LMC6492 Dual/LMC6494 Quad CMOS Rail-to-Rail Input and Output Operational Amplifier General Description Features The LMC6492/LMC6494 amplifiers were specifically developed for single supply applications that operate from -40C to +125C. This feature is well-suited for automotive systems because of the wide temperature range. A unique design topology enables the LMC6492/LMC6494 common-mode voltage range to accommodate input signals beyond the rails. This eliminates non-linear output errors due to input signals exceeding a traditionally limited common-mode voltage range. The LMC6492/LMC6494 signal range has a high CMRR of 82 dB for excellent accuracy in non-inverting circuit configurations. (Typical unless otherwise noted) n Rail-to-Rail input common-mode voltage range, guaranteed over temperature n Rail-to-Rail output swing within 20 mV of supply rail, 100 k load n Operates from 5V to 15V supply n Excellent CMRR and PSRR 82 dB n Ultra low input current 150 fA n High voltage gain (RL = 100 k) 120 dB n Low supply current (@ VS = 5V) 500 A/Amplifier n Low offset voltage drift 1.0 V/C The LMC6492/LMC6494 rail-to-rail input is complemented by rail-to-rail output swing. This assures maximum dynamic signal range which is particularly important in 5V systems. Ultra-low input current of 150 fA and 120 dB open loop gain provide high accuracy and direct interfacing with high impedance sources. Applications n n n n n Automotive transducer amplifier Pressure sensor Oxygen sensor Temperature sensor Speed sensor Connection Diagrams 14-Pin DIP/SO 8-Pin DIP/SO 01204901 Top View 01204902 Top View (c) 2004 National Semiconductor Corporation DS012049 www.national.com LMC6492 Dual/LMC6494 Quad CMOS Rail-to-Rail Input and Output Operational Amplifier August 2000 LMC6492 Dual/LMC6494 Quad Absolute Maximum Ratings (Note 1) Junction Temperature (Note 4) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. 150C Operating Conditions (Note 1) 2.5V V+ 15.5V Supply Voltage ESD Tolerance (Note 2) 2000V Differential Input Voltage Supply Voltage Junction Temperature Range (V+) + 0.3V, (V-) - 0.3V LMC6492AE, LMC6492BE -40C TJ +125C LMC6494AE, LMC6494BE -40C TJ +125C Voltage at Input/Output Pin Supply Voltage (V+ - V-) 16V 5 mA 30 mA Current at Input Pin Current at Output Pin (Note 3) Current at Power Supply Pin Lead Temp. (Soldering, 10 sec.) Storage Temperature Range Thermal Resistance (JA) N Package, 8-Pin Molded DIP 108C/W 40 mA M Package, 8-Pin Surface Mount 171C/W 260C N Package, 14-Pin Molded DIP 78C/W M Package, 14-Pin Surface Mount -65C to +150C 118C/W DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25C, V+ = 5V, V- = 0V, VCM = VO = V+/2 and RL > 1 M. Boldface limits apply at the temperature extremes Symbol Parameter Conditions Typ (Note 5) VOS Input Offset Voltage 0.11 TCVOS Input Offset Voltage 1.0 LMC6492AE LMC6492BE LMC6494AE LMC6494BE Limit Limit (Note 6) (Note 6) 3.0 6.0 3.8 6.8 Units mV max V/C Average Drift IB Input Bias Current (Note 11) 0.15 200 200 pA max IOS Input Offset Current (Note 11) 0.075 100 100 pA max RIN Input Resistance CIN Common-Mode > 10 Tera 3 pF Input Capacitance CMRR +PSRR -PSRR VCM AV Common-Mode 0V VCM 15V Rejection Ratio V+ = 15V 82 65 63 60 58 63 dB min 0V VCM 5V 82 65 60 58 Positive Power Supply 5V V+ 15V, 82 65 63 dB Rejection Ratio VO = 2.5V 60 58 min Negative Power Supply 0V V- -10V, 65 63 dB Rejection Ratio VO = 2.5V 60 58 min Input Common-Mode V+ = 5V and 15V V- -0.3 -0.25 -0.25 V Voltage Range For CMRR 50 dB 0 0 max V+ + 0.3 V+ + 0.25 V+ + 0.25 V V+ V+ min Large Signal Voltage Gain www.national.com 82 RL = 2 k: Sourcing 300 V/mV (Note 7) Sinking 40 min 2 (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25C, V+ = 5V, V- = 0V, VCM = VO = V+/2 and RL > 1 M. Boldface limits apply at the temperature extremes Symbol Parameter Conditions Typ (Note 5) VO Output Swing V+ = 5V Limit (Note 6) 4.9 4.8 4.8 V 4.7 4.7 min 0.1 0.18 0.18 V 0.24 0.24 max 4.5 4.5 V 4.24 4.24 min 0.5 0.5 V 