LMC6442 Dual Micropower Rail-to-Rail Output Single Supply Operational Amplifier General Description Key Specifications The LMC6442 is ideal for battery powered systems, where very low supply current (less than one microamp per amplifier) and Rail-to-Rail output swing is required. It is characterized for 2.2V to 10V operation, and at 2.2V supply, the LMC6442 is ideal for single (Li-Ion) or two cell (NiCad or alkaline) battery systems. The LMC6442 is designed for battery powered systems that require long service life through low supply current, such as smoke and gas detectors, and pager or personal communications systems. Operation from single supply is enhanced by the wide common mode input voltage range which includes the ground (or negative supply) for ground sensing applications. Very low (5fA, typical) input bias current and near constant supply current over supply voltage enhance the LMC6442’s performance near the end-of-life battery voltage. Designed for closed loop gains of greater than plus two (or minus one), the amplifier has typically 9.5 KHz GBWP (Gain Bandwidth Product). Unity gain can be used with a simple compensation circuit, which also allows capacitive loads of up to 300 pF to be driven, as described in the Application Notes section. For compact assembly the LMC6442 is available in the MSOP 8 pin package, about one half the size required by the SOIC 8 pin package. 8 pin DIP and 8 pin SOIC are also available. Features (Typical, VS = 2.2V) n Output Swing to within 30 mV of supply rail n High voltage gain n Gain Bandwidth Product n Guaranteed for: n Low Supply Current 0.95 µA/Amplifier n Input Voltage Range −0.3V to V+ -0.9V n Power consumption 2.1 µW/Amplifier n Stable for AV ≥+2 or AV ≤ −1 103 dB 9.5 KHz 2.2V, 5V, 10V Applications n n n n n n n n Portable instruments Smoke/gas/CO/fire detectors Pagers/cell phones Instrumentation Thermostats Occupancy sensors Cameras Active badges Connection Diagram DS100064-40 Top View Ordering Information Package 8-pin SO-8 Temperature Range Industrial −40˚C to +85˚C Military −55˚C to +125˚C NSC Supplied Drawing AS LMC6442AIM, LMC6442IM - M08A Rails LMC6442AIMX, LMC6442IMX - M08A 2.5K Tape and Reel © 1999 National Semiconductor Corporation DS100064 Package Marking LMC6442AIM LMC6442IM www.national.com LMC6442 Dual Micropower Rail-to-Rail Output Single Supply Operational Amplifier September 1997 Ordering Information Package MSOP 8-pin DIP 8-pin CDIP 10-pin SO www.national.com (Continued) Temperature Range NSC Supplied Drawing AS Package Marking Industrial −40˚C to +85˚C Military −55˚C to +125˚C LMC6442AIMM, LMC6442IMM - MUA08A Rails LMC6442AIMMX, LMC6442IMMX - MUA08A 3K Tape A08A and Reel LMC6442AIN, LMC6442IN - N08E - Rails LMC6442AIN, LMC6442IN 5962-9761301QPA J08A Rails LMC6442AMJ-QML 5962-976130IQPA 5962-9761301QXA WG10A Trays LMC6442AMWG-Q 9761301QXA 2 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Operating Ratings(Note 1) ESD Tolerance (Note 2) Junction Temperature ± Supply Voltages Differential Input Voltage Voltage at Input/Output Pin ± 5 mA ± 30 mA Current at Output Pin(Notes 3, 7) Lead Temp. (soldering 10 sec) Storage Temp. Range: Thermal Resistance (θJA) 16V Current at Input Pin (Note 10) 260˚C −65˚C to +150˚C Junction Temp. (Note 4) −40˚C < TJ < +85˚C Range: LMC6442AI, LMC6442I (V+) + 0.3V, (V−) − 0.3V Supply Voltage (V+ − V−): 1.8V ≤ VS ≤ 11V Supply Voltage 2 kV M Package, 8-pin Surface Mount 193˚C/W MSOP Package 235˚C/W N Package, 8-pin Molded DIP 115˚C/W 150˚C 2.2V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 2.2V, V− = 0V, VCM = VO = V +/2, and RL = 1 MΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Typ (Note 5) LMC6442AI LMC6442I Limit Limit (Note 6) (Note 6) Units DC Electrical Characteristics VOS Input Offset Voltage TCVOS Temp. coefficient of input offset voltage IB Input Bias Current (Note 14) Input Offset Current (Note 14) CMRR Common Mode Rejection Ratio −0.1V ≤ VCM ≤0.5V CIN Common Mode Input Capacitance PSRR Power Supply Rejection Ratio VCM Input Common-Mode Voltage Range IOS AV VO ISC IS Large Signal Voltage Gain Output Swing Output Short Circuit Current Supply Current (2 amplifiers) −0.75 ±3 ±4 ±7 ±8 mV max 0.4 µV/˚C 0.005 4 4 pA max 0.0025 2 2 pA max 92 67 67 67 67 dB min 4.7 VS = 2.5 V to 10V CMRR ≥ 50 dB 95 75 75 75 75 dB min 1.3 1.05 0.95 1.05 0.95 V min −0.2 0 −0.2 0 V max −0.3 