LMC6024 LMC6024 Low Power CMOS Quad Operational Amplifier Literature Number: SNOS621C LMC6024 Low Power CMOS Quad Operational Amplifier General Description The LMC6024 is a CMOS quad operational amplifier which can operate from either a single supply or dual supplies. Its performance features include an input common-mode range that reaches V-, low input bias current and voltage gain (into 100 k and 5 k loads) that is equal to or better than widely accepted bipolar equivalents, while the power supply requirement is less than 1 mW. This chip is built with National's advanced Double-Poly Silicon-Gate CMOS process. See the LMC6022 datasheet for a CMOS dual operational amplifier with these same features. Features n Specified for 100 k and 5 k loads n High voltage gain 120 dB n Low offset voltage drift 2.5 V/C n n n n n n Ultra low input bias current 40 fA Input common-mode range includes V- Operating range from +5V to +15V supply Low distortion 0.01% at 1 kHz Slew rate 0.11 V/s Micropower operation 1 mW Applications n n n n n n n High-impedance buffer or preamplifier Current-to-voltage converter Long-term integrator Sample-and-hold circuit Peak detector Medical instrumentation Industrial controls Connection Diagram 14-Pin DIP/SO 01123501 Top View (c) 2004 National Semiconductor Corporation DS011235 www.national.com LMC6024 Low Power CMOS Quad Operational Amplifier August 2000 LMC6024 Absolute Maximum Ratings (Note 1) Output Short Circuit to V- If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Junction Temperature 150C ESD Tolerance (Note 4) 1000V Differential Input Voltage Supply Voltage Supply Voltage (V+ - V-) 16V Power Dissipation Voltage at Output/Input Pin -40C TJ +85C Temperature Range 260C Storage Temperature Range (Note 3) Operating Ratings Lead Temperature (Soldering, 10 sec.) (Note 2) -65C to +150C Supply Voltage Range (V+) + 0.3V, (V-) - 0.3V 5 mA 18 mA Current at Input Pin Current at Output Pin Current at Power Supply Pin Output Short Circuit to V+ 4.75V to 15.5V Power Dissipation (Note 10) Thermal Resistance (JA), (Note 11) 35 mA (Note 12) 14-Pin DIP 85C/W 14-Pin SO 115C/W DC Electrical Characteristics The following specifications apply for V+ = 5V, V- = 0V, VCM = 1.5V, VO = 2.5V, and RL = 1M unless otherwise noted. Boldface limits apply at the temperature extremes; all other limits TJ = 25C. Typical Symbol Parameter Conditions (Note 5) LMC6024I Limit Units (Note 6) VOS Input Offset Voltage 1 VOS/T Input Offset Voltage 2.5 V/C pA 9 11 mV Max Average Drift IB Input Bias Current 0.04 IOS Input Offset Current 0.01 200 Max 100 Max pA >1 RIN Input Resistance CMRR Common Mode 0V VCM 12V Rejection Ratio V+ = 15V +PSRR Positive Power Supply 5V V+ 15V -PSRR Negative Power Supply 0V V- -10V Tera 83 63 dB 61 Min 83 63 dB 61 Min 94 74 dB 73 Min Rejection Ratio Rejection Ratio VCM Input Common-Mode V+ = 5V and 15V Voltage Range For CMRR 50 DB -0.4 V+ - 1.9 -0.1 V 0 Max V+ - 2.3 V + AV Large Signal Voltage Gain RL = 100 k (Note 7) 1000 Sourcing Min 200 V/mV 100 Min Sinking 500 90 V/mV 40 Min RL = 5 k (Note 7) 1000 100 V/mV 75 Min 50 V/mV 20 Min Sourcing Sinking www.national.com V - 2.5 250 2 (Continued) The following specifications apply for V+ = 5V, V- = 0V, VCM = 1.5V, VO = 2.5V, and RL = 1M unless otherwise noted. Boldface limits apply at the temperature extremes; all other limits TJ = 25C. Symbol Parameter Conditions Typical LMC6024I (Note 5) Limit Units (Note 6) VO Output Voltage Swing V+ = 5V 4.987 RL = 100 k to 2.5V 0.004 V+ = 5V 4.940 RL = 5 k to 2.5V 0.040 V+ = 15V 14.970 RL = 100 k to 7.5V 0.007 V+ = 15V 14.840 RL = 5 k to 7.5V 0.110 IO Output Current V+ = 5V 22 Supply Current All Four Amplifiers VO = 1.5V 3 V Max 4.20 V 4.00 Min 0.25 V 0.35 Max 14.00 V 13.90 Min 0.06 V 0.09 Max 13.70 V 13.50 Min 0.32 V 0.40 Max mA 21 13 mA 9 Min 40 23 mA 15 Min 39 23 mA 15 Min 160 240 A 280 Max (Note 12) IS 0.06 0.09 Min Sourcing, VO = 0V Sinking, VO = 13V Min 9 (Note 2) V+ = 15V V 4.43 13 Sourcing, VO = 0V Sinking VO = 5V 4.40 www.national.com LMC6024 DC Electrical Characteristics LMC6024 AC Electrical Characteristics The following