LMC6064 Precision CMOS Quad Micropower Operational Amplifier General Description Features The LMC6064 is a precision quad low offset voltage, micropower operational amplifier, capable of precision single supply operation. Performance characteristics include ultra low input bias current, high voltage gain, rail-to-rail output swing, and an input common mode voltage range that includes ground. These features, plus its low power consumption make the LMC6064 ideally suited for battery powered applications. Other applications using the LMC6064 include precision full-wave rectifiers, integrators, references, sample-and-hold circuits, and true instrumentation amplifiers. This device is built with National’s advanced double-Poly Silicon-Gate CMOS process. For designs that require higher speed, see the LMC6084 precision quad operational amplifier. For single or dual operational amplifier with similar features, see the LMC6061 or LMC6062 respectively. (Typical Unless Otherwise Noted) n Low offset voltage: 100 µV n Ultra low supply current: 16 µA/Amplifier n Operates from 4.5V to 15V single supply n Ultra low input bias current: 10 fA n Output swing within 10 mV of supply rail, 100k load n Input common-mode range includes V− n High voltage gain: 140 dB n Improved latchup immunity PATENT PENDING Applications n n n n n n n Instrumentation amplifier Photodiode and infrared detector preamplifier Transducer amplifiers Hand-held analytic instruments Medical instrumentation D/A converter Charge amplifier for piezoelectric transducers Connection Diagram 14-Pin DIP/SO DS011466-1 Top View Ordering Information Temperature Range Package Military −55˚C to +125˚C 14-Pin LMC6064AMN Molded DIP Industrial −40˚C to +85˚C LMC6064AIN Transport Media N14A Rail LMC6064IN 14-Pin LMC6064AIM Small Outline LMC6064IM 14-Pin NSC Drawing LMC6064AMJ M14A Rail Tape and Reel J14A Rail Ceramic DIP © 1999 National Semiconductor Corporation DS011466 www.national.com LMC6064 Precision CMOS Quad Micropower Operational Amplifier November 1994 Absolute Maximum Ratings (Note 1) Differential Input Voltage Voltage at Input/Output Pin Supply Voltage (V+ − V−) Output Short Circuit to V+ Output Short Circuit to V− Lead Temperature (Soldering, 10 sec.) Storage Temp. Range Junction Temperature ESD Tolerance (Note 4) ± 10 mA ± 30 mA Current at Input Pin Current at Output Pin Current at Power Supply Pin Power Dissipation If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. ± Supply Voltage 40 mA (Note 3) Operating Ratings (Note 1) (V+) +0.3V, (V−) −0.3V 16V (Note 11) (Note 2) Temperature Range LMC6064AM LMC6064AI, LMC6064I Supply Voltage Thermal Resistance (θJA) (Note 12) 14-Pin Molded DIP 14-Pin SO Power Dissipation 260˚C −65˚C to +150˚C 150˚C 2 kV −55˚C ≤ TJ ≤ +125˚C −40˚C ≤ TJ ≤ +85˚C 4.5V ≤ V+ ≤ 15.5V 81˚C/W 126˚C/W (Note 10) DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. Boldface limits apply at the temperature extremes. V+ = 5V, V− = 0V, VCM = 1.5V, VO = 2.5V and RL > 1M unless otherwise specified. Symbol VOS TCVOS Parameter Conditions Input Offset Voltage Typ LMC6064AM LMC6064AI (Note 5) Limit Limit Limit (Note 6) (Note 6) (Note 6) 350 350 800 µV 1200 900 1300 Max 100 Input Offset Voltage LMC6064I 1.0 Units µV/˚C Average Drift IB IOS Input Bias Current Input Offset Current RIN Input Resistance CMRR Common Mode −PSRR 5V ≤ V+ ≤ 15V VO = 2.5V 85 Rejection Ratio Negative Power Supply 0V ≤ V− ≤ −10V 100 Rejection Ratio VCM Input Common-Mode V+ = 5V and 15V Voltage Range for CMRR ≥ 60 dB −0.4 V+ − 1.9 AV Large Signal RL = 100 kΩ Voltage Gain (Note 7) RL = 25 kΩ Sourcing 4000 4 Max 100 2 2 Max 75 75 66 dB 70 72 63 Min pA Tera Ω 