Sourcing (Note 11) 100 Sinking(Note 11) VO = 0.22V to 2V 94 VID = 100 mV (Note 13) pF dB min 103 80 80 2.18 2.15 2.15 2.15 2.15 V min mV max VID = −100 mV (Note 13) 22 60 60 60 60 Sourcing, VID = 100 mV (Notes 12, 13) Sinking, VID = −100 mV (Notes 12, 13) RL = open 50 18 17 18 17 50 20 19 20 19 1.90 2.4 3.0 2.6 3.2 V+ = 1.8V, RL = open 2.10 µA min µA max AC Electrical Characteristics SR Slew Rate (Note 8) 2.2 3 V/ms www.national.com 2.2V Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 2.2V, V− = 0V, VCM = VO = V +/2, and RL = 1 MΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Typ (Note 5) LMC6442AI LMC6442I Limit Limit (Note 6) (Note 6) Units AC Electrical Characteristics GBWP Gain-Bandwidth Product φm Phase Margin (Note 15) 9.5 KHz 63 Degree 5V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V +/2, and RL = 1 MΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Typ (Note 5) LMC6442AI Limit (Note 6) LMC6442I Limit (Note 6) Units −0.75 ±3 ±4 ±7 ±8 mV max DC Electrical Characteristics VOS Input Offset Voltage TCVOS Temp. coefficient of input offset voltage IB Input Bias Current (Note 14) Input Offset Current (Note 14) CMRR Common Mode Rejection Ratio −0.1V ≤ VCM ≤3.5V CIN Common Mode Input Capacitance PSRR Power Supply Rejection Ratio VCM Input Common-Mode Voltage Range IOS AV VO ISC IS Large Signal Voltage Gain Output Swing Output Short Circuit Current Supply Current (2 amplifiers) 0.4 µV/˚C 0.005 4 4 pA max 0.0025 2 2 pA max 102 70 70 70 70 4.1 VS = 2.5 V to 10V CMRR ≥ 50 dB 75 75 75 75 dB min 4.1 3.85 3.75 3.85 3.75 V min −0.2 0 −0.2 0 V max −0.4 100 Sinking (Note 11) VO = 0.5V to 4.5V 94 100 mV 13) −100 mV 13) Sourcing, VID = 100 mV (Notes 12, 13) Sinking, VID = −100 mV (Notes 12, 13) RL = open pF 95 Sourcing (Note 11) VID = (Note VID = (Note dB min dB min 103 80 80 4.99 4.95 4.95 4.95 4.95 V min 20 50 50 50 50 mV max 500 300 200 300 200 350 200 150 200 150 1.90 2.4 3.0 2.6 3.2 µA max 2.5 2.5 V/ms µA min AC Electrical Characteristics SR Slew Rate (Note 8) 4.1 GBWP Gain-Bandwidth Product 10 KHz φm Phase Margin 64 Degree THD Total Harmonic Distortion 0.08 % www.national.com (Note 15) AV = +2, f = 100 Hz, RL = 10MΩ, VOUT = 1 Vpp 4 10V Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 10V, V− = 0V, VCM = VO = V +/2, and RL = 1 MΩ to V+/2. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Typ (Note 5) LMC6442AI Limit (Note 6) LMC6442I Limit (Note 6) Units −1.5 ±3 ±4 ±7 ±8 mV max DC Electrical Characteristics VOS Input Offset Voltage TCVOS Temp. coefficient of input offset voltage IB Input Bias Current (Note 14) Input Offset Current (Note 14) CMRR Common Mode Rejection Ratio −0.1V ≤ VCM ≤8.5V CIN Common Mode Input Capacitance PSRR Power Supply Rejection Ratio VCM Input Common-Mode Voltage Range IOS AV VO ISC IS Large Signal Voltage Gain Output Swing Output Short Circuit Current Supply Current (2 amplifiers) 0.4 µV/˚C 0.005 4 4 pA max 0.0025 2 2 pA max 105 70 70 70 70 dB min 3.5 VS = 2.5 V to 10V CMRR ≥ 50 dB pF 95 75 75 75 75 dB min 9.1 8.85 8.75 8.85 8.75 V min −0.2 0 −0.2 0 V max −0.4 Sourcing (Note 11) 120 Sinking (Note 11) VO = 0.5V to 9.5V 100 dB min 104 80 80 VID = 100 mV (Note 13) VID = −100 mV(Note 13) 9.99 9.97 9.97 9.97 9.97 V min 22 50 50 50 50 mV max Sourcing, VID = 100 mV (Notes 12, 13) Sinking, VID = −100 mV (Notes 12, 13) RL = open 2100 1200 1000 1200 1000 900 600 500 600 500 1.90 2.4 3.0 2.6 3.2 µA max 2.5 2.5 V/ms µA min AC Electrical Characteristics SR Slew Rate(Note 8) 4.1 GBWP Gain-Bandwidth Product 10.5 KHz φm Phase Margin 68 Degree en Input-Referred Voltage Noise 170 nV/√Hz in Input-Referred Current Noise 0.0002 pA/√Hz 85 dB Crosstalk Rejection (Note 15) RL = open f = 10 Hz RL = open f = 10 Hz (Note 9) 5 www.national.com Electrical Characteristics (continued) 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 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 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 unless otherwise specified. Note 7: Do not short circuit output to V+,when V+ is greater than 13V or reliability will be adversely affected. Note 8: Slew rate is the slower of the rising and falling slew rates. Note 9: Input referred, V+ = 10V and RL = 10 MΩ connected to 5V. Each amp excited in turn with 1 KHz to produce about 10 Vpp output. Note 10: Limiting input pin current is only necessary for input voltages that exceed absolute