LMC6442 Dual Micropower Rail-to-Rail Output Single Supply Operational Amplifier General Description Features 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. (Typical, VS = 2.2V) n Output Swing to within 30 mV of supply rail n High voltage gain 103 dB n Gain Bandwidth Product 9.5 KHz n Guaranteed for: 2.2V, 5V, 10V n Low Supply Current 0.95 µA/Amplifier n Input Voltage Range −0.3V to V+ -0.9V n 2.1 µW/Amplifier Power consumption n Stable for AV ≥+2 or AV ≤ −1 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. 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 10006440 Top View © 2004 National Semiconductor Corporation DS100064 www.national.com LMC6442 Dual Micropower Rail-to-Rail Output Single Supply Operational Amplifier August 2000 LMC6442 Absolute Maximum Ratings (Note 1) Junction Temp. (Note 4) 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) Voltage at Input/Output Pin ± Supply Voltages Range: LMC6442AI, LMC6442I Thermal Resistance (θJA) 16V ± 5 mA ± 30 mA Current at Input Pin (Note 10) Current at Output Pin(Notes 3, 7) Lead Temp. (soldering 10 sec) 260˚C Storage Temp. Range: −40˚C < TJ < +85˚C Junction Temperature (V+) + 0.3V, (V−) − 0.3V Supply Voltage (V+ − V−): 1.8V ≤ VS ≤ 11V Supply Voltage 2 kV Differential Input Voltage 150˚C −65˚C to +150˚C M Package, 8-pin Surface Mount 193˚C/W MSOP Package 235˚C/W N Package, 8-pin Molded DIP 115˚C/W 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 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) Common Mode Rejection Ratio −0.1V ≤ VCM ≤0.5V IOS CMRR CIN Common Mode Input Capacitance PSRR Power Supply Rejection Ratio VCM Input Common-Mode Voltage Range AV VO ISC IS 0.4 µV/˚C 0.005 4 4 pA max 0.0025 2 2 pA max 92 67 67 67 67 4.7 VS = 2.5 V to 10V CMRR ≥ 50 dB dB min pF 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 Large Signal Voltage Gain Sourcing (Note 11) 100 Sinking(Note 11) 94 VO = 0.22V to 2V 103 80 80 Output Swing VID = 100 mV (Note 13) 2.18 2.15 2.15 2.15 2.15 V min mV max Output Short Circuit Current Supply Current (2 amplifiers) VID = −100 mV (Note 13) 22 60 60 60 60 Sourcing, VID = 100 mV (Notes 12, 13) 50 18 17 18 17 Sinking, VID = −100 mV (Notes 12, 13) 50 20 19 20 19 1.90 2.4 3.0 2.6 3.2 RL = open + V = 1.8V, RL = open 2.10 dB min µA min µA max AC Electrical Characteristics SR Slew Rate (Note 8) www.national.com 2.2 2 V/ms (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 GBWP Gain-Bandwidth Product φm Phase Margin Typ (Note 5) Conditions (Note 15) LMC6442AI Limit (Note 6) LMC6442I Limit (Note 6) Units 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) Common Mode Rejection Ratio −0.1V ≤ VCM ≤3.5V IOS CMRR CIN Common Mode Input Capacitance PSRR Power Supply Rejection Ratio VCM Input Common-Mode Voltage Range 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 dB min 4.1 VS = 2.5 V to 10V CMRR ≥ 50 dB pF 95 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 Sourcing (Note 11) 100 Sinking (Note 11) 94 dB min VO = 0.5V to 4.5V 103 80 80 VID = 100 mV (Note 13) 4.99 4.95 4.95 4.95 4.95 V min VID = −100 mV (Note 13) 20 50 50 50 50 mV max Sourcing, VID = 100 mV (Notes 12, 13) 500 300 200 300 200 Sinking, VID = −100 mV (Notes 12, 13) 350 200 150 200 150 RL = open 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 (Note 15) 3 www.national.com LMC6442 2.2V Electrical Characteristics LMC6442 5V 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 to V+/2. Boldface limits apply at the temperature extremes. Symbol Parameter THD Total Harmonic Distortion Typ (Note 5) Conditions AV = +2, f = 100 Hz, RL = 10MΩ, VOUT = 1 Vpp LMC6442AI Limit (Note 6) LMC6442I Limit (Note 6) 0.08 Units % 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) Common Mode Rejection Ratio −0.1V ≤ VCM ≤8.5V IOS CMRR CIN Common Mode Input Capacitance PSRR Power Supply Rejection Ratio VCM Input Common-Mode Voltage Range AV VO ISC IS 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 Large Signal Voltage Gain Sourcing (Note 11) 120 Sinking (Note 11) 100 VO = 0.5V to 9.5V 104 80 80 Output Swing VID = 100 mV (Note 13) 9.99 9.97 9.97 9.97 9.97 V min VID = −100 mV(Note 13) 22 50 50 50 50 mV max Sourcing, VID = 100 mV (Notes 12, 13) 2100 1200 1000 1200 1000 Sinking, VID = −100 mV (Notes 12, 13) 900 600 500 600 500 RL = open 1.90 2.4 3.0 2.6 3.2 µA max 2.5 2.5 V/ms Output Short Circuit Current Supply Current (2 amplifiers) dB min µA min AC Electrical Characteristics SR Slew Rate(Note 8) 4.1 GBWP Gain-Bandwidth Product 10.5 KHz φm Phase Margin (Note 15) 68 Degree en Input-Referred Voltage Noise RL = open f = 10 Hz 170 nV/√Hz www.national.com 4 (Continued) 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 in Parameter Typ (Note 5) Conditions Input-Referred Current Noise RL = open f = 10 