LM2772 Low-Ripple Switched Capacitor Step-Down Regulator General Description Features The LM2772 is a switched capacitor step-down regulator that produces a 1.2V output. It is capable of supplying loads up to 150mA with 3% output voltage regulation over line, load, and temperature. The LM2772 operates with an input voltage from 3.0V to 5.5V, accommodating 1-cell Li-Ion batteries and chargers. The LM2772 utilizes a highly efficient regulated multi-gain charge pump. Pre-regulated 1.1MHz fixed-frequency switching results in very low ripple and noise on both the input and the output. When output currents are low, the part automatically switches to a low-ripple PFM regulation mode to maintain high efficiency over the entire load range. The LM2772 is available in National’s 10-pad Leadless Leadframe No-Pullback Package (LLP-10). ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Low-Noise Fixed Frequency Operation 1.2V Output Voltage 3% Output Voltage Regulation Li-Ion (3.6V) to 1.2V with 80% Efficiency Very Low Output Ripple: 8mV @ 150mA Output Currents up to 150mA 2.7V to 5.5V Input Voltage Range Shutdown Disconnects Load from VIN 1.1MHz Switching Frequency No Inductors…Small Solution Size Short Circuit and Thermal Protection LLP-10 Package (3mm × 3mm × 0.8mm) Applications ■ DSP, Memory, and Microprocessor Power Supplies ■ Mobile Phones and Pagers ■ Portable Electronic Devices Typical Application Circuit LM2772 Efficiency vs. Low-Dropout Linear Regulator (LDO) Efficiency 20216401 © 2007 National Semiconductor Corporation 202164 20216413 www.national.com LM2772 Low-Ripple Switched Capacitor Step-Down Regulator December 2006 LM2772 Connection Diagram and Package Mark Information 10-Pin Non-Pullback Leadless Frame Package (LLP-10) National Semiconductor Package Number SDA10A 20216402 Pin Descriptions Pin # Name 1 VIN Description 2 GND Ground 3 VOUT Output Voltage 4 C3- Flying Capacitor 3: Negative Terminal 5 C3+ Flying Capacitor 3: Positive Terminal 6 C2- Flying Capacitor 2: Negative Terminal 7 C2+ Flying Capacitor 2: Positive Terminal 8 C1- Flying Capacitor 1: Negative Terminal 9 C1+ Flying Capacitor 1: Positive Terminal 10 EN Enable Pin Logic Input. Applying a logic HIGH voltage signal enables the part. A logic LOW voltage signal places the the device in shutdown. Input Voltage: Recommended VIN operating range 3.0V to 5.5V. Order Information Output Voltages Order Number Package Mark ID 1.2V LM2772SD XXXXX = ¢Z¢2¢X YYYYY = L2772 1.2V www.national.com LM2772SDX XXXXX = ¢Z¢2¢X YYYYY = L2772 2 Package SDA10A Non-Pullback LLP Supplied as: 1000 Units, Tape and Reel 4500 Units, Tape and Reel Operating Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. (Notes 1, 2) VIN Pin Voltage EN Pin Voltage Continuous Power Dissipation (Note 3) Junction Temperature (TJ-MAX) Storage Temperature Range Maximum Lead Temperature (Note 4) ESD Rating (Note 5) Human Body Model: Input Voltage Range Recommended Load Current Range Junction Temperature (TJ) Range Ambient Temperature (TA) Range (Note 6) -0.3V to 6.0V -0.3V to (VIN+0.3V) w/ 6.0V max Internally Limited 2.7V to 5.5V 0mA to 150mA -30°C to +110°C -30°C to +85°C Thermal Properties 150ºC -65ºC to +150º C 265ºC Electrical Characteristics LM2772 Absolute Maximum Ratings (Notes 1, 2) Junction-to-Ambient Thermal Resistance (θJA), LLP10 Package (Note 7) 55°C/W 2.0kV (Notes 2, 8) Limits in standard typeface are for TJ = 25ºC. Limits in boldface type apply over the full operating junction temperature range (-30° C ≤ TJ ≤ +110°C) . Unless otherwise noted, specifications apply to the LM2772 Typical Application Circuit (pg. 1) with: VIN = 3.6V; V(EN) = 1.8V, CIN = C1 = C2 = C3 = 1.0µF, COUT = 4.7µF. (Note 9) Symbol Parameter Condition Min Typ Max 0mA ≤ IOUT ≤ 150mA 1.164 (−3%) 1.2 1.236 (+3%) 0mA ≤ IOUT ≤ 150mA 1.178 (−1.8%) 1.2 1.236 (+3.0%) 3.0V ≤ VIN ≤ 5.5V VOUT 1.2V Output Voltage Regulation 0mA ≤ IOUT ≤ 150mA Units V VOUT/IOUT Output Load Regulation VOUT/VIN Output Line Regulation E Power Efficiency IOUT = 150mA IQ Quiescent Supply Current IOUT = 0mA (Note 10) 47 VR Fixed Frequency Output Ripple 40mA ≤ IOUT ≤ 150mA 8 mV VR–PFM PFM–Mode Output Ripple IOUT < 40mA 12 mV ISD Shutdown Current V(EN) = 0V FSW Switching Frequency 3.0V ≤ VIN ≤ 5.5V ICL Output Current Limit tON Turn-on Time