.01dBV (0.70Vrms) -3.01dBV (0.70Vrms) - 10 +15dB - 15 Input (2) : -18.01dBV (0.126Vrms) *Pre Gain = +15dB - 20 Figure 3. Level Diagram *1Vrms=0dBV=2.83Vpp (sin wave) Rev.04.9 – 12 – 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] TYPICAL APPLICATION CIRCUIT Li-ion Battery C4 L1 ERRO PDN VFB C9 VBAT VCOIL Boost DCDC DVDDI FC1 FC0 PG2 PG1 PG0 VSS3 C1 VDD1 VCLN Pre Gain INL C5 D1 LPF ClassD L Piezo Speaker VCLP C7 VSS1 VSS4 VDD2 Pre Gain INR C6 VC C3 LPF VCLN Class-D R VREF Piezo Speaker VCLP C8 VSS2 Figure 4 AK7846 Application Schematic Recommended external components are shown in Table. 3 as follows. Reference L1 D1 C1 C3 C4, C5, C6 C7,C8 C9 Type Inductor ※ Diode / Schottky Capacitor / Ceramic Capacitor / Ceramic Capacitor / Ceramic Capacitor / Ceramic Value Manufacturer CoilCraft TDK Part No. LPS3010-102ML TFC252008MC-1R0 Size (mm) 2.95 ×2.95 ×0.9 2.5 ×2.0 ×0.8 (30V, 1A) SANYO SS1003EJ 1.6 × 0.8 × 0.6 10µF / 25V Taiyo Yuden TMK325BJ106MD-B 3.2 × 2.5 × 0.85 0.01µF / 16V Taiyo Yuden EMK105BJ103KV 1.0 × 0.5 × 0.5 0.1µF / 16V Taiyo Yuden EMK105BJ104KV-B 1.0 × 0.5 × 0.5 2.2µF / 16V Taiyo Yuden EDK107BJ225KA 1.6 × 0.8 × 0.8 1.0uF Table. 3 External Recommendation Parts ※Chose one of inductors in Table. 3 Selection of L1, C1 and D1 are very important because they affect DCDC converter paformance directly. For stability operation, AKM recommends them described in Table. 3 Rev.04.9 – 13 – 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] 1. Grounding and Power Supply Decoupling The AK7846 requires careful attention to power supply and grounding arrangements. VBAT is usually supplied from Li-Ion battery in the system. VDD1 and VDD2 are supplied from smoothed boosted voltage. VSS1, VSS2, VSS3 and VSS4 must be connected to analog ground plane. Analog and digital ground in the system should be connected together near where the supplies are brought onto the printed circuit board. Decoupling capacitors with the small value ceramic should be as close to the AK7846 as possible. 2. Voltage Reference VC is a signal ground of this device. A 0.01µF ceramic capacitor (C3) between VC and VSS4 pin eliminates 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 analog Inputs AC-coupling capacitors are necessary in series to INL and INR respectively. 4. 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 AK7846 or Class-D outputs away as far away as possible from the devices such as antennas that are sensitive to high frequency noise. 5. Effect on RF bands Power Booster or Class-D Outputs may affect high frequency signal outside the AK7846. Apply previous section (4. Class-D Outputs) in PCB layout. 6. Drivable Piezo Speakers The AK7846 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. 7. Boost DCDC Converter Ceramic capacitor (C1, C9), Inductance (L1) and Schottky Diode (D1) should be located as close to the AK7846 as possible. Rev.04.9 – 14 – 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] PACKAGE ■ MARKING 7846 XXXX 1 A XXXX : Date code (4 digit) ■ 31pin WL-CSP Package Outline (Unit : mm) Rev.04.9 – 15 – 2008/03 AKEMDAKEMD CONFIDENTIAL [AK7846] IMPORTANT NOTICE These products and their specifications are subject to change without notice. Before considering any use or application, consult the Asahi Kasei Microsystems Co., Ltd. (AKM) sales office or authorized distributor concerning their current status. AKM assumes no liability for infringement of any patent, intellectual property, or other right 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. AKM products are neither intended nor authorized for use as critical components in any safety, life support, or other hazard related device or system, and AKM assumes no responsibility relating to any such use, except with the express written consent of the Representative Director of AKM. As used here: 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. 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. It is the responsibility of the buyer or distributor of an AKM product who distributes, disposes of, or otherwise places the product with a third party to notify that 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 AKM harmless from any and all claims arising from the use of said product in the absence of such notification. Rev.04.9 – 16 – 2008/03