LMV771/LMV772/LMV774 Single/Dual/Quad, Low Offset, Low Noise, RRO Operational Amplifiers General Description Features The LMV771/LMV772/LMV774 are Single, Dual, and Quad low noise precision operational amplifiers intended for use in a wide range of applications. Other important characteristics of the family include extended operating temperature range, −40˚C to 125˚C, tiny SC70-5 package for LMV771, and low input bias current. (Typical 2.7V Supply Values; Unless Otherwise Noted) n Guaranteed 2.7V and 5V specifications n Maximum VOS (LMV771) 850µV (limit) n Voltage Noise — f = 100Hz 12.5nV/ — f = 10kHz 7.5nV/ n Rail-to-Rail output swing — w/600Ω load 100mV from rail — w/2kΩ load 50mV from rail n Open loop gain w/2kΩ load 100dB n VCM 0 to V+ -0.9V n Supply current (per amplifier) 550µA n Gain bandwidth product 3.5MHz n Temperature range −40˚C to 125˚C The extended temperature range of −40˚C to 125˚C allows the LMV771/LMV772/LMV774 to accommodate a broad range of applications. LMV771 expands National Semiconductor’s Silicon Dust™ amplifier portfolio offering enhancements in size, speed, and power savings. The LMV771/ LMV772/LMV774 are guaranteed to operate over the voltage range of 2.7V to 5.0V and all have rail-to-rail output. The LMV771/LMV772/LMV774 family is designed for precision, low noise, low voltage, and miniature systems. These amplifiers provide rail-to-rail output swing into heavy loads. The maximum input offset voltage for LMV771 is 850 µV at room temperature and the input common mode voltage range includes ground. The LMV771 is offered in the tiny SC70-5 package, LMV772 in space saving MSOP-8 and SOIC-8, and the LMV774 in TSSOP-14. Connection Diagram Applications n n n n n n n Transducer amplifier Instrumentation amplifier Precision current sensing Data acquisition systems Active filters and buffers Sample and hold Portable/battery powered electronics Instrumentation Amplifier SC70-5 20039667 Top View © 2003 National Semiconductor Corporation 20039636 DS200396 www.national.com LMV771/LMV772/LMV774 Single/Dual/Quad, Low Offset, Low Noise, RRO Operational Amplifiers November 2003 LMV771/LMV772/LMV774 Absolute Maximum Ratings Storage Temperature Range (Note 1) Junction Temperature (Note 5) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage 200V Human Body Model + Supply Voltage (V –V ) −40˚C to 125˚C Thermal Resistance (θJA) ± Supply Voltage − 2.7V to 5.5V Temperature Range 2000V Differential Input Voltage 150˚C Operating Ratings (Note 1) ESD Tolerance (Note 2) Machine Model −65˚C to 150˚C SC70-5 Package 5.5V 440 ˚C/W Output Short Circuit to V+ (Note 3) 8-Pin MSOP Output Short Circuit to V− (Note 4) 8-Pin SOIC 190˚C/W 14-Pin TSSOP 155˚C/W Mounting Temperture Infrared or Convection (20 sec) 235˚C Wave Soldering Lead Temp (10 sec) 260˚C 235˚C/W 2.7V DC Electrical Characteristics (Note 13) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol VOS Parameter Input Offset Voltage Condition − = 0V, VCM = V+/2, VO = V+/2 and Min (Note 7) Typ (Note 6) Max (Note 7) LMV771 0.3 0.85 1.0 LMV772/LMV774 0.3 1.0 1.2 mV TCVOS Input Offset Voltage Average Drift IB Input Bias Current (Note 8) −0.1 100 pA IOS Input Offset Current (Note 8) 0.004 100 pA IS Supply Current (Per Amplifier) 550 900 910 µA CMRR Common Mode Rejection Ratio 0.5 ≤ VCM ≤ 1.2V 74 72 80 PSSR Power Supply Rejection Ratio 2.7V ≤ V+ ≤ 5V 82 76 90 VCM Input Common-Mode Voltage Range For CMRR ≥ 50dB 0 AV Large Signal Voltage Gain (Note 9) RL = 600Ω to 1.35V, VO = 0.2V to 2.5V, (Note 10) 92 80 100 RL = 2kΩ to 1.35V, VO = 0.2V to 2.5V, (Note 11) 98 86 100 RL = 600Ω to 1.35V VIN = ± 100mV, (Note 10) 0.11 0.14 0.084 to 2.62 2.59 2.56 RL = 2kΩ to 1.35V VIN = ± 100mV, (Note 11) 0.05 0.06 0.026 to 2.68 2.65 2.64 Sourcing, VO = 0V VIN = 100mV 18 11 24 Sinking, VO = 2.7V VIN = −100mV 18 11 22 VO IO Output Swing Output Short Circuit Current www.national.com −0.45 Units 2 µV/˚C dB dB 1.8 V dB V mA (Note 13) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5.0V, V Boldface limits apply at the temperature extremes. Symbol Parameter − Conditions = 0V, VCM = V+/2, VO = V+/2 and RL > 1MΩ. Min (Note 