LMV931 Single / LMV932 Dual / LMV934 Quad 1.8V, RRIO Operational Amplifiers General Description Features The LMV931/LMV932/LMV934 are low voltage, low power operational amplifiers. LMV931/LMV932/LMV934 are guaranteed to operate from +1.8V to +5.0V supply voltages and have rail-to-rail input and output. LMV931/LMV932/LMV934 input common mode voltage extends 200mV beyond the supplies which enables user enhanced functionality beyond the supply voltage range. The output can swing rail-to-rail unloaded and within 105mV from the rail with 600Ω load at 1.8V supply. The LMV931/LMV932/LMV934 are optimized to work at 1.8V which make them ideal for portable two-cell battery powered systems and single cell Li-Ion systems. (Typical 1.8V Supply Values; Unless Otherwise Noted) n Guaranteed 1.8V, 2.7V and 5V specifications n Output swing — w/600Ω load 80mV from rail — w/2kΩ load 30mV from rail n VCM 200mV beyond rails n Supply current (per channel) 100µA n Gain bandwidth product 1.4MHz n Maximum VOS 4.0mV n Ultra tiny packages n Temperature range −40˚C to 125˚C LMV931/LMV932/LMV934 exhibit excellent speed-power ratio, achieving 1.4MHz gain bandwidth product at 1.8V supply voltage with very low supply current. The LMV931/LMV932/ LMV934 are capable of driving a 600Ω load and up to 1000pF capacitive load with minimal ringing. LMV931/ LMV932/LMV934 have a high DC gain of 101dB, making them suitable for low frequency applications. The single LMV931 is offered in space saving SC70-5 and SOT23-5 packages. The dual LMV932 are in MSOP-8 and SOIC-8 packages and the quad LMV934 are in TSSOP-14 and SOIC-14 packages. These small packages are ideal solutions for area constrained PC boards and portable electronics such as cellular phones and PDAs. Applications n n n n n n n Consumer communication Consumer computing PDAs Audio pre-amp Portable/battery-powered electronic equipment Supply current monitoring Battery monitoring Typical Application 200326H0 © 2002 National Semiconductor Corporation DS200326 www.national.com LMV931 Single / LMV932 Dual / LMV934 Quad 1.8V, RRIO Operational Amplifiers December 2002 LMV931 Single / LMV932 Dual / LMV934 Quad Absolute Maximum Ratings Infrared or Convection (20 sec) (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) Supply Voltage Range ESD Tolerance (Note 2) Machine Model 1.8V to 5.0V Temperature Range 200V Human Body Model 235˚C −40˚C to 125˚C Thermal Resistance (θJA) 2000V SC70-5 414˚C/W SOT23-5 265˚C/W Output Short Circuit to V+ (Note 3) MSOP-8 235˚C/W Output Short Circuit to V− (Note 3) SOIC-8 175˚C/W Storage Temperature Range TSSOP-14 155˚C/W SOIC-14 127˚C/W Differential Input Voltage + − Supply Voltage (V –V ) Junction Temperature (Note 4) ± Supply Voltage 5.5V −65˚C to 150˚C 150˚C Mounting Temp. 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 > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10) Symbol VOS Parameter Input Offset Voltage Condition Min (Note 6) Typ (Note 5) Max (Note 6) Units LMV931 (Single) 1 4 6 mV LMV932 (Dual) LMV934 (Quad) 1 5.5 7.5 mV TCVOS Input Offset Voltage Average Drift 5.5 IB Input Bias Current 15 35 50 nA IOS Input Offset Current 13 25 40 nA IS Supply Current (per channel) 103 185 205 CMRR Common Mode Rejection Ratio LMV931, 0 ≤ VCM ≤ 0.6V 1.4V ≤ VCM ≤ 1.8V (Note 8) 60 55 78 LMV932 and LMV934 0 ≤ VCM ≤ 0.6V 1.4V ≤ VCM ≤ 1.8V (Note 8) 55 50 76 −0.2V ≤ VCM ≤ 0V 1.8V ≤ VCM ≤ 2.0V 50 72 75 70 100 V− −0.2 −0.2 to 2.1 PSRR Power Supply Rejection