VIL Logic-low Input Voltage 3.0V ≤ VIN ≤ 5.5V Logic-high Input Voltage 3.0V ≤ VIN ≤ 5.5V IIH Logic-high Input Current V(EN) = 1.8V (Note 11) IIL Logic-low Input Current Logic Input = 0V VIH 0.80 VIN = 5.5V 0V ≤ VOUT ≤ 0.2V 0.15 mV/mA 0.2 %/V 80 % µA 50 0.01 0.3 µA 1.15 1.50 MHz 500 mA 150 µs 0 0.63 V 1.1 VIN V 5 µA 0.01 µA Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics tables. Note 2: All voltages are with respect to the potential at the GND pins. Note 3: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ=150ºC (typ.) and disengages at TJ=140ºC (typ.). Note 4: For detailed information on soldering requirements and recommendations, please refer to National Semiconductor's Application Note 1187 (AN-1187): Leadless Leadframe Package (LLP). Note 5: The Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. MIL-STD-883 3015.7 Note 6: Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 110ºC), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (θJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (θJA × PD-MAX). 3 www.national.com LM2772 Note 7: Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power dissipation exists, special care must be paid to thermal dissipation issues. Note 8: Min and Max limits are guaranteed by design, test, or statistical analysis. Typical numbers are not guaranteed, but do represent the most likely norm. Note 9: CIN, COUT, C1, C2, C3: Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics. Note 10: VOUT is set to 1.3V during this test (Device is not switching). Note 11: There is a 350kΩ pull-down resistor connected internally between the EN pin and GND. Block Diagram 20216403 www.national.com 4 Unless otherwise specified: VIN = 3.6V, CIN = C1 = C2 = C3 = 1.0µF, COUT = 4.7µF, TA = 25ºC. Capacitors are low-ESR multi-layer ceramic capacitors (MLCC's). Output Voltage vs. Output Current Output Voltage vs. Input Voltage 20216412 20216414 Efficiency vs. Input Voltage Operating Supply Current 20216413 20216426 5 www.national.com LM2772 Typical Performance Characteristics LM2772 Input and Output Voltage Ripple, Load = 150mA Load Step 10mA to 150mA, VIN = 3.6V 20216415 20216423 CH1: VIN, Scale: 50mV/Div, AC Coupled CH3: VOUT, Scale: 10mV/Div, AC Coupled Time scale: 1µs/Div CH3: VOUT; Scale: 50mV/Div, AC Coupled CH4: IOUT; Scale: 100mA/Div Time scale: 40µs/Div Load Step 10mA to 150mA, VIN = 4.7V Line Step 3.5V to 4.0V with Load = 150mA 20216421 20216424 CH2: VIN; Scale: 1V/Div, DC Coupled CH3: VOUT; Scale: 20mV/Div, AC Coupled Time scale: 400µs/Div CH3: VOUT; Scale: 50mV/Div, AC Coupled CH4: IOUT; Scale: 100mA/Div Time scale: 40µs/Div Line Step 4.0V to 3.5V with Load = 150mA Oscillator Frequency vs. Input Voltage 20216422 CH2: VIN; Scale: 1V/Div, DC Coupled CH3: VOUT; Scale: 20mV/Div, AC Coupled Time scale: 400µs/Div www.national.com 20216425 6 LM2772 Startup Behavior, Load = 150mA 20216416 CH1: VOUT; Scale: 200mV/Div, DC Coupled Time scale: 20µs/Div 7 www.national.com LM2772 SHUTDOWN The LM2772 is in shutdown mode when the voltage on the enable pin (EN) is logic-low. In shutdown, the LM2772 draws virtually no supply current. When in shutdown, the output of the LM2772 is completely disconnected from the input. Internal feedback resistors pull the output voltage down to 0V during shutdown. Operation Description OVERVIEW The LM2772 is a switched capacitor converter that produces a regulated, low voltage output. The core of the part is a highly efficient charge pump that utilizes fixed frequency pre-regulation and Pulse Frequency Modulation to minimize ripple and power losses over wide input voltage and output current ranges. A description of the principal operational characteristics of the LM2772 is detailed in the Circuit Description, and Efficiency Performance sections. These sections refer to details in the Block Diagram. SOFT START The LM2772 employs soft start circuitry to prevent excessive input inrush currents during startup. At startup, the output voltage gradually rises from 0V to the nominal output voltage. This occurs in 150µs (typ.). Soft-start is engaged when the part is enabled, including situations where voltage is established simultaneously on the VIN and EN pins. CIRCUIT DESCRIPTION The core of the LM2772 is a two-phase charge pump controlled by an internally