7) (Note 12) Typ (Note 6) Max (Note 7) Units SR Slew Rate 1.4 V/µs GBW Gain-Bandwidth Product 3.5 MHz Φm Phase Margin 79 Deg Gm Gain Margin en Input-Referred Voltage Noise (Flatband) f = 10kHz 7.5 nV/ en Input-Referred Voltage Noise (l/f) f = 100Hz 12.5 nV/ in Input-Referred Current Noise f = 1kHz 0.001 pA/ THD Total Harmonic Distortion f = 1kHz, AV = +1 RL = 600Ω, VIN = 1 VPP 0.007 −15 dB % 5.0V DC Electrical Characteristics (Note 13) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5.0V, V RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol VOS Parameter Input Offset Voltage Condition − = 0V, VCM = V+/2, VO = V+/2 and Min (Note 7) Typ (Note 6) Max (Note 7) LMV771 0.25 0.85 1.0 LMV772/LMV774 0.25 1.0 1.2 Units mV TCVOS Input Offset Voltage Average Drift −0.35 IB Input Bias Current (Note 8) −0.23 100 pA IOS Input Offset Current (Note 8) 0.017 100 pA IS Supply Current (Per Amplifier) 600 950 960 µA CMRR Common Mode Rejection Ratio 0.5 ≤ VCM ≤ 3.5V 80 79 90 PSRR Power Supply Rejection Ratio 2.7V ≤ V+ ≤ 5V 82 76 90 VCM Input Common-Mode Voltage Range For CMRR ≥ 50dB 0 AV Large Signal Voltage Gain (Note 9) RL = 600Ω to 2.5V, VO = 0.2V to 4.8V, (Note 10) 92 89 100 RL = 2kΩ to 2.5V, VO = 0.2V to 4.8V, (Note 11) 98 95 100 RL = 600Ω to 2.5V VIN = ± 100mV, (Note 10) 0.15 0.23 0.112 to 4.9 4.85 4.77 RL = 2kΩ to 2.5V VIN = ± 100mV, (Note 11) 0.06 0.07 0.035 to 4.97 4.94 4.93 Sourcing, VO = 0V VIN = 100mV 35 35 75 Sinking, VO = 2.7V VIN = −100mV 35 35 66 VO IO Output Swing Output Short Circuit Current (Note 8),(Note 14) 3 µV/˚C dB dB 4.1 V dB V mA www.national.com LMV771/LMV772/LMV774 2.7V AC Electrical Characteristics LMV771/LMV772/LMV774 5.0V AC Electrical Characteristics (Note 13) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5.0V, V Boldface limits apply at the temperature extremes. Symbol Parameter Conditions (Note 12) − = 0V, VCM = V+/2, VO = V+/2 and RL > 1MΩ. Min (Note 7) Typ (Note 6) Max (Note 7) Units SR Slew Rate 1.4 V/µs GBW Gain-Bandwidth Product 3.5 MHz Φm Phase Margin 79 Deg Gm Gain Margin en Input-Referred Voltage Noise (Flatband) f = 10kHz 6.5 nV/ en Input-Referred Voltage Noise (l/f) f = 100Hz 12 nV/ pA/ −15 in Input-Referred Current Noise f = 1kHz 0.001 THD Total Harmonic Distortion f = 1kHz, AV = +1 RL = 600Ω, VIN = 1 VPP 0.007 dB % 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, 1.5kΩ in series with 100pF. Machine model, 0Ω in series with 20pF. Note 3: Shorting output to V+ will adversely affect reliability. Note 4: Shorting output to V− will adversely affect reliability. Note 5: 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)–T A)/θJA. All numbers apply for packages soldered directly into a PC board. Note 6: Typical Values represent the most likely parametric norm. Note 7: All limits are guaranteed by testing or statistical analysis. Note 8: Limits guaranteed by design. Note 9: RL is connected to mid-supply. The output voltage is set at 200mV from the rails. VO = GND + 0.2V and VO = V+ −0.2V Note 10: For LMV772/LMV774, temperature limits apply to −40˚C to 85˚C. Note 11: For LMV772/LMV774, temperature limits apply to −40˚C to 85˚C. If RL is relaxed to 10kΩ, then for LMV772/LMV774 temperature limits apply to −40˚C to 125˚C. Note 12: Connected as voltage follower with 2VPP step input. Number specified is the slower of positive and negative slew rates. Note 13: Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of the device such that TJ = TA . No guarantee of parametric performance is indicated in the electrical tables under the conditions of internal self-heating where TJ > TA. Absolute Maximum Rating indicated junction temperature limits beyond which the device may be permanently degraded, either mechanically or electrically. Note 14: Continuous operation of the device with an output short circuit current larger than 35mA may cause permanent damage to the device. www.national.com 4 Package Part Number LMV771MG SC70-5 LMV771MGX LMV772MA 8-Pin SOIC LMV772MAX LMV772MM 8-Pin MSOP LMV772MMX LMV774MT 14-Pin TSSOP LMV774MTX Package Marking A75 LMV772MA A91A LMV774MT Transport Media NSC Drawing 1k Units Tape and Reel 3k Units