Ratio 1.8V ≤ V+ ≤ 5V CMVR Input Common-Mode Voltage Range For CMRR Range ≥ 50dB AV Large Signal Voltage Gain LMV931 (Single) Large Signal Voltage Gain LMV932 (Dual) LMV934 (Quad) www.national.com TA = 25˚C V TA = 125˚C V− +0.2 dB V+ +0.2 V+ V V+ −0.2 RL = 600Ω to 0.9V, VO = 0.2V to 1.6V, VCM = 0.5V 77 73 101 RL = 2kΩ to 0.9V, VO = 0.2V to 1.6V, VCM = 0.5V 80 75 105 RL = 600Ω to 0.9V, VO = 0.2V to 1.6V, VCM = 0.5V 75 72 90 RL = 2kΩ to 0.9V, VO = 0.2V to 1.6V, VCM = 0.5V 78 75 100 2 µA dB − TA −40˚C to 85˚C µV/˚C dB dB (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 1.8V, V − = 0V, VCM = V+/2, VO = V+/2 and RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10) Symbol VO Parameter Output Swing Condition RL = 600Ω to 0.9V VIN = ± 100mV Min (Note 6) Typ (Note 5) 1.65 1.63 1.72 0.077 1.75 1.74 RL = 2kΩ to 0.9V VIN = ± 100mV Output Short Circuit Current 0.105 0.120 1.77 0.024 IO Max (Note 6) Sourcing, VO = 0V VIN = 100mV 4 3.3 8 Sinking, VO = 1.8V VIN = −100mV 7 5 9 Units V 0.035 0.04 mA 1.8V AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 1.8V, V Boldface limits apply at the temperature extremes. See (Note 10) Symbol Parameter Conditions − = 0V, VCM = V+/2, VO = V+/2 and RL > 1 MΩ. Min (Note 6) (Note 7) Typ (Note 5) Max (Note 6) Units SR Slew Rate 0.35 V/µs GBW Gain-Bandwidth Product 1.4 MHz Φm Phase Margin 67 deg Gm Gain Margin 7 dB en Input-Referred Voltage Noise f = 1kHz, VCM = 0.5V in Input-Referred Current Noise f = 1kHz 0.06 THD Total Harmonic Distortion f = 1kHz, AV = +1 RL = 600Ω, VIN = 1 VPP 0.023 % Amp-to-Amp Isolation (Note 9) 123 dB 60 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 > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10) Symbol VOS Parameter Input Offset Voltage Condition Min (Note 6) Typ (Note 5) Max (Note 6) Units LMV931 (Single) 1 4 6 mV LMV932 (Dual) LMV934 (Quad) 1 5.5 7.5 mV TCVOS Input Offset Voltage Average Drift 5.5 IB Input Bias Current 15 35 50 nA IOS Input Offset Current 8 25 40 nA IS Supply Current (per channel) 105 190 210 3 µV/˚C µA www.national.com LMV931 Single / LMV932 Dual / LMV934 Quad 1.8V DC Electrical Characteristics LMV931 Single / LMV932 Dual / LMV934 Quad 2.7V DC Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V − = 0V, VCM = V+/2, VO = V+/2 and RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10) Symbol CMRR Parameter Common Mode Rejection Ratio Condition Min (Note 6) Typ (Note 5) LMV931, 0 ≤ VCM ≤ 1.5V 2.3V ≤ VCM ≤ 2.7V (Note 8) 60 55 81 LMV932 and LMV934 0 ≤ VCM ≤ 1.5V 2.3V ≤ VCM ≤ 2.7V (Note 8) 55 50 80 −0.2V ≤ VCM ≤ 0V 2.7V ≤ VCM ≤ 2.9V 50 74 1.8V ≤ V+ ≤ 5V VCM = 0.5V 75 70 100 V− −0.2 −0.2 to 3.0 PSRR Power Supply Rejection Ratio VCM Input Common-Mode Voltage For CMRR Range Range ≥ 50dB TA = 25˚C TA = −40˚C to 85˚C TA = 125˚C AV VO − V− +0.2 V+ −0.2 104 RL = 2kΩ to 1.35V, VO = 0.2V to 2.5V 92 91 110 Large Signal Voltage Gain LMV932 (Dual) LMV934 (Quad) RL = 600Ω to 1.35V, VO = 0.2V to 2.5V 78 75 90 RL = 2kΩ to 1.35V, VO = 0.2V to 2.5V 81 78 100 Output Swing RL = 600Ω to 1.35V VIN = ± 100mV 2.55 2.53 2.62 2.65 2.64 Sourcing, VO = 0V VIN = 100mV 20 15 30 Sinking, VO = 0V VIN = −100mV 18 12 25 V dB dB 0.110 0.130 2.675 0.025 Output Short Circuit Current V+ +0.2 V+ 0.083 IO dB V 87 86 RL = 2kΩ to 1.35V VIN = ± 100mV Units dB RL = 600Ω to 1.35V, VO = 0.2V to 2.5V Large Signal Voltage Gain LMV931 (Single) Max (Note 6) V 0.04 0.045 mA 2.7V AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V − = 0V, VCM = 1.0V, VO = 1.35V and RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10) Symbol Parameter Conditions Typ (Note 5) Max (Note 6) Units SR Slew Rate 0.4 V/µs GBW Gain-Bandwidth Product 1.4 MHz Φm Phase Margin 70 deg Gm Gain Margin 7.5 dB en Input-Referred Voltage Noise f = 1kHz, VCM = 0.5V in Input-Referred Current Noise f = 1kHz www.national.com (Note 7) Min (Note 6) 57 0.082 4 (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V − = 0V, VCM = 1.0V, VO = 1.35V and RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10) Symbol THD Parameter Conditions Total Harmonic Distortion f = 1kHz, AV = +1 RL = 600kΩ, VIN = 1VPP Amp-to-Amp Isolation (Note 9) Min (Note 6) Typ (Note 5) Max (Note 6) Units 0.022 % 123 dB 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 > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10) Symbol VOS Parameter Input Offset Voltage Condition Min (Note 6) Typ (Note 5) Max (Note 6) Units LMV931 (Single) 1 4 6 mV LMV932 (Dual) LMV934 (Quad) 1 5.5 7.5 mV TCVOS Input Offset Voltage Average Drift 5.5 IB Input Bias Current 14 35 50 nA IOS Input Offset Current 9 25 40 nA IS Supply Current (per channel) 116 210 230 CMRR Common Mode Rejection Ratio 0 ≤ VCM ≤ 3.8V 4.6V ≤ VCM ≤ 5.0V (Note 8) 60 55 86 −0.2V ≤ VCM ≤ 0V 5.0V ≤ VCM ≤ 5.2V 50 78 75 70 100 V− −0.2 −0.2 to 5.3 PSRR Power Supply Rejection Ratio 1.8V ≤ V+ ≤ 5V VCM = 0.5V CMVR Input Common-Mode Voltage Range For CMRR Range ≥ 50dB TA = 25˚C TA = −40˚C to 85˚C TA = 125˚C AV VO V+ −0.3 RL = 2kΩ to 2.5V, VO = 0.2V to 4.8V 94 93 113 Large Signal Voltage Gain LMV932 (Dual) LMV934 (Quad) RL = 600Ω to 2.5V, VO = 0.2V to 4.8V 81 78 90 RL = 2kΩ to 2.5V, VO = 0.2V to 4.8V 85 82 100 Output Swing RL = 600Ω to 2.5V VIN = ± 100mV 4.855 4.835 4.890 0.120 4.945 4.935 V dB dB 0.160 0.180 4.967 0.037 5 V+ +0.2 V− +0.3 102 RL = 2kΩ to 2.5V VIN = ± 100mV dB V+ 88 87 µA dB V− RL = 600Ω to 2.5V, VO = 0.2V to 4.8V Large Signal Voltage Gain LMV931 (Single) µV/˚C V 0.065 0.075 www.national.com LMV931 Single / LMV932 Dual / LMV934 Quad 2.7V AC Electrical Characteristics LMV931 Single / LMV932 Dual / LMV934 Quad 5V DC Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5V, V − = 0V, VCM = V+/2, VO = V+/2 and RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10) Symbol IO Parameter Output Short Circuit Current Condition Min (Note 6) Typ (Note 5) LMV931, Sourcing, VO = 0V VIN = 100mV 80 68 100 Sinking, VO = 5V VIN = −100mV 58 45 65 Max (Note 6) Units mA 5V AC Electrical Characteristics Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5V, V − = 0V, VCM = V+/2, VO = 2.5V and R L > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10) Symbol Parameter Conditions Min (Note 6) Max (Note 6) Units SR Slew Rate 0.42 V/µs GBW Gain-Bandwidth Product 1.5 MHz Φm Phase Margin 71 deg Gm Gain Margin 8 dB en Input-Referred Voltage Noise f = 1kHz, VCM = 1V in Input-Referred Current Noise f = 1kHz THD Total Harmonic Distortion f = 1kHz, AV = +1 RL = 600Ω, VO = 1 V Amp-to-Amp Isolation (Note 7) Typ (Note 5) 50 0.07 0.022 % 123 dB PP (Note 9) 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, 200Ω in series with 100pF. 