October 2004 LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad High Precision, Rail-to-Rail Output Operational Amplifier General Description Features The LMP201X is a new precision amplifier family that offers unprecedented accuracy and stability at an affordable price and is offered in miniature packages. 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 LMP201X 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 LMP201X are rail-to-rail output, a low supply current of 930 µA, and wide gain-bandwidth product of 3 MHz. These extremely versatile features found in the LMP201X provide high performance and ease of use. (For VS = 5V, Typical unless otherwise noted) n Low guaranteed VOS over temperature n Low noise with no 1/f n High CMRR n High PSRR n High AVOL n Wide gain-bandwidth product n High slew rate n Low supply current n Rail-to-rail output n No external capacitors required 60 µV 35nV/ 130 dB 120 dB 130 dB 3MHz 4V/µs 930µA 30mV Applications n Precision instrumentation amplifiers n Thermocouple amplifiers n Strain gauge bridge amplifier Connection Diagrams 5-Pin SOT23 8-Pin SOIC 8-Pin MSOP 20071538 20071502 Top View Top View 20071542 Top View 14-Pin TSSOP 14-Pin LLP 20071539 Top View 20071541 Top View © 2004 National Semiconductor Corporation DS200715 www.national.com LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad High Precision, Rail-to-Rail Output Operational Amplifier PRELIMINARY LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Absolute Maximum Ratings (Note 1) Current at Output Pin 30 mA If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Current at Power Supply Pin 50 mA Operating Ratings (Note 1) ESD Tolerance Human Body Model Supply Voltage 2000V Machine Model Supply Voltage Common-Mode Input Voltage 200V 5.8V Operating Temperature Range −0.3 ≤ VCM ≤ VCC +0.3V Lead Temperature (soldering 10 sec.) Differential Input Voltage Current at Input Pin 2.7V to 5.25V Storage Temperature Range −65˚C to 150˚C LMP2011MF, LMP2011MFX −40˚C to 125˚C LMP2011MA, LPM2011MAX −40˚C to 125˚C LMP2012MM, LMP2011MMX −40˚C to 125˚C +300˚C LMP2014SD, LMP2014SDX −40˚C to 125˚C ± Supply Voltage LMP2014MT, LMP2014MTX 0˚C to 70˚C 30 mA 2.7V DC Electrical Characteristics V+ = 2.7V, V- = 0V, V TCVOS Unless otherwise specified, all limits guaranteed for T J = 25˚C, = 1.35V, VO = 1.35V and RL > 1 MΩ. Boldface limits apply at the temperature extremes. Typ (Note 2) Max (Note 3) Input Offset Voltage 0.8 25 60 µV Offset Calibration Time 0.5 10 12 ms Symbol VOS CM Parameter Conditions Min (Note 3) Units Input Offset Voltage 0.015 µV/˚C Long-Term Offset Drift 0.006 µV/month Lifetime VOS Drift 2.5 µV IIN Input Current -3 pA IOS Input Offset Current 6 pA RIND Input Differential Resistance CMRR Common Mode Rejection Ratio PSRR Power Supply Rejection Ratio AVOL Open Loop Voltage Gain VO Output Swing 9 −0.3 ≤ VCM ≤ 0.9V 0 ≤ VCM ≤ 0.9V 95 90 dB 120 95 90 dB RL = 10 kΩ 130 95 90 RL = 2 kΩ 124 90 85 RL = 10 kΩ to 1.35V VIN(diff) = ± 0.5V 2.665 2.655 RL = 2 kΩ to 1.35V VIN(diff) = ± 0.5V Output Current ROUT Output Impedance IS Supply Current per Channel www.national.com 2.630 2.615 dB 2.68 0.033 IO MΩ 130 0.060 0.075 V 2.65 0.061 0.085 0.105 Sourcing, VO = 0V VIN(diff) = ± 0.5V 12 5 3 Sinking, VO = 5V VIN(diff) = ± 0.5V 18 5 3 0.919 1.20 1.50 V mA Ω 2 mA TJ = 25˚C, V+ = 2.7V, V - = 0V, VCM = 1.35V, VO = 1.35V, and RL > 1 MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter GBW Gain-Bandwidth Product SR θm Min (Note 3) Conditions Typ (Note 2) Max (Note 3) Units 3 MHz Slew Rate 4 V/µs Phase Margin 60 Deg Gm Gain Margin −14 en Input-Referred Voltage Noise 35 in Input-Referred Current Noise enp-p Input-Referred Voltage Noise trec Input Overload Recovery Time tS Output Settling time dB nV/ pA/ RS = 100Ω, DC