LM4917 LM4917 Ground-Referenced, 95mW Stereo Headphone Amplifier Literature Number: SNAS238F Ground-Referenced, 95mW Stereo Headphone Amplifier General Description Key Specifications The LM4917 is a stereo, output capacitor-less headphone amplifier capable of delivering 95mW of continuous average power into a 16 load with less than 1% THD+N from a single 3V power supply. The LM4917 provides high quality audio reproduction with minimal external components. A ground referenced output eliminates the output coupling capacitors typically required by single-ended loads, reducing component count, cost and board space consumption. This makes the LM4917 ideal for mobile phones and other portable equipment where board space is at a premium. Eliminating the output coupling capacitors also improves low frequency response. The LM4917 operates from a single 1.4V to 3.6V power supply, features low 0.02% THD+N and 70dB PSRR. Independent right/left channel low-power shutdown controls provide power saving flexibility for mono/stereo applications. Superior click and pop suppression eliminates audible transients during start up and shutdown. Short circuit and thermal overload protection protects the device during fault conditions. Improved PSRR at 1kHz 70dB (typ) Power Output at VDD = 3V, RL = 16, THD 1% Shutdown Current 95mW (typ) 0.01A (typ) Features Ground referenced outputs High PSRR Available in space-saving TSSOP package Ultra low current shutdown mode Improved pop & click circuitry eliminates noises during turn-on and turn-off transitions 1.4 - 3.6V operation No output coupling capacitors, snubber networks, bootstrap capacitors Shutdown either channel independently Applications Notebook PCs Desktop PCs Mobile Phone PDAs Portable electronic devices Block Diagram 200893b8 FIGURE 1. Circuit Block Diagram Boomer(R) is a registered trademark of National Semiconductor Corporation. (c) 2011 National Semiconductor Corporation 200893 www.national.com LM4917 Ground-Referenced, 95mW Stereo Headphone Amplifier May 31, 2011 LM4917 LM4917 Typical Application 200893b2 FIGURE 2. Typical Audio Amplifier Application Circuit www.national.com 2 LM4917 Connection Diagrams TSSOP Package TSSOP Marking 200893b7 Z - Assembly Plant Code XY - Date Code TT - Traceability 200893a4 Top View Order Number LM4917MT See NS Package Number MTC14 LLP Package LLP Marking 200893c4 Z - Assembly Plant Code XY - Date Code TT - Traceability 200893c0 Top View Order Number LM4917SD See NS Package Number SDA14A Pin Descriptions Pin Name Function 1 SD_LC Active_Low Shutdown, Left Channel 2 CPVDD Charge Pump Power Supply 3 CCP+ Positive Terminal-Charge Pump Flying Capacitor 4 PGND Power Ground 5 CCP- Negative Terminal- Charge Pump Flying Capacitor 6 VCP_OUT Charge Pump Output 7 -AVDD Negative Power Supply-Amplifier 8 L_OUT Left Channel Output Positive Power Supply-Amplifier 9 AVDD 10 L_IN Left Channel Input 11 R_OUT Right Channel Output 12 SD_RC Active_Low Shutdown, Right Channel 13 R_IN Right Channel Input 14 SGND Signal Ground 3 www.national.com LM4917 Junction Temperature Thermal Resistance Absolute Maximum Ratings (Note 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage Storage Temperature Input Voltage Power Dissipation (Note 3) ESD Susceptibility (Note 4) ESD Susceptibility (Note 5) 4.0V -65C to +150C -0.3V to VDD + 0.3V Internally Limited 2000V 200V Electrical Characteristics VDD = 3V 150C JC (TSSOP) 40C/W JA (TSSOP) 109C/W Operating Ratings Temperature Range TMIN TA TMAX -40C TA 85C 1.4V VCC 3.6V Supply Voltage (VDD) (Note 1, Note 2) The following specifications apply for VDD = 3V, AV = 1, and 16 load unless otherwise specified. Limits apply to TA = 25C. LM4917 Parameter Conditions Typ (Note 6) Limit (Note 7, Note 8) Units (Limits) Quiescent Power Supply Current VIN = 0V, IO = 0A, both channels enabled 11 20 mA (max) VIN = 0V, IO = 0A, one channel enabled 9 Symbol IDD mA ISD Shutdown Current VSD_LC = VSD_RC = GND 0.01 1 A (max) VOS Output Offset Voltage RL = 32 1 10 mV (max) PO Output Power THD+N = 1% (max); f = 1kHz, RL = 16 95 50 mW (min) THD+N = 1% (max); f = 1kHz, RL = 32 82 mW 0.02 % THD+N Total Harmonic Distortion + Noise PO = 50mW, f = 1kHz, RL = 32 (A-weighted) single channel PSRR Power Supply Rejection Ratio VRIPPLE = 200mV sine p-p, f = 1kHz f = 20kHz 70 55 dB SNR Signal-to-Noise Ratio RL = 32, POUT = 20mW, f = 1kHz 100 dB VIH Shutdown Input Voltage High VIH = 0.7*CPVDD V (min) VIL Shutdown Input Voltage Low VIL = 0.3*CPVDD V (max) TWU Wake Up Time From Shutdown 339 s (max) XTALK Crosstalk 70 dB IL Input Leakage Current 0.1 nA RL = 16, PO = 1.6mW, f = 1kHz Note 1: All voltages are measured with respect to the GND pin unless otherwise specified. Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions that guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is given; however, the typical value is a good indication of device performance. Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, JA, and the ambient temperature, TA. The maximum allowable power dissipation is PDMAX = (TJMAX - TA) / JA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4917, see power derating currents for more information. Note 4: Human body model, 100pF discharged through a 1.5k resistor. Note 5: Machine Model, 220pF-240pF discharged through all pins. Note 6: Typicals are measured at 25C and represent the parametric norm. Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level). Note 8: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis. Note 9: If the product is in shutdown mode and VDD exceeds 3.6V (to a max of 4V VDD) then most of the excess current will flow through the ESD protection circuits. If the source impedance limits the current to a max of 10mA, then the part will be protected. If the part is enabled when VDD is above 4V circuit performance will be curtailed or the part may be permanently damaged. Note 10: Human body model, 100pF discharged through a 1.5k resistor. www.national.com 4 LM4917 External Components Description (Figure 1) Components Functional Description Inverting input resistance which sets the closed-loop gain in conjunction with Rf. This resistor also forms a 1. Ri 2. Ci pass filter with Ri at fc = 1 / (2RiCi). Refer to the section Proper Selection of External Components, for an explanation of how to determine the value of Ci. 3. Rf Feedback resistance which sets the closed-loop gain in conjunction with Ri. 4. C1 Flying capacitor. Low ESR ceramic capacitor (100m) 5. C2 Output capacitor. Low ESR ceramic capacitor (100m) 6. C3 Tantalum capacitor. Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing section for information concerning proper placement and selection of the supply bypass capacitor. 7. C4 Ceramic capacitor. Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing section for information concerning proper placement and selection of the supply bypass capacitor. high-pass filter with Ci at fc = 1 / (2RiCi). Input coupling capacitor which blocks the DC voltage at the amplifier's input terminals. Also creates a high- 5 www.national.com LM4917 Typical Performance Characteristics THD+N vs Frequency VDD = 1.4V, RL = 32, PO = 1mW THD+N vs Frequency VDD = 1.8V, RL = 16, PO = 5mW 20089341 20089339 THD+N vs Frequency VDD = 1.8V, RL = 32, PO = 5mW THD+N vs Frequency VDD = 1.8V, RL = 32, PO = 10mW 20089338 20089348 THD+N vs Frequency VDD = 3.0V, RL = 16, PO = 10mW THD+N vs Frequency VDD = 3.0V, RL = 16, PO = 25mW 20089336 20089334 www.national.com 6 LM4917 THD+N vs Frequency VDD = 3.0V, RL = 16, PO = 50mW THD+N vs Frequency VDD = 3.0V, RL = 32, PO = 5mW 20089333 20089332 THD+N vs Frequency VDD = 3.0V, RL = 32, PO = 10mW THD+N vs Frequency VDD = 3.0V, RL = 32, PO = 25mW 20089331 20089328 Gain Flatness vs Frequency RIN = 20k, CIN = 0.39F Output Power vs Supply Voltage RL = 16 20089354 20089347 7 www.national.com LM4917 Output Power vs Supply Voltage RL = 32 PSRR vs Frequency VDD = 1.8V, RL = 16 200893c6 20089345 PSRR vs Frequency VDD = 1.8V, RL = 32 PSRR vs Frequency VDD = 3.0V, RL = 16 20089344 20089343 PSRR vs Frequency VDD = 3.0V, RL = 32 THD+N vs Output Power VDD = 1.4V, RL = 32, f = 1kHz 20089342 www.national.com 20089327 8 LM4917 THD+N vs Output Power VDD = 1.8V, RL = 16, f = 1kHz THD+N vs Output Power VDD = 1.8V, RL = 32, f = 1kHz 20089326 20089325 THD+N vs Output Power VDD = 3.0V, RL = 16, f = 1kHz THD+N vs Output Power VDD = 3.0V, RL = 32, f = 1kHz 20089324 20089322 Power Dissipation vs Output Power VDD = 1.8V, RL = 16 Power Dissipation vs Output Power VDD = 1.8V, RL = 32 20089349 20089350 9 www.national.com LM4917 Power Dissipation vs Output Power VDD = 3V, RL = 16 Power Dissipation vs Output Power VDD = 3V, RL = 32 20089351 20089352 Supply Current vs Supply Voltage 20089353 www.national.com 10 ELIMINATING THE OUTPUT COUPLING CAPACITOR The LM4917 features a low noise inverting charge pump that generates an internal negative supply voltage. This allows the outputs of the LM4917 to be biased about GND instead of a nominal DC voltage, like traditional headphone amplifiers. Because there is no DC component, the large DC blocking capacitors (typically 220F) are not necessary. The coupling capacitors are replaced by two, small ceramic charge pump capacitors, saving