LMV301 Low Input Bias Current, 1.8V Op Amp w/ Rail-to-Rail Output General Description Key Specifications The LMV301 CMOS operational amplifier is ideal for single supply, low voltage operation with a guaranteed operating voltage range from 1.8V to 5V. The low input bias current of less than 0.182pA typical, eliminates input voltage errors that may originate from small input signals. This makes the LMV301 ideal for electrometer applications requiring low input leakage such as sensitive photodetection transimpedance amplifiers and sensor amplifiers. The LMV301 also features a rail-to-rail output voltage swing in addition to a input common-mode range that includes ground. The LMV301 will drive a 600Ω resistive load and up to 1000pF capacitive load in unity gain follower applications. The low supply voltage also makes the LMV301 well suited for portable two-cell battery systems and single cell Li-Ion systems. The LMV301 exhibits excellent speed-power ratio, achieving 1MHz at unity gain with low supply current. The high DC gain of 100dB makes it ideal for other low frequency applications. The LMV301 is offered in a space saving SC-70 package, which is only 2.0X2.1X1.0mm. It is also similar to the LMV321 except the LMV301 has a CMOS input. (Typical values unless otherwise specified) n Input bias current 0.182pA n Gain bandwidth product 1MHz n Supply voltage @ 1.8V 1.8V to 5V n Supply current 150µA n Input referred voltage noise @ 1kHz 40nV/ n DC Gain (600Ω load) 100dB n Output voltage range @ 1.8V 0.024 to 1.77V n Input common-mode voltage range −0.3V to V+ - 1.2V Connection Diagram Applications Circuit Applications n n n n n Thermocouple amplifiers Photo current amplifiers Transducer amplifiers Sample and hold circuits Low frequency active filters SC70-5 Low Leakage Sample and Hold 20019307 20019301 Top View Ordering Information Package Part Number Package Marking Transport Media NSC Drawing 5-Pin SC70-5 LMV301MG A48 1k Units Tape and Reel MAA05A LMV301MGX © 2001 National Semiconductor Corporation DS200193 3k Units Tape and Reel www.national.com LMV301 Low Input Bias Current, 1.8V Op Amp w/ Rail-to-Rail Output March 2001 LMV301 Absolute Maximum Ratings (Note 1) Mounting Temperature Infrared or Convection (20 sec) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. ESD Tolerance (Note 7) Machine Model + Supply Voltage 2000V Differential Input Voltage − Supply Voltage (V - V ) 1.8V to 5.0V −40˚C ≤ TJ ≤ +85˚C Temperature Range ± Supply Voltage Thermal Resistance (θJA) 5.5V Output Short Circuit to V+ (Note 2) Ultra Tiny SC70-5 Package Output Short Circuit to V− (Note 2) 5-pin Surface Mount Storage Tempeature Range 150˚C Operating Ratings(Note 1) 200V Human Body Model 235˚C Junction Temperature (Note 3) 478˚C/W −65˚C to 150˚C 1.8V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 1.8V, V− = 0V, VCM = V+/2, VO = V+/2, and RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter Condition Min (Note 5) VCM = 0.4V, V+ = 1.3V, = V− = −0.5V Typ (Note 4) Max (Note 5) Units 0.9 8 9 mV 0.182 35 50 pA 150 250 275 µA VOS Input Offset Voltage IB Input Bias Current IS Supply Current VCM = 0.4V, V+ = 1.3V, = V− = −0.5V CMRR Common Mode Rejection Ratio 0.3V ≤ VCM ≤ 0.9V 62 60 108 dB PSRR Power Supply Rejection Ratio 1.8V ≤ V+ ≤ 5V, 0.9 ≤ VCM ≤ 2.5V 67 62 110 dB VCM Input Common-Mode Voltage For CMRR ≥ 50dB Range AV Large Signal Voltage Gain Sourcing Sinking VO Output Swing −0.3 0 RL = 600Ω to 0V, V+ = 1.2V, V− = −0.6V, VO = −0.2V to 0.8V, VCM = 0V 80 75 119 RL = 2kΩ to 0V, V+ = 1.2V, V− = −0.6V, VO = −0.2V to 0.8V, VCM = 0V 80 75 111 RL = 600Ω to 0V, V+ = 1.2V, V− = −0.6V, VO = −0.2V to 0.8V, VCM = 0V 80 75 94 RL = 2kΩ to 0V, V+ = 1.2V, V− = −0.6V, VO = −0.2V to 0.8V, VCM = 0V 80 75 96 1.65 1.63 1.72 RL = 600Ω to 0.9V VIN = ± 100mV VOH RL = 2kΩ to 0.9V VIN = ± 100mV VOH VOL 0.074 1.75 1.74 VOL IO Output Short Circuit Current Sourcing, VO = 0V, VIN = 100mV Sinking, VO = 1.8V, VIN = −100mV www.national.com 0.6 2 dB dB V 0.100 1.77 0.024 V V V 0.035 0.040 V 4 3.3 8.4 mA 7 9.8 mA − = 1.8V, V = 0V, VCM Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = V /2, VO = V /2, and RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol + + Parameter Condition (Note 6) Typ (Note 4) Units 0.57 V/µs SR Slew Rate GBW Gain Bandwidth Product 1 MHz φm Phase Margin 60 Deg Gm Gain Margin 10 en Input-Referred Voltage Noise f = 1kHz, VCM = 0.5V f = 100kHz THD Total Harmonic Distortion f = 1kHz, AV = +1 RL = 600kΩ, VIN = 1VPP dB 40 30 nV/ 0.089 % 2.7V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V− = 0V, VCM = V+/2, VO = V+/2, and RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter Condition Min (Note 5) VCM = 0.35V, V+ = 1.7V, V− = −1V Typ (Note 4) Max (Note 5) Units 0.9 8 9 mV 0.182 35 50 pA 153 250 275 µA VOS Input Offset Voltage IB Input Bias Current IS Supply Current VCM = 0.35V, V+ = 1.7V, V− = −1V CMRR Common Mode Rejection Ratio −0.15V ≤ VCM ≤ 1.35V 62 60 115 dB PSRR Power Supply Rejection Ratio 1.8V ≤ V+ ≤ 5V 67 62 110 dB VCM Input Common-Mode Voltage For CMRR ≥ 50dB Range AV Large Signal Voltage Gain Sourcing Sinking VO Output Swing −0.3 0 RL = 600Ω to 0V, V+ = 1.35V, V− = −1.35V, VO = −1V to 1V, VCM = 0V 80 75 100 RL = 2kΩ to 0V, V+ = 1.35V, V− = −1.35V, VO = −1V to 1V, VCM = 0V 83 77 114 RL = 600Ω to 0V, V+ = 1.35V, V− = −1.35V, VO = −1V to 1V, VCM = 0V 80 75 98 RL = 2kΩ to 0V, V+ = 1.35V, V− = −1.35V, VO = −1V to 1V, VCM = 0V 80 75 99 2.550 2.530 2.62 2.650 2.640 2.675 RL = 600Ω to 1.35V VIN = ± 100mV VOH RL = 2kΩ to 1.35V VIN = ± 100mV VOH VOL 0.078 VOL IO Output Short Circuit Current 1.5 0.024 V dB dB V 0.100 V V 0.045 V Sourcing, VO = 0V, VIN = 100mV 20 15 32 mA Sinking, VO = 2.7V, VIN = −100mV 19 12 24 mA 3 www.national.com LMV301 1.8V AC Electrical Characteristics LMV301 2.7V AC Electrical Characteristics − = 2.7V, V = 0V, VCM Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 1.0V, VO = 1.35V and RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter Condition (Note 6) Typ (Note 4) Units 0.60 V/µs SR Slew Rate GBW Gain Bandwidth Product 1 MHz φm Phase Margin 65 Deg Gm Gain Margin 10 en Input-Referred Voltage Noise f = 1kHz, VCM = 0.5V f = 100kHz THD Total Harmonic Distortion f = 1kHz, AV = +1 RL = 600kΩ, VIN = 1VPP dB 40 30 nV/ 0.077 % 5V DC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5V, V− = 0V, VCM = V+/2, VO = V+/2, and RL > 1MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter Condition Min (Note 5) VCM = 0.5V, V+ = 3V, V− = −2V Typ (Note 4) Max (Note 5) Units 0.9 8 9 mV 0.182 35 50 pA 163 260 285 µA VOS Input Offset Voltage IB Input Bias Current IS Supply Current VCM = 0.5V, V+ = 3V, V− = −2V CMRR Common Mode Rejection Ratio −1.3V ≤ VCM ≤ 2.5V 62 61 111 dB PSRR Power Supply Rejection Ratio 1.8V ≤ V+ ≤ 5V 67 62 110 dB VCM Input Common-Mode Voltage Range For CMRR ≥ 50dB AV Large Signal Voltage Gain Sourcing RL = 600Ω to 0V, V+ = 2.5V, V− = −2.5V, VO = −2V to 2V, VCM = 0V 86 82 117 RL = 2kΩ to 0V, V+ = 2.5V, V− = −2.5V, VO = −2V to 2V, VCM = 0V 89 85 116 RL = 600Ω to 0V, V+ = 2.5V, V− = −2.5V, VO = −2V to 2V, VCM = 0V 80 75 105 RL = 2kΩ to 0V, V+ = 2.5V, V− = −2.5V, VO = −2V to 2V, VCM = 0V 80 75 107 4.850 4.840 4.893 Sinking VO Output Swing −0.3 0 VOH RL = 600Ω to 2.5V VIN = ± 100mV VOL VOH RL = 2kΩ to 2.5V VIN = ± 100mV IO Output Short Circuit Current www.national.com 3.8 0.1 4.935 VOL dB dB V 0.150 1.160 4.966 0.034 V V V 0.065 0.075 V Sourcing, VO = 0V, VIN = 100mV 85 68 108 mA Sinking, VO = 5V, VIN = −100mV 60 45 69 mA 4 − 5V, V = 0V, VCM Symbol Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = = V /2, VO = 2.5V and RL > 1MΩ. Boldface limits apply at the temperature extremes. + Parameter Condition (Note 6) Typ (Note 4) Units 0.66 V/µs SR Slew Rate GBW Gain Bandwidth Product 1 MHz φm Phase Margin 70 Deg Gm Gain Margin 15 en Input-Referred Voltage Noise f = 1kHz, VCM = 1V f = 100kHz THD Total Harmonic Distortion f = 1kHz, AV = +1 RL = 600Ω, VO = 1VPP dB 40 30 nV/ 0.069 % 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: Applies to both single 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 45mA 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. All numbers apply for packages soldered directly into a PC board. Note 4: Typical value represent the most likely parametric norm. Note 5: All limits are guaranteed by testing or statistical analysis. Note 6: V+ = 5V. Connected as voltage follower with 5V step input. Number specified is the slower of the positive and negative slew rates. Note 7: Human body model, 1.5kΩ in series with 100pF. Machine model, 200Ω in series with 100pF. Simplified Schematic 20019302 5 www.national.com LMV301 5V AC Electrical Characteristics LMV301 Typical Performance Characteristics Unless otherwise specified, TA = 25˚C. Supply Current vs. Supply Voltage Output Negative Swing vs. Supply Voltage 20019359 20019360 Output Negative Swing vs. Supply Voltage Output Positive Swing vs. Supply Voltage 20019361 20019362 Output Positive Swing vs. Supply Voltage VOS vs. VCM 20019363 www.national.com 20019365 6 Unless otherwise specified, TA = 25˚C. (Continued) VOS vs. VCM VOS vs. VCM 20019366 20019367 Sourcing Current vs. Output Voltage Sinking Current vs. Output Voltage 20019368 20019369 Sourcing Current vs. Output Voltage Sinking Current vs. Output Voltage 20019370 20019371 7 www.national.com LMV301 Typical Performance Characteristics LMV301 Typical Performance Characteristics Unless otherwise specified, TA = 25˚C. (Continued) Sourcing Current vs. Output Voltage Sinking Current vs. Output Voltage 20019373 20019372 IBIAS Current vs. VCM Open Loop Frequency Response 20019353 20019364 Open Loop Frequency Response Open Loop Frequency Response 20019355 20019354 www.national.com 8 LMV301 Typical Performance Characteristics Unless otherwise specified, TA = 25˚C. (Continued) Open Loop Frequency Response Open Loop Frequency Response 20019357 20019356 Open Loop Frequency Response Noise vs. Frequency Response 20019358 20019374 Noise vs. Frequency Response Noise vs. Frequency Response 20019375 20019376 9 www.national.com LMV301 Typical Performance Characteristics Unless otherwise specified, TA = 25˚C. (Continued) Small Signal Response Large Signal Response 20019346 20019345 Small Signal Response Large Signal Response 20019347 20019348 Small Signal Response Large Signal Response 20019349 www.national.com 20019350 10 Unless otherwise specified, TA = 25˚C. (Continued) Small Signal Response Large Signal Response 20019352 20019351 11 www.national.com LMV301 Typical Performance Characteristics LMV301 Application Hints Compensating Input Capacitance The high input resistance of the LMV301 op amp allows the use of large feedback and source resistor values without losing gain accuracy due to loading. However, the circuit will be especially sensitive to its layout when these large value resistors are used. Every amplifier has some capacitance