0.65 0.65 max 14.4 14.4 V 14.0 14.0 min 0.16 0.35 0.35 V 0.5 0.5 max 14.1 13.4 13.4 V 13.0 13.0 min 1.0 1.0 V 1.5 1.5 max 16 16 10 10 11 11 4.7 + RL = 600 to V /2 0.3 14.7 RL = 2 k to V+/2 V+ = 15V RL = 600 to V+/2 0.5 ISC Output Short Circuit Current + V = 5V ISC Output Short Circuit Current + V = 15V IS Supply Current Sourcing, VO = 0V 25 Sinking, VO = 5V 22 Sourcing, VO = 0V 30 Sinking, VO = 5V (Note 8) 30 LMC6492 + 20 30 30 22 mA 2.1 2.1 max 1.3 1.95 1.95 mA 2.3 2.3 max 3.5 3.5 mA 4.2 4.2 max 3.9 3.9 mA 4.6 4.6 max 2.0 2.6 3 20 mA min 1.75 V+ = +5V, VO = V+/2 V+ = +15V, VO = V+/2 28 1.75 V+ = +15V, VO = V+/2 LMC6494 8 28 1.0 V = +5V, VO = V /2 LMC6494 8 22 + LMC6492 Units Limit RL = 2 k to V /2 V+ = 15V LMC6492BE LMC6494BE (Note 6) + V+ = 5V LMC6492AE LMC6494AE www.national.com LMC6492 Dual/LMC6494 Quad DC Electrical Characteristics LMC6492 Dual/LMC6494 Quad AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25C, V+ = 5V, V- = 0V, VCM = VO = V+/2 and RL > 1 M. Boldface limits apply at the temperature extremes Symbol SR Parameter Slew Rate GBW Gain-Bandwidth Product m Gm en in Conditions (Note 9) LMC6492AE LMC6492BE Typ LMC6494AE LMC6494BE (Note 5) Limit Limit (Note 6) (Note 6) 0.7 0.7 0.5 0.5 1.3 V+ = 15V Units Vs min 1.5 MHz Phase Margin 50 Deg Gain Margin 15 dB dB Amp-to-Amp Isolation (Note 10) 150 Input-Referred F = 1 kHz 37 Voltage Noise VCM = 1V Input-Referred F = 1 kHz 0.06 F = 1 kHz, AV = -2 0.01 Current Noise T.H.D. Total Harmonic Distortion RL = 10 k, VO = -4.1 VPP F = 10 kHz, AV = -2 % RL = 10 k, VO = 8.5 VPP 0.01 V+ = 10V 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. Note 2: Human body model, 1.5 k in series with 100 pF. Note 3: Applies to both single-supply and split-supply operation. Continuous short operation at elevated ambient temperature can result in exceeding the maximum allowed junction temperature at 150C. Output currents in excess of 30 mA over long term may adversely affect reliability. Note 4: The maximum power dissipation is a function of TJ(max), JA and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(max) - TA)/JA. All numbers apply for packages soldered directly into a PC board. Note 5: Typical Values represent the most likely parametric norm. Note 6: All limits are guaranteed by testing or statistical analysis. Note 7: V+ = 15V, VCM = 7.5V and RL connected to 7.5V. For Sourcing tests, 7.5V VO 11.5V. For Sinking tests, 3.5V VO 7.5V. Note 8: Do not short circuit output to V+, when V+ is greater than 13V or reliability will be adversely affected. Note 9: V+ = 15V. Connected as voltage follower with 10V step input. Number specified is the slower of the positive and negative slew rates. Note 10: Input referred, V+ = 15V and RL = 100 k connected to 7.5V. Each amp excited in turn with 1 kHz to produce VO = 12 VPP. Note 11: Guaranteed limits are dictated by tester limits and not device performance. Actual performance is reflected in the typical value. www.national.com 4 LMC6492 Dual/LMC6494 Quad Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified Supply Current vs Supply Voltage Input Current vs Temperature 01204925 01204926 Sourcing Current vs Output Voltage Sourcing Current vs Output Voltage 01204927 01204928 Sourcing Current vs Output Voltage Sinking Current vs Output Voltage 01204930 01204929 5 www.national.com LMC6492 Dual/LMC6494 Quad Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) Sinking Current vs Output Voltage Sinking Current vs Output Voltage 01204931 01204932 Output Voltage Swing vs Supply Voltage Input Voltage Noise vs Frequency 01204934 01204933 Input Voltage Noise vs Input Voltage Input Voltage Noise vs Input Voltage 01204935 www.national.com 01204936 6 Input Voltage Noise vs Input Voltage Crosstalk Rejection vs Frequency 01204937 01204938 Crosstalk Rejection vs Frequency Positive PSRR vs Frequency 01204939 01204940 Negative PSRR vs Frequency CMRR vs Frequency 01204941 01204942 7 www.national.com LMC6492 Dual/LMC6494 