board space and cost. Eliminating the output coupling capacitors also improves low frequency response. The headphone impedance and the output capacitor form a high pass filter that not only blocks the DC component of the output, but also attenuates low frequencies, impacting the bass response. Because the LM4917 does not require the output coupling capacitors, the low frequency response of the device is not degraded by external components. In addition to eliminating the output coupling capacitors, the ground referenced output nearly doubles the available dynamic range of the LM4917 when compared to a traditional headphone amplifier operating from the same supply voltage. PDMAX = (TJMAX - TA) / (JA) For package TSSOP, JA = 109C/W. TJMAX = 150C for the LM4917. Depending on the ambient temperature, TA, of the system surroundings, Equation 2 can be used to find the maximum internal power dissipation supported by the IC packaging. If the result of Equation 1 is greater than that of Equation 2, then either the supply voltage must be decreased, the load impedance increased or TA reduced. For the typical application of a 3V power supply, with a 16 load, the maximum ambient temperature possible without violating the maximum junction temperature is approximately 119.9C provided that device operation is around the maximum power dissipation point. Power dissipation is a function of output power and thus, if typical operation is not around the maximum power dissipation point, the ambient temperature may be increased accordingly. Refer to the Typical Performance Characteristics curves for power dissipation information for lower output powers. OUTPUT TRANSIENT ('CLICK AND POPS') ELIMINATED The LM4917 contains advanced circuitry that virtually eliminates output transients ('clicks and pops'). This circuitry prevents all traces of transients when the supply voltage is first applied or when the part resumes operation after coming out of shutdown mode. To ensure optimal click and pop performance under low gain configurations (less than 0dB), it is critical to minimize the RC combination of the feedback resistor RF and stray input capacitance at the amplifier inputs. A more reliable way to lower gain or reduce power delivered to the load is to place a current limiting resistor in series with the load as explained in the Minimizing Output Noise / Reducing Output Power section. POWER SUPPLY BYPASSING As with any power amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. Applications that employ a 3V power supply typically use a 4.7F in parallel with a 0.1F ceramic filter capacitors to stabilize the power supply's output, reduce noise on the supply line, and improve the supply's transient response. However, their presence does not eliminate the need for a local 0.1F supply bypass capacitor, CS, connected between the LM4917's supply pins and ground. Keep the length of leads and traces that connect capacitors between the LM4917's power supply pin and ground as short as possible. AMPLIFIER CONFIGURATION EXPLANATION As shown in Figure 2, the LM4917 has two operational amplifiers internally. The two amplifiers have externally configurable gain, and the closed loop gain is set by selecting the ratio of Rf to Ri. Consequently, the gain for each channel of the IC is MICRO POWER SHUTDOWN The voltage applied to the SD_LC (shutdown left channel) pin and the SD_RC (shutdown right channel) pin controls the LM4917's shutdown function. When active, the LM4917's micropower shutdown feature turns off the amplifiers' bias circuitry, reducing the supply current. The trigger point is 0.3*CPVDD for a logic-low level, and 0.7*CPVDD for logic-high level. The low 0.01A(typ) shutdown current is achieved by appling a voltage that is as near as ground a possible to the SD_LC/SD_RC pins. A voltage that is higher than ground may increase the shutdown current. There are a few ways to control the micro-power shutdown. These include using a single-pole, single-throw switch, a microprocessor, or a microcontroller. When using a switch, connect an external 100k pull-up resistor between the SD_LC/SD_RC pins and VDD. Connect the switch between the SD_LC/SD_RC pins and ground. Select normal amplifier operation by opening the switch. Closing the switch connects the SD_LC/SD_RC pins to ground, activating micro-power shutdown. The switch and resistor guarantee that the SD_LC/SD_RC pins will not float. This prevents unwanted AV = -(Rf / Ri) Since this an output ground-referenced amplifier, by driving the headphone through ROUT (Pin 11) and LOUT (Pin 8), the LM4917 does not require