to 10 Hz AV = +1, RL = 2 kΩ 1V Step 850 nVpp 50 ms 1% 0.1% 0.01% AV = −1, RL = 2 kΩ 1V Step ns 1% 0.1% 0.01% 5V DC Electrical Characteristics - 5V, V = 0V, V Symbol VOS TCVOS CM Unless otherwise specified, all limits guaranteed for T = 2.5V, VO = 2.5V and RL > 1MΩ. Boldface limits apply at the temperature extremes. = 25˚C, V+ = Typ (Note 2) Max (Note 3) Input Offset Voltage 0.12 25 60 µV Offset Calibration Time 0.5 10 12 ms Parameter Conditions Min (Note 3) J Units Input Offset Voltage 0.015 µV/˚C Long-Term Offset Drift 0.006 µV/month Lifetime VOS Drift 2.5 µV IIN Input Current -3 pA IOS Input Offset Current 6 pA RIND Input Differential Resistance 9 MΩ CMRR Common Mode Rejection Ratio PSRR Power Supply Rejection Ratio AVOL Open Loop Voltage Gain VO Output Swing −0.3 ≤ VCM ≤ 3.2 0 ≤ VCM ≤ 3.2 130 100 90 dB 120 95 90 dB RL = 10 kΩ 130 105 100 RL = 2 kΩ 132 95 90 RL = 10 kΩ to 2.5V VIN(diff) = ± 0.5V 4.96 4.95 4.978 0.040 4.895 4.875 RL = 2 kΩ to 2.5V VIN(diff) = ± 0.5V 0.070 0.085 V 4.919 0.091 3 dB 0.115 0.140 V www.national.com LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad 2.7V AC Electrical Characteristics LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad 5V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for T J = 25˚C, V+ = 5V, V- = 0V, V Symbol IO CM = 2.5V, VO = 2.5V and RL > 1MΩ. Boldface limits apply at the temperature extremes. (Continued) Typ (Note 2) Max (Note 3) Sourcing, VO = 0V VIN(diff) = ± 0.5V 15 8 6 Sinking, VO = 5V V IN(diff) = ± 0.5V 17 8 6 Parameter Min (Note 3) Conditions Output Current Units mA Ω ROUT Output Impedance IS Supply Current per Channel 0.930 1.20 1.50 mA 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 GBW Gain-Bandwidth Product SR θm Min (Note 3) Conditions Typ (Note 2) Max (Note 3) Units 3 MHz Slew Rate 4 V/µs Phase Margin 60 deg Gm Gain Margin −15 dB 35 en Input-Referred Voltage Noise in Input-Referred Current Noise enp-p Input-Referred Voltage Noise trec Input Overload Recovery Time tS Output Settling time nV/ pA/ RS = 100Ω, DC to 10 Hz AV = +1, RL = 2 kΩ 1V Step 850 nVpp 50 ms 1% 0.1% 0.01% AV = −1, RL = 2 kΩ 1V Step ns 1% 0.1% 0.01% 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. Note 2: Typical values represent the most likely parametric norm. Note 3: Limits are 100% production tested at 25˚C. Limits over the operating temperature range are guaranteed through correlations using statistical quality control (SQC) method. Ordering Information Package Part Number 5-Pin SOT23 LMP2011MFX 8-Pin MSOP LMP2012MMX AN1A LMP2012MM LMP2011MA LMP2011MAX 14-Pin LLP LMP2014SDX www.national.com Package Marking LMP2011MF 8-Pin SOIC 14-Pin TSSOP Temperature Range AP1A −40˚C to 125˚C LMP2011MA LMP2014SD LMP2014MT LMP2014MTX P2014SD 0˚C to 70˚C LMP2014MT 4 Transport Media 1k Units Tape and Reel 3k Units Tape and Reel 1k Units Tape and Reel 3.5k Units Tape and Reel 95 Units/Rail 2.5k Units Tape and Reel 250 Units Tape and Reel 2.5 Units Tape and Reel 94 Units/Rail 2.5k Units Tape and Reel NSC Drawing MF05A MUA08A M08A SRC14A MTC14 LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Typical Performance Characteristics TA =25C, VS = 5V unless otherwise specified. Supply Current vs. Supply Voltage Offset Voltage vs. Supply Voltage 20071525 20071524 Offset Voltage vs. Common Mode Offset Voltage vs. Common Mode 20071535 20071534 Voltage Noise vs. Frequency Input Bias Current vs. Common Mode 20071503 20071504 5 www.national.com LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Typical Performance Characteristics (Continued) PSRR vs. Frequency PSRR vs. Frequency 20071507 20071506 Output Sourcing @ 2.7V Output Sourcing @ 5V 20071527 20071526 Output Sinking @ 2.7V Output Sinking @ 5V 20071528 www.national.com 20071529 6 (Continued) Max Output