generated non-overlapping clock. The charge pump operates by using external flying capacitors C1, C2, and C3 to transfer charge from the input to the output. At input voltages below 3.5V (typ.) the LM2772 operates in a 1/2x Gain, with the input current being equal to 1/2 of the load current. At input voltages between 3.5V to 4.6V(typ.) the part utilizes a gain of 2/5x, resulting in an input current equal to 2/5 times the load current. At input voltages above 4.6V (typ.), the part is in a gain of 1/3, with the input current being 1/3 of the load current. The two phases of the switched capacitor switching cycle will be referred to as the "charge phase" and the "discharge phase". During the charge phase, the flying capacitor is charged by the input supply. After half of the switching cycle [ t = 1/(2×FSW) ], the LM2772 switches to the discharge phase. In this configuration, the charge that was stored on the flying capacitors in the charge phase is transferred to the output. The LM2772 uses fixed frequency pre-regulation to regulate the output voltage to 1.2V during moderate to high load currents. The input and output connections of the flying capacitors are made with internal MOS switches. Pre-regulation limits the gate drive of the MOS switch connected between the voltage input and the flying capacitors. Controlling the on resistance of this switch limits the amount of charge transferred into and out of each flying capacitor during the charge and discharge phases, and in turn helps to keep the output ripple very low. When output currents are low (<40mA typ.), the LM2772 automatically switches to a low-ripple Pulse Frequency Modulation (PFM) form of regulation. In PFM mode, the flying capacitors stay in the discharge phase until the output voltage drops below a predetermined trip point. When this occurs, the flying capacitors switch back to the charge phase. After being charged, the flying capacitors repeat the process of staying in the discharge phase and switching to the charge phase when necessary. THERMAL SHUTDOWN Protection from damage related to overheating is achieved with a thermal shutdown feature. When the junction temperature rises to 150ºC (typ.), the part switches into shutdown mode. The LM2772 disengages thermal shutdown when the junction temperature of the part is reduced to 140ºC (typ.). Due to the high efficiency of the LM2772, thermal shutdown and/or thermal cycling should not be encountered when the part is operated within specified input voltage, output current, and ambient temperature operating ratings. If thermal cycling is seen under these conditions, the most likely cause is an inadequate PCB layout that does not allow heat to be sufficiently dissipated out of the LLP package. CURRENT LIMIT PROTECTION The LM2772 charge pump contains current limit protection circuitry that protects the device during VOUT fault conditions where excessive current is drawn. Output current is limited to 500mA (typ). Application Information RECOMMENDED CAPACITOR TYPES The LM2772 requires 5 external capacitors for proper operation. Surface-mount multi-layer ceramic capacitors are recommended. These capacitors are small, inexpensive and have very low equivalent series resistance (ESR, ≤ 15mΩ typ.). Tantalum capacitors, OS-CON capacitors, and aluminum electrolytic capacitors generally are not recommended for use with the LM2772 due to their high ESR, as compared to ceramic capacitors. For most applications, ceramic capacitors with an X7R or X5R temperature characteristic are preferred for use with the LM2772. These capacitors have tight capacitance tolerance (as good as ±10%) and hold their value over temperature (X7R: ±15% over -55ºC to 125ºC; X5R: ±15% over -55ºC to 85ºC). Capacitors with a Y5V or Z5U temperature characteristic are generally not recommended for use with the LM2772. These types of capacitors typically have wide capacitance tolerance (+80%, -20%) and vary significantly over temperature (Y5V: +22%, -82% over -30ºC to +85ºC range; Z5U: +22%, -56% over +10ºC to +85ºC range). Under some conditions, a 1µFrated Y5V or Z5U capacitor could have a capacitance as low as 0.1µF. Such detrimental deviation is likely to cause Y5V and Z5U capacitors to fail to meet the minimum capacitance requirements