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 −40˚C to +125˚C. 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. 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. (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 kΩ 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 kΩ) 120 dB n Low supply current ( @ VS = 5V) 500 µA/Amplifier n Low offset voltage drift 1.0 µV/˚C Applications n n n n n Automotive transducer amplifier Pressure sensor Oxygen sensor Temperature sensor Speed sensor Connection Diagrams 8-Pin DIP/SO 14-Pin DIP/SO DS012049-1 Top View DS012049-2 Top View © 1999 National Semiconductor Corporation DS012049 www.national.com LMC6492 Dual/LMC6494 Quad CMOS Rail-to-Rail Input and Output Operational Amplifier October 1994 Ordering Information Package 8-Pin Small Outline Temperature Range Extended −40˚C to +125˚C 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 LMC6494BEN www.national.com 2 N14A 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. ESD Tolerance (Note 2) Differential Input Voltage Voltage at Input/Output Pin Supply Voltage (V+ − V−) Current at Input Pin Current at Output Pin (Note 3) Current at Power Supply Pin Lead Temp. (Soldering, 10 sec.) Storage Temperature Range 150˚C Operating Conditions (Note 1) Supply Voltage Junction Temperature Range LMC6492AE, LMC6492BE LMC6494AE, LMC6494BE Thermal Resistance (θJA) N Package, 8-Pin Molded DIP M Package, 8-Pin Surface Mount N Package, 14-Pin Molded DIP M Package, 14-Pin Surface Mount 2000V ± Supply Voltage (V+) + 0.3V, (V−) − 0.3V 16V ± 5 mA ± 30 mA 40 mA 260˚C −65˚C to +150˚C 2.5V ≤ V+ ≤ 15.5V −40˚C ≤ TJ ≤ +125˚C −40˚C ≤ TJ ≤ +125˚C 108˚C/W 171˚C/W 78˚C/W 118˚C/W DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2 and RL > 1 MΩ. Boldface limits apply at the temperature extremes Symbol VOS TCVOS Parameter Conditions Input Offset Voltage LMC6492AE LMC6492BE Typ LMC6494AE LMC6494BE (Note 5) Limit Limit (Note 6) (Note 6) 3.0 6.0 mV 3.8 6.8 max 0.11 Input Offset Voltage 1.0 Units µV/˚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 Ω 3 pF Input Capacitance CMRR Common-Mode Rejection Ratio +PSRR 0V ≤ VCM ≤ 5V 82 82 0V ≤ V− ≤ −10V, VO = 2.5V 82 Input Common-Mode V+ = 5V and 15V V− −0.3 Voltage Range For CMRR ≥ 50 dB Negative Power Supply Rejection Ratio VCM 82 5V ≤ V+ ≤ 15V, VO = 2.5V Positive Power Supply Rejection Ratio −PSRR 0V ≤ VCM ≤ 15V V+ = 15V V+ + 0.3 65 63 60 58 65 63 60 58 65 63 dB 60 58 min 65 63 dB 60 58 min −0.25 −0.25 V 0 0 max V+ + 0.25 V+ + 0.25 V V+ min V AV Large Signal Voltage Gain dB min + RL = 2 kΩ: Sourcing 300 V/mV (Note 7) Sinking 40 min 3 www.national.com DC Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2 and RL > 1 MΩ. Boldface limits apply at the temperature extremes Symbol VO Parameter Output Swing Conditions V+ = 5V RL = 2 kΩ to V+/2 LMC6492AE LMC6492BE Typ LMC6494AE LMC6494BE (Note 5) Limit Limit (Note 6) (Note 6) 4.9 0.1 V+ = 5V RL = 600Ω to V+/2 4.7 0.3 V+ = 15V RL = 2 kΩ to V+/2 14.7 0.16 V+ = 15V RL = 600Ω to V+/2 14.1 0.5 ISC ISC IS Output Short Circuit Current Sourcing, VO = 0V 25 4.8 4.8 V 4.7 4.7 min 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 0.35 0.35 V 0.5 0.5 max 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 V+ = 5V Sinking, VO = 5V 22 11 8 8 Output Short Circuit Current Sourcing, VO = 0V 30 28 28 20 20 V+ = 15V Sinking, VO = 5V (Note 8) 30 LMC6492 V+ = +5V, VO = V+/2 1.0 LMC6492 V+ = +15V, VO = V+/2 1.3 LMC6494 V+ = +5V, VO = V+/2 2.0 LMC6494 V+ = +15V, VO = V+/2 2.6 Supply Current www.national.com 4 Units mA min 30 30 22 22 1.75 1.75 mA 2.1 2.1 max 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 AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2 and RL > 1 MΩ. Boldface limits apply at the temperature extremes Symbol SR Parameter Slew Rate