Hz Crosstalk Rejection (Note 9) LMC6442AI Limit (Note 6) LMC6442I Limit (Note 6) Units 0.0002 pA/√Hz 85 dB 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 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 10006408 10006409 5 www.national.com LMC6442 10V Electrical Characteristics LMC6442 Typical Performance Characteristics VS = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Total Supply Current vs Supply Voltage (Positive Input Overdrive) Input Bias Current vs Temperature 10006410 10006441 Offset Voltage vs Common Mode Voltage (VS = 5V) Offset Voltage vs Common Mode Voltage (VS = 2.2V) 10006406 10006407 Offset Voltage vs Common Mode Voltage (VS = 10V) Swing Towards V− vs Supply Voltage 10006403 10006442 www.national.com 6 LMC6442 Typical Performance Characteristics VS = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Swing Towards V+ vs Supply Voltage Swing From Rail(s) vs Temperature 10006402 10006401 Output Source Current vs Output Voltage Output Sink Current vs Output Voltage 10006449 10006448 Maximum Output Voltage vs Load Resistance Large Signal Voltage Gain vs Supply Voltage 10006452 10006424 7 www.national.com LMC6442 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 10006426 10006419 Open Loop Gain/Phase vs Frequency For Various CL (ZL = 100 KΩ II CL) Gain Bandwidth Product vs Supply Voltage 10006421 10006425 Phase Margin (Worst Case) vs Supply Voltage CMRR vs Frequency 10006423 www.national.com 10006434 8 LMC6442 Typical Performance Characteristics VS = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Positive Slew Rate vs Supply Voltage PSRR vs Frequency 10006412 10006415 Negative Slew Rate vs Supply Voltage Cross-Talk Rejection vs Frequency 10006411 10006418 Input Voltage Noise vs Frequency Output Impedance vs Frequency 10006433 10006416 9 www.national.com LMC6442 Typical Performance Characteristics VS = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) THD+N vs Frequency THD+N vs Amplitude 10006428 10006427 Small Signal Step Response (AV=+2) (CL=12 pF, 100 pF) Maximum Output Swing vs Frequency 10006429 10006453 Small Signal Step Response (AV = − 1) (CL=1MΩ II 100 pF, 200 pF) Large Signal Step Response (AV=+2) (CL=100 pF) 10006430 www.national.com 10006451 10 LMC6442 Typical Performance Characteristics VS = 5V, Single Supply, TA = 25˚C unless otherwise specified (Continued) Small Signal Step Response (AV = + 1) For Various CL Large Signal Step Response (AV = +1) (CL= 200pF) 10006431 10006432 Closed loop gain, AV is given by: Applications Information 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: 10006436 FIGURE 2. “T” Network Used to Replace High Value Resistor 10006435 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: 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. 11 www.national.com LMC6442 Applications Information 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. (Continued) 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. 10006422 FIGURE 3. “T” Network Values for Various Values of R For convenience, Fig. 3 shows R1 vs RF for different values of R. 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. 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−. 10006447 FIGURE 4. Minimum Operating Gain vs Capactive Load 10006443 FIGURE 5. Isolating Resistor Value vs Capactive Load www.national.com 12 LMC6442 Application Circuits Micropower Single Supply Voltage to Frequency Converter 10006445 V + = 5V: IS < 10µA, f/VC = 4.3 (Hz/V) 10006446 Gain Stage with Current Boosting 10006454 13 www.national.com LMC6442 Application Circuits (Continued) Offset Nulling Schemes 10006444 Ordering Information Temperature Range Package 8-pin SO-8 MSOP 8-pin DIP 8-pin CDIP 10-pin SO www.national.com Industrial −40˚C to +85˚C Military −55˚C to +125˚C NSC Drawing Supplied AS Package Marking LMC6442AIM, LMC6442IM - M08A Rails LMC6442AIMX, LMC6442IMX - M08A LMC6442AIM 2.5K Tape and LMC6442IM Reel LMC6442AIMM, LMC6442AIMMX, LMC6442IMM, LMC6442IMMX - MUA08A Rails 3K Tape and Reel A08A LMC6442AIMMX, LMC6442IMMX - MUA08A LMC6442AIN, LMC6442IN - N08E - Rails LMC6442AIN, LMC6442IN 5962-9761301QPA J08A Rails LMC6442AMJ-QML 5962-976130IQPA 5962-9761301QXA WG10A Trays LMC6442AMWG-Q 9761301QXA 14 LMC6442 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 LMC6442INX NS Package Number N08E 15 www.national.com LMC6442 Dual Micropower Rail-to-Rail Output Single Supply Operational Amplifier Physical Dimensions 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 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: [email protected] Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Support Center Email: [email protected] National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: [email protected] Tel: 81-3-5639-7560