SM72501MFX

SM72501 SolarMagic Precision, CMOS Input, RRIO, Wide Supply Range Amplifier May 10, 2011 SM72501 SolarMagic Precision, CMOS Input, RRIO, Wide Supply Range Amplifier General Description The SM72501 is a low offset voltage, rail-to-rail input and output precision amplifier with a CMOS input stage and a wide supply voltage range. The SM72501 is ideal for sensor interface and other instrumentation applications. The guaranteed low offset voltage of less than ±200 µV along with the guaranteed low input bias current of less than ±1 pA makes the SM72501 ideal for precision applications. The SM72501 is built utilizing VIP50 technology, which allows the combination of a CMOS input stage and a 12V common mode and supply voltage range. This makes the SM72501 a great choice in many applications where conventional CMOS parts cannot operate under the desired voltage conditions. The SM72501 has a rail-to-rail input stage that significantly reduces the CMRR glitch commonly associated with rail-torail input amplifiers. This is achieved by trimming both sides of the complimentary input stage, thereby reducing the difference between the NMOS and PMOS offsets. The output of the SM72501 swings within 40 mV of either rail to maximize the signal dynamic range in applications requiring low supply voltage. The SM72501 is offered in the space saving 5-Pin SOT23. This small package is an ideal solution for area constrained PC boards and portable electronics. Features ■ Renewable Energy Grade Unless otherwise noted, typical values at VS = 5V ±200 µV (max) ■ Input offset voltage ±200 fA ■ Input bias current 9 nV/√Hz ■ Input voltage noise 130 dB ■ CMRR 130 dB ■ Open loop gain −40°C to 125°C ■ Temperature range 2.5 MHz ■ Unity gain bandwidth 715 µA ■ Supply current (SM72501) 2.7V to 12V ■ Supply voltage range ■ Rail-to-rail input and output Applications ■ ■ ■ ■ ■ ■ High impedance sensor interface Battery powered instrumentation High gain amplifiers DAC buffer Instrumentation amplifier Active filters Typical Application 30142105 Precision Current Source © 2011 National Semiconductor Corporation 301421 www.national.com SM72501 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. ESD Tolerance (Note 2) Storage Temperature Range Junction Temperature (Note 3) Soldering Information −65°C to +150°C +150°C 235°C 260°C (Note 1) −40°C to +125°C 2.7V to 12V 265°C/W  Infrared or Convection (20 sec)  Wave Soldering Lead Temp. (10 sec)  Human Body Model  Machine Model Charge-Device Model VIN Differential Supply Voltage (VS = V+ – V−) Voltage at Input/Output Pins Input Current 2000V 200V 1000V ±300 mV 13.2V V++ 0.3V, V− − 0.3V 10 mA (Note 4) Operating Ratings Temperature Range (Note 3) Supply Voltage (VS = V+ – V−) Package Thermal Resistance (θJA (Note 3)) 5-Pin SOT23 3V Electrical Characteristics Unless otherwise specified, all limits are guaranteed for TA = 25°C, V+ = 3V, V− = 0V, VCM = V+/2, and RL > 10 kΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol VOS TCVOS IB Parameter Input Offset Voltage Input Offset Voltage Temperature Drift Input Bias Current (Note 7) (Note 7, Note 8) −40°C ≤ TA ≤ 85°C (Note 7, Note 8) −40°C ≤ TA ≤ 125°C IOS CMRR PSRR CMVR AVOL Input Offset Current Common Mode Rejection Ratio Power Supply Rejection Ratio Common Mode Voltage Range Open Loop Voltage Gain 0V ≤ VCM ≤ 3V 2.7V ≤ V+ ≤ 12V, Vo = V+/2 CMRR ≥ 80 dB CMRR ≥ 77 dB RL = 2 kΩ VO = 0.3V to 2.7V RL = 10 kΩ VO = 0.2V to 2.8V VOUT Output Voltage Swing High RL = 2 kΩ to V+/2 RL = 10 kΩ to V+/2 Output Voltage Swing Low RL = 2 kΩ to V+/2 RL = 10 kΩ to V+/2 IOUT Output Current (Note 3, Note 9) Sourcing VO = V+/2 VIN = 100 mV Sinking VO = V+/2 VIN = −100 mV IS SR Supply Current Slew Rate (Note 10) AV = +1, VO = 2 VPP 10% to 90% 2 Conditions Min (Note 6) Typ (Note 5) ±37 ±1 ±0.2 ±0.2 40 Max (Note 6) ±200 ±500 ±5 ±1 ±50 ±1 ±400 Units μV μV/°C pA fA dB dB 3.2 3.2 V 86 80 86 82 –0.2 –0.2 100 96 100 96 130 98 114 124 40 30 40 20 80 120 40 60 60 80 40 50 dB mV from V+ mV 25 