maximum input voltage ratings. Note 11: RL connected to V+/2. For Sourcing Test, VO > V+/2. For Sinking tests, VO < V+/2. Note 12: Output shorted to ground for sourcing, and shorted to V+ for sinking short circuit current test. Note 13: VID is differential input voltage referenced to inverting input. Note 14: Limits guaranteed by design. Note 15: See the Typical Performance Characteristics and Application Notes sections for more details. Typical Performance Characteristics Total Supply Current vs Supply Voltage VS = 5V, Single Supply, TA = 25˚C unless otherwise specified Total Supply Current vs Supply Voltage (Negative Input Overdrive) Total Supply Current vs Supply Voltage (Positive Input Overdrive) DS100064-8 DS100064-9 Input Bias Current vs Temperature Offset Voltage vs Common Mode Voltage (VS = 2.2V) DS100064-10 Offset Voltage vs Common Mode Voltage (VS = 5V) DS100064-41 DS100064-6 www.national.com 6 DS100064-7 Typical Performance Characteristics VS = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Offset Voltage vs Common Mode Voltage (VS = 10V) Swing Towards V− vs Supply Voltage Swing Towards V+ vs Supply Voltage DS100064-3 DS100064-2 DS100064-42 Swing From Rail(s) vs Temperature Output Source Current vs Output Voltage Output Sink Current vs Output Voltage DS100064-49 DS100064-48 DS100064-1 Maximum Output Voltage vs Load Resistance Large Signal Voltage Gain vs Supply Voltage Open Loop Gain/Phase vs Frequency DS100064-52 DS100064-24 DS100064-19 7 www.national.com Typical Performance Characteristics VS = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Open Loop Gain/Phase vs Frequency For Various CL (ZL = 1 MΩ II CL) Open Loop Gain/Phase vs Frequency For Various CL (ZL = 100 KΩ II CL) Gain Bandwidth Product vs Supply Voltage DS100064-21 DS100064-26 Phase Margin (Worst Case) vs Supply Voltage DS100064-25 PSRR vs Frequency CMRR vs Frequency DS100064-15 DS100064-34 DS100064-23 Positive Slew Rate vs Supply Voltage Negative Slew Rate vs Supply Voltage DS100064-12 www.national.com Cross-Talk Rejection vs Frequency DS100064-11 8 DS100064-18 Typical Performance Characteristics VS = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Input Voltage Noise vs Frequency Output Impedance vs Frequency THD+N vs Frequency DS100064-28 DS100064-16 THD+N vs Amplitude DS100064-33 Maximum Output Swing vs Frequency Small Signal Step Response (AV = +2) (CL = 12 pF, 100 pF) DS100064-27 DS100064-29 DS100064-53 Large Signal Step Response (AV = +2) (CL = 100 pF) Small Signal Step Response (AV = − 1) (CL = 1MΩ II 100 pF, 200 pF) Small Signal Step Response (AV = + 1) For Various CL DS100064-30 DS100064-51 9 DS100064-31 www.national.com Typical Performance Characteristics VS = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Large Signal Step Response (AV = +1) (CL = 200pF) DS100064-32 Application Notes Using LMC6442 in unity gain applications: LMC6442 is optimized for maximum bandwidth and minimal external components when operating at a minimum closed loop gain of +2 (or −1). However, it is also possible to operate the device in a unity gain configuration by adding external compensation as shown in Figure 1: DS100064-36 FIGURE 2. “T” Network Used to Replace High Value Resistor It must be noted, however, that using this scheme, the realizable bandwidth would be less than the theoretical maximum. With feedback factor, β, defined as: DS100064-35 FIGURE 1. AV = +1 Operation by adding Cc and Rc Using this compensation technique it is possible to drive capacitive loads of up to 300 pF without causing oscillations (see the Typical Performance Characteristics for step response plots). This compensation can also be used with other gain settings in order to improve stability, especially when driving capacitive loads (for optimum performance, Rc and Cc may need to be adjusted). BW(−3 dB) ≈ GBWP • β In this case, assuming a GBWP of about 10 KHz, the expected BW would be around 50 Hz (vs 100 Hz with the conventional inverting amplifier). Looking at the problem from a different view, with RF defined by AV • Rin, one could select a value for R in the “T” Network and then determine R1 based on this selection: Using “T” Network: Compromises need to be made whenever high gain inverting stages need to achieve a high input impedance as well. This is especially important in low current applications which tend to deal