LMV2011 High Precision, Rail-to-Rail Output Operational Amplifier General Description Features The LMV2011 is a new precision amplifier that offers unprecedented accuracy and stability at an affordable price and is offered in miniature (SOT23-5) package and in 8 lead SOIC package. This device utilizes patented techniques to measure and continually correct the input offset error voltage. The result is an amplifier which is ultra stable over time and temperature. It has excellent CMRR and PSRR ratings, and does not exhibit the familiar 1/f voltage and current noise increase that plagues traditional amplifiers. The combination of the LMV2011 characteristics makes it a good choice for transducer amplifiers, high gain configurations, ADC buffer amplifiers, DAC I-V conversion, and any other 2.7V-5V application requiring precision and long term stability. Other useful benefits of the LMV2011 are rail-to-rail output, a low supply current of 930µA, and wide gain-bandwidth product of 3MHz. These extremely versatile features found in the LMV2011 provide high performance and ease of use. (For Vs = 5V, Typical unless otherwise noted) ■ Low Guaranteed Vos over temperature ■ Low Noise with no 1/f ■ High CMRR ■ High PSRR ■ High AVOL ■ Wide gain-bandwidth product ■ High slew rate ■ Low supply current ■ Rail-to-rail output ■ No external capacitors required 35µV 35nV/√Hz 130dB 120dB 130dB 3MHz 4V/µs 930µA 30mV Applications ■ Precision Instrumentation Amplifiers ■ Thermocouple Amplifiers ■ Strain Gauge Bridge Amplifier Connection Diagrams 5-Pin SOT23 8-Pin SOIC 20051502 20051538 Top View Top View Ordering Information Package 5-Pin SOT23 8-Pin SOIC Part Number Package Marking LMV2011MF A84A LMV2011MFX LMV2011MA LMV2011MA LMV2011MAX © 2008 National Semiconductor Corporation 200515 Transport Media 1k Units Tape and Reel 3k Units Tape and Reel 95 Units/Rail 2.5k Units Tape and Reel NSC Drawing MF05A M08A www.national.com LMV2011 High Precision, Rail-to-Rail Output Operational Amplifier July 1, 2008 LMV2011 Current At Output Pin Current At Power Supply Pin Junction Temperature (TJ) Lead Temperature (soldering 10 sec.) 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 Human Body Model Machine Model Supply Voltage Common-Mode Input Voltage Differential Input Voltage Current At Input Pin 2000V 200V 5.5V Operating Ratings 30mA 50mA 150°C +300°C (Note 1) Supply Voltage Storage Temperature Range Operating Temperature Range −0.3≤ VCM ≤ VCC +0.3V ± Supply Voltage 30mA 2.7V to 5.25V −65°C to 150°C 0°C to 70°C 2.7V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for T J = 25°C, V+ = 2.7V, V- = 0V, V CM = 1.35V, VO = 1.35V and RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol VOS TCVOS Typ Max Units Input Offset Voltage Parameter Conditions Min 0.8 25 35 μV Offset Calibration Time 0.5 10 12 ms Input Offset Voltage 0.015 μV/°C Long-Term Offset Drift 0.006 μV/month 2.5 Input Current -3 IOS Input Offset Current 6 pA RIND Input Differential Resistance 9 MΩ CMRR Common Mode Rejection Ratio PSRR AVOL VO −0.3 ≤ VCM ≤ 0.9V pA 130 95 90 dB Power Supply Rejection Ratio 2.7V ≤ V+ ≤ 5V 120 95 90 dB Open Loop Voltage Gain RL = 10kΩ 130 95 90 RL = 2kΩ 124 90 85 Output Swing 0 ≤ VCM ≤ 0.9V 2.665 2.655 RL = 10kΩ to 1.35V VIN(diff) = ±0.5V 2.630 2.615 RL = 2kΩ to 1.35V VIN(diff) = ±0.5V Output Current 0.060 0.075 0.061 0.085 0.105 Sourcing, VO = 0V VIN(diff) = ±0.5V 12 5 3 Sinking, VO = 5V V IN(diff) = ±0.5V 18 5 3 Output Impedance 0.05 IS Supply Current 0.919 2 V 2.65 ROUT www.national.com dB 2.68 0.033 IO 5 μV Lifetime VOS Drift IIN V mA Ω 1.20 1.50 mA TJ = 25°C, V+ = 2.7V, V - = 0V, VCM = 1.35V, VO = 1.35V, and RL > Symbol Parameter Conditions Min Typ Max Units GBW Gain-Bandwidth Product 3 MHz SR Slew Rate 4 V/μs θm Phase Margin 60 Deg Gm Gain Margin −14 dB en Input-Referred Voltage Noise 35 nV/ in Input-Referred Current Noise 150 fA/ enp-p Input-Referred Voltage Noise RS = 100Ω, DC to 10Hz 850 nVpp trec Input Overload Recovery Time 50 ms ts Output Settling Time 0.9 μs 1% AV = −1, RL = 2kΩ 1V Step 0.1% 49 