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 45mA 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)–T A)/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. Note 7: V+ = 5V. Connected as voltage follower with 5V step input. Number specified is the slower of the positive and negative slew rates. Note 8: For guaranteed temperature ranges, see Input Common-Mode Voltage Range specifications. Note 9: Input referred, V+ = 5V and RL = 100kΩ connected to 2.5V. Each amp excited in turn with 1kHz to produce VO = 3VPP. Note 10: 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 conditions of internal self-heating where TJ > TA. See Applications section for information of temperature derating of the device. Absolute Maximum Ratings indicated junction temperature limits beyond which the device may be permanently degraded, either mechanically or electrically. www.national.com 6 5-Pin SC70-5/SOT23-5 (LMV931) 8-Pin MSOP/SOIC (LMV932) 14-Pin TSSOP/SOIC (LMV934) 200326AO Top View 200326G13 200326G12 Top View Top View Ordering Information Package 5-Pin SC70 5-Pin SOT23 8-Pin MSOP 8-Pin SOIC 14-Pin TSSOP 14-Pin SOIC Part Number LMV931MG LMV931MGX LMV931MF LMV931MFX LMV932MM LMV932MMX LMV932MA LMV932MAX LMV934MT LMV934MTX LMV934MA LMV934MAX Packaging Marking A74 A79A A86A LMV932MA LMV934MT LMV934MA 7 Transport Media 1k Units Tape and Reel 3k Units Tape and Reel 1k Units Tape and Reel 3k Units Tape and Reel 1k Units Tape and Reel 3.5k Units Tape and Reel Rails 2.5k Units Tape and Reel Rails 2.5k Units Tape and Reel Rails 2.5k Units Tape and Reel NSC Drawing MAA05A MF05A MUA08A M08A MTC14 M14A www.national.com LMV931 Single / LMV932 Dual / LMV934 Quad Connection Diagrams LMV931 Single / LMV932 Dual / LMV934 Quad Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply, TA = 25˚C. Supply Current vs. Supply Voltage (LMV931) Sourcing Current vs. Output Voltage 20032622 20032625 Sinking Current vs. Output Voltage Output Voltage Swing vs. Supply Voltage 20032628 20032649 Output Voltage Swing vs. Supply Voltage Gain and Phase vs. Frequency 20032650 www.national.com 200326G8 8 LMV931 Single / LMV932 Dual / LMV934 Quad Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply, TA = 25˚C. (Continued) Gain and Phase vs. Frequency Gain and Phase vs. Frequency 200326G9 200326G10 Gain and Phase vs. Frequency CMRR vs. Frequency 20032639 200326G11 PSRR vs. Frequency Input Voltage Noise vs. Frequency 20032658 20032656 9 www.national.com LMV931 Single / LMV932 Dual / LMV934 Quad Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply, TA = 25˚C. (Continued) Input Current Noise vs. Frequency THD vs. Frequency 20032666 20032667 THD vs. Frequency Slew Rate vs. Supply Voltage 20032669 20032668 Small Signal Non-Inverting Response Small Signal Non-Inverting Response 20032670 www.national.com 20032671 10 Small Signal Non-Inverting Response Large Signal Non-Inverting Response 20032672 20032673 Large Signal Non-Inverting Response Large Signal Non-Inverting Response 20032674 20032675 Short Circuit Current vs. Temperature (Sinking) Short Circuit Current vs. Temperature (Sourcing) 20032676 20032677 11 www.national.com LMV931 Single / LMV932 Dual / LMV934 Quad Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply, TA = 25˚C. (Continued) LMV931 Single / LMV932 Dual / LMV934 Quad Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply, TA = 25˚C. (Continued) Offset Voltage vs. Common Mode Range Offset Voltage vs. Common Mode Range 20032636 20032637 Offset Voltage vs. Common Mode Range 20032638 www.national.com 12 LMV931 Single / LMV932 Dual / LMV934 Quad Application Note 1.0 INPUT AND OUTPUT STAGE The rail-to-rail input stage of this family provides more flexibility for the designer. The LMV931/LMV932/LMV934 use a complimentary PNP and NPN input stage in