Conditions (Note 9) LMC6492AE LMC6492BE Typ LMC6494AE LMC6494BE (Note 5) Limit Limit (Note 6) (Note 6) 1.3 V+ = 15V 0.7 0.7 0.5 0.5 Units Vµs min GBW Gain-Bandwidth Product 1.5 MHz φm Phase Margin 50 Deg Gm Gain Margin 15 dB 150 dB Amp-to-Amp Isolation en in Input-Referred (Note 10) F = 1 kHz Voltage Noise VCM = 1V Input-Referred F = 1 kHz 0.06 F = 1 kHz, AV = −2 RL = 10 kΩ, VO = −4.1 VPP F = 10 kHz, AV = −2 0.01 RL = 10 kΩ, VO = 8.5 VPP V+ = 10V 0.01 37 Current Noise T.H.D. Total Harmonic Distortion % 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 kΩ 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 150˚C. 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), θJA and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(max) − TA)/θJA. 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 kΩ 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. Typical Performance Characteristics VS = +15V, Single Supply, TA = 25˚C unless otherwise specified Supply Current vs Supply Voltage Input Current vs Temperature Sourcing Current vs Output Voltage DS012049-25 DS012049-26 5 DS012049-27 www.national.com Typical Performance Characteristics VS = +15V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Sourcing Current vs Output Voltage Sourcing Current vs Output Voltage DS012049-28 Sinking Current vs Output Voltage Sinking Current vs Output Voltage Input Voltage Noise vs Frequency DS012049-30 DS012049-29 DS012049-31 Output Voltage Swing vs Supply Voltage DS012049-32 Input Voltage Noise vs Input Voltage DS012049-34 www.national.com Sinking Current vs Output Voltage Input Voltage Noise vs Input Voltage DS012049-35 6 DS012049-33 DS012049-36 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Input Voltage Noise vs Input Voltage Crosstalk Rejection vs Frequency DS012049-37 Positive PSRR vs Frequency Crosstalk Rejection vs Frequency DS012049-38 Negative PSRR vs Frequency CMRR vs Frequency DS012049-40 CMRR vs Input Voltage DS012049-39 DS012049-41 CMRR vs Input Voltage DS012049-42 CMRR vs Input Voltage DS012049-43 DS012049-44 7 DS012049-45 www.national.com Typical Performance Characteristics VS = +15V, Single Supply, TA = 25˚C unless otherwise specified (Continued) ∆VOS vs CMR ∆VOS vs CMR Input Voltage vs Output Voltage DS012049-46 Input Voltage vs Output Voltage Open Loop Frequency Response DS012049-49 Open Loop Frequency Response vs Temperature Open Loop Frequency Response DS012049-50 Maximum Output Swing vs Frequency 8 DS012049-51 Gain and Phase vs Capacitive Load DS012049-53 DS012049-52 www.national.com DS012049-48 DS012049-47 DS012049-54 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Gain and Phase vs Capacitive Load Open Loop Output Impedance vs Frequency DS012049-55 Slew Rate vs Supply Voltage Open Loop Output Impedance vs Frequency DS012049-56 Non-Inverting Large Signal Pulse Response Non-Inverting Large Signal Pulse Response DS012049-59 DS012049-58 Non-Inverting Large Signal Pulse Response DS012049-57 Non-Inverting Small Signal Pulse Response DS012049-61 Non-Inverting Small Signal Pulse Response DS012049-62 9 DS012049-60 DS012049-63 www.national.com Typical Performance Characteristics VS = +15V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Non-Inverting Small Signal Pulse Response Inverting Large Signal Pulse Response DS012049-64 Inverting Large Signal Pulse Response Inverting Large Signal Pulse Response DS012049-65 Inverting Small Signal Pulse Response DS012049-67 Inverting Small Signal Pulse Response DS012049-66 Inverting Small Signal Pulse Response DS012049-68 Stability vs Capacitive Load DS012049-69 Stability vs Capacitive Load DS012049-70 DS012049-71 www.national.com 10 DS012049-72 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Stability vs Capacitive Load Stability vs Capacitive Load Stability