0.01% 100 5V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for T J = 25°C, V+ = 5V, V- = 0V, V CM = 2.5V, VO = 2.5V and RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol VOS TCVOS Typ Max Units Input Offset Voltage Parameter Conditions Min 0.12 25 35 μV Offset Calibration Time 0.5 10 12 ms Input Offset Voltage 0.015 μV/°C Long-Term Offset Drift 0.006 μV/month 2.5 Input Current -3 IOS Input Offset Current 6 pA RIND Input Differential Resistance 9 MΩ CMRR Common Mode Rejection Ratio PSRR AVOL VO −0.3 ≤ VCM ≤ 3.2 pA 130 100 90 dB Power Supply Rejection Ratio 2.7V ≤ V+ ≤ 5V 120 95 90 dB Open Loop Voltage Gain RL = 10kΩ 130 105 100 RL = 2kΩ 132 95 90 Output Swing 0 ≤ VCM ≤ 3.2 4.96 4.95 RL = 10kΩ to 2.5V VIN(diff) = ±0.5V 4.895 4.875 RL = 2kΩ to 2.5V VIN(diff) = ±0.5V Output Current 0.070 0.085 V 4.919 0.091 0.115 0.140 Sourcing, VO = 0V VIN(diff) = ±0.5V 15 8 6 Sinking, VO = 5V V IN(diff) = ±0.5V 17 8 6 ROUT Output Impedance 0.05 IS Supply Current per Channel 0.930 3 dB 4.978 0.040 IO 5 μV Lifetime VOS Drift IIN V mA Ω 1.20 1.50 mA www.national.com LMV2011 2.7V AC Electrical Characteristics 1MΩ. Boldface limits apply at the temperature extremes. LMV2011 5V AC Electrical Characteristics TJ = 25°C, V+ = 5V, V - = 0V, VCM = 2.5V, VO = 2.5V, and RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min Typ Max Units GBW Gain-Bandwidth Product 3 MHz SR Slew Rate 4 V/μs θm Phase Margin 60 deg Gm Gain Margin −15 dB en Input-Referred Voltage Noise 35 nV/ in Input-Referred Current Noise 150 fA/ enp-p Input-Referred Voltage Noise RS = 100Ω, DC to 10Hz 850 nVpp trec Input Overload Recovery Time ts Output Settling Time AV = −1, RL = 2kΩ 1V Step 50 ms 1% 0.8 us 0.1% 36 0.01% 100 Note 1: Absolute Maximum Ratings indicate limits beyond which damage 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 test conditions, see the Electrical Characteristics. www.national.com 4 LMV2011 Typical Performance Characteristics TA=25C, VS= 5V unless otherwise specified. Supply Current vs. Supply Voltage Offset Voltage vs. Supply Voltage 20051525 20051524 Offset Voltage vs. Common Mode Offset Voltage vs. Common Mode 20051535 20051534 Voltage Noise vs. Frequency Input Bias Current vs. Common Mode 20051503 20051504 5 www.national.com LMV2011 PSRR vs. Frequency PSRR vs. Frequency 20051507 20051506 Output Sourcing @ 2.7V Output Sourcing @ 5V 20051527 20051526 Output Sinking @ 2.7V Output Sinking @ 5V 20051528 www.national.com 20051529 6 LMV2011 Max Output Swing vs. Supply Voltage Max Output Swing vs. Supply Voltage 20051530 20051531 Min Output Swing vs. Supply Voltage Min Output Swing vs. Supply Voltage 20051532 20051533 CMRR vs. Frequency Open Loop Gain and Phase vs. Supply Voltage 20051508 20051505 7 www.national.com LMV2011 Open Loop Gain and Phase vs. RL @ 2.7V Open Loop Gain and Phase vs. RL @ 5V 20051509 20051510 Open Loop Gain and Phase vs. CL @ 2.7V Open Loop Gain and Phase vs. CL @ 5V 20051512 20051511 Open Loop Gain and Phase vs. Temperature @ 2.7V Open Loop Gain and Phase vs. Temperature @ 5V 20051536 www.national.com 20051537 8 LMV2011 THD+N vs. AMPL THD+N vs. Frequency 20051513 20051514 0.1Hz − 10Hz Noise vs. Time 20051515 9 www.national.com LMV2011 Application Information THE BENEFITS OF LMV2011 NO 1/f NOISE Using patented methods, the LMV2011 eliminates the 1/f noise present in other amplifiers. That noise, which increases as frequency decreases, is a major source of measurement error in all DC-coupled measurements. Low-frequency noise appears as a constantly-changing signal in series with any measurement being made. As a result, even when the measurement is made rapidly, this constantly-changing noise signal will corrupt the result. The value of this noise signal can be surprisingly large. For example: If a conventional amplifier and a noise corner of has a flat-band noise level of 10nV/ 10Hz, the RMS noise at 0.001Hz is 1µV/ . This is equivalent to a 0.50µV peak-to-peak error, in the frequency range 0.001 Hz to 1.0 Hz. In a circuit with a gain of 1000, this produces a 0.50mV