output coupling capacitors. The typical single-ended amplifier configuration where one side of the load is connected to ground requires large, expensive output capacitors. POWER DISSIPATION Power dissipation is a major concern when using any power amplifier and must be thoroughly understood to ensure a successful design. Equation 1 states the maximum power dissipation point for a single-ended amplifier operating at a given supply voltage and driving a specified output load. PDMAX = (VDD) 2 / (22RL) (2) (1) 11 www.national.com LM4917 Since the LM4917 has two operational amplifiers in one package, the maximum internal power dissipation point is twice that of the number which results from Equation 1. Even with the large internal power dissipation, the LM4917 does not require heat sinking over a large range of ambient temperature. From Equation 1, assuming a 3V power supply and a 16 load, the maximum power dissipation point is 28mW per amplifier. Thus the maximum package dissipation point is 56mW. The maximum power dissipation point obtained must not be greater than the power dissipation that results from Equation 2: Application Information LM4917 state changes. In a system with a microprocessor or microcontroller, use a digital output to apply the control voltage to the SD_LC/SD_RC pins. Driving the SD_LC/SD_RC pins with active circuitry eliminates the pull-up resistor. performance characteristics and may affect overall system performance. SELECTING PROPER EXTERNAL COMPONENTS Optimizing the LM4917's performance requires properly selecting external components. Though the LM4917 operates well when using external components with wide tolerances, best performance is achieved by optimizing component values. The LM4917 is unity-gain stable, giving a designer maximum design flexibility. The gain should be set to no more than a given application requires. This allows the amplifier to achieve minimum THD+N and maximum signal-to-noise ratio. These parameters are compromised as the closed-loop gain increases. However, low gain demands input signals with greater voltage swings to achieve maximum output power. Fortunately, many signal sources such as audio CODECs have outputs of 1VRMS (2.83VP-P). Please refer to the Audio Power Amplifier Design section for more information on selecting the proper gain. Design a Dual 90mW/16 Audio Amplifier AUDIO POWER AMPLIFIER DESIGN Given: Power Output 1Vrms (max) Input Impedance 20k Bandwidth 100Hz-20kHz 0.50dB The design begins by specifying the minimum supply voltage necessary to obtain the specified output power. One way to find the minimum supply voltage is to use the Output Power vs Supply Voltage curve in the Typical Performance Characteristics section. Another way, using Equation (5), is to calculate the peak output voltage necessary to achieve the desired output power for a given load impedance. For a single-ended application, the result is Equation (5). (4) VDD [2VOPEAK + (VDOTOP + VDOBOT)] (5) The Output Power vs Supply Voltage graph for a 16 load indicates a minimum supply voltage of 3.1V. This is easily met by the commonly used 3.3V supply voltage. The additional voltage creates the benefit of headroom, allowing the LM4917 to produce peak output power in excess of 90mW without clipping or other audible distortion. The choice of supply voltage must also not create a situation that violates maximum power dissipation as explained above in the Power Dissipation section. Remember that the maximum power dissipation point from Equation (1) must be multiplied by two since there are two independent amplifiers inside the package. Once the power dissipation equations have been addressed, the required gain can be determined from Equation (6). Input Capacitor Value Selection Amplifying the lowest audio frequencies requires high value input coupling capacitor (Ci in Figure 2). A high value capacitor can be expensive and may compromise space efficiency in portable designs. In many cases, however, the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 150Hz. Applications using speakers with this limited frequency response reap little improvement by using high value input and output capacitors. Besides affecting system cost and size, Ci has an effect on the LM4917's click and pop performance. The magnitude of the pop is directly proportional to the input capacitor's size. Thus, pops can be minimized by selecting an input capacitor value that is no higher than necessary to meet the desired -3dB frequency. As shown in Figure 2, the input resistor, Ri and the input capacitor, Ci, produce a -3dB high pass