LMV951 1V, 2.7 MHz, Rail-to-Rail Input and Output Amplifier with Shutdown Option General Description Features The LMV951 amplifier is capable of operating at supply voltages from 0.9V to 3V with guaranteed specs at 1V and 1.8V single supply. (Typical 1.0V supply, unless otherwise noted) n Guaranteed 1V single supply operation n Wide bandwidth n No VOS glitch over the input CMVR n No input IBIAS current reversal over VCM range n Buffered output stage n High output drive capability n Output short circuit — Sink current 35 mA — Source current 45 mA n Rail-to-rail buffered output — @ 600Ω load 32 mV from either rail 12 mV from either rail — @ 2 kΩ load n Temperature range −40˚C to 125˚C The input common mode range extends to both power supply rails without the offset glitch and input bias current phase reversal inherent to most rail to rail input amplifiers. Contrary to a conventional rail to rail output amplifier the LMV951 has a buffered output stage providing an open loop gain which is relatively unaffected by resistive output loading. At 1V supply voltage, the LMV951 is able to source and sink in excess of 35 mA and offers a gain bandwidth product of 2.7 MHz. In shutdown mode the LMV951 consumes less than 50 nA of supply current. Applications n Battery operated systems n Battery monitoring n Supply current monitoring Virtual Ground Circuit Open Loop Gain and Phase 20123145 20123154 © 2006 National Semiconductor Corporation DS201231 www.national.com LMV951 1V, 2.7 MHz, Rail-to-Rail Input and Output Amplifier with Shutdown Option October 2006 LMV951 Absolute Maximum Ratings (Note 1) Current at Input Pin If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Junction Temperature (Note 3) ± 10 mA +150˚C Mounting Temperature Infrared or Convection (20 sec) 235˚C ESD Tolerance (Note 2) Human Body Model 2000V Machine Model Operating Ratings (Note 1) 200V Supply Voltage (V+ – V−) Temperature Range (Note 3) 3.1V ± 0.3V VIN Differential Voltage at Input/Output Pin 0.9V to 3V Thermal Resistance (θJA) (Note 3) V+ +0.3V, V− −0.3V 1V Electrical Characteristics −40˚C to +125˚C Supply Voltage 170˚C/W (Note 4) Unless otherwise specified, all limits guaranteed for at TA = 25˚C, V+ = 1, V− = 0V, VCM = 0.5V, Shutdown = 0V, and RL = 1 MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (Note 5) Typ (Note 6) Max (Note 5) 2.8 3.0 VOS Input Offset Voltage 1.5 TC VOS Input Offset Average Drift 0.15 IB Input Bias Current IOS Input Offset Current CMRR Common Mode Rejection Ratio PSRR VCM AV VOUT Power Supply Rejection Ratio Input Common-Mode Voltage Range Large Signal Voltage Gain Output Voltage Swing High Output Voltage Swing Low IOUT IS SR Output Short Circuit Current (Note 7) Supply Current Slew Rate www.national.com 32 67 55 77 0.1V ≤ VCM ≤ 1V 76 73 85 1V ≤ V+ ≤ 1.8V, VCM = 0.5V 70 67 92 1V ≤ V+ ≤ 3V, VCM = 0.5V 68 65 85 nA nA dB dB CMRR ≥ 67 dB 0 1.2 CMRR ≥ 55 dB 0 1.2 VOUT = 0.1V to 0.9V RL = 600Ω to 0.5V 90 85 106 VOUT = 0.1V to 0.9V RL = 2 kΩ to 0.5V 90 86 112 RL = 600Ω to 0.5V 50 62 25 RL = 2 kΩ to 0.5V 25 36 12 RL = 600Ω to 0.5V 70 85 32 RL = 2 kΩ to 0.5V 35 40 10 Sourcing VO = 0V, VIN(DIFF) = ± 0.2V 20 15 45 Sinking VO = 1V, VIN(DIFF) = ± 0.2V 20 13 35 V dB mV from rail mA Active Mode VSD < 0.4V 370 480 520 Shutdown Mode VSD > 0.6V 0.01 1.0 3.0 (Note 8) 1.4 2 mV µV/˚C 80 85 0.2 0V ≤ VCM ≤ 1V Units µA V/µs (Note 4) LMV951 1V Electrical Characteristics (Continued) Unless otherwise specified, all limits guaranteed for at TA = 25˚C, V+ = 1, V− = 0V, VCM = 0.5V, Shutdown = 0V, and RL = 1 MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (Note 