Swing vs. Supply Voltage Max Output Swing vs. Supply Voltage 20071530 20071531 Min Output Swing vs. Supply Voltage Min Output Swing vs. Supply Voltage 20071532 20071533 CMRR vs. Frequency Open Loop Gain and Phase vs. Supply Voltage 20071508 20071505 7 www.national.com LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Typical Performance Characteristics LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Typical Performance Characteristics (Continued) Open Loop Gain and Phase vs. RL @ 2.7V Open Loop Gain and Phase vs. RL @ 5V 20071509 20071510 Open Loop Gain and Phase vs. CL @ 2.7V Open Loop Gain and Phase vs. CL @ 5V 20071512 20071511 Open Loop Gain and Phase vs. Temperature @ 2.7V Open Loop Gain and Phase vs. Temperature @ 5V 20071536 www.national.com 20071537 8 (Continued) THD+N vs. AMPL THD+N vs. Frequency 20071513 20071514 0.1 Hz − 10 Hz Noise vs. Time 20071515 9 www.national.com LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Typical Performance Characteristics LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Application Information THE BENEFITS OF LMP201X NO 1/f NOISE Using patented methods, the LMP201X 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. Lowfrequency 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 constantlychanging noise signal will corrupt the result. The value of this noise signal can be surprisingly large. For example: If a conventional amplifier has a flat-band noise level of 10nV/ and a noise corner of 10 Hz, the RMS noise at 0.001 . This is equivalent to a 0.50 µV peak-toHz is 1µV/ peak error, in the frequency range 0.001 Hz to 1.0 Hz. In a circuit with a gain of 1000, this produces a 0.50 mV peakto-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 LMP201X will only have a 0.21 mV 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. 20071516 FIGURE 1. The wide bandwidth of the LMP201X 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 10 pF capacitor. (Figure 1) The typical time for the output to recover to 1% of the applied pulse is 80 ns. 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 LMP201X 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. The LMP201X 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 steelbased leadframe materials can produce over 35 µV/˚C when soldered onto a copper trace. This can result in thermocouple noise that is equal to the LMP201X 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 LMP201X 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. MORE BENEFITS The LMP201X offers the benefits mentioned above and more. It has a rail-to-rail output and consumes only 950 µA of supply current while providing excellent DC and AC electrical performance. In DC performance, the LMP201X achieves 130 dB of CMRR, 120 dB of PSRR and 130 dB of open loop gain. In AC performance, the LMP201X provides 3 MHz of gain-bandwidth product and 4 V/µs of slew rate. HOW THE LMP201X WORKS The LMP201X uses new, patented techniques to achieve the high DC accuracy traditionally associated with chopperstabilized amplifiers without the major drawbacks produced by chopping. The LMP201X 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 op amp. 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 150 Hz; the rest is mixing products. Add an input signal and the noise gets much worse. Compare this plot with Figure 3 of the LMP201X. This data was taken under the exact same conditions. The auto-zero action is visible at about 30 kHz but note the absence of mixing products at other frequencies. As a result, the LMP201X has very low distortion of 0.02% and very low mixing products. OVERLOAD RECOVERY The LMP201X recovers from input overload much faster than most chopper-stabilized op amps. Recovery from driving the amplifier to 2X the full scale output, only requires about 40 ms. Many chopper-stabilized amplifiers will take from 250 ms 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 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. (Continued) 20071517 FIGURE 2. 