LMC6482 CMOS Dual Rail-To-Rail Input and Output Operational Amplifier General Description Features The LMC6482 provides a common-mode range that extends to both supply rails. This rail-to-rail performance combined with excellent accuracy, due to a high CMRR, makes it unique among rail-to-rail input amplifiers. It is ideal for systems, such as data acquisition, that require a large input signal range. The LMC6482 is also an excellent upgrade for circuits using limited common-mode range amplifiers such as the TLC272 and TLC277. Maximum dynamic signal range is assured in low voltage and single supply systems by the LMC6482's rail-to-rail output swing. The LMC6482's rail-to-rail output swing is guaranteed for loads down to 600. (Typical unless otherwise noted) n Rail-to-Rail Input Common-Mode Voltage Range (Guaranteed Over Temperature) n Rail-to-Rail Output Swing (within 20mV of supply rail, 100k load) n Guaranteed 3V, 5V and 15V Performance n Excellent CMRR and PSRR: 82dB n Ultra Low Input Current: 20fA n High Voltage Gain (RL = 500k): 130dB n Specified for 2k and 600 loads n Available in MSOP Package Guaranteed low voltage characteristics and low power dissipation make the LMC6482 especially well-suited for battery-operated systems. Applications LMC6482 is also available in MSOP package which is almost half the size of a SO-8 device. See the LMC6484 data sheet for a Quad CMOS operational amplifier with these same features. Data Acquisition Systems Transducer Amplifiers Hand-held Analytic Instruments Medical Instrumentation Active Filter, Peak Detector, Sample and Hold, pH Meter, Current Source n Improved Replacement for TLC272, TLC277 n n n n n 3V Single Supply Buffer Circuit Rail-To-Rail Input Rail-To-Rail Output 01171303 01171301 01171302 Connection Diagram 01171304 (c) 2004 National Semiconductor Corporation DS011713 www.national.com LMC6482 CMOS Dual Rail-To-Rail Input and Output Operational Amplifier September 2003 LMC6482 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) Voltage at Input/Output Pin Operating Ratings 3.0V V+ 15.5V Junction Temperature Range Supply Voltage -55C TJ +125C LMC6482AM (V+) +0.3V, (V-) -0.3V Supply Voltage (V+ - V-) (Note 1) Supply Voltage 1.5kV Differential Input Voltage 150C 16V -40C TJ +85C LMC6482AI, LMC6482I 5mA Current at Input Pin (Note 12) Thermal Resistance (JA) Current at Output Pin N Package, 8-Pin Molded DIP 30mA (Notes 3, 8) Current at Power Supply Pin M Package, 8-Pin Surface Mount 40mA Lead Temperature (Soldering, 10 sec.) 155C/W MSOP package, 8-Pin Mini SO 260C Storage Temperature Range 90C/W 194C/W -65C to +150C DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25C, V+ = 5V, V- = 0V, VCM = VO = V+/2 and RL > 1M. Boldface limits apply at the temperature extremes. Symbol VOS TCVOS Parameter Conditions Typ (Note 5) Input Offset Voltage 0.11 Input Offset Voltage LMC6482AI LMC6482I LMC6482M Limit Limit Limit (Note 6) (Note 6) (Note 6) 0.750 3.0 3.0 mV 1.35 3.7 3.8 max 1.0 Units V/C Average Drift IB Input Current (Note 13) 0.02 4.0 4.0 10.0 pA max IOS Input Offset Current CIN Common-Mode (Note 13) 0.01 2.0 2.0 5.0 pA max 3 pF > 10 Tera Input Capacitance RIN Input Resistance CMRR Common Mode 0V VCM 15.0V Rejection Ratio V+ = 15V 82 0V VCM 5.0V 70 65 65 67 62 60 82 70 65 65 67 62 60 82 70 65 65 dB 67 62 60 min 70 65 65 dB 67 62 60 min - 0.25 - 0.25 - 0.25 V 0 0 0 max V+ + 0.25 V+ + 0.25 V+ + 0.25 V V+ min 120 V/mV + V = 5V +PSRR Positive Power Supply Rejection Ratio -PSRR Negative Power Supply VCM 5V V+ 15V, V- = 0V VO = 2.5V -5V V- -15V, V+ = 0V Rejection Ratio VO = -2.5V Input Common-Mode V+ = 5V and 15V Voltage Range For CMRR 50dB 82 V- - 0.3 V+ + 0.3V V AV Large Signal RL = 2k Voltage Gain (Notes 7, 13) RL = 600 V + Sourcing 666 140 84 72 60 min Sinking 75 35 35 35 V/mV 20 20 18 min Sourcing 300 80 50 50 V/mV 48 30 25 min Sinking 35 20 15 15 V/mV (Notes 7, 13) www.national.com + 2 120 dB min (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25C, V+ = 5V, V- = 0V, VCM = VO = V+/2 and RL > 1M. Boldface limits apply at the temperature extremes. Symbol VO Parameter Output Swing Conditions Typ (Note 5) V+ = 5V LMC6482AI LMC6482I LMC6482M Limit Limit Limit (Note 6) (Note 6) (Note 6) 13 10 8 min 4.9 4.8 4.8 4.8 V 4.7 4.7 4.7 min 0.1 0.18 0.18 0.18 V 0.24 0.24 0.24 max 4.5 4.5 4.5 V 4.24 4.24 4.24 min 0.5 0.5 0.5 V 0.65 0.65 0.65 max 14.4 14.4 14.4 V 14.2 14.2 14.2 min 0.16 0.32 0.32 0.32 V 0.45 0.45 0.45 max 14.1 13.4 13.4 13.4 V 13.0 13.0 13.0 min 1.0 1.0 1.0 V 1.3 1.3 1.3 max 16 16 16 mA 12 12 10 min + RL = 2k to V /2 V+ = 5V 4.7 + RL = 600 to V /2 0.3 V+ = 15V 14.7 RL = 2k to V+/2 V+ = 15V RL = 600 to V+/2 0.5 ISC Output Short Circuit Sourcing, VO = 0V 20 Current V+ = 5V ISC Sinking, VO = 5V Output Short Circuit 15 Sourcing, VO = 0V 11 11 11 mA 9.5 9.5 8.0 min 28 28 28 mA 22 22 20 min 30 30 30 mA 24 24 22 min 1.0 1.4 1.4 1.4 mA 1.8 1.8 1.9 max 1.3 1.6 1.6 1.6 mA 1.9 1.9 2.0 max 30 Current V+ = 15V Sinking, VO = 12V 30 (Note 8) IS Supply Current Both Amplifiers + + V = +5V, VO = V /2 Both Amplifiers Units V+ = 15V, VO = V+/2 AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25C, V+ = 5V, V- = 0V, VCM = VO = V+/2, and RL > 1M. Boldface limits apply at the temperature extremes. Symbol SR Parameter Slew Rate GBW Gain-Bandwidth Product m Gm en in Conditions Typ (Note 5) (Note 9) 1.3 V+ = 15V LMC6482AI LMC6482I LMC6482M Limit Limit Limit (Note 6) (Note 6) (Note 6) 1.0 0.9 0.9 0.7 0.63 0.54 Units V/s min 1.5 MHz Phase Margin 50 Deg Gain Margin 15 dB Amp-to-Amp Isolation (Note 10) 150 dB Input-Referred F = 1kHz 37 nV/Hz Voltage Noise Vcm = 1V Input-Referred F = 1kHz 0.03 pA/Hz Current Noise 3 www.national.com LMC6482 DC Electrical Characteristics LMC6482 AC Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25C, V+ = 5V, V- = 0V, VCM = VO = V+/2, and RL > 1M. Boldface limits apply at the temperature extremes. Symbol T.H.D. Parameter Total Harmonic Distortion Conditions Typ (Note 5) LMC6482AI LMC6482I LMC6482M Limit Limit Limit (Note 6) (Note 6) (Note 6) F = 10kHz, AV = -2 Units % RL = 10k, VO = 4.1 VPP 0.01 F = 10kHz, AV = -2 RL = 10k, VO = 8.5 VPP 0.01 % V+ = 10V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25C, V+ = 3V, V- = 0V, VCM = VO = V+/2 and RL > 1M. Symbol VOS TCVOS Parameter Conditions Typ (Note 5) Input Offset Voltage LMC6482AI LMC6482M Units Limit Limit Limit (Note 6) (Note 6) (Note 6) 2.0 3.0 3.0 mV 2.7 3.7 3.8 max 0.9 Input Offset Voltage LMC6482I 2.0 V/C 0.02 pA Average Drift IB Input Bias Current IOS Input Offset Current CMRR Common Mode PSRR Power Supply 0.01 pA 0V VCM 3V 74 64 60 60 3V V+ 15V, V- = 0V 80 68 60 60 V- -0.25 0 0 0 Rejection Ratio min Rejection Ratio VCM Input Common-Mode dB dB min For CMRR 50dB Voltage Range V max V+ + 0.25 V+ V+ V+ V min VO Output Swing RL = 2k to V+/2 + RL = 600 to V /2 2.8 V 0.2 V 2.7 2.5 2.5 2.5 V min 0.37 0.6 0.6 0.6 V 0.825 1.2 1.2 1.2 mA 1.5 1.5 1.6 max max IS Supply Current Both Amplifiers AC Electrical Characteristics Unless otherwise specified, V+ = 3V, V- = 0V, VCM = VO = V+/2, and RL > 1M. Symbol Parameter SR Slew Rate GBW Gain-Bandwidth Product T.H.D. Total Harmonic Distortion Conditions Typ (Note 5) (Note 11) F = 10kHz, AV = -2 LMC6482AI LMC6482I LMC6482M Limit Limit Limit (Note 6) (Note 6) (Note 6) Units 0.9 V/s 1.0 MHz 0.01 % RL = 10k, VO = 2 VPP Note 1: Absolute Maximum Ratings indicate limts 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, 1.5k in series with 100pF. All pins rated per method 3015.6 of MIL-STD-883. This is a Class 1 device rating. www.national.com 4 (Continued) Note 3: Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the maximum allowed junction temperature of 150C. Output currents in excess of 30mA 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 either the positive or 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: Connected as voltage Follower with 2V step input. Number specified is the slower of either the positive or negative slew rates. Note 12: Limiting input pin current is only necessary for input voltages that exceed absolute maximum input voltage ratings. Note 13: Guaranteed limits are dictated by tester limitations and not device performance. Actual performance is reflected in the typical value. Note 14: For guaranteed Military Temperature parameters see RETS6482X. Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified Supply Current vs. Supply Voltage Input Current vs. Temperature 01171340 01171341 Sourcing Current vs. Output Voltage Sourcing Current vs. Output Voltage 01171342 01171343 5 www.national.com LMC6482 AC Electrical Characteristics LMC6482 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) Sourcing Current vs. Output Voltage Sinking Current vs. Output Voltage 01171345 01171344 Sinking Current vs. Output Voltage Sinking Current vs. Output Voltage 01171346 01171347 Output Voltage Swing vs. Supply Voltage Input Voltage Noise vs. Frequency 01171349 01171348 www.national.com 6 Input Voltage Noise vs. Input Voltage Input Voltage Noise vs. Input Voltage 01171350 01171351 Input Voltage Noise vs. Input Voltage Crosstalk Rejection vs. Frequency 01171352 01171353 Crosstalk Rejection vs. Frequency Positive PSRR vs. Frequency 01171354 01171355 7 www.national.com LMC6482 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) LMC6482 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) Negative PSRR vs. Frequency CMRR vs. Frequency 01171356 01171357 CMRR vs. Input Voltage CMRR vs. Input Voltage 01171358 01171359 VOS vs. CMR CMRR vs. Input Voltage 01171360 www.national.com 01171361 8 VOS vs. CMR Input Voltage vs. Output Voltage 01171363 01171362 Input Voltage vs. Output Voltage Open Loop Frequency Response 01171364 01171365 Open Loop Frequency Responce Open Loop Frequency Response vs. Temperature 01171367 01171366 9 www.national.com LMC6482 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) LMC6482 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) Maximum Output Swing vs. Frequency Gain and Phase vs. Capacitive Load 01171368 01171369 Gain and Phase vs. Capacitive Load Open Loop Output Impedance vs. Frequency 01171370 01171371 Open Loop Output Impedance vs. Frequency Slew Rate vs. Supply Voltage 01171373 01171372 www.national.com 10 Non-Inverting Large Signal Pulse Response Non-Inverting Large Signal Pulse Response 01171374 01171375 Non-Inverting Large Signal Pulse Response Non-Inverting Small Signal Pulse Response 01171376 01171377 Non-Inverting Small Signal Pulse Response Non-Inverting Small Signal Pulse Response 01171378 01171379 11 www.national.com LMC6482 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) LMC6482 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) Inverting Large Signal Pulse Response Inverting Large Signal Pulse Response 01171380 01171381 Inverting Large Signal Pulse Response Inverting Small Signal Pulse Response 01171382 01171383 Inverting Small Signal Pulse Response Inverting Small Signal Pulse Response 01171384 01171385 www.national.com 12 Stability vs. Capacitive Load Stability vs. Capacitive Load 01171386 01171387 Stability vs. Capacitive Load Stability vs. Capacitive Load 01171388 01171389 Stability vs. Capacitive Load Stability vs. Capacitive Load 01171390 01171391 13 www.national.com LMC6482 Typical Performance Characteristics VS = +15V, Single Supply, TA = 25C unless otherwise specified (Continued) LMC6482 Application Information 1.0 AMPLIFIER TOPOLOGY The LMC6482 incorporates specially designed widecompliance range current mirrors and the body effect to extend input common mode range to each supply rail. Complementary paralleled differential input stages, like the type used in other CMOS and bipolar rail-to-rail input amplifiers, were not used because of their inherent accuracy problems due to CMRR, cross-over distortion, and openloop gain variation. The LMC6482's input stage design is complemented by an output stage capable of rail-to-rail output swing even when driving a large load. Rail-to-rail output swing is obtained by taking the output directly from the internal integrator instead of an output buffer stage. 