specifications apply for V+ = 5V, V- = 0V, VCM = 1.5V, VO = 2.5V, and RL = 1M unless otherwise noted. Boldface limits apply at the temperature extremes; all other limits TJ = 25C. Typical Symbol Parameter Conditions (Note 5) LMC6024I Limit Units (Note 6) SR Slew Rate GBW Gain-Bandwidth Product M Phase Margin GM Gain Margin (Note 8) 0.11 0.05 0.03 V/s Min 0.35 MHz 50 Deg 17 dB Amp-to-Amp Isolation (Note 9) 130 dB en Input-Referred Voltage Noise F = 1 kHz 42 in Input-Referred Current Noise F = 1 kHz 0.0002 Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component 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. Continuous short circuit operation at elevated ambient temperature and/or multiple Op Amp shorts can result in exceeding the maximum allowed junction temperature of 150C. Output currents in excess of 30 mA over long term may adversly affect reliability. Note 3: 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. Note 4: Human body model, 100 pF discharge through a 1.5 k resistor. Note 5: Typical values represent the most likely parametric norm. Note 6: All limits are guaranteed by testing or correlation. 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 k connected to 7.5V. Each amp excited in turn with 1 kHz to produce VO = 13 VPP. Note 10: For operating at elevated temperatures the device must be derated based on the thermal resistance JA with PD = (TJ - TA)/JA. Note 11: All numbers apply for packages soldered directly into a PC board. Note 12: Do not connect output to V+ when V+ is greater than 13V or reliability may be adversely affected. www.national.com 4 LMC6024 Typical Performance Characteristics VS = 7.5V, TA = 25C unless otherwise specified Supply Current vs Supply Voltage Input Bias Current vs Temperature 01123527 01123528 Common-Mode Voltage Range vs Temperature Output Characteristics Current Sinking 01123530 01123529 Output Characteristics Current Sourcing Input Voltage Noise vs Frequency 01123531 01123532 5 www.national.com LMC6024 Typical Performance Characteristics VS = 7.5V, TA = 25C unless otherwise specified Crosstalk Rejection vs Frequency CMRR vs Frequency 01123534 01123533 Power Supply Rejection Ratio vs Frequency CMRR vs Temperature 01123535 01123536 Open-Loop Voltage Gain vs Temperature Open-Loop Frequency Response 01123538 01123537 www.national.com (Continued) 6 Gain and Phase Responses vs Load Capacitance (Continued) Gain and Phase Responses vs Temperature 01123539 01123540 Non-Inverting Slew Rate vs Temperature Gain Error (VOS vs VOUT) 01123542 01123541 Large-Signal Pulse Non-Inverting Response (AV = +1) Inverting Slew Rate vs Temperature 01123543 01123544 7 www.national.com LMC6024 Typical Performance Characteristics VS = 7.5V, TA = 25C unless otherwise specified LMC6024 Typical Performance Characteristics VS = 7.5V, TA = 25C unless otherwise specified Non-Inverting Small Signal Pulse Response (AV = +1) (Continued) Inverting Large-Signal Pulse Response 01123546 01123545 Inverting Small-Signal Pulse Response Stability vs Capacitive Load 01123547 01123504 Note 13: Avoid resistive loads of less than 500, as they may cause instability. Stability vs Capacitive Load 01123505 www.national.com 8 AMPLIFIER TOPOLOGY The topology chosen for the LMC6024 is unconventional (compared to general-purpose op amps) in that the traditional unity-gain buffer output stage is not used; instead, the output is taken directly from the output of the integrator, to allow rail-to-rail output swing. Since the buffer traditionally delivers the power to the load, while maintaining high op amp gain and stability, and must withstand shorts to either rail, these tasks now fall to the integrator. As a result of these demands, the integrator is a compound affair with an embedded gain stage that is doubly fed forward (via Cf and Cff) by a dedicated unity-gain compensation driver. In addition, the output portion of the integrator is a push-pull configuration for delivering heavy loads. While sinking current the whole amplifier path consists of three gain stages with one stage fed forward, whereas while sourcing the path contains four gain stages with two fed forward. 