which the PNP stage senses common mode voltage near V− and the NPN stage senses common mode voltage near V+. The transition from the PNP stage to NPN stage occurs 1V below V+. Since both input stages have their own offset voltage, the offset of the amplifier becomes a function of the input common mode voltage and has a crossover point at 1V below V+. This VOS crossover point can create problems for both DC and AC coupled signals if proper care is not taken. Large input signals that include the VOS crossover point will cause distortion in the output signal. One way to avoid such distortion is to keep the signal away from the crossover. For example, in a unity gain buffer configuration and with VS = 5V, a 5V peak-to-peak signal will contain input-crossover distortion while a 3V peak-to-peak signal centered at 1.5V will not contain input-crossover distortion as it avoids the crossover point. Another way to avoid large signal distortion is to use a gain of −1 circuit which avoids any voltage excursions at the input terminals of the amplifier. In that circuit, the common mode DC voltage can be set at a level away from the VOS cross-over point. For small signals, this transition in VOS shows up as a VCM dependent spurious signal in series with the input signal and can effectively degrade small signal parameters such as gain and common mode rejection ratio. To resolve this problem, the small signal should be placed such that it avoids the VOS crossover point. In addition to the rail-to-rail performance, the output stage can provide enough output current to drive 600Ω loads. Because of the high current capability, care should be taken not to exceed the 150˚C maximum junction temperature specification. 20032659 FIGURE 1. Canceling the Offset Voltage due to Input Bias Current Typical Applications 3.0 HIGH SIDE CURRENT SENSING The high side current sensing circuit (Figure 2) is commonly used in a battery charger to monitor charging current to prevent over charging. A sense resistor RSENSE is connected to the battery directly. This system requires an op amp with rail-to-rail input. The LMV931/LMV932/LMV934 are ideal for this application because its common mode input range goes up to the rail. 2.0 INPUT BIAS CURRENT CONSIDERATION The LMV931/LMV932/LMV934 family has a complementary bipolar input stage. The typical input bias current (IB) is 15nA. The input bias current can develop a significant offset voltage. This offset is primarily due to IB flowing through the negative feedback resistor, RF. For example, if IB is 50nA and RF is 100kΩ, then an offset voltage of 5mV will develop (VOS = IB x RF). Using a compensation resistor (RC), as shown in Figure 1, cancels this effect. But the input offset current (IOS) will still contribute to an offset voltage in the same manner. 200326H0 FIGURE 2. High Side Current Sensing 13 www.national.com LMV931 Single / LMV932 Dual / LMV934 Quad Typical Applications In Figure 3 the circuit is referenced to ground, while in Figure 4 the circuit is biased to the positive supply. These configurations implement the half wave rectifier since the LMV931/ LMV932/LMV934 can not respond to one-half of the incoming waveform. It can not respond to one-half of the incoming because the amplifier can not swing the output beyond either rail therefore the output disengages during this half cycle. During the other half cycle, however, the amplifier achieves a half wave that can have a peak equal