01171339 FIGURE 2. A 7.5V Input Signal Greatly Exceeds the 3V Supply in Figure 3 Causing No Phase Inversion Due to RI 2.0 INPUT COMMON-MODE VOLTAGE RANGE Unlike Bi-FET amplifier designs, the LMC6482 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. Applications that exceed this rating must externally limit the maximum input current to 5mA with an input resistor (RI) as shown in Figure 3. 01171311 FIGURE 3. RI Input Current Protection for Voltages Exceeding the Supply Voltages 3.0 RAIL-TO-RAIL OUTPUT The approximated output resistance of the LMC6482 is 180 sourcing and 130 sinking at VS = 3V and 110 sourcing and 80 sinking at Vs = 5V. Using the calculated output resistance, maximum output voltage swing can be estimated as a function of load. 01171310 FIGURE 1. An Input Voltage Signal Exceeds the LMC6482 Power Supply Voltages with No Output Phase Inversion 4.0 CAPACITIVE LOAD TOLERANCE The LMC6482 can typically directly drive a 100pF load with VS = 15V at unity gain without oscillating. The unity gain follower is the most sensitive configuration. Direct capacitive loading reduces the phase margin of op-amps. The combination of the op-amp's output impedance and the capacitive load induces phase lag. This results in either an underdamped pulse response or oscillation. Capacitive load compensation can be accomplished using resistive isolation as shown in Figure 4. This simple technique is useful for isolating the capacitive inputs of multiplexers and A/D converters. The absolute maximum input voltage is 300mV 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. www.national.com 14 LMC6482 Application Information (Continued) 01171317 FIGURE 4. Resistive Isolation of a 330pF Capacitive Load 01171316 FIGURE 7. Pulse Response of LMC6482 Circuit in Figure 6 5.0 COMPENSATING FOR INPUT CAPACITANCE It is quite common to use large values of feedback resistance with amplifiers that have ultra-low input current, like the LMC6482. Large feedback resistors can react with small values of input capacitance due to transducers, photodiodes, and circuits board parasitics to reduce phase margins. 01171318 FIGURE 5. Pulse Response of the LMC6482 Circuit in Figure 4 Improved frequency response is achieved by indirectly driving capacitive loads, as shown in Figure 6. 01171319 FIGURE 8. Canceling the Effect of Input Capacitance The effect of input capacitance can be compensated for by adding a feedback capacitor. The feedback capacitor (as in Figure 8), Cf, is first estimated by: 01171315 FIGURE 6. LMC6482 Noninverting Amplifier, Compensated to Handle a 330pF Capacitive Load or R1 CIN R2 Cf which typically provides significant overcompensation. Printed circuit board stray capacitance may be larger or smaller than that of a bread-board, so the actual optimum value for Cf may be different. The values of Cf should be checked on the actual circuit. (Refer to the LMC660 quad CMOS amplifier data sheet for a more detailed discussion.) R1 and C1 serve to counteract the loss of phase margin by feeding forward the high frequency component of the output signal back to the amplifiers inverting input, thereby preserving phase margin in the overall feedback loop. The values of R1 and C1 are experimentally determined for the desired pulse response. The resulting pulse response can be seen in Figure 7. 15 www.national.com LMC6482 Application Information (Continued) 6.0 PRINTED-CIRCUIT-BOARD LAYOUT FOR HIGH-IMPEDANCE WORK It is generally recognized that any circuit which must operrate with less than 1000pA of leakage current requires special layout of the PC board. When one wishes to take advantage of the ultra-low input current of the LMC6482, typically less than 20fA, 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 through it may sometimes appear acceptably low, because under conditions of high humidity or dust or contamination, the surface leakage will be appreciable. 