75 75 66 dB 70 72 63 Min 84 84 74 dB 70 81 71 Min −0.1 −0.1 −0.1 V 0 0 0 Max V+ − 2.3 V+ − 2.3 V+ − 2.3 V V+ − 2.6 V+ − 2.5 V+ − 2.5 Min 400 400 300 V/mV 200 300 200 Min 180 90 V/mV Sinking 3000 180 70 100 60 Min Sourcing 3000 400 400 200 V/mV 150 150 80 Min Sinking 2000 100 100 70 V/mV 35 50 35 Min (Note 7) www.national.com 4 > 10 85 Positive Power Supply pA 100 0.005 0V ≤ VCM ≤ 12.0V V+ = 15V Rejection Ratio +PSRR 0.010 2 DC Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. Boldface limits apply at the temperature extremes. V+ = 5V, V− = 0V, VCM = 1.5V, VO = 2.5V and RL > 1M unless otherwise specified. Symbol VO Parameter Output Swing Conditions V+ = 5V RL = 100 kΩ to 2.5V Typ LMC6064AM LMC6064AI (Note 5) Limit Limit Limit (Note 6) (Note 6) (Note 6) 4.995 0.005 V+ = 5V RL = 25 kΩ to 2.5V 4.990 0.010 V+ = 15V RL = 100 kΩ to 7.5V 14.990 0.010 V+ = 15V RL = 25 kΩ to 7.5V 14.965 0.025 IO Output Current V+ = 5V Sourcing, VO = 0V 22 Sinking, VO = 5V IO Output Current V+ = 15V 21 Sourcing, VO = 0V 25 Sinking, VO = 13V 35 (Note 11) IS Supply Current All Four Amplifiers V+ = +5V, VO = 1.5V 64 All Four Amplifiers V+ = +15V, VO = 7.5V 80 3 LMC6064I Units 4.990 4.990 4.950 V 4.970 4.980 4.925 Min 0.010 0.010 0.050 V 0.030 0.020 0.075 Max 4.975 4.975 4.950 V 4.955 4.965 4.850 Min 0.020 0.020 0.050 V 0.045 0.035 0.150 Max 14.975 14.975 14.950 V 14.955 14.965 14.925 Min 0.025 0.025 0.050 V 0.050 0.035 0.075 Max 14.900 14.900 14.850 V 14.800 14.850 14.800 Min 0.050 0.050 0.100 V 0.200 0.150 0.200 Max 16 16 13 mA 8 10 8 Min 16 16 16 mA 7 8 8 Min 15 15 15 mA 9 10 10 Min 24 24 24 mA 7 8 8 Min 76 76 92 µA 120 92 112 Max 94 94 114 µA 140 110 132 Max www.national.com AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, Boldface limits apply at the temperature extremes. V+ = 5V, V− = 0V, VCM = 1.5V, VO = 2.5V and RL > 1M unless otherwise specified. Symbol SR Parameter Slew Rate GBW Gain-Bandwidth Product θm Phase Margin Conditions (Note 8) Typ LMC6064AM LMC6064AI (Note 5) Limit Limit Limit (Note 6) (Note 6) (Note 6) 20 20 15 8 10 7 35 LMC6064I Units V/ms Min 100 kHz 50 Deg Amp-to-Amp Isolation (Note 9) 155 dB en Input-Referred Voltage Noise F = 1 kHz 83 in Input-Referred Current Noise F = 1 kHz 0.0002 T.H.D. Total Harmonic Distortion F = 1 kHz, AV = −5 RL = 100 kΩ, VO = 2 VPP 0.01 % ± 5V Supply 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 do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Note 2: Applies to both single-supply and split-supply operation. Continous short circuit operation at elevated ambient temperature can result in exceeding the maximum allowed junction temperature of 150˚C. Output currents in excess of ± 30 mA over long term may adversely affect reliability. Note 3: 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. Note 4: Human body model, 1.5 kΩ in series with 100 pF. 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, 2.5V ≤ VO ≤ 7.5V. Note 8: V+ = 15V. Connected as Voltage Follower with 10V step input. Number specified is the slower of the positive and negative slew rates. Note 9: Input referred V+ = 15V and RL = 100 kΩ connected to 7.5V. Each amp excited in turn with 100 Hz to produce VO = 12 VPP. Note 10: For operating at elevated temperatures the device must be derated based on the thermal resistance θJA with PD = (TJ–TA)/θJA. Note 11: Do not connect output to V+, when V+ is greater than 13V or reliability witll be adversely affected. Note 12: All numbers apply for packages soldered directly into a PC board. Note 13: For guaranteed Military Temperature Range parameters see RETSMC6064X. www.national.com 4 Typical Performance Characteristics Distribution