vs Capacitive Load DS012049-73 DS012049-74 DS012049-75 Stability vs Capacitive Load DS012049-76 ceeding this absolute maximum rating, as in Figure 2, can cause excessive current to flow in or out of the input pins possibly affecting reliability. Application Notes 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. DS012049-9 FIGURE 2. A ± 7.5V Input Signal Greatly Exceeds the 5V Supply in Figure 3 Causing No Phase Inversion Due to RI 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. DS012049-8 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 ex11 www.national.com Application Notes 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. (Continued) DS012049-10 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 110Ω sourcing and 80Ω 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: DS012049-12 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 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 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 1012Ω, 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. or 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. 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 1011Ω will only cause 0.05 pA of leakage current. See Figure 7 for typical connections of guard rings for standard op-amp configurations. DS012049-11 FIGURE 4. Cancelling the Effect of Input Capacitance www.national.com 12 Application Notes (Continued) DS012049-13 FIGURE 6. Examples of Guard Ring in PC Board Layout DS012049-17 DS012049-14 (Input pins are lifted out of PC board and soldered directly to components. All other pins connected to PC board). Inverting Amplifier FIGURE 8. Air Wiring Application Circuits DC Summing Amplifier (VIN ≥ 0VDC and VO ≥ VDC DS012049-15 Non-Inverting Amplifier DS012049-16 Follower FIGURE 7. Typical Connections of Guard Rings DS012049-18 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. Where: V0 = V1 + V2 − V3 – (V1 + V2 ≥ (V3 + V4) to keep 13 V4 V0 > 0VDC www.national.com Application Circuits (Continued) Rail-to-Rail Single Supply Low Pass Filter High Input Z, DC Differential Amplifier DS012049-22 DS012049-19 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. For (CMRR depends on this resistor ratio match) As shown: VO = 2(V2 − V1) Low Voltage Peak Detector with Rail-to-Rail Peak Capture Range Photo Voltaic-Cell Amplifier DS012049-23 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. DS012049-20 Pressure Sensor Instrumentation Amplifier DS012049-24 Rf = Rx Rf >> R1, R2, R3, and R4 DS012049-21 If R1 = R5, R3 = R6, and R4 = R7; then 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 ∴AV ≈ 100 for circuit shown (R2 = 9.3k). www.national.com 14 Application Circuits • 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. (Continued) 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. Spice Macromodel A spice macromodel is available for the LMC6492/4. This model includes accurate simulation of: 15 www.national.com 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 16 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 17 www.national.com LMC6492 Dual/LMC6494 Quad CMOS Rail-to-Rail Input and Output Operational Amplifier 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 OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 2. A critical component is any component of a life support 1. Life support devices or systems are devices or sysdevice or system whose failure to perform can be reatems which, (a) are intended for surgical implant into sonably expected to cause the failure of the life support the body, or (b) support or sustain life, and whose faildevice or system, or to affect its safety or effectiveness. ure 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. 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