20071518 FIGURE 4. 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 LMP201X 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 300 MHz of overall GBW (AV = 100) while keeping the worst case output shift due to VOS less than 4 mV. The LMP201X 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, non-inverting 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. 20071504 FIGURE 3. INPUT CURRENTS The LMP201X’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, 0.5 nA 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 1 kΩ can provide some protection against very large transients or overloads, and will not increase the offset significantly. 11 www.national.com LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Application Information LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Application Information (Continued) 20071520 FIGURE 6. 20071519 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 feedback 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. FIGURE 5. TABLE 1. Composite Amplifier Measured Performance AV R1 Ω R2 Ω C2 pF BW MHz SR en p-p (V/µs) (mVPP) 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 In terms of the measured output peak-to-peak noise, the following relationship holds between output noise voltage, en p-p, for different closed-loop gain, AV, settings, where −3 dB Bandwidth is BW: 20071521 FIGURE 7. www.national.com 12 1/f corner frequency = 100 Hz AV = 2000 (Continued) LMP201X AS ADC INPUT AMPLIFIER Measurement time = 100 sec Bandwidth = 2 Hz The LMP201X 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. This example will result in about 2.2 mVPP (1.9 LSB) of output noise contribution due to the op amp alone, compared to about 594 µVPP (less than 0.5 LSB) when that op amp is replaced with the LMP201X which has no 1/f contribution. If the measurement time is increased from 100 seconds to 1 hour, the improvement realized by using the LMP201X would be a factor of about 4.8 times (2.86 mVPP compared to 596 µV when LMP201X is used) mainly because the LMP201X accuracy is not compromised by increasing the observation time. D) Copper leadframe construction minimizes any thermocouple effects which would degrade low level/high gain data conversion application accuracy (see discussion under "The Benefits of the LMP201X" section above). 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 LMP201X used as an ADC amplifier (Figure 7 and Figure 8). B) Fast large-signal settling time to 0.01% of final value (1.4 µs) allows 12 bit accuracy at 100 KHZ 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 op amp performance, based on a typical low-noise, high-performance commerciallyavailable device, for comparison: Op amp flatband noise = 8nV/ 20071522 FIGURE 8. 13 www.national.com LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Application Information LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Physical Dimensions inches (millimeters) unless otherwise noted 5-Pin SOT23 NS Package Number MF0A5 8-Pin MSOP NS Package Number MUA08A www.national.com 14 LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 8-Pin SOIC NS Package Number M08A 14-Pin TSSOP NS Package Number MTC14 15 www.national.com LMP2011 Single/ LMP2012 Dual/ LMP2014 Quad High Precision, Rail-to-Rail Output Operational Amplifier Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 14-LLP NS Package Number SRC14A National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. 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