5) Typ (Note 6) Max (Note 5) Units GBWP Gain Bandwidth Product en Input - Referred Voltage Noise f = 1 kHz 2.7 25 nV/ MHz in Input-Referred Current Noise f = 1 kHz 10 pA/ THD Total Harmonic Distortion f = 1 kHz, AV = 1, RL = 1 kΩ 0.02 ISD Shutdown Pin Current Active Mode, VSD = 0V .001 1 Shutdown Mode, VSD = 1V .001 1 VSD Shutdown Pin Voltage Range Active Mode Shutdown Mode 1.8V Electrical Characteristics % 0 0.4 0.6 1 µA V (Note 4) Unless otherwise specified, all limits guaranteed for at TA = 25˚C, V+ = 1.8V, V− = 0V, VCM = 0.9V, Shutdown = 0V, and RL = 1 MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (Note 5) Typ (Note 6) Max (Note 5) 2.8 3.0 VOS Input Offset Voltage 1.5 TC VOS Input Offset Average Drift 0.15 IB Input Bias Current 36 Units mV µV/˚C 80 85 nA IOS Input Offset Current 0.2 nA CMRR Common Mode Rejection Ratio 0V ≤ VCM ≤ 1.8V 82 80 93 dB PSRR Power Supply Rejection Ratio 1V ≤ V+ ≤ 1.8V, VCM = 0.5V 70 67 92 1V ≤ V+ ≤ 3V, VCM = 0.5V 68 65 85 VCM AV VOUT Input Common-Mode Voltage Range Large Signal Voltage Gain Output Voltage Swing High Output Voltage Swing Low IOUT IS Output Short Circuit Current (Note 7) Supply Current dB CMRR ≥ 82 dB −0.2 2 CMRR ≥ 80 dB −0.2 2 VOUT = 0.2 to 1.6V RL = 600Ω to 0.9V 86 83 110 VOUT = 0.2 to 1.6V RL = 2 kΩ to 0.9V 86 83 116 RL = 600Ω to 0.9V 50 60 33 RL = 2 kΩ to 0.9V 25 34 13 RL = 600Ω to 0.9V 80 105 54 RL = 2 kΩ to 0.9V 35 44 17 Sourcing VO = 0V, VIN(DIFF) = ± 0.2V 50 35 85 Sinking VO = 1.8V, VIN(DIFF) = ± 0.2V 45 25 80 dB mV from rail mA Active Mode VSD < 0.5V 570 780 880 Shutdown Mode VSD > 1.3V 0.3 2.2 10 3 V µA www.national.com LMV951 1.8V Electrical Characteristics (Note 4) (Continued) Unless otherwise specified, all limits guaranteed for at TA = 25˚C, V+ = 1.8V, V− = 0V, VCM = 0.9V, Shutdown = 0V, and RL = 1 MΩ. Boldface limits apply at the temperature extremes. Symbol Parameter Conditions Min (Note 5) Typ (Note 6) SR Slew Rate GBWP Gain Bandwidth Product en Input - Referred Voltage Noise f = 1 kHz in Input-Referred Current Noise f = 1 kHz THD Total Harmonic Distortion f = 1 kHz, AV = 1, RL = 1 kΩ 0.02 ISD Shutdown Pin Current Active Mode, VSD = 0V .001 1 Shutdown Mode, VSD = 1.8V .001 1 VSD (Note 8) Max (Note 5) Shutdown Pin Voltage Range Active Mode Shutdown Mode Units 1.4 V/µs 2.8 MHz 25 nV/ 10 pA/ % 0 0.5 1.3 1.8 µA V 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, applicable std. MIL-STD-883, Method 3015.7. Machine Model, applicable std. JESD22-A115-A (ESD MM std. of JEDEC) Field-Induced Charge-Device Model, applicable std. JESD22-C101-C (ESD FICDM std. of JEDEC). Note 3: The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is PD = TJ(MAX) - TA)/θJA. All numbers apply for packages soldered directly onto a PC Board. Note 4: Electrical table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions is very limited self-heating of the device. Note 5: All limits are guaranteed by testing or statistical analysis. Note 6: Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will also depend on the application and configuration. The typical values are not tested and are not guaranteed on shipped production material. Note 7: The short circuit test is a momentary test, the short circuit duration is 1.5 ms Note 8: Number specified is the average of the positive and negative slew rates. Connection Diagram 6-Pin SOT23 20123101 Top View Ordering Information Package 6-Pin SOT23 www.national.com Part Number LMV951MK LMV951MKX Package Marking Transport Media 1k Units Tape and Reel AS3A 3k Units Tape and Reel 4 NSC Drawing MK06A LMV951 Simplified Schematic 20123104 5 www.national.com