filter cutoff frequency that is found using Equation (3). (6) Thus, a minimum gain of 1.2 allows the LM4917 to reach full output swing and maintain low noise and THD+N perfromance. For this example, let AV = 1.5. The amplifiers overall gain is set using the input (Ri ) and feedback (Rf ) resistors. With the desired input impedance set at 20k, the feedback resistor is found using Equation (7). AV = Rf / Ri (7) The value of Rf is 30k. The last step in this design is setting the amplifier's -3db frequency bandwidth. To achieve the desired 0.25dB pass band magnitude variation limit, the low frequency response must extend to at lease one-fifth the lower bandwidth limit and the high frequency response must extend to at least five times the upper bandwidth limit. The gain variation for both (3) Also, careful consideration must be taken in selecting a certain type of capacitor to be used in the system. Different types of capacitors (tantalum, electrolytic, ceramic) have unique www.national.com 16 Input Level Charge Pump Capacitor Selection Choose low ESR (<100m) ceramic capacitors for optimum performance. Low ESR capacitors keep the charge pump output impedance to a minimum, extending the headroom on the negative supply. Choose capacitors with an X7R dielectric for best performance over temperature. Charge pump load regulation and output resistance is affected by the value of the flying capacitor (C1). A larger valued C1 improves load regulation and minimizes charge pump output resistance. The switch on-resistance and capacitor ESR dominates the output resistance for capacitor values above 2.2F. The output ripple is affected by the value and ESR of the output capacitor (C2). Larger valued capacitors reduce output ripple on the negative power supply. Lower ESR capacitors minimizes the output ripple and reduces the output resistance of the charge pump. fi-3dB = 1 / 2RiCi 90mW Load Impedance 12 fL = 100Hz / 5 = 20Hz order filter -3dB point. Thus, a frequency of 20Hz is used in the following equations to ensure that the response is better than 0.5dB down at 100Hz. (8) Ci 1 / (2*20k*20Hz) = 0.397F; use 0.39F (10) and fH = 20kHz x 5 = 100kHz The high frequency pole is determined by the product of the desired high frequency pole, fH, and the closed-loop gain, AV. With a closed-loop gain of 1.5 and fH = 100kHz, the resulting GBWP = 150kHz which is much smaller than the LM4917's GBWP of 3MHz. This figure displays that if a designer has a need to design an amplifier with a higher gain, the LM4917 can still be used without running into bandwidth limitations. (9) As stated in the External Components section, both Ri in conjunction with Ci, and RL, create first order highpass filters. Thus to obtain the desired low frequency response of 100Hz within 0.5dB, both poles must be taken into consideration. The combination of two single order filters at the same frequency forms a second order response. This results in a signal which is down 0.34dB at five times away from the single 13 www.national.com LM4917 response limits is 0.17dB, well within the 0.25dB desired limit. The results are LM4917 LM4917 SO Demo Board Artwork Top Overlay Top Layer 20089304 20089305 Bottom Layer 20089321 www.national.com 14 LM4917 LM4917 LLP Demo Board Artwork Top Overlay Top Layer 200893c2 200893c3 Bottom Layer 200893c1 LM4917 Reference Design Boards Bill Of Materials Part Description Qty LM4917 Mono Reference Design Board 1 LM4917 Audio AMP 1 U1 Tantalum Cap 1F 16V 10 1 Cs Ceramic Cap 0.39F 50V Z50 20 2 Ci Resistor 20k 1/10W 5 4 Ri, Rf Resistor 100k 1/10W 5 1 Rpu Jumper Header Vertical Mount 2X1, 0.100 1 J1 15 Ref Designator www.national.com LM4917 PCB Layout Guidelines General Mixed Signal Layout Recommendation This section provides practical guidelines for mixed signal PCB layout that involves various digital/analog power and ground traces. Designers should note that these are only "rule-of-thumb" recommendations and the actual results will depend heavily on the final layout. Power and Ground Circuits For two layer mixed signal design, it is important to isolate the digital power and ground trace paths from the analog power and ground trace paths. Star trace routing techniques (bringing individual traces back to a central point rather than daisy chaining traces together in a serial manner) can greatly enhance low level signal performance. Star trace routing refers to using individual traces to feed power and ground to each circuit or even device. This technique will require a greater amount of design time, but will not increase the final price of the board. The only