of the LM2772. Net capacitance of a ceramic capacitor decreases with increased DC bias. This degradation can result in lower capacitance than expected on the input and/or output, resulting in EFFICIENCY PERFORMANCE Charge-pump efficiency is derived in the following two ideal equations (supply current and other losses are neglected for simplicity): IIN = G × IOUT E = (VOUT × IOUT) ÷ (VIN × IIN) = VOUT ÷ (G × VIN) In the equations, G represents the charge pump gain. Efficiency is at its highest as G×VIN approaches VOUT. Refer to the efficiency graph in the Typical Performance Characteristics section for detailed efficiency data. The transition between gains of 1/2, 2/5, and 1/3 are clearly distinguished by the sharp discontinuity in the efficiency curve. www.national.com 8 Manufacturer Contact Information AVX www.avx.com Murata www.murata.com Taiyo-Yuden www.t-yuden.com TDK www.component.tdk.com Vishay-Vitramon www.vishay.com INPUT CAPACITOR AND INPUT VOLTAGE RIPPLE The input capacitor (CIN) is a reservoir of charge that aids a quick transfer of charge from the supply to the flying capacitors during the charge phase of operation. The input capacitor helps to keep the input voltage from drooping at the start of the charge phase when the flying capacitors are connected to the input. It also filters noise on the input pin, keeping this noise out of sensitive internal analog circuitry that is biased off the input line. Much like the relationship between the output capacitance and output voltage ripple, input capacitance has a dominant and first-order effect on input ripple magnitude. Increasing (decreasing) the input capacitance will result in a proportional decrease (increase) in input voltage ripple. Input voltage, output current, and flying capacitance also will affect input ripple levels to some degree. In typical high-current applications, a 1µF low-ESR ceramic capacitor is recommended on the input. Different input capacitance values can be used to reduce ripple, shrink the solution size, and/or cut the cost of the solution. But changing the input capacitor may also require changing the flying capacitor and/or output capacitor to maintain good overall circuit performance. Performance of the LM2772 with different capacitor setups is discussed below in Recommended Capacitor Configurations. OUTPUT CAPACITOR AND OUTPUT VOLTAGE RIPPLE The output capacitor in the LM2772 circuit (COUT) directly impacts the magnitude of output voltage ripple. Other prominent factors also affecting output voltage ripple include input voltage, output current and flying capacitance. Due to the complexity of the regulation topology, providing equations or models to approximate the magnitude of the ripple can not be easily accomplished. But one important generalization can be made: increasing (decreasing) the output capacitance will result in a proportional decrease (increase) in output voltage ripple. In typical high-current applications, a 4.7µF low-ESR ceramic output capacitor is recommended. Different output capacitance values can be used to reduce ripple, shrink the solution size, and/or cut the cost of the solution. But changing the output capacitor may also require changing the flying capacitor and/or input capacitor to maintain good overall circuit performance. Performance of the LM2772 with different capacitor setups in discussed in the section Recommended Capacitor Configurations. High ESR in the output capacitor increases output voltage ripple. If a ceramic capacitor is used at the output, this is usually not a concern because the ESR of a ceramic capacitor is typically very low and has only a minimal impact on ripple magnitudes. If a different capacitor type with higher ESR is used (tantalum, for example), the ESR could result in high ripple. To eliminate this effect, the net output ESR can be significantly reduced by placing a low-ESR ceramic capacitor in parallel with the primary output capacitor. The low ESR of the ceramic capacitor will be in parallel with the higher ESR, resulting in a low net ESR based on the principles of parallel resistance reduction. FLYING CAPACITORS The flying capacitors (C1, C2, C3) transfer charge from the input to the output. Flying capacitance can impact both output current capability and