01171321 Inverting Amplifier To minimize the effect of any surface leakage, lay out a ring of foil completely surrounding the LM6482's inputs and the terminals of capacitors, diodes, conductors, resistors, relay terminals, etc. connected to the op-amp's inputs, as in Figure 9. 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 1012, which is normally considered a very large resistance, could leak 5pA if the trace were a 5V bus adjacent to the pad of the input. This would cause a 250 times degradation from the LMC6482's actual performance. However, if a guard ring is held within 5 mV of the inputs, then even a resistance of 1011 would cause only 0.05pA of leakage current. See Figure 10 for typical connections of guard rings for standard op-amp configurations. 01171322 Non-Inverting Amplifier 01171323 Follower FIGURE 10. Typical Connections of Guard Rings 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 11. 01171320 FIGURE 9. Example of Guard Ring in P.C. Board Layout 01171324 (Input pins are lifted out of PC board and soldered directly to components. All other pins connected to PC board.) FIGURE 11. Air Wiring www.national.com 16 (Continued) 8.0 UPGRADING APPLICATIONS The LMC6484 quads and LMC6482 duals have industry standard pin outs to retrofit existing applications. System performance can be greatly increased by the LMC6482's features. The key benefit of designing in the LMC6482 is increased linear signal range. Most op-amps have limited input common mode ranges. Signals that exceed this range generate a non-linear output response that persists long after the input signal returns to the common mode range. 7.0 OFFSET VOLTAGE ADJUSTMENT Offset voltage adjustment circuits are illustrated in Figure 12 Figure 13. Large value resistances and potentiometers are used to reduce power consumption while providing typically 2.5mV of adjustment range, referred to the input, for both configurations with VS = 5V. Linear signal range is vital in applications such as filters where signal peaking can exceed input common mode ranges resulting in output phase inverison or severe distortion. 9.0 DATA ACQUISITION SYSTEMS Low power, single supply data acquisition system solutions are provided by buffering the ADC12038 with the LMC6482 (Figure 14). Capable of using the full supply range, the LMC6482 does not require input signals to be scaled down to meet limited common mode voltage ranges. The LMC4282 CMRR of 82dB maintains integral linearity of a 12-bit data acquisition system to 0.325 LSB. Other rail-torail input amplifiers with only 50dB of CMRR will degrade the accuracy of the data acquisition system to only 8 bits. 01171325 FIGURE 12. Inverting Configuration Offset Voltage Adjustment 01171326 FIGURE 13. Non-Inverting Configuration Offset Voltage Adjustment 17 www.national.com LMC6482 Application Information LMC6482 Application Information (Continued) 01171328 FIGURE 14. Operating from the same Supply Voltage, the LMC6482 buffers the ADC12038 maintaining excellent accuracy 10.0 INSTRUMENTATION CIRCUITS The LMC6482 has the high input impedance, large commonmode range and high CMRR needed for designing instrumentation circuits. Instrumentation circuits designed with the LMC6482 can reject a larger range of common-mode signals than most in-amps. This makes instrumentation circuits designed with the LMC6482 an excellent choice of noisy or industrial environments. Other applications that benefit from www.national.com these features include analytic medical instruments, magnetic field detectors, gas detectors, and silicon-based tranducers. A small valued potentiometer is used in series with Rg to set the differential gain of the 3 op-amp instrumentation circuit in Figure 15. This combination is used instead of one large valued potentiometer to increase gain trim accuracy and reduce error due to vibration. 