extra parts required may be some jumpers. Avoiding Shorts on the Charge Pump Outputs For the LM4917SD package, the exposed dap is connected to the substrate of the device. Because LM4917's charge pump is powered by both a negative and positive supply the exposed dap must be left floating. This will avoid shorting the charge pump outputs. Single-Point Power / Ground Connections The analog power traces should be connected to the digital traces through a single point (link). A "PI-filter" can be helpful in minimizing high frequency noise coupling between the analog and digital sections. Further, place digital and analog power traces over the corresponding digital and analog ground traces to minimize noise coupling. Placement of Digital and Analog Components All digital components and high-speed digital signal traces should be located as far away as possible from analog components and circuit traces. 20089355 FIGURE 3. Bottom View of LM4917SD Package Avoiding Typical Design / Layout Problems Avoid ground loops or running digital and analog traces parallel to each other (side-by-side) on the same PCB layer. When traces must cross over each other do it at 90 degrees. Running digital and analog traces at 90 degrees to each other from the top to the bottom side as much as possible will minimize capacitive noise coupling and cross talk. Minimization of THD PCB trace impedance on the power, ground, and all output traces should be minimized to achieve optimal THD performance. Therefore, use PCB traces that are as wide as possible for these connections. As the gain of the amplifier is increased, the trace impedance will have an ever increasing adverse affect on THD performance. At unity-gain (0dB) the parasitic trace impedance effect on THD performance is reduced but still a negative factor in the THD performance of the LM4917 in a given application. www.national.com 16 LM4917 Physical Dimensions inches (millimeters) unless otherwise noted TSSOP Order Number LM4917MT NS Package Number MTC14 LLP Order Number LM4917SD NS Package Number SDA14A 17 www.national.com LM4917 Ground-Referenced, 95mW Stereo Headphone Amplifier Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Design Support Amplifiers www.national.com/amplifiers WEBENCH(R) Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage References www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Applications & Markets www.national.com/solutions Mil/Aero www.national.com/milaero PowerWise(R) Solutions Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors SolarMagicTM www.national.com/solarmagic PLL/VCO www.national.com/wireless www.national.com/training PowerWise(R) Design University 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(c) 2011 National Semiconductor Corporation For the most current product information visit us at www.national.com National Semiconductor Americas Technical Support Center Email: support@nsc.com Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Technical Support Center Email: europe.support@nsc.com National Semiconductor Asia Pacific Technical Support Center Email: ap.support@nsc.com National Semiconductor Japan Technical Support Center Email: jpn.feedback@nsc.com IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI's terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI's standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and applications using TI components. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in such safety-critical applications. TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are specifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet military specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated products in automotive applications, TI will not be responsible for any failure to meet such requirements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Applications Audio www.ti.com/audio Communications and Telecom www.ti.com/communications Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps DLP(R) Products www.dlp.com Energy and Lighting www.ti.com/energy DSP dsp.ti.com Industrial www.ti.com/industrial Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical Interface interface.ti.com Security www.ti.com/security Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive Microcontrollers microcontroller.ti.com Video and Imaging RFID www.ti-rfid.com OMAP Mobile Processors www.ti.com/omap Wireless Connectivity www.ti.com/wirelessconnectivity TI E2E Community Home Page www.ti.com/video e2e.ti.com Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright (c) 2011, Texas Instruments Incorporated