01123507 FIGURE 2. Rx, Cx Improve Capacitive Load Tolerance Capacitive load driving capability is enhanced by using a pull up resistor to V+ Figure 3. Typically a pull up resistor conducting 50 A 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). 01123506 FIGURE 1. LMC6024 Circuit Topology (Each Amplifier) 01123526 The large signal voltage gain while sourcing is comparable to traditional bipolar op amps, for load resistance of at least 5 k. The gain while sinking is higher than most CMOS op amps, due to the additional gain stage; however, when driving load resistance of 5 k or less, the gain will be reduced as indicated in the Electrical Characterisitics. The op amp can drive load resistance as low as 500 without instability. FIGURE 3. Compensating for Large Capacitive Loads with a Pull Up Resistor 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 LMC6024, typically less than 0.04 pA, it is essential to have an excellent layout. Fortunately, the techniques for 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 LMC6024's inputs and the terminals of capacitors, diodes, conductors, resistors, relay terminals, etc. connected to the op-amp's inputs. See 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 1012 ohms, which is normally considered a very large resistance, could leak 5 pA if the trace were a 5V bus adjacent to the pad of an input. COMPENSATING INPUT CAPACITANCE Refer to the LMC660 or LMC662 datasheets to determine whether or not a feedback capacitor will be necessary for compensation and what the value of that capacitor would be. CAPACITIVE LOAD TOLERANCE Like many other op amps, the LMC6024 may oscillate when its applied load appears capacitive. The threshold of oscillation varies both with load and circuit gain. The configuration most sensitive to oscillation is a unity-gain follower. See the Typical Performance Characteristics. The load capacitance interacts with the op amp's output resistance to create an additional pole. If this pole frequency is sufficiently low, it will degrade the op amp's phase margin so that the amplifier is no longer stable at low gains. The addition of a small resistor (50 to 100) in series with the op amp's output, and a capacitor (5 pF to 10 pF) from inverting input to output pins, returns the phase margin to a safe value without interfering with lower-frequency circuit operation. Thus, larger values of capacitance can be toler- 9 www.national.com LMC6024 ated without oscillation. Note that in all cases, the output will ring heavily when the load capcitance is near the threshold for oscillation. Application Hints LMC6024 Application Hints haps a minor (2:1) degradation of the amplifier's performance. See Figure 5a, Figure 5b, Figure 5c for typical connections of guard rings for standard op-amp configurations. If both inputs are active and at high impedance, the guard can be tied to ground and still provide some protection; see Figure 5d. (Continued) This would cause a 100 times degradation from the LMC6024's actual performance. However, if a guard ring is held within 5 mV of the inputs, then even a resistance of 1011 ohms would cause only 0.05 pA of leakage current, or per- 01123508 FIGURE 4. Example of Guard Ring in P.C. Board Layout (Using the LMC6024) 01123511 (c) Follower 01123509 (a) Inverting Amplifier 01123510 01123512 (b) Non-Inverting Amplifier (d) Howland Current Pump FIGURE 5. Guard Ring Connections 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 www.national.com 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. 