between each input and AC ground, and also some differential capacitance between the inputs. When the feedback network around an amplifier is resistive, this input capacitance (along with any additional capacitance due to circuit board traces, the socket, etc.) and the feedback resistors create a pole in the feedback path. In the following General Operational Amplifier circuit, Figure 1, the frequency of this pole is the following value of feedback capacitor is recommended: If the feedback capacitor should be: where CS is the total capacitance at the inverting input, including amplifier input capacitance and any stray capacitance from the IC socket (if one is used), circuit board traces, etc., and RP is the parallel combination of RF and RIN. This formula, as well as all formulae derived below, apply to inverting and non-inverting op amp configurations. When the feedback resistors are smaller than a few kΩ, the frequency of the feedback pole will be quite high, since CS is generally less than 10pF. If the frequency of the feedback pole is much higher than the “ideal” closed-loop bandwidth (the nominal closed-loop bandwidth in the absence of CS), the pole will have a negligible effect on stability, as it will add only a small amount of phase shift. However, if the feedback pole is less than approximately 6 to 10 times the “ideal” −3dB frequency, a feedback capacitor, CF, should be connected between the output and the inverting input of the op amp. This condition can also be stated in terms of the amplifier’s low frequency noise gain. To maintain stability a feedback capacitor will probably be needed if Note that these capacitor values are usually significantly smaller than those given by the older, more conservative formula: 20019306 CS consists of the amplifier’s input capacitance plus any stray capacitance from the circuit board and socket. CF compensates for the pole caused by CS and the feedback resistors. where FIGURE 1. General Operational Amplifier Circuit Using the smaller capacitor will give much higher bandwidth with little degradation of transient response. It may be necessary in any of the above cases to use a somewhat larger feedback capacitor to allow for unexpected stray capacitance, or to tolerate additional phase shifts in the loop, or excessive capacitive load, or to decrease the noise or bandwidth, or simply because the particular circuit implementation needs more feedback capacitance to be sufficiently stable. For example, a printed circuit board’s stray capacitance may be larger or smaller than the breadboard’s, so the actual optimum value for CF may be different from the one estimated using the breadboard. In most cases, the values of CF should be checked on the actual circuit, starting with the computed value. is the amplifier’s low frequency noise gain and GBW is the amplifier’s gain bandwidth product. An amplifier’s low frequency noise gain is represented by the formula regardless of whether the amplifier is being used in inverting or non-inverting mode. Note that a feedback capacitor is more likely to be needed when the noise gain is low and/or the feedback resistor is large. If the above condition is met (indicating a feedback capacitor will probably be needed), and the noise gain is large enough that: www.national.com 12 LMV301 Application Hints (Continued) Capacitive Load Tolerance Like many other op amps, the LMV301 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. 