ripple magnitudes. If flying capacitance is too small, the LM2772 may not be able to regulate the output voltage when load currents are high. On the other hand, if the flying capacitance is too large, the flying capacitor might overwhelm the input and output capacitors, resulting in increased input and output ripple. In typical high-current applications, 1µF low-ESR ceramic capacitors are recommended for the flying capacitors. Polarized capacitors (tantalum, aluminum electrolytic, etc.) must not be used for the flying capacitor, as they could become reversebiased during LM2772 operation. RECOMMENDED CAPACITOR CONFIGURATIONS The data in Table 1 can be used to assist in the selection of a capacitor configuration that best balances solution size and cost with the electrical requirements of the application. As previously discussed, input and output ripple voltages will vary with output current and input voltage. The numbers provided show expected ripple voltage with VIN = 3.6V and a load current of 150mA. The table offers a first look at approximate ripple levels and provides a comparison of different capacitor configurations, but is not intended to be a guarantee of performance. With any capacitance configuration chosen, always verify that the performance of the ripple waveforms are suitable for the intended application. The same capacitance value must be used for all the flying capacitors. 9 www.national.com LM2772 higher ripple voltages and currents. Using capacitors at DC bias voltages significantly below the capacitor voltage rating will usually minimize DC bias effects. Consult capacitor manufacturers for information on capacitor DC bias characteristics. Capacitance characteristics can vary quite dramatically with different application conditions, capacitor types, and capacitor manufacturers. It is strongly recommended that the LM2772 circuit be thoroughly evaluated early in the design-in process with the mass-production capacitors of choice. This will help ensure that any such variability in capacitance does not negatively impact circuit performance. The table below lists some leading ceramic capacitor manufacturers. LM2772 TABLE 1. LM2772 Performance with Different Capacitor Configurations (Note 12) Note 12: Refer to the text in the Recommended Capacitor Configurations section for detailed information on the data in this table CAPACITOR CONFIGURATION (VIN = 3.6V) Layout Guidelines TYPICAL INPUT RIPPLE TYPICAL OUTPUT RIPPLE CIN = 1µF, COUT = 4.7µF, C1, C2, C3 = 1µF 54mV 4mV CIN = 1µF, COUT = 2.2µF, C1, C2, C3 = 1µF 48mV 6mV CIN = 0.47µF, COUT = 4.7µF, C1, C2, C3 = 1µF 83mV 5mV CIN = 0.47µF, COUT = 3.3µF, C1, C2, C3 = 1µF 82mV 4mV CIN = 0.47µF, COUT = 3.3µF, C1, C2, C3 = 0.47µF 83mV 5mV www.national.com Proper board layout will help to ensure optimal performance of the LM2772 circuit. The following guidelines are recommended: • Place capacitors as close to the LM2772 as possible, and preferably on the same side of the board as the IC. • Use short, wide traces to connect the external capacitors to the LM2772 to minimize trace resistance and inductance. • Use a low resistance connection between ground and the GND pin of the LM2772. Using wide traces and/or multiple vias to connect GND to a ground plane on the board is most advantageous. 10 LM2772 Physical Dimensions inches (millimeters) unless otherwise noted SDA10A: 10-Pin Non-Pullback Leadless Leadframe Package 3.0mm × 3.0mm × 0.8mm 11 www.national.com LM2772 Low-Ripple Switched Capacitor Step-Down Regulator Notes THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS, IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS. EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness. National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. Copyright© 2007 National Semiconductor Corporation For the most current product information visit us at www.national.com National Semiconductor Americas Customer Support Center Email: [email protected] Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530-85-86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +49 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Support Center Email: [email protected] National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: [email protected] Tel: 81-3-5639-7560