with high resistance values. Using a traditional inverting amplifier, gain is inversely proportional to the resistor value tied between the inverting terminal and input while the input impedance is equal to this value. For example, in order to build an inverting amplifier with an input impedance of 10MΩ and a gain of 100, one needs to come up with a feedback resistor of 1000MΩ -an expensive task. An alternate solution is to use a “T” Network in the feedback path, as shown in Fig. 2. Closed loop gain, AV is given by: DS100064-22 FIGURE 3. “T” Network Values for Various Values of R www.national.com 10 Application Notes Referring to the Typical Performance Characteristics plot of Phase Margin (Worst Case) vs Supply Voltage, note that Phase Margin increases as the equivalent output load resistance is lowered. This plot shows the expected Phase Margin when the device output is very close to V−, which is the least stable condition of operation. Comparing this Phase Margin value to the one read off the Open Loop Gain/Phase vs Frequency plot, one can predict the improvement in Phase Margin if the output does not swing close to V−. This dependence of Phase Margin on output voltage is minimized as long as the output load, RL, is about 1MΩ or less. Output Phase Reversal: The LMC6442 is immune against this behavior even when the input voltages exceed the common mode voltage range. Output Time Delay: Due to the ultra low power consumption of the device, there could be as long as 2.5 ms of time delay from when power is applied to when the device output reaches its final value. (Continued) For convenience, Fig. 3 shows R1 vs RF for different values of R. Design Considerations for Capacitive Loads: As with many other opamps, the LMC6442 is more stable at higher closed loop gains when driving a capacitive load. Figure 4 shows minimum closed loop gain versus load capacitance, to achieve less than 10% overshoot in the output small signal response. In addition, the LMC6442 is more stable when it provides more output current to the load and when its output voltage does not swing close to V−. The LMC6442 is more tolerant to capacitive loads when the equivalent output load resistance is lowered or when output voltage is 1V or greater from the V− supply. The capacitive load drive capability is also improved by adding an isolating resistor in series with the load and the output of the device. Figure 5 shows the value of this resistor for various capacitive loads (AV = −1), while limiting the output to less than 10 % overshoot. DS100064-47 FIGURE 4. Minimum Operating Gain vs Capactive Load DS100064-43 FIGURE 5. Isolating Resistor Value vs Capactive Load 11 www.national.com Application Circuits Micropower Single Supply Voltage to Frequency Converter DS100064-45 V + = 5V: IS < 10µA, f/VC = 4.3 (Hz/V) DS100064-46 www.national.com 12 Application Circuits (Continued) Gain Stage with Current Boosting DS100064-54 Offset Nulling Schemes DS100064-44 13 www.national.com Physical Dimensions inches (millimeters) unless otherwise noted 8-Lead (0.150″ Wide) Molded Small Outline Package, JEDEC Order Number LMC6442AIM or LMC6442IM or LMC6442AIMX or LMC6442IMX NS Package Number M08A 8-Lead (0.300″ Wide) Molded Dual-In-Line Package Order Number LMC6442AIN or LMC6442IN or LMC6442AINX or LMC6442INX NS Package Number N08E www.national.com 14 inches (millimeters) unless otherwise noted (Continued) 8-Lead (0.118″ Wide) Molded Mini Small Outline Package Order Number LMC6442AIMM or LMC6442IMM or LMC6442AIMMX or LMC6442IMMX NS Package Number MUA08A 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: 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. National Semiconductor Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: [email protected] www.national.com National Semiconductor Europe Fax: +49 (0) 1 80-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 1 80-530 85 85 English Tel: +49 (0) 1 80-532 78 32 Français Tel: +49 (0) 1 80-532 93 58 Italiano Tel: +49 (0) 1 80-534 16 80 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. National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: [email protected] National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 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. LMC6442 Dual Micropower Rail-to-Rail Output Single Supply Operational Amplifier Physical Dimensions