15 25 20 42 42 0.670 0.9 1.0 1.2 mA mA V/μs www.national.com SM72501 Symbol GBW THD+N en in Parameter Gain Bandwidth Total Harmonic Distortion + Noise Input Referred Voltage Noise Density Input Referred Current Noise Density Conditions Min (Note 6) Typ (Note 5) 2.5 0.02 9 1 Max (Note 6) Units MHz % nV/ f = 1 kHz, AV = 1, R.L = 10 kΩ f = 1 kHz f = 100 kHz fA/ 5V Electrical Characteristics (Note 4) Unless otherwise specified, all limits are guaranteed for TA = 25°C, V+ = 5V, V− = 0V, VCM = V+/2, and RL > 10 kΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol VOS TCVOS IB Parameter Input Offset Voltage Input Offset Voltage Temperature Drift Input Bias Current (Note 7) (Note 7, Note 8) −40°C ≤ TA ≤ 85°C (Note 7, Note 8) −40°C ≤ TA ≤ 125°C IOS CMRR PSRR CMVR AVOL Input Offset Current Common Mode Rejection Ratio Power Supply Rejection Ratio Common Mode Voltage Range Open Loop Voltage Gain 0V ≤ VCM ≤ 5V 2.7V ≤ V+ ≤ 12V, VO = V+/2 CMRR ≥ 80 dB CMRR ≥ 78 dB RL = 2 kΩ VO = 0.3V to 4.7V RL = 10 kΩ VO = 0.2V to 4.8V VOUT Output Voltage Swing High RL = 2 kΩ to V+/2 RL = 10 kΩ to V+/2 Output Voltage Swing Low RL = 2 kΩ to V+/2 RL = 10 kΩ to V+/2 IOUT Output Current (Note 3, Note 9) Sourcing VO = V+/2 VIN = 100 mV Sinking VO = V+/2 VIN = −100 mV IS SR GBW THD+N Supply Current Slew Rate (Note 10) Gain Bandwidth Total Harmonic Distortion + Noise f = 1 kHz, AV = 1, RL = 10 kΩ AV = +1, VO = 4 VPP 10% to 90% 40 28 40 28 88 83 86 82 –0.2 –0.2 100 96 100 96 119 130 60 40 50 30 66 76 0.715 1.0 2.5 0.02 1.0 1.2 mA 110 130 50 70 80 90 40 50 dB 40 130 100 5.2 5.2 ±0.2 Conditions Min (Note 6) Typ (Note 5) ±37 ±1 ±0.2 Max (Note 6) ±200 ±500 ±5 ±1 ±50 ±1 ±400 pA Units μV μV/°C fA dB dB V mV from V+ mV mA V/μs MHz % 3 www.national.com SM72501 Symbol en in Parameter Input Referred Voltage Noise Density Input Referred Current Noise Density f = 1 kHz f = 100 kHz Conditions Min (Note 6) Typ (Note 5) 9 1 Max (Note 6) Units nV/ fA/ ±5V Electrical Characteristics (Note 4) Unless otherwise specified, all limits are guaranteed for TA = 25°C, V+ = 5V, V− = −5V, VCM = 0V, and RL > 10 kΩ to 0V. Boldface limits apply at the temperature extremes. Symbol VOS TCVOS IB Parameter Input Offset Voltage Input Offset Voltage Temperature Drift Input Bias Current (Note 7) (Note 7, Note 8) −40°C ≤ TA ≤ 85°C (Note 7, Note 8) −40°C ≤ TA ≤ 125°C IOS CMRR PSRR CMVR AVOL Input Offset Current Common Mode Rejection Ratio Power Supply Rejection Ratio Common Mode Voltage Range Open Loop Voltage Gain −5V ≤ VCM ≤ 5V 2.7V ≤ V+ ≤ 12V, VO = 0V CMRR ≥ 80 dB CMRR ≥ 78 dB RL = 2 kΩ VO = −4.7V to 4.7V RL = 10 kΩ VO = −4.8V to 4.8V VOUT Output Voltage Swing High RL = 2 kΩ to 0V RL = 10 kΩ to 0V Output Voltage Swing Low RL = 2 kΩ to 0V RL = 10 kΩ to 0V IOUT Output Current (Note 3, Note 9) Sourcing VO = 0V VIN = 100 mV Sinking VO = 0V VIN = −100 mV IS SR GBW THD+N en in Supply Current Slew Rate (Note 10) Gain Bandwidth Total Harmonic Distortion + Noise Input Referred Voltage Noise Density Input Referred Current Noise Density f = 1 kHz, AV = 1, RL = 10 kΩ f = 1 kHz f = 100 kHz AV = +1, VO = 9 VPP 10% to 90% 50 35 50 35 92 88 86 82 −5.2 −5.2 100 98 100 98 121 134 90 40 90 40 86 84 0.790 1.1 2.5 0.02 9 1 1.1 1.3 mA 150 170 80 100 130 150 50 60 dB 40 138 98 5.2 5.2 ±0.2 Conditions Min (Note 6) Typ (Note 5) ±37 ±1 ±0.2 Max (Note 6) ±200 ±500 ±5 1 ±50 1 ±400 pA Units μV μV/°C fA dB dB V mV from V+ mV from V– mA V/μs MHz % nV/ fA/ Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics Tables. www.national.com 4 SM72501 Note 2: Human Body Model, applicable std. MIL-STD-883, Method 3015.7. Machine Model, applicable std. JESD22-A115-A (ESD MM std. of JEDEC) FieldInduced Charge-Device Model, applicable std. JESD22-C101-C (ESD FICDM std. of JEDEC). Note 3: The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(MAX) – TA)/ θJA. All numbers apply for packages soldered directly onto a PC Board. Note 4: Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of the device such that TJ = TA. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self-heating where TJ > TA. Note 5: Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not guaranteed on shipped production material. Note 6: Limits are 100% production tested at 25°C. Limits over the operating temperature range are guaranteed through correlations using the Statistical Quality Control (SQC) method. Note 7: This parameter is guaranteed by design and/or characterization and is not tested in production. Note 8: Positive current corresponds to current flowing into the device. Note 9: The short circuit test is a momentary test. Note 10: The number specified is the slower of positive and negative slew rates. 5 www.national.com SM72501 Connection Diagram 5-Pin SOT23 30142102 Top View Ordering Information Package 5-Pin SOT23 5-Pin SOT23 5-Pin SOT23 Part Number SM72501MFE SM72501MF SM72501MFX Package Marking S501 S501 S501 Transport Media 250 Units Tape and Reel 1000 Units Tape and Reel 3000 Units Tape and Reel NSC Drawing MF05A MF05A MF05A www.national.com 6 SM72501 Typical Performance Characteristics Offset Voltage Distribution Unless otherwise noted: TA = 25°C, VCM = VS/2, RL > 10 kΩ. TCVOS Distribution 30142136 30142141 Offset Voltage Distribution TCVOS Distribution 30142137 30142142 Offset Voltage Distribution TCVOS Distribution 30142138 30142143 7 www.national.com SM72501 Offset Voltage vs. Temperature CMRR vs. Frequency 30142106 30142150 Offset Voltage vs. Supply Voltage Offset Voltage vs. VCM 30142110 30142107 Offset Voltage vs. VCM Offset Voltage vs. VCM 30142108 30142109 www.national.com 8 SM72501 Input Bias Current vs. VCM Input Bias Current vs. VCM 30142146 30142130 Input Bias Current vs. VCM Input Bias Current vs. VCM 30142147 30142131 Input Bias Current vs. VCM Input Bias Current vs. VCM 30142148 30142149 9 www.national.com SM72501 PSRR vs. Frequency Supply Current vs. Supply Voltage (Per Channel) 30142145 30142111 Sinking Current vs. Supply Voltage Sourcing Current vs. Supply Voltage 30142113 30142112 Output Voltage vs. Output Current Slew Rate vs. Supply Voltage 30142116 30142117 www.national.com 10 SM72501 Open Loop Frequency Response Open Loop Frequency Response 30142115 30142114 Large Signal Step Response Small Signal Step Response 30142118 30142120 Large Signal Step Response Small Signal Step Response 30142119 30142126 11 www.national.com SM72501 Input Voltage Noise vs. Frequency Open Loop Gain vs. Output Voltage Swing 30142127 30142152 Output Swing High vs. Supply Voltage Output Swing Low vs. Supply Voltage 30142133 30142135 Output Swing High vs. Supply Voltage Output Swing Low vs. Supply Voltage 30142132 30142134 www.national.com 12 SM72501 THD+N vs. Frequency THD+N vs. Output Voltage 30142128 30142129 13 www.national.com SM72501 Application Information SM72501 The SM72501 is a low offset voltage, rail-to-rail input and output precision amplifier with a CMOS input stage and wide supply voltage range of 2.7V to 12V. The SM72501 has a very low input bias current of only ±200 fA at room temperature. The wide supply voltage range of 2.7V to 12V over the extensive temperature range of −40°C to 125°C makes the SM72501 an excellent choice for low voltage precision applications with extensive temperature requirements. The SM72501 has only ±37 μV of typical input referred offset voltage and this offset is guaranteed to be less than ±500 μV over temperature. This minimal offset voltage allows more accurate signal detection and amplification in precision applications. The low input bias current of only ±200 fA along with the low gives the SM72501 input referred voltage noise of 9 nV/ superiority for use in sensor applications. Lower levels of noise from the SM72501 means better signal fidelity and a higher signal-to-noise ratio. National Semiconductor is heavily committed to precision amplifiers and the market segment they serve. Technical support and extensive characterization data is available for sensitive applications or applications with a constrained