of LMC6064 Input Offset Voltage (TA = +25˚C) Distribution of LMC6064 Input Offset Voltage (TA = −55˚C) DS011466-15 Input Bias Current vs Temperature Distribution of LMC6064 Input Offset Voltage (TA = +125˚C) DS011466-16 Supply Current vs Supply Voltage DS011466-18 Common Mode Rejection Ratio vs Frequency DS011466-17 Input Voltage vs Output Voltage DS011466-19 Power Supply Rejection Ratio vs Frequency DS011466-20 Input Voltage Noise vs Frequency DS011466-22 DS011466-23 DS011466-21 5 www.national.com Typical Performance Characteristics Output Characteristics Sourcing Current (Continued) Output Characteristics Sinking Current Gain and Phase Response vs Temperature (−55˚C to +125˚C) DS011466-24 DS011466-25 Gain and Phase Response vs Capacitive Load with RL = 20 kΩ Gain and Phase Response vs Capacitive Load with RL = 500 kΩ DS011466-26 Open Loop Frequency Response DS011466-29 DS011466-27 Inverting Small Signal Pulse Response DS011466-28 Inverting Large Signal Pulse Response DS011466-30 www.national.com Non-Inverting Small Signal Pulse Response DS011466-31 6 DS011466-32 Typical Performance Characteristics Non-Inverting Large Signal Pulse Response (Continued) Crosstalk Rejection vs Frequency DS011466-33 Stability vs Capacitive Load, RL = 20 kΩ DS011466-34 DS011466-35 Stability vs Capacitive Load RL = 1 MΩ DS011466-36 Applications Hints The effect of input capacitance can be compensated for by adding a capacitor. Place a capacitor, Cf, around the feedback resistor (as in Figure 1 ) such that: AMPLIFIER TOPOLOGY The LMC6064 incorporates a novel op-amp design topology that enables it to maintain rail-to-rail output swing even when driving a large load. Instead of relying on a push-pull unity gain output buffer stage, the output stage is taken directly from the internal integrator, which provides both low output impedance and large gain. Special feed-forward compensation design techniques are incorporated to maintain stability over a wider range of operating conditions than traditional micropower op-amps. These features make the LMC6064 both easier to design with, and provide higher speed than products typically found in this ultra-low power class. 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 the LMC662 for a more detailed discussion on compensating for input capacitance. COMPENSATING FOR INPUT CAPACITANCE It is quite common to use large values of feedback resistance for amplifiers with ultra-low input current, like the LMC6064. Although the LMC6064 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 and 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 LMC6064 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). DS011466-4 FIGURE 1. Canceling the Effect of Input Capacitance 7 www.national.com Applications Hints (Continued) 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 LMC6064, typically less than 10 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 LMC6064’s inputs and the terminals of capacitors, diodes, conductors, resistors, relay terminals etc. connected to the op-amp’s inputs, as in Figure 4. 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. This would cause a 100 times degradation from the LMC6064’s actual performance. However, if a guard ring is held within 5 mV of the inputs, then even a resistance of 1011Ω would cause only 0.05 pA of leakage current. See Figure 5 for typical connections of guard rings for standard op-amp configurations. 