18 LMC6482 Application Information (Continued) 01171329 FIGURE 15. Low Power 3 Op-Amp Instrumentation Amplifier A 2 op-amp instrumentation amplifier designed for a gain of 100 is shown in Figure 16. Low sensitivity trimming is made for offset voltage, CMRR and gain. Low cost and low power consumption are the main advantages of this two op-amp circuit. Higher frequency and larger common-mode range applications are best facilitated by a three op-amp instrumentation amplifier. 01171330 FIGURE 16. Low-Power Two-Op-Amp Instrumentation Amplifier 11.0 SPICE MACROMODEL A spice macromodel is available for the LMC6482. This model includes accurate simulation of: * Input common-mode voltage range * Frequency and transient response * GBW dependence on loading conditions * Quiescent and dynamic supply current * Output swing dependence on loading conditions and many more characteristics as listed on the macromodel disk. Contact your local National Semiconductor sales office to obtain an operational amplifier spice model library disk. 19 www.national.com LMC6482 Typical Single-Supply Applications The circuit in Figure 17 uses a single supply to half wave rectify a sinusoid centered about ground. RI limits current into the amplifier caused by the input voltage exceeding the supply voltage. Full wave rectification is provided by the circuit in Figure 19. 01171331 FIGURE 17. Half-Wave Rectifier with Input Current Protection (RI) 01171333 FIGURE 19. Full Wave Rectifier with Input Current Protection (RI) 01171332 FIGURE 18. Half-Wave Rectifier Waveform 01171334 FIGURE 20. Full Wave Rectifier Waveform www.national.com 20 LMC6482 Typical Single-Supply Applications (Continued) 01171336 01171335 FIGURE 22. Positive Supply Current Sense FIGURE 21. Large Compliance Range Current Source 01171337 FIGURE 23. Low Voltage Peak Detector with Rail-to-Rail Peak Capture Range diode leakage current. The ultra-low input current of the LMC6482 has a negligible effect on droop. In Figure 23 dielectric absorption and leakage is minimized by using a polystyrene or polyethylene hold capacitor. The droop rate is primarily determined by the value of CH and 01171338 FIGURE 24. Rail-to-Rail Sample and Hold The LMC6482's high CMRR (82dB) allows excellent accuracy throughout the circuit's rail-to-rail dynamic capture range. 21 www.national.com LMC6482 Typical Single-Supply Applications (Continued) 01171327 FIGURE 25. Rail-to-Rail Single Supply Low Pass Filter The low pass filter circuit in Figure 25 can be used as an anti-aliasing filter with the same voltage supply as the A/D converter. Filter designs can also take advantage of the LMC6482 ultra-low input current. The ultra-low input current yields Package Temperature Range Military Industrial -55C to +125C -40C to +85C 8-Pin LMC6482AIN, Molded DIP LMC6482IN 8-pin LMC6482AIM, LMC6482AIMX Small Outline LMC6482IM, LMC6482IMX 8-pin LMC6482AMJ/883 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. Ordering Information NSC Drawing Transport Media N08E Rail Package Marking LMC6482MN, LMC6482AIN, LMC6482IN M08A Rail LMC6482AIM, LMC6482IM Tape and Reel J08A Rail LMC6482AMJ/883Q5962-9453401MPA Rail A10 Ceramic DIP 8-pin LMC6482IMM Mini SO LMC6482IMMX www.national.com MUA08A Tape and Reel 22 LMC6482 Physical Dimensions inches (millimeters) unless otherwise noted 8-Pin Ceramic Dual-In-Line Package Order Number LMC6482AMJ/883 NS Package Number J08A 8-Pin Small Outline Package Order Package Number LMC6482AIM, LMC6482AIMX, LMC6482IM or LMC6482IMX NS Package Number M08A 23 www.national.com LMC6482 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 8-Pin Molded Dual-In-Line Package Order Package Number LMC6482AIN, LMC6482IN NS Package Number N08E 8-Lead Mini Small Outline Molded Package, JEDEC Order Number LMC6482IMM, or LMC6482IMMX NS Package Number MUA08A www.national.com 24 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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