error budget. The SM72501 is offered in the space saving 5-Pin SOT23. This small package is an ideal solution for area constrained PC boards and portable electronics. CAPACITIVE LOAD The SM72501 can be connected as a non-inverting unity gain follower. This configuration is the most sensitive to capacitive loading. The combination of a capacitive load placed on the output of an amplifier along with the amplifier's output impedance creates a phase lag which in turn reduces the phase margin of the amplifier. If the phase margin is significantly reduced, the response will be either underdamped or it will oscillate. In order to drive heavier capacitive loads, an isolation resistor, RISO, in Figure 1 should be used. By using this isolation resistor, the capacitive load is isolated from the amplifier's output, and hence, the pole caused by CL is no longer in the feedback loop. The larger the value of RISO, the more stable the output voltage will be. If values of RISO are sufficiently large, the feedback loop will be stable, independent of the value of CL. However, larger values of RISO result in reduced output swing and reduced output current drive. INPUT CAPACITANCE CMOS input stages inherently have low input bias current and higher input referred voltage noise. The SM72501 enhances this performance by having the low input bias current of only ±200 fA, as well as, a very low input referred voltage noise of . In order to achieve this a larger input stage has 9 nV/ been used. This larger input stage increases the input capacitance of the SM72501. The typical value of this input capacitance, CIN, for the SM72501 is 25 pF. The input capacitance will interact with other impedances such as gain and feedback resistors, which are seen on the inputs of the amplifier, to form a pole. This pole will have little or no effect on the output of the amplifier at low frequencies and DC conditions, but will play a bigger role as the frequency increases. At higher frequencies, the presence of this pole will decrease phase margin and will also cause gain peaking. In order to compensate for the input capacitance, care must be taken in choosing the feedback resistors. In addition to being selective in picking values for the feedback resistor, a capacitor can be added to the feedback path to increase stability. The DC gain of the circuit shown in Figure 2 is simply –R2/ R1. 30142144 FIGURE 2. Compensating for Input Capacitance For the time being, ignore CF. The AC gain of the circuit in Figure 2 can be calculated as follows: This equation is rearranged to find the location of the two poles: (1) 30142121 FIGURE 1. Isolating Capacitive Load As shown in Equation 1, as values of R1 and R2 are increased, the magnitude of the poles is reduced, which in turn decreases the bandwidth of the amplifier. Whenever possible, it is best to choose smaller feedback resistors. Figure 3 shows the effect of the feedback resistor on the bandwidth of the SM72501. www.national.com 14 SM72501 DIODES BETWEEN THE INPUTS The SM72501 has a set of anti-parallel diodes between the input pins, as shown in Figure 5. These diodes are present to protect the input stage of the amplifier. At the same time, they limit the amount of differential input voltage that is allowed on the input pins. A differential signal larger than one diode voltage drop might damage the diodes. The differential signal between the inputs needs to be limited to ±300 mV or the input current needs to be limited to ±10 mA. 30142154 FIGURE 3. Closed Loop Gain vs. Frequency Equation 1 has two poles. In most cases, it is the presence of pairs of poles that causes gain peaking. In order to eliminate this effect, the poles should be placed in Butterworth position, since poles in Butterworth position do not cause gain peaking. To achieve a Butterworth pair, the quantity under the square root in Equation 1 should be set to equal −1. Using this fact and the relation between R1 and R2, R2 = −AV R1, the optimum value for R1 can be found. This is shown in Equation 2. If R1 is chosen to be larger than this optimum value, gain peaking will occur. 