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 dominate 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 2. DS011466-5 FIGURE 2. LMC6064 Noninverting Gain of 10 Amplifier, Compensated to Handle Capacitive Loads In the circuit of Figure 2, R1 and C1 serve to counteract the loss of phase margin by feeding the high frequency component of the output signal back to the amplifier’s inverting input, thereby preserving phase margin in the overall feedback loop. Capacitive load driving capability is enhanced by using a pull up resistor to V+ (Figure 3). Typically a pull up resistor conducting 10 µA or more will significantly improve capacitive load responses. The value of the pull up resistor must be determined based on the current sinking capability of the amplifier with respect to the desired output swing. Open loop gain of the amplifier can also be affected by the pull up resistor (see Electrical Characteristics). DS011466-7 FIGURE 4. Example of Guard Ring in P.C. Board Layout DS011466-6 FIGURE 3. Compensating for Large Capacitive Loads with a Pull Up Resistor www.national.com 8 Applications Hints Latchup (Continued) CMOS devices tend to be susceptible to latchup due to their internal parasitic SCR effects. The (I/O) input and output pins look similar to the gate of the SCR. There is a minimum current required to trigger the SCR gate lead. The LMC6064 and LMC6082 are designed to withstand 100 mA surge current on the I/O pins. Some resistive method should be used to isolate any capacitance from supplying excess current to the I/O pins. In addition, like an SCR, there is a minimum holding current for any latchup mode. Limiting current to the supply pins will also inhibit latchup susceptibility. DS011466-8 Inverting Amplifier DS011466-11 DS011466-9 (Input pins are lifted out of PC board and soldered directly to components. All other pins connected to PC board). Non-Inverting Amplifier FIGURE 6. Air Wiring Typical Single-Supply Applications (V+ = 5.0 VDC) The extremely high input impedance, and low power consumption, of the LMC6064 make it ideal for applications that require battery-powered instrumentation amplifiers. Examples of these types of applications are hand-held pH probes, analytic medical instruments, magnetic field detectors, gas detectors, and silicon based pressure transducers. DS011466-10 Follower FIGURE 5. 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 6. Figure 7 shows an instrumentation amplifier that features high differential and common mode input resistance ( > 1014Ω), 0.01% gain accuracy at AV = 100, excellent CMRR with 1 kΩ imbalance in bridge source resistance. Input current is less than 100 fA and offset drift is less than 2.5 µV/˚C. R2 provides a simple means of adjusting gain over a wide range without degrading CMRR. R7 is an initial trim used to maximize CMRR without using super precision matched resistors. For good CMRR over temperature, low drift resistors should be used. 9 www.national.com Typical Single-Supply Applications (Continued) DS011466-12 If R1 = R5, R3 = R6, and R4 = R7; then ∴AV ≈ 100 for circuit shown (R2 = 9.822k). FIGURE 7. Instrumentation Amplifier DS011466-13 FIGURE 8. Low-Leakage Sample and Hold DS011466-14 FIGURE 9. 1 Hz Square Wave Oscillator www.national.com 10 Physical Dimensions inches (millimeters) unless otherwise noted 14-Pin Ceramic Dual-In-Line Package Order Number LMC6064AMJ/883 NS Package Number J14A 14-Pin Small Outline Package Order Number LMC6064AIM or LMC6064IM NS Package Number M14A 11 www.national.com LMC6064 Precision CMOS Quad Micropower Operational Amplifier Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 14-Pin Molded Dual-In-Line Package Order Number LMC6064AMN, LMC6064AIN or LMC6064IN NS Package Number N14A 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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