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. As shown in Figure 2, the addition of a small resistor (50Ω to 100Ω) in series with the op amp’s output, and a capacitor (5pF to 10pF) 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 tolerated without oscillation. Note that in all cases, the output will ring heavily when the load capacitance is near the threshold for oscillation. 20019323 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 100pA of leakage current requires special layout of the PC board. When one wishes to take advantage of the low bias current of the LMV301, typically less than 0.182pA, 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 acceptable low, because under conditions of the high humidity or dust or contamination, the surface leakage will be appreciable. To minimized the effect of any surface leakage, lay out a ring of foil completely surrounding the LMV301’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. The 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 5pA if the trace were a 5V bus adjacent to the pad of an input. This would cause a 100 times degradation from the LMV301’s actual performance. However, if a guard ring is held within 5mV of the inputs, then even a resistance of 1011Ω would cause only 0.05pA of leakage current, or perhaps a minor (2:1) degradation of the amplifier 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. 20019305 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 500µA 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. 20019377 FIGURE 4. Example, using the LMV301, of Guard Ring in P.C. Board Layout 13 www.national.com LMV301 Application Hints (Continued) 20019317 (a) Inverting Amplifier 20019318 (b) Non-Inverting Amplifier 20019319 (c) Follower 20019320 (d) Howland Current Pump FIGURE 5. Guard Ring Connections www.national.com 14 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 (Continued) 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 20019321 (Input pins are lifted out of PC board and soldered directly to components. All other pins connected to PC board.) FIGURE 6. Air Wiring 15 www.national.com LMV301 Application Hints LMV301 Typical Single-Supply Applications Power Amplifier (V+ = 5.0 VDC) Low-Leakage Sample-and-Hold 20019311 20019307 10Hz Bandpass Filter Sine-Wave Oscillator 20019312 fO = 10 Hz Q = 2.1 Gain = −8.8 10 Hz High-Pass Filter 20019309 Oscillator frequency is determined by R1, R2, C1, and C2: fosc = 1/2πRC, where R = R1 = R2 and C = C1 = C2. This circuit, as shown, oscillates at 2.0kHz with a peak-to-peak output swing of 4.5V. 20019313 1 Hz Square-Wave Oscillator fc = 10 Hz d = 0.895 Gain = 1 2 dB passband ripple 1 Hz Low-Pass Filter (Maximally Flat, Dual Supply Only) 20019310 20019314 fc = 1 Hz d = 1.414 Gain = 1.57 www.national.com 16 LMV301 SC70-5 Tape Dimensions 20019396 SC70-5 Tape Format Tape Format Tape Section # Cavities Cavity Status Cover Tape Status Leader (Start End) 0 (min) Empty Sealed 75 (min) Empty Sealed Carrier 3000 Filled Sealed 250 Filled Sealed 125 (min) Empty Sealed 0 (min) Empty Sealed Trailer (Hub End) 17 www.national.com LMV301 SC70-5 Reel Dimensions 20019397 8mm 7.00 330.00 0.059 1.50 0.512 13.00 0.795 20.20 2.165 55.00 0.331+ 0.059/−0.000 8.40 + 1.50/− 0.00 0.567 14.40 W1 + 0.078/−0.039 W1 + 2.00/−1.00 Tape Size A B C D N W1 W2 W3 www.national.com 18 LMV301 Low Input Bias Current, 1.8V Op Amp w/ Rail-to-Rail Output Physical Dimensions inches (millimeters) unless otherwise noted SC70-5 NS Package Number MAA05A 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. 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) 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 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. 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