Quad Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) LMC6492 Dual/LMC6494 Quad Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) CMRR vs Input Voltage CMRR vs Input Voltage 01204943 01204944 VOS vs CMR CMRR vs Input Voltage 01204945 01204946 VOS vs CMR Input Voltage vs Output Voltage 01204948 01204947 www.national.com 8 Input Voltage vs Output Voltage Open Loop Frequency Response 01204949 01204950 Open Loop Frequency Response Open Loop Frequency Response vs Temperature 01204952 01204951 Maximum Output Swing vs Frequency Gain and Phase vs Capacitive Load 01204953 01204954 9 www.national.com LMC6492 Dual/LMC6494 Quad Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) LMC6492 Dual/LMC6494 Quad Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) Gain and Phase vs Capacitive Load Open Loop Output Impedance vs Frequency 01204955 01204956 Open Loop Output Impedance vs Frequency Slew Rate vs Supply Voltage 01204958 01204957 Non-Inverting Large Signal Pulse Response Non-Inverting Large Signal Pulse Response 01204959 www.national.com 01204960 10 Non-Inverting Large Signal Pulse Response Non-Inverting Small Signal Pulse Response 01204961 01204962 Non-Inverting Small Signal Pulse Response Non-Inverting Small Signal Pulse Response 01204964 01204963 Inverting Large Signal Pulse Response Inverting Large Signal Pulse Response 01204965 01204966 11 www.national.com LMC6492 Dual/LMC6494 Quad Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) LMC6492 Dual/LMC6494 Quad Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) Inverting Large Signal Pulse Response Inverting Small Signal Pulse Response 01204967 01204968 Inverting Small Signal Pulse Response Inverting Small Signal Pulse Response 01204969 01204970 Stability vs Capacitive Load Stability vs Capacitive Load 01204971 www.national.com 01204972 12 Stability vs Capacitive Load Stability vs Capacitive Load 01204973 01204974 Stability vs Capacitive Load Stability vs Capacitive Load 01204975 01204976 Application Hints INPUT COMMON-MODE VOLTAGE RANGE Unlike Bi-FET amplifier designs, the LMC6492/4 does not exhibit phase inversion when an input voltage exceeds the negative supply voltage. Figure 1 shows an input voltage exceeding both supplies with no resulting phase inversion on the output. 01204908 FIGURE 1. An Input Voltage Signal Exceeds the LMC6492/4 Power Supply Voltages with No Output Phase Inversion The absolute maximum input voltage is 300 mV beyond either supply rail at room temperature. Voltages greatly exceeding this absolute maximum rating, as in Figure 2, can cause excessive current to flow in or out of the input pins possibly affecting reliability. 13 www.national.com LMC6492 Dual/LMC6494 Quad Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) LMC6492 Dual/LMC6494 Quad Application Hints or (Continued) R1 CIN R2 Cf Since it is often difficult to know the exact value of CIN, Cf can be experimentally adjusted so that the desired pulse response is achieved. Refer to the LMC660 and LMC662 for a more detailed discussion on compensating for input capacitance. 01204909 FIGURE 2. A 7.5V Input Signal Greatly Exceeds the 5V Supply in Figure 3 Causing No Phase Inversion Due to RI 01204911 FIGURE 4. Cancelling the Effect of Input Capacitance Applications that exceed this rating must externally limit the maximum input current to 5 mA with an input resistor (RI) as shown in Figure 3. CAPACITIVE LOAD TOLERANCE All rail-to-rail output swing operational amplifiers have voltage gain in the output stage. A compensation capacitor is normally included in this integrator stage. The frequency location of the dominant pole is affected by the resistive load on the amplifier. Capacitive load driving capability can be optimized by using an appropriate resistive load in parallel with the capacitive load (see Typical Curves). Direct capacitive loading will reduce the phase margin of many op-amps. A pole in the feedback loop is created by the combination of the op-amp's output impedance and the capacitive load. This pole induces phase lag at the unity-gain crossover frequency of the amplifier resulting in either an oscillatory or underdamped pulse response. With a few external components, op amps can easily indirectly drive capacitive loads, as shown in Figure 5. 