Tape and Reel 95 Units/Rail 2.5k Units Tape and Reel 1k Units Tape and Reel 3.5k Units Tape and Reel 95 Units/Rail 2.5k Units Tape and Reel MAA05A M08A MUA08A MTC14 Connection Diagrams SC70-5 8-Pin MSOP/SOIC 20039667 Top View 14-Pin TSSOP 20039671 Top View 5 20039672 Top View www.national.com LMV771/LMV772/LMV774 Ordering Information LMV771/LMV772/LMV774 Typical Performance Characteristics VOS vs. VCM Over Temperature VOS vs. VCM Over Temperature 20039626 20039627 Output Swing vs. VS Output Swing vs. VS 20039625 20039624 Output Swing vs. VS IS vs. VS Over Temperature 20039630 20039623 www.national.com 6 LMV771/LMV772/LMV774 Typical Performance Characteristics (Continued) VIN vs. VOUT VIN vs. VOUT 20039628 20039629 Sourcing Current vs. VOUT (Note 14) Sourcing Current vs. VOUT (Note 14) 20039631 20039664 Sinking Current vs. VOUT (Note 14) Sinking Current vs. VOUT (Note 14) 20039632 20039663 7 www.national.com LMV771/LMV772/LMV774 Typical Performance Characteristics (Continued) Input Voltage Noise vs. Frequency Input Bias Current Over Temperature 20039608 20039635 Input Bias Current Over Temperature Input Bias Current Over Temperature 20039634 20039633 THD+N vs. Frequency THD+N vs. VOUT 20039607 www.national.com 20039666 8 (Continued) Slew Rate vs. Supply Voltage Open Loop Frequency Response Over Temperature 20039601 20039602 Open Loop Frequency Response Open Loop Frequency Response 20039603 20039604 Open Loop Gain & Phase with Cap. Loading Open Loop Gain & Phase with Cap. Loading 20039605 20039606 9 www.national.com LMV771/LMV772/LMV774 Typical Performance Characteristics LMV771/LMV772/LMV774 Typical Performance Characteristics (Continued) Non-Inverting Small Signal Pulse Response Non-Inverting Large Signal Pulse Response 20039617 20039611 Non-Inverting Small Signal Pulse Response Non-Inverting Large Signal Pulse Response 20039610 20039616 Non-Inverting Small Signal Pulse Response Non-Inverting Large Signal Pulse Response 20039615 www.national.com 20039609 10 (Continued) Inverting Small Signal Pulse Response Inverting Large Signal Pulse Response 20039619 20039614 Inverting Small Signal Pulse Response Inverting Large Signal Pulse Response 20039620 20039613 Inverting Small Signal Pulse Response Inverting Large Signal Pulse Response 20039618 20039612 11 www.national.com LMV771/LMV772/LMV774 Typical Performance Characteristics LMV771/LMV772/LMV774 Typical Performance Characteristics (Continued) Stability vs. VCM Stability vs. VCM 20039621 20039622 PSRR vs. Frequency CMRR vs. Frequency 20039665 20039668 Crosstalk Rejection vs. Frequency 20039694 www.national.com 12 LMV771/LMV772/LMV774 The LMV771/LMV772/LMV774 is a family of precision amplifiers with very low noise and ultra low offset voltage. LMV771/LMV772/LMV774’s extended temperature range of −40˚C to 125˚C enables the user to design this family of products in a variety of applications including automotive. (1) By Ohm’s Law: LMV771 has a maximum offset voltage of 1mV over the extended temperature range. This makes LMV771 ideal for applications where precision is of importance. LMV772/LMV774 have a maximum offset voltage of 1mV at room temperature and 1.2mV over the extended temperature range of −40˚C to 125˚C. Care must be given when LMV772/LMV774 are designed in applications with heavy loads under extreme temperature conditions. As indicated in the DC tables, the LMV772/LMV774’s gain and output swing may be reduced at temperatures between 85˚C and 125˚C with loads heavier than 2kΩ. (2) However: INSTRUMENTATION AMPLIFIER (3) Measurement of very small signals with an amplifier requires close attention to the input impedance of the amplifier, gain of the overall signal on the inputs, and the gain on each input since we are only interested in the difference of the two inputs and the common signal is considered noise. A classic solution is an instrumentation amplifier. Instrumentation amplifiers have a finite, accurate, and stable gain. Also they have extremely high input impedances and very low output impedances. Finally they have an extremely high CMRR so that the amplifier can only respond to the