LM48580

LM48580 High Efficiency Class H, High Voltage, Haptic Piezo Actuator / Ceramic Speaker Driver LM48580 February 23, 2010 High Efficiency Class H, High Voltage, Haptic Piezo Actuator / Ceramic Speaker Driver General Description The LM48580 is a fully differential, high voltage driver for piezo actuators and ceramic speakers for portable multi-media devices. Part of National’s Powerwise product line, the LM48580’s Class H architecture offers significant power savings compared to traditional Class AB amplifiers. The device provides 30VP-P output drive while consuming just 15mW of quiescent power. The LM48580 is a single supply driver with an integrated boost converter which allows the device to deliver 30VP-P from a single 3.6V supply. The LM48580 has three pin-programmable gain settings and a low power Shutdown mode that reduces quiescent current consumption to 0.1µA. The LM48580 is available in an ultrasmall 12-bump micro SMD package (1.46mm x 1.97mm). Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Class H Driver Integrated Boost Converter Bridge-tied Load Output Differential Input Three Pin-Programmable Gains Low Supply Current Minimum external components Micro-power shutdown Thermal overload protection Available in space-saving 12-bump microSMD package Applications ■ ■ ■ ■ Touch screen Smart Phones Tablet PCs Portable Electronic Devices MP3 Players Key Specifications ■ Output Voltage at VDD = 3.6V RL = 6μF+10Ω, THD+N ≤ 1% ■ Quiescent Power Supply current at 3.6V 2.7mA (typ) 800mW (typ) 0.1μA (typ) 30VP-P (typ) ■ Power Dissipation at 25VP-P ■ Shutdown current Typical Application 30108070 FIGURE 1. Typical Application Circuit Boomer® is a registered trademark of National Semiconductor Corporation. © 2010 National Semiconductor Corporation 301080 www.national.com LM48580 Connection Diagrams TL Package 1.46mm x 1.97mm x 0.6mm 12–Bump micro SMD Marking 30108072 Top View XY = Date code TT = Die traceability G = Boomer Family M3 = LM48580TL 30108071 Top View Order Number LM48580TL See NS Package Number TLA12Z1A TLA12 Package View (Bumps Up) 30108031 www.national.com 2 LM48580 Ordering Information Ordering Information Table Order Number LM48580TL Package Drawing Number TLA12Z1A TLA12Z1A Package 12 Bump µSMD Transport Media 250 units on tape and reel 3000 units on tape and reel MSL Level 1 1 Green Status RoHS & no Sb/Br RoHS & no Sb/Br LM48580TLX 12 Bump µSMD Pin Descriptions TABLE 1. Bump Descriptions Bump A1 A2 A3 B1 Name OUT+ SGND IN+ OUTAmplifier Ground Amplifier Non-Inverting Input Amplifier Inverting Output Gain Select: GAIN = float: AV = 18dB GAIN = GND: AV = 24dB GAIN = VDD: AV = 30dB Amplifier Inverting Input Amplifier Supply Voltage. Connect to VBST Active Low Shutdown. Drive SHDN low to disable device. Connect SHDN to VDD for normal operation. Power Supply Boost Converter Output Boost Converter Switching Node Boost Converter Ground Description Amplifier Non-Inverting Output B2 GAIN B3 C1 C2 C3 D1 D2 D3 INVAMP SHDN VDD VBST SW PGND 3 www.national.com LM48580 Absolute Maximum Ratings (Note 1, Note 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (Note 1) SW Voltage VBST Voltage VAMP Input Voltage Power Dissipation (Note 3) ESD Rating, Human Body Model (Note 4) ESD Rating, Machine Model (Note 5) 6V 25V 21V 17V −0.3V to VDD + 0.3V Internally limited 2kV 150V ESD Rating, Charge Device Model (Note 6) Storage Temperature Junction Temperature Thermal Resistance 750V −65°C to + 150°C 150°C 64 °C/W  θJA (TLA12Z1A) Soldering Information See AN-1112 "Micro SMD Wafer Level Chip Scale Package." Operating Ratings Temperature Range TMIN ≤ TA ≤ TMAX (Note 10) Supply Voltage VDD (Note 1, Note 2) −40°C ≤ TA ≤ +85°C 2.5V ≤ VDD ≤ 5.5V The following specifications apply for RL = 6μF + 10Ω, CBST = 1μF, CIN = 0.47μF, AV = 24dB unless otherwise specified. Limits apply for TA = 25°C. LM48580 Symbol VDD IDD Parameter Supply Voltage Range VIN = 0V, RL = ∞ Quiescent Power Supply Current VDD = 3.6V VDD = 3V VOUT = 25P-P, f = 200Hz PD ISD TWU VOS AV RIN RIN VIN Power Consumption Shutdown Current Wake-up Time VDD = 3.6V VDD = 3V Shutdown Enabled From Shutdown GAIN = FLOAT GAIN = GND GAIN = VDD to GND to VDD AV = 18dB f = 200Hz, THD+N = 1% VDD = 3.6V VDD = 3V f = 2kHz, THD+N = 