10 magnitude of I-, the leakage of the capacitor and socket must be taken into account. Switch S2 should be left shorted most of the time, or else the dielectric absorption of the capacitor C2 could cause errors. Similarly, if S1 is shorted momentarily (while leaving S2 shorted) (Continued) where Cx is the stray capacitance at the +input. Typical Single-Supply Applications (V+ = 5.0 VDC) 01123513 Photodiode Current-to-Voltage Converter (Input pins are lifted out of PC board and soldered directly to components. All other pins connected to PC board.) FIGURE 6. Air Wiring BIAS CURRENT TESTING The test method of Figure 7 is appropriate for bench-testing bias current with reasonable accuracy. To understand its operation, first close switch S2 momentarily. When S2 is opened, then 01123515 Note 14: A 5V bias on the photodiode can cut its capacitance by a factor of 2 or 3, leading to improved response and lower noise. However, this bias on the photodiode will cause photodiode leakage (also known as its dark current). Micropower Current Source 01123514 01123516 (Upper limit of output range dictated by input common-mode range; lower limit dictated by minimum current requirement of LM385.) FIGURE 7. Simple Input Bias Current Test Circuit A suitable capacitor for C2 would be a 5 pF or 10 pF silver mica, NPO ceramic, or air-dielectric. When determining the 11 www.national.com LMC6024 Application Hints LMC6024 Typical Single-Supply Applications (V+ = 5.0 VDC) (Continued) Low-Leakage Sample-and-Hold 01123517 Instrumentation Amplifier 01123518 If R1 = R5, R3 = R6, and R4 = R7; Then AV 100 for circuit shown. For good CMRR over temperature, low drift resistors should be used. Matching of R3 to R6 and R4 to R7 affects CMRR. Gain may be adjusted through R2. CMRR may be adjusted through R7. 10 Hz Bandpass Filter 10 Hz High-Pass Filter (2 dB Dip) 01123520 fc = 10 Hz d = 0.895 01123519 fO = 10 Hz Gain = 1 Q = 2.1 Gain = -8.8 www.national.com 12 LMC6024 Typical Single-Supply Applications (V+ = 5.0 VDC) (Continued) 1 Hz Low-Pass Filter (Maximally Flat, Dual Supply Only) 01123521 High Gain Amplifier with Offset Voltage Reduction 01123522 Gain = -46.8 Output offset voltage reduced to the level of the input offset voltage of the bottom amplifier (typically 1 mV), referred to VBIAS. Ordering Information Temperature Range Package NSC Drawing LMC6024IM 14-Pin M14A LMC6024IMX Small Outline Industrial -40C TJ +85C 13 Transport Media Rail Tape and Reel www.national.com LMC6024 Low Power CMOS Quad Operational Amplifier Physical Dimensions inches (millimeters) unless otherwise noted 14-Pin Small Outline Molded Package (M) Order Number LMC6024IM NS Package Number M14A 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. BANNED SUBSTANCE COMPLIANCE National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ``Banned Substances'' as defined in CSP-9-111S2. National Semiconductor Americas Customer Support Center Email: new.feedback@nsc.com Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Francais Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Support Center Email: ap.support@nsc.com National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: jpn.feedback@nsc.com Tel: 81-3-5639-7560 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI's terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI's standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and applications using TI components. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in such safety-critical applications. TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are specifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet military specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated products in automotive applications, TI will not be responsible for any failure to meet such requirements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Applications Audio www.ti.com/audio Communications and Telecom www.ti.com/communications Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps DLP(R) Products www.dlp.com Energy and Lighting www.ti.com/energy DSP dsp.ti.com Industrial www.ti.com/industrial Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical Interface interface.ti.com Security www.ti.com/security Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive Microcontrollers microcontroller.ti.com Video and Imaging RFID www.ti-rfid.com OMAP Mobile Processors www.ti.com/omap Wireless Connectivity www.ti.com/wirelessconnectivity TI E2E Community Home Page www.ti.com/video e2e.ti.com Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright (c) 2011, Texas Instruments Incorporated