30142125 FIGURE 5. Input of SM72501 (2) In Figure 2, CF is added to compensate for input capacitance and to increase stability. Additionally, CF reduces or eliminates the gain peaking that can be caused by having a larger feedback resistor. Figure 4 shows how CF reduces gain peaking. 30142155 FIGURE 4. Closed Loop Gain vs. Frequency with Compensation 15 www.national.com SM72501 PRECISION CURRENT SOURCE The SM72501 can be used as a precision current source in many different applications. Figure 6 shows a typical precision current source. This circuit implements a precision voltage controlled current source. Amplifier A1 is a differential amplifier that uses the voltage drop across RS as the feedback signal. Amplifier A2 is a buffer that eliminates the error current from the load side of the RS resistor that would flow in the feedback resistor if it were connected to the load side of the RS resistor. In general, the circuit is stable as long as the closed loop bandwidth of amplifier A2 is greater then the closed loop bandwidth of amplifier A1. Note that if A1 and A2 are the same type of amplifiers, then the feedback around A1 will reduce its bandwidth compared to A2. combination. This is because each individual amplifier acts as an independent noise source, and the average noise of independent sources is the quadrature sum of the independent sources divided by the number of sources. For N identical amplifiers, this means: Figure 7 shows a schematic of this input voltage noise reduction circuit. Typical resistor values are: RG = 10Ω, RF = 1 kΩ, and RO = 1 kΩ. 30142105 FIGURE 6. Precision Current Source The equation for output current can be derived as follows: Solving for the current I results in the following equation: LOW INPUT VOLTAGE NOISE The SM72501 has a very low input voltage noise of 9 nV/ . This input voltage noise can be further reduced by placing N amplifiers in parallel as shown in Figure 7. The total voltage noise on the output of this circuit is divided by the square root of the number of amplifiers used in this parallel 30142156 FIGURE 7. Noise Reduction Circuit www.national.com 16 SM72501 TOTAL NOISE CONTRIBUTION The SM72501 has very low input bias current, very low input current noise, and very low input voltage noise. As a result, these amplifiers are ideal choices for circuits with high impedance sensor applications. Figure 8 shows the typical input noise of the SM72501 as a function of source resistance where: en denotes the input referred voltage noise ei is the voltage drop across source resistance due to input referred current noise or ei = RS * in et shows the thermal noise of the source resistance eni shows the total noise on the input. Where: HIGH IMPEDANCE SENSOR INTERFACE Many sensors have high source impedances that may range up to 10 MΩ. The output signal of sensors often needs to be amplified or otherwise conditioned by means of an amplifier. The input bias current of this amplifier can load the sensor's output and cause a voltage drop across the source resistance as shown in Figure 9, where VIN+ = VS – IBIAS*RS The last term, IBIAS*RS, shows the voltage drop across RS. To prevent errors introduced to the system due to this voltage, an op amp with very low input bias current must be used with high impedance sensors. This is to keep the error contribution by IBIAS*RS less than the input voltage noise of the amplifier, so that it will not become the dominant noise factor. The input current noise of the SM72501 is so low that it will not become the dominant factor in the total noise unless source resistance exceeds 300 MΩ, which is an unrealistically high value. As is evident in Figure 8, at lower RS values, total noise is dominated by the amplifier's input voltage noise. Once RS is larger than a few kilo-Ohms, then the dominant noise factor becomes the thermal noise of RS. As mentioned before, the current noise will not be the dominant noise factor for any practical application. 