01204910 FIGURE 3. RI Input Current Protection for Voltages Exceeding the Supply Voltages RAIL-TO-RAIL OUTPUT The approximate output resistance of the LMC6492/4 is 110 sourcing and 80 sinking at Vs = 5V. Using the calculated output resistance, maximum output voltage swing can be esitmated as a function of load. COMPENSATING FOR INPUT CAPACITANCE It is quite common to use large values of feedback resistance for amplifiers with ultra-low input current, like the LMC6492/4. Although the LMC6492/4 is highly stable over a wide range of operating conditions, certain precautions must be met to achieve the desired pulse response when a large feedback resistor is used. Large feedback resistors with even small values of input capacitance, due to transducers, photodiodes, and circuit board parasitics, reduce phase margins. When high input impedances are demanded, guarding of the LMC6492/4 is suggested. Guarding input lines will not only reduce leakage, but lowers stray input capacitance as well. (See Printed-Circuit-Board Layout for High Impedance Work). The effect of input capacitance can be compensated for by adding a capacitor, Cf, around the feedback resistors (as in Figure 1 ) such that: www.national.com 01204912 FIGURE 5. LMC6492/4 Noninverting Amplifier, Compensated to Handle Capacitive Loads PRINTED-CIRCUIT-BOARD LAYOUT FOR HIGH-IMPEDANCE WORK It is generally recognized that any circuit which must operate with less than 1000 pA of leakage current requires special layout of the PC board. When one wishes to take advantage of the ultra-low bias current of the LMC6492/4, typically 150 fA, it is essential to have an excellent layout. Fortunately, the techniques of obtaining low leakages are quite 14 which is at the same voltage as the amplifier inputs, since no leakage current can flow between two points at the same potential. For example, a PC board trace-to-pad resistance of 1012, which is normally considered a very large resistance, could leak 5 pA if the trace were a 5V bus adjacent to the pad of the input. (Continued) simple. First, the user must not ignore the surface leakage of the PC board, even though it may sometimes appear acceptably low, because under conditions of high humidity or dust or contamination, the surface leakage will be appreciable. To minimize the effect of any surface leakage, lay out a ring of foil completely surrounding the LMC6492/4's inputs and the terminals of components connected to the op-amp's inputs, as in Figure 6. To have a significant effect, guard rings should be placed on both the top and bottom of the PC board. This PC foil must then be connected to a voltage This would cause a 33 times degradation from the LMC6492/4's actual performance. If a guard ring is used and held within 5 mV of the inputs, then the same resistance of 1011 will only cause 0.05 pA of leakage current. See Figure 7 for typical connections of guard rings for standard op-amp configurations. 01204913 FIGURE 6. Examples of Guard Ring in PC Board Layout The designer should be aware that when it is inappropriate to lay out a PC board for the sake of just a few circuits, there is another technique which is even better than a guard ring on a PC board: Don't insert the amplifier's input pin into the board at all, but bend it up in the air and use only air as an insulator. Air is an excellent insulator. In this case you may have to forego some of the advantages of PC board construction, but the advantages are sometimes well worth the effort of using point-to-point up-in-the-air wiring. See Figure 8. 