to the total supply voltage. RI should be large enough not to load the LMV931/LMV932/LMV934. (Continued) 4.0 HALF-WAVE RECTIFIER WITH RAIL-TO-GROUND OUTPUT SWING Since the LMV931/LMV932/LMV934 input common mode range includes both positive and negative supply rails and the output can also swing to either supply, achieving halfwave rectifier functions in either direction is an easy task. All that is needed are two external resistors; there is no need for diodes or matched resistors. The half wave rectifier can have either positive or negative going outputs, depending on the way the circuit is arranged. 200326C4 200326C2 200326C3 FIGURE 3. Half-Wave Rectifier with Rail-To-Ground Output Swing Referenced to Ground 200326C1 200326B9 200326C0 FIGURE 4. Half-Wave Rectifier with Negative-Going Output Referenced to VCC voltages. Remember that even with rail-to-rail outputs, the output can not swing past the supplies so the combined common mode voltages plus the signal should not be greater that the supplies or limiting will occur. For additional applications, see National Semiconductor application notes AN–29, AN–31, AN–71, and AN–127. 5.0 INSTRUMENTATION AMPLIFIER WITH RAIL-TO-RAIL INPUT AND OUTPUT Some manufactures make a non-“rail-to-rail”-op amp rail-torail by using a resistive divider on the inputs. The resistors divide the input voltage to get a rail-to-rail input range. The problem with this method is that it also divides the signal, so in order to get the obtained gain, the amplifier must have a higher closed loop gain. This raises the noise and drift by the internal gain factor and lowers the input impedance. Any mismatch in these precision resistors reduces the CMRR as well. The LMV981/LMV982 is rail-to-rail and therefore doesn’t have these disadvantages. Using three of the LMV981/LMV982 amplifiers, an instrumentation amplifier with rail-to-rail inputs and outputs can be made as shown in Figure 5. In this example, amplifiers on the left side act as buffers to the differential stage. These buffers assure that the input impedance is very high and require no precision matched resistors in the input stage. They also assure that the difference amp is driven from a voltage source. This is necessary to maintain the CMRR set by the matching R1-R2 with R3-R4. The gain is set by the ratio of R2/R1 and R3 should equal R1 and R4 equal R2. With both rail-to-rail input and output ranges, the input and output are only limited by the supply www.national.com 200326G4 FIGURE 5. Rail-to-rail Instrumentation Amplifier 14 LMV931 Single / LMV932 Dual / LMV934 Quad Simplified Schematic 200326A9 15 www.national.com LMV931 Single / LMV932 Dual / LMV934 Quad Physical Dimensions inches (millimeters) unless otherwise noted 5-Pin SC70 NS Package Number MAA05A 5-Pin SOT23 NS Package Number MF05A www.national.com 16 LMV931 Single / LMV932 Dual / LMV934 Quad Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 8-Pin MSOP NS Package Number MUA08A 8-Pin SOIC NS Package Number M08A 17 www.national.com LMV931 Single / LMV932 Dual / LMV934 Quad Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 14-Pin TSSOP NS Package Number MTC14 14-Pin SOIC NS Package Number M14A www.national.com 18 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 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. 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. LMV931 Single / LMV932 Dual / LMV934 Quad 1.8V, RRIO Operational Amplifiers Notes