differential signal. A typical instrumentation amplifier is shown in Figure 1. So we have: (4) Now looking at the output of the instrumentation amplifier: (5) Substituting from equation 4: (6) This shows the gain of the instrumentation amplifier to be: −K(2a+1) Typical values for this circuit can be obtained by setting: a = 12 and K= 4. This results in an overall gain of −100. Figure 2 shows typical CMRR characteristics of this Instrumentation amplifier over frequency. Three LMV771 amplifiers are used along with 1%resistors to minimize resistor mismatch. Resistors used to build the circuit are: R1 = 21.6kΩ, R11 = 1.8kΩ, R2 = 2.5kΩ with K = 40 and a = 12. This results in an overall gain of −1000, −K(2a+1) = −1000. 20039636 FIGURE 1. There are two stages in this amplifier. The last stage, output stage, is a differential amplifier. In an ideal case the two amplifiers of the first stage, input stage, would be set up as buffers to isolate the inputs. However they cannot be connected as followers because of real amplifiers mismatch. That is why there is a balancing resistor between the two. The product of the two stages of the gain will give the gain of the instrumentation amplifier. Ideally, the CMRR should be infinity. However the output stage has a small non-zero common mode gain which results from resistor mismatch. 13 www.national.com LMV771/LMV772/LMV774 In the input stage of the circuit, current is the same across all resistors. This is due to the high input impedance and low input bias current of the LMV771. With the node equations we have: Application Note LMV771/LMV772/LMV774 Application Note Simplifying this further results in: (Continued) (8) or (9) Now, substituting ω=2πf, so that the calculations are in f(Hz) and and not ω(rad/s), and setting the DC gain (10) Set: 20039673 FIGURE 2. CMRR vs. Frequency (11) Low pass filters are known as lossy integrators because they only behave as an integrator at higher frequencies. Just by looking at the transfer function one can predict the general form of the bode plot. When the f/fO ratio is small, the capacitor is in effect an open circuit and the amplifier behaves at a set DC gain. Starting at fO, −3dB corner, the capacitor will have the dominant impedance and hence the circuit will behave as an integrator and the signal will be attenuated and eventually cut. The bode plot for this filter is shown in the following picture: ACTIVE FILTER Active Filters are circuits with amplifiers, resistors, and capacitors. The use of amplifiers instead of inductors, which are used in passive filters, enhances the circuit performance while reducing the size and complexity of the filter. The simplest active filters are designed using an inverting op amp configuration where at least one reactive element has been added to the configuration. This means that the op amp will provide "frequency-dependent" amplification, since reactive elements are frequency dependent devices. LOW PASS FILTER The following shows a very simple low pass filter. 20039647 20039653 FIGURE 3. FIGURE 4. The transfer function can be expressed as follows: By KCL: (7) www.national.com 14 LMV771/LMV772/LMV774 Application Note (Continued) HIGH PASS FILTER In a similar approach, one can derive the transfer function of a high pass filter. A typical first order high pass filter is shown below: 20039658 20039654 FIGURE 6. FIGURE 5. BAND PASS FILTER Writing the KCL for this circuit : (V1 denotes the voltage between C and R1) (12) (13) Solving these two equations to find the transfer function and using: 20039660 FIGURE 7. (high frequency gain) Combining a low pass filter and a high pass filter will generate a band pass filter. In this network the input impedance forms the high pass filter while the feedback impedance forms the low pass filter. Choosing the corner frequencies so that f1 < f2, then all the frequencies in between, f1 ≤ f ≤ f2, will pass through the filter while frequencies below f1 and above f2 will be cut off. The transfer function can be easily calculated using the same methodology as before. and Which results: (14) Looking at the transfer function, it is clear that when f/fO is small, the capacitor is open and hence no signal is getting in to the amplifier. As the frequency increases the amplifier starts operating. At f = fO the capacitor behaves like a short circuit and the amplifier will have a constant, high frequency, gain of HO. The bode plot of the transfer function follows: (15) Where The transfer function is presented in the following figure. 