01204914 Inverting Amplifier 01204917 01204915 (Input pins are lifted out of PC board and soldered directly to components. All other pins connected to PC board). Non-Inverting Amplifier FIGURE 8. Air Wiring 01204916 Follower FIGURE 7. Typical Connections of Guard Rings 15 www.national.com LMC6492 Dual/LMC6494 Quad Application Hints LMC6492 Dual/LMC6494 Quad Application Circuits Instrumentation Amplifier DC Summing Amplifier (VIN 0VDC and VO VDC 01204918 Where: V0 = V1 + V2 - V3 - V4 (V1 + V2 (V3 + V4) to keep V0 > 0VDC 01204921 High Input Z, DC Differential Amplifier If R1 = R5, R3 = R6, and R4 = R7; then AV 100 for circuit shown (R2 = 9.3k). Rail-to-Rail Single Supply Low Pass Filter 01204919 For 01204922 (CMRR depends on this resistor ratio match) As shown: VO = 2(V2 - V1) This low-pass filter circuit can be used as an anti-aliasing filter with the same supply as the A/D converter. Filter designs can also take advantage of the LMC6492/4 ultra-low input current. The ultra-low input current yields negligible offset error even when large value resistors are used. This in turn allows the use of smaller valued capacitors which take less board space and cost less. Photo Voltaic-Cell Amplifier Low Voltage Peak Detector with Rail-to-Rail Peak Capture Range 01204920 01204923 Dielectric absorption and leakage is minimized by using a polystyrene or polypropylene hold capacitor. The droop rate is primarily determined by the value of CH and diode leakage current. Select low-leakage current diodes to minimize drooping. www.national.com 16 In a manifold absolute pressure sensor application, a strain gauge is mounted on the intake manifold in the engine unit. Manifold pressure causes the sensing resistors, R1, R2, R3 and R4 to change. The resistors change in a way such that R2 and R4 increase by the same amount R1 and R3 decrease. This causes a differential voltage between the input of the amplifier. The gain of the amplifier is adjusted by Rf. (Continued) Pressure Sensor Spice Macromodel A spice macromodel is available for the LMC6492/4. This model includes accurate simulation of: * Input common-model voltage range * Frequency and transient response * GBW dependence on loading conditions * Quiescent and dynamic supply current * Output swing dependence on loading conditions and many other characteristics as listed on the macromodel disk. Contact your local National Semiconductor sales office to obtain an operational amplifier spice model library disk. 01204924 Rf = Rx Rf >> R1, R2, R3, and R4 Ordering Information Package 8-Pin Small Outline Temperature Range Extended -40C to +125C LMC6492AEM Transport Media NSC Drawing Rails M08A LMC6492BEM LMC6492AEMX Tape and Reel LMC6492BEMX 8-Pin Molded DIP LMC6492AEN Rails N08A Rails M14A LMC6492BEN 14-Pin Small Outline LMC6494AEM LMC6494BEM LMC6494AEMX Tape and Reel LMC6494BEMX 14-Pin Molded DIP LMC6494AEN Rails N14A LMC6494BEN 17 www.national.com LMC6492 Dual/LMC6494 Quad Application Circuits LMC6492 Dual/LMC6494 Quad Physical Dimensions inches (millimeters) unless otherwise noted 8-Pin Small Outline Package Order Number LMC6492AEM or LMC6492BEM NS Package Number M08A 14-Pin Small Outline Package Order Number LMC6494AEM or LMC6494BEM NS Package Number M14A www.national.com 18 LMC6492 Dual/LMC6494 Quad Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 8-Lead (0.300" Wide) Molded Dual-In-Line Package Order Number LMC6492AEN or LMC6492BEN NS Package Number N08A 14-Lead Molded Dual-In-Line Package Order Number LMC6494AEN or LMC6494BEN NS Package Number N14A 19 www.national.com LMC6492 Dual/LMC6494 Quad CMOS Rail-to-Rail Input and Output Operational Amplifier Notes 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. For the most current product information visit us at www.national.com. LIFE SUPPORT POLICY NATIONAL'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems 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. 2. A critical component is any component of 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. 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