5% VDD = 3.6V VDD = 3V VDD = 3.6V + 200mVp-p sine, Inputs AC GND fRIPPLE = 217Hz, fRIPPLE = 1kHz VCM = 200mVP-P sine fRIPPLE = 217Hz fRIPPLE = 1kHz 56 55 dB dB 75 71 dB dB 30.5 30.5 11 8.5 0.16 1 17.5 23.5 29.5 46 800 830 0.5 1.4 63 18 24 30 52 2 1.6 360 18.5 24.5 30.5 58 575 131 3 mW mW µA ms mV dB dB dB kΩ kΩ kΩ VP-P VP-P VP-P VP-P VP-P % 2.7 3 4 mA mA Conditions Min (Note 8) 2.5 Typ (Note 7) Max (Note 8) 5.5 Units (Limits) V Electrical Characteristics VDD = 3.6V Differential Output Offset Voltage VDD = 3.6V Gain Input Resistance Gain Input Resistance Maximum Input Voltage Range VOUT Output Voltage 25 THD+N PSRR Total Harmonic Distortion + Noise VOUT = 25VP-P, f = 200Hz Power Supply Rejection Ratio (Figure TBD) Common Mode Rejection Ratio (Figure TBD) CMRR www.national.com 4 LM48580 LM48580 Symbol Parameter Boost Converter Switching Frequency Boost Converter Current Limit Logic High Input Threshold Logic Low Input Threshold Input Leakage Current SHDN SHDN SHDN 0.1 1.2 0.45 1 Conditions Min (Note 8) Typ (Note 7) 2.1 1100 Max (Note 8) Units (Limits) MHz mA V V μA fSW ILIMIT VIH VIL IIN Note 1: “Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or other conditions beyond those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating Conditions indicate conditions at which the device is functional and the device should not be operated beyond such conditions. All voltages are measured with respect to the ground pin, unless otherwise specified. Note 2: The Electrical Characteristics tables list guaranteed specifications under the listed Recommended Operating Conditions except as otherwise modified or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and are not guaranteed. Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature, TA. The maximum allowable power dissipation is PDMAX = (TJMAX − TA) / θJA or the given in Absolute Maximum Ratings, whichever is lower. Note 4: Human body model, applicable std. JESD22-A114C. Note 5: Machine model, applicable std. JESD22-A115-A. Note 6: Charge device model, applicable std. JESD22-C101-C. Note 7: Typical values represent most likely parametric norms at TA = +25ºC, and at the Recommended Operation Conditions at the time of product characterization and are not guaranteed. Note 8: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. 30108073 FIGURE 2. PSRR Test Circuit 30108074 FIGURE 3. CMRR Test Circuit 5 www.national.com LM48580 Typical Performance Characteristics THD+N vs Frequency VDD = 3.6V, VOUT = 9VP-P RL = 6μF + 10Ω THD+N vs Frequency VDD = 4.2V, VOUT = 10VP-P RL = 6μF + 10Ω 30108011 30108012 Output Voltage vs Frequency VDD = 3.6V, THD+N = 5% RL = 6μF + 10Ω Output Voltage vs Frequency VDD = 4.2V, THD+N = 5% RL = 6μF + 10Ω 30108013 30108014 THD+N vs Output Voltage VDD = 3.6V, RL = 6μF + 10Ω THD+N vs Output Voltage VDD = 4.2V, RL = 6μF + 10Ω 30108009 30108010 www.national.com 6 LM48580 Power Consumption vs Output Voltage VDD = 3.6V, RL = 6μF + 10Ω Power Consumption vs Output Voltage VDD = 4.2V, RL = 6μF + 10Ω 30108015 30108016 Output Voltage vs Supply Voltage RL = 6μF + 10Ω, f = 200Hz PSRR vs Frequency VDD = 3.6V, VRIPPLE = 200mVP-P RL = 6μF + 10Ω, f = 200Hz 30108017 30108019 CMRR vs Frequency VDD = 3.6V, VCM = 1VP-P RL = 6μF + 10Ω 30108019 7 www.national.com LM48580 Application Information GENERAL AMPLIFIER FUNCTION The LM48580 is a fully differential, Class H ceramic element driver for ceramic speakers and haptic actuators. The integrated, high efficiency boost converter dynamically adjusts the amplifier’s supply voltage based on the output signal, increasing headroom and improving efficiency compared to a conventional Class AB driver. The fully differential amplifier takes advantage of the increased headroom and bridge-tied load (BTL) architecture, delivering significantly more voltage than a single-ended amplifier. CLASS H OPERATION Class H is a modification of another amplifier class (typically Class B or Class AB) to increase efficiency and reduce power dissipation. To decrease power dissipation, Class H uses a tracking power supply that monitors the output signal and adjusts the supply accordingly. When the amplifier output is below 3VP-P, the nominal boost voltage is 6V. As the amplifier output increases above 3VP-P, the boost voltage tracks the amplifier output as shown in Figure 4. When the amplifier output falls below 3VP-P, the boost converter returns to its nominal output voltage. Power dissipation is greatly reduced compared to conventional Class AB drivers. 