15 www.national.com LMV771/LMV772/LMV774 Application Note STATE VARIABLE ACTIVE FILTER State variable active filters are circuits that can simultaneously represent high pass, band pass, and low pass filters. The state variable active filter uses three separate amplifiers to achieve this task. A typical state variable active filter is shown in Figure 9. The first amplifier in the circuit is connected as a gain stage. The second and third amplifiers are connected as integrators, which means they behave as low pass filters. The feedback path from the output of the third amplifier to the first amplifier enables this low frequency signal to be fed back with a finite and fairly low closed loop gain. This is while the high frequency signal on the input is still gained up by the open loop gain of the 1st amplifier. This makes the first amplifier a high pass filter. The high pass signal is then fed in to a low pass filter. The outcome is a band pass signal, meaning the second amplifier is a band pass filter. This signal is then fed into the third amplifiers input and so the third amplifier behaves as a simple low pass filter. (Continued) 20039662 FIGURE 8. 20039674 FIGURE 9. The transfer function of each filter needs to be calculated. The derivations will be more trivial if each stage of the filter is shown on its own. The three components are: 20039680 20039681 For A1 the relationship between input and output is: www.national.com 16 A design example is shown here: (Continued) Designing a bandpass filter with center frequency of 10kHz and Quality factor of 5.5 To do this, first consider the quality factor. It is best to pick convenient values for the capacitors. C2 = C3 = 1000pF. Also, choose R1 = R4 = 30kΩ. Now Values of R5 and R6 need to be calculated. With the chosen values for the capacitors and resistors, Q reduces to: This relationship depends on the output of all the filters. The input-output relationship for A2 can be expressed as: And finally this relationship for A3 is as follows: or Re-arranging these equations, one can find the relationship between VO and VIN (transfer function of the lowpass filter), VO1 and VIN (transfer function of the highpass filter), and VO2 and VIN (transfer function of the bandpass filter) These relationships are as follows: R5 = 10R6 R6 = 1.5kΩ R5 = 15kΩ Also, for f = 10kHz, value of center frequency is ωc = 2πf = 62.8kHz. Lowpass filter Using the expressions above, the appropriate resistor values will be R2 = R3 = 16kΩ. The following graphs show the transfer function of each of the filters. The DC gain of this circuit is: 20039690 The following graphics show the frequency response of each of the stages when using LMV774 as the amplifier: Highpass filter Bandpass Filter The center frequency and quality factor for all of these filters is the same. The values can be calculated in the following manner: 20039691 FIGURE 10. Lowpass Filter Frequency Response 17 www.national.com LMV771/LMV772/LMV774 Application Note LMV771/LMV772/LMV774 Application Note (Continued) 20039692 FIGURE 11. Bandpass Filter Frequency Response 20039693 FIGURE 12. Highpass Filter Frequency Response www.national.com 18 LMV771/LMV772/LMV774 Physical Dimensions inches (millimeters) unless otherwise noted SC70-5 NS Package Number MAA05A 8-Pin SOIC NS Package Number M08A 19 www.national.com LMV771/LMV772/LMV774 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 8-Pin MSOP NS Package Number MUA08A 14-Pin TSSOP NS Package Number MTC14 www.national.com 20 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 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. LMV771/LMV772/LMV774 Single/Dual/Quad, Low Offset, Low Noise, RRO Operational Amplifiers Notes