peak-to-peak output error. This number of 0.001 Hz might appear unreasonably low, but when a data acquisition system is operating for 17 minutes, it has been on long enough to include this error. In this same time, the LMV2011 will only have a 0.21mV output error. This is smaller by 2.4 x. Keep in mind that this 1/f error gets even larger at lower frequencies. At the extreme, many people try to reduce this error by integrating or taking several samples of the same signal. This is also doomed to failure because the 1/f nature of this noise means that taking longer samples just moves the measurement into lower frequencies where the noise level is even higher. The LMV2011 eliminates this source of error. The noise level is constant with frequency so that reducing the bandwidth reduces the errors caused by noise. Another source of error that is rarely mentioned is the error voltage caused by the inadvertent thermocouples created when the common "Kovar type" IC package lead materials are soldered to a copper printed circuit board. These steel-based leadframe materials can produce over 35μV/°C when soldered onto a copper trace. This can result in thermocouple noise that is equal to the LMV2011 noise when there is a temperature difference of only 0.0014°C between the lead and the board! For this reason, the lead-frame of the LMV2011 is made of copper. This results in equal and opposite junctions which cancel this effect. The extremely small size of the SOT-23 package results in the leads being very close together. This further reduces the probability of temperature differences and hence decreases thermal noise. 20051516 FIGURE 1. Overload Recovery Test The wide bandwidth of the LMV2011 enhances performance when it is used as an amplifier to drive loads that inject transients back into the output. ADCs (Analog-to-Digital Converters) and multiplexers are examples of this type of load. To simulate this type of load, a pulse generator producing a 1V peak square wave was connected to the output through a 10pF capacitor. (Figure 1) The typical time for the output to recover to 1% of the applied pulse is 80ns. To recover to 0.1% requires 860ns. This rapid recovery is due to the wide bandwidth of the output stage and large total GBW. NO EXTERNAL CAPACITORS REQUIRED The LMV2011 does not need external capacitors. This eliminates the problems caused by capacitor leakage and dielectric absorption, which can cause delays of several seconds from turn-on until the amplifier's error has settled. MORE BENEFITS The LMV2011 offers the benefits mentioned above and more. It has a rail-to-rail output and consumes only 950µA of supply current while providing excellent DC and AC electrical performance. In DC performance, the LMC2001 achieves 130dB of CMRR, 120dB of PSRR and 130dB of open loop gain. In AC performance, the LMV2011 provides 3MHz of gain-bandwidth product and 4V/µs of slew rate. HOW THE LMV2011 WORKS The LMV2011 uses new, patented techniques to achieve the high DC accuracy traditionally associated with chopper-stabilized amplifiers without the major drawbacks produced by chopping. The LMV2011 continuously monitors the input offset and corrects this error. The conventional chopping process produces many mixing products, both sums and differences, between the chopping frequency and the incoming signal frequency. This mixing causes large amounts of distortion, particularly when the signal frequency approaches the chopping frequency. Even without an incoming signal, the chopper harmonics mix with each other to produce even more trash. If this sounds unlikely or difficult to understand, look at the plot (Figure 2), of the output of a typical (MAX432) chopper-stabilized opamp. This is the output when there is no incoming signal, just the amplifier in a gain of -10 with the input grounded. The chopper is operating at about 150Hz; the rest is mixing products. Add an input signal and the noise gets much worse. Compare this plot with Figure 3 of the LMV2011. This data was taken under the exact same