30108021 FIGURE 4. Class H Operation PROPERTIES OF PIEZOELECTRIC ELEMENTS Piezoelectric elements such as ceramic speakers or piezoelectric haptic actuators are capacitive in nature. Due to their capacitive nature, piezoelectric elements appear as low impedance loads at high frequencies (typically above 5kHz). A resistor in series with the piezoelectric element is required to ensure the amplifier does not see a short at high frequencies. The value of the series resistor depends on the capacitance of the element, the frequency content of the output signal, and the desired frequency response. Higher valued resistors minimize power dissipation at high frequencies, but also impacts the frequency response. This configuration is ideal for use with haptic actuators, where the majority of the signal content is typically below 2kHz. Conversely, lower valued resistors maximize frequency response, while increasing power dissipation at high frequency. This configuration is ideal for ceramic speaker applications, where high frequency audio content needs to be reproduced. Resistor values are typically between 10Ω and 20Ω. DIFFERENTIAL AMPLIFIER EXPLANATION The LM48580 features a fully differential amplifier. A differential amplifier amplifies the difference between the two input signals. A major benefit of the fully differential amplifier is the improved common mode rejection ratio (CMRR) over single ended input amplifiers. The increased CMRR of the differential amplifier reduces sensitivity to ground offset related noise injection, especially important in noisy systems. THERMAL SHUTDOWN The LM48580 features thermal shutdown that protects the device during thermal overload conditions. When the junction temperature exceeds +160°C, the device is disabled. The LM48580 remains disabled until the die temperature falls below the +160°C and SHDN is toggled. GAIN SETTING The LM48580 features three internally configured gain settings 18, 24, and 30dB. The device gain is selected through a single pin (GAIN). The gain settings are shown in Table 2. TABLE 2. Gain Setting Gain FLOAT GND VDD Gain Setting 18dB 24dB 30dB www.national.com 8 LM48580 SHUTDOWN FUNCTION The LM48580 features a low current shutdown mode. Set SD = GND to disable the amplifier and boost converter and reduce supply current to 0.01µA. SINGLE-ENDED INPUT CONFIGURATION The LM48580 is compatible with single-ended sources. When configured for single-ended inputs, input capacitors must be used to block and DC component at the input of the device. Figure 5 shows the typical single-ended applications circuit. 30108022 FIGURE 5. Single-Ended Configuration PROPER SELECTION OF EXTERNAL COMPONENTS Boost Converter Capacitor Selection The LM48580 boost converter requires three external capacitors for proper operation: a 1μF supply bypass capacitor, and 1μF + 100pF output reservoir capacitors. Place the supply bypass capacitor as close to VDD as possible. Place the reservoir capacitors as close to VBST and VAMP as possible. Low ESR surface-mount multi-layer ceramic capacitors with X7R or X5R temperature characteristics are recommended. Select output capacitors with voltage rating of 25V or higher. Tantalum, OS-CON and aluminum electrolytic capacitors are not recommended. See Table 4 for suggested capacitor manufacturers. BOOST CONVERTER OUTPUT CAPACITOR SELECTION Inductor Selection The LM48580 boost converter is designed for use with a 4.7μH inductor. Table 3 lists various inductors and their manufacturers. Choose an inductor with a saturation current rating greater than the maximum operating peak current of the LM48580 (> 1A). This ensures that the inductor does not saturate, preventing excess efficiency loss, over heating and possible damage to the inductor. Additionally, choose an inductor with the lowest possible DCR (series resistance) to further minimize efficiency losses. TABLE 3. Recommended Inductors MANUFACTURER Taiyo Yuden Coilcraft PART# BRL3225T4R7M LP3015 INDUCTANCE/ ISAT 4.7µH/1.1A 4.7µH/1.1A Diode Selection Use a Schottkey diode as shown in Figure 1. A 20V diode such as the NSR0520V2T1G from On Semiconductor is recommended. The NSR0520V2T1G is designed to handle a maximum average current of 500mA. PCB LAYOUT GUIDELINES Minimize trace impedance of the power, ground and all output traces for optimum performance. Voltage loss due to trace resistance between the LM48580 and the load results in decreased output power and efficiency. Trace resistance between the power supply and ground has the same effect as a poorly regulated supply, increased ripple and reduced peak output power. Use wide traces for power supply inputs and amplifier outputs to minimize losses due to trace resistance, as well as route heat away from the device. Proper grounding improves audio performance, minimizes crosstalk between channels and prevents switching noise from interfering with the audio signal. Use of power and ground planes is recommended. Place all digital components and route digital signal traces as far as possible from analog components and traces. Do not run digital and analog traces in parallel on the same PCB layer. If digital and analog signal lines must cross either over or under each other, ensure that they cross in a perpendicular fashion. 9 www.national.com LM48580 Demoboard Bill of Materials TABLE 4. Demoboard Bill of Materials DESIGNATOR C1 QUANTITY 10µF ±10% 16V 1 Tantalum Capacitor (B Case) AVX TPSB106K016R0800 1µF ±10% 16V X5R C2 1 Ceramic Capacitor (603) Panasonic ECJ-1VB1C105K Murata GRM188R61C105KA93D 1µF ±10% 25V X5R C3 1 Ceramic Capacitor (603) Panasonic ECJ-1VB1E105K Murata GRM188R61E105KA12D 100pF ±5% 50V C0G C4 1 Ceramic Capacitor (603) Panasonic ECJ-1VC1H101J Murata GRM1885C1H101JA01D 4.7µF ±10% 10V X5R C5, C6 2 Ceramic Capacitor (603) Panasonic ECJ-1VB1A474K Murata GRM188R61A474KA61D 0.1µF ±10% 50V X7R C7 1 Ceramic Capacitor (603) Panasonic ECJ-1VB1H104K Murata GRM188R71H104KA93D C8 D1 UNSTUFFED 20V, 500mA 1 Schottky Diode (SOD-523) ON Semiconductor NSR0520V2T1G L1 JU1, JU2 LM48580TL 1 2 1 4.7µH ±20% 1.1A Inductor Taiyo Yuden BRL3225T4R7M 3-Pin Header LM48580TL (12-Bump microSMD) DESCRIPTION www.national.com 10 LM48580 Demo Board Schematic 30108006 11 www.national.com LM48580 PC Board Layout 30108008 Top Silk Screen 30108007 Top Layer 30108003 30108005 Layer 2 Layer 3 30108002 30108001 Bottom Silkscreen Bottom Layer www.national.com 12 LM48580 Revision History Rev 1.0 Date 02/23/10 Initial released. Description 13 www.national.com LM48580 Physical Dimensions inches (millimeters) unless otherwise noted Thin micro SMD Order Number LM48580TL NS Package Number TLA12Z1A X1 = 1.463±0.03mm X2 = 1.970±0.03mm X3 = 0.600±0.075mm www.national.com 14 LM48580 Notes 15 www.national.com LM48580 High Efficiency Class H, High Voltage, Haptic Piezo Actuator / Ceramic Speaker Driver Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Amplifiers Audio Clock and Timing Data Converters Interface LVDS Power Management Switching Regulators LDOs LED Lighting Voltage References PowerWise® Solutions Temperature Sensors PLL/VCO www.national.com/amplifiers www.national.com/audio www.national.com/timing www.national.com/adc www.national.com/interface www.national.com/lvds www.national.com/power www.national.com/switchers www.national.com/ldo www.national.com/led www.national.com/vref www.national.com/powerwise WEBENCH® Tools App Notes Reference Designs Samples Eval Boards Packaging Green Compliance Distributors Quality and Reliability Feedback/Support Design Made Easy Design Support www.national.com/webench www.national.com/appnotes www.national.com/refdesigns www.national.com/samples www.national.com/evalboards www.national.com/packaging www.national.com/quality/green www.national.com/contacts www.national.com/quality www.national.com/feedback www.national.com/easy www.national.com/solutions www.national.com/milaero www.national.com/solarmagic www.national.com/training Applications & Markets Mil/Aero PowerWise® Design University Serial Digital Interface (SDI) www.national.com/sdi www.national.com/wireless www.national.com/tempsensors SolarMagic™ THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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