30142159 FIGURE 9. Noise Due to IBIAS pH electrodes are very high impedance sensors. As their name indicates, they are used to measure the pH of a solution. They usually do this by generating an output voltage which is proportional to the pH of the solution. pH electrodes are calibrated so that they have zero output for a neutral solution, pH = 7, and positive and negative voltages for acidic or alkaline solutions. This means that the output of a pH electrode is bipolar and has to be level shifted to be used in a single supply system. The rate of change of this voltage is usually shown in mV/pH and is different for different pH sensors. Temperature is also an important factor in a pH electrode reading. The output voltage of the senor will change with temperature. Figure 10 shows a typical output voltage spectrum of a pH electrode. Note that the exact values of output voltage will be different for different sensors. In this example, the pH electrode has an output voltage of 59.15 mV/pH at 25°C. 30142158 FIGURE 8. Total Input Noise 30142160 FIGURE 10. Output Voltage of a pH Electrode The temperature dependence of a typical pH electrode is shown in Figure 11. As is evident, the output voltage changes with changes in temperature. 17 www.national.com SM72501 30142161 FIGURE 11. Temperature Dependence of a pH Electrode The schematic shown in Figure 12 is a typical circuit which can be used for pH measurement. The LM35 is a precision integrated circuit temperature sensor. This sensor is differentiated from similar products because it has an output voltage linearly proportional to Celcius measurement, without the need to convert the temperature to Kelvin. The LM35 is used to measure the temperature of the solution and feeds this reading to the Analog to Digital Converter, ADC. This infor- mation is used by the ADC to calculate the temperature effects on the pH readings. The LM35 needs to have a resistor, RT in Figure 12, to –V+ in order to be able to read temperatures below 0°C. RT is not needed if temperatures are not expected to go below zero. The output of pH electrodes is usually large enough that it does not require much amplification; however, due to the very high impedance, the output of a pH electrode needs to be buffered before it can go to an ADC. Since most ADCs are operated on single supply, the output of the pH electrode also needs to be level shifted. Amplifier A1 buffers the output of the pH electrode with a moderate gain of +2, while A2 provides the level shifting. VOUT at the output of A2 is given by: VOUT = −2VpH + 1.024V. The LM4140A is a precision, low noise, voltage reference used to provide the level shift needed. The ADC used in this application is the ADC12032 which is a 12-bit, 2 channel converter with multiplexers on the inputs and a serial output. The 12-bit ADC enables users to measure pH with an accuracy of 0.003 of a pH unit. Adequate power supply bypassing and grounding is extremely important for ADCs. Recommended bypass capacitors are shown in Figure 12. It is common to share power supplies between different components in a circuit. To minimize the effects of power supply ripples caused by other components, the op amps need to have bypass capacitors on the supply pins. Using the same value capacitors as those used with the ADC are ideal. The combination of these three values of capacitors ensures that AC noise present on the power supply line is grounded and does not interfere with the amplifiers' signal. 30142162 FIGURE 12. pH Measurement Circuit www.national.com 18 SM72501 Physical Dimensions inches (millimeters) unless otherwise noted 5-Pin SOT23 NS Package Number MF05A 19 www.national.com SM72501 SolarMagic Precision, CMOS Input, RRIO, Wide Supply Range Amplifier 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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