conditions. The auto-zero action is visible at about 30kHz but note the absence of mixing products at other frequencies. As a result, the LMV2011 has very low distortion of 0.02% and very low mixing products. OVERLOAD RECOVERY The LMV2011 recovers from input overload much faster than most chopper-stabilized opamps. Recovery from driving the amplifier to 2X the full scale output, only requires about 40ms. Many chopper-stabilized amplifiers will take from 250ms to several seconds to recover from this same overload. This is because large capacitors are used to store the unadjusted offset voltage. www.national.com 10 20051517 FIGURE 2. The Output of a Chopper Stabilized Op Amp (MAX432) 20051518 FIGURE 4. Precision Strain Gauge Amplifier Extending Supply Voltages and Output Swing by Using a Composite Amplifier Configuration: In cases where substantially higher output swing is required with higher supply voltages, arrangements like the ones shown in Figure 5 and Figure 6 could be used. These configurations utilize the excellent DC performance of the LMV2011 while at the same time allow the superior voltage and frequency capabilities of the LM6171 to set the dynamic performance of the overall amplifier. For example, it is possible to achieve ±12V output swing with 300MHz of overall GBW (AV = 100) while keeping the worst case output shift due to VOS less than 4mV. The LMV2011 output voltage is kept at about mid-point of its overall supply voltage, and its input common mode voltage range allows the V- terminal to be grounded in one case (Figure 5, inverting operation) and tied to a small non-critical negative bias in another (Figure 6, noninverting operation). Higher closed-loop gains are also possible with a corresponding reduction in realizable bandwidth. Table 1 shows some other closed loop gain possibilities along with the measured performance in each case. 20051504 FIGURE 3. The Output of the LMV2011 INPUT CURRENTS The LMV2011's input currents are different than standard bipolar or CMOS input currents in that it appears as a current flowing in one input and out the other. Under most operating conditions, these currents are in the picoamp level and will have little or no effect in most circuits. These currents tend to increase slightly when the common-mode voltage is near the minus supply. (See the typical curves.) At high temperatures such as 85°C, the input currents become larger, 0.5nA typical, and are both positive except when the VCM is near V−. If operation is expected at low common-mode voltages and high temperature, do not add resistance in series with the inputs to balance the impedances. Doing this can cause an increase in offset voltage. A small resistance such as 1kΩ can provide some protection against very large transients or overloads, and will not increase the offset significantly. 11 www.national.com LMV2011 PRECISION STRAIN-GAUGE AMPLIFIER This Strain-Gauge amplifier (Figure 4) provides high gain (1006 or ~60 dB) with very low offset and drift. Using the resistors' tolerances as shown, the worst case CMRR will be greater than 108 dB. The CMRR is directly related to the resistor mismatch. The rejection of common-mode error, at the output, is independent of the differential gain, which is set by R3. The CMRR is further improved, if the resistor ratio matching is improved, by specifying tighter-tolerance resistors, or by trimming. LMV2011 It should be kept in mind that in order to minimize the output noise voltage for a given closed-loop gain setting, one could minimize the overall bandwidth. As can be seen from Equation 1 above, the output noise has a square-root relationship to the Bandwidth. In the case of the inverting configuration, it is also possible to increase the input impedance of the overall amplifier, by raising the value of R1, without having to increase the feed-back resistor, R2, to impractical values, by utilizing a "Tee" network as feedback. See the LMC6442 data sheet (Application Notes section) for more details on this. 20051519 FIGURE 5. Composite Amplifier Configuration 20051521 TABLE 1. Composite Amplifier Measured Performance AV R1 (Ω) R2 (Ω) C2 (pF) BW (MHz) 50 200 10k 8 3.3 178 37 100 100 10k 10 2.5 174 70 100 1k 100k 0.67 3.1 170 70 500 200 100k 1.75 1.4 96 250 1000 100 100k 2.2 0.98 64 400 FIGURE 7. AC Coupled ADC Driver SR en p-p (V/μs) (mVPP) LMV2011 AS ADC INPUT AMPLIFIER The LMV2011 is a great choice for an amplifier stage immediately before the input of an ADC (Analog-to-Digital Converter), whether AC or DC coupled. See Figure 7 and Figure 8. This is because of the following important characteristics: A) Very low offset voltage and offset voltage drift over time and temperature allow a high closed-loop gain setting without introducing any short-term or long-term errors. For example, when set to a closed-loop gain of 100 as the analog input amplifier for a 12-bit A/D converter, the overall conversion error over full operation temperature and 30 years life of the part (operating at 50°C) would be less than 5 LSBs. B) Fast large-signal settling time to 0.01% of final value (1.4μs) allows 12 bit accuracy at 100KHZ or more sampling rate. C) No flicker (1/f) noise means unsurpassed data accuracy over any measurement period of time, no matter how long. Consider the following opamp performance, based on a typical low-noise, high-performance commerciallyavailable device, for comparison: Opamp flatband noise = 8nV/ 1/f corner frequency = 100Hz AV = 2000 Measurement time = 100 sec Bandwidth = 2Hz This example will result in about 2.2 mVPP (1.9 LSB) of output noise contribution due to the opamp alone, compared to about 594μVPP (less than 0.5 LSB) when that opamp is replaced with the LMV2011 which has no 1/f contribution. If the measurement time is increased from 100 seconds to 1 hour, the improvement realized by using the LMV2011 would be a factor of about 4.8 times (2.86mVPP compared to 596μV when LMV2011 is used) mainly because the LMV2011 accuracy is not compromised by increasing the observation time. D) Copper leadframe construction minimizes any thermocouple effects which would degrade low level/high gain In terms of the measured output peak-to-peak noise, the following relationship holds between output noise voltage, en pp, for different closed-loop gain, AV, settings, where −3dB Bandwidth is BW: (1) 20051520 FIGURE 6. Composite Amplifier Configuration www.national.com 12 20051522 FIGURE 8. DC Coupled ADC Driver 13 www.national.com LMV2011 E) Rail-to-Rail output swing maximizes the ADC dynamic range in 5-Volt single-supply converter applications. Below are some typical block diagrams showing the LMV2011 used as an ADC amplifier (Figure 7 and Figure 8). data conversion application accuracy (see discussion under "The Benefits of the LMV2011" section above). LMV2011 Physical Dimensions inches (millimeters) unless otherwise noted 5-Pin SOT23 NS Package Number MF0A5 8-Pin SOIC NS Package Number M08A www.national.com 14 LMV2011 Notes 15 www.national.com LMV2011 High Precision, Rail-to-Rail Output Operational Amplifier Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBENCH www.national.com/webench Audio www.national.com/audio Analog University www.national.com/AU Clock Conditioners www.national.com/timing App Notes www.national.com/appnotes Data Converters www.national.com/adc Distributors www.national.com/contacts Displays www.national.com/displays Green Compliance www.national.com/quality/green Ethernet www.national.com/ethernet Packaging www.national.com/packaging Interface www.national.com/interface Quality and Reliability www.national.com/quality LVDS www.national.com/lvds Reference Designs www.national.com/refdesigns Power Management www.national.com/power Feedback www.national.com/feedback Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www.national.com/led PowerWise www.national.com/powerwise Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors Wireless (PLL/VCO) www.national.com/wireless THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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