LMV951 Typical Performance Characteristics Unless otherwise specified, all limits are guaranteed for TA = 25˚C, V+ = 1V, V− = 0V, VCM = V+/2 = VO. Boldface limits apply at the temperature extremes. Supply Current vs. Supply Voltage Supply Current vs. Supply Voltage in Shutdown Mode 20123106 20123105 Supply Current vs. Shutdown Voltage Supply Current vs. Shutdown Voltage 20123108 20123107 Supply Current vs. Shutdown Voltage VOS vs. VCM 20123110 20123109 www.national.com 6 VOS vs. VCM VOS vs. VCM 20123111 20123112 VOS vs. Supply Voltage IBIAS vs. VCM 20123113 20123151 IBIAS vs. VCM IBIAS vs. VCM 20123153 20123152 7 www.national.com LMV951 Typical Performance Characteristics Unless otherwise specified, all limits are guaranteed for TA = 25˚C, V+ = 1V, V− = 0V, VCM = V+/2 = VO. Boldface limits apply at the temperature extremes. (Continued) LMV951 Typical Performance Characteristics Unless otherwise specified, all limits are guaranteed for TA = 25˚C, V+ = 1V, V− = 0V, VCM = V+/2 = VO. Boldface limits apply at the temperature extremes. (Continued) Sourcing Current vs. Supply Voltage Sinking Current vs Supply Voltage 20123114 20123115 Sourcing Current vs. Output Voltage Sinking Current vs. Output Voltage 20123116 20123117 Sourcing Current vs. Output Voltage Sinking Current vs. Output Voltage 20123118 www.national.com 20123119 8 Sourcing Current vs. Output Voltage Sinking Current vs. Output Voltage 20123120 20123121 Positive Output Swing vs. Supply Voltage Negative Output Swing vs. Supply Voltage 20123122 20123123 Positive Output Swing vs. Supply Voltage Negative Output Swing vs. Supply Voltage 20123125 20123124 9 www.national.com LMV951 Typical Performance Characteristics Unless otherwise specified, all limits are guaranteed for TA = 25˚C, V+ = 1V, V− = 0V, VCM = V+/2 = VO. Boldface limits apply at the temperature extremes. (Continued) LMV951 Typical Performance Characteristics Unless otherwise specified, all limits are guaranteed for TA = 25˚C, V+ = 1V, V− = 0V, VCM = V+/2 = VO. Boldface limits apply at the temperature extremes. (Continued) Open Loop Gain and Phase with Capacitive Load Open Loop Gain and Phase with Resistive Load 20123127 20123126 Open Loop Gain and Phase with Capacitive Load Open Loop Gain and Phase with Resistive Load 20123129 20123128 Open Loop Gain and Phase with Capacitive Load Open Loop Gain and Phase with Resistive Load 20123130 www.national.com 20123131 10 Small Signal Transient Response, AV = +1 Large Signal Transient Response, AV = +1 20123133 20123132 Small Signal Transient Response, AV = +1 Large Signal Transient Response, AV = +1 20123134 20123135 Small Signal Transient Response, AV = +1 Large Signal Transient Response, AV = +1 20123136 20123137 11 www.national.com LMV951 Typical Performance Characteristics Unless otherwise specified, all limits are guaranteed for TA = 25˚C, V+ = 1V, V− = 0V, VCM = V+/2 = VO. Boldface limits apply at the temperature extremes. (Continued) LMV951 Typical Performance Characteristics Unless otherwise specified, all limits are guaranteed for TA = 25˚C, V+ = 1V, V− = 0V, VCM = V+/2 = VO. Boldface limits apply at the temperature extremes. (Continued) Phase Margin vs. Capacitive Load (stability) Phase Margin vs. Capacitive Load (stability) 20123138 20123139 Phase Margin vs. Capacitive Load (stability) PSRR vs. Frequency 20123140 20123141 CMRR vs. Frequency Input Referenced Voltage Noise vs. Frequency 20123143 20123142 www.national.com 12 THD+N vs. Frequency THD+N vs. Frequency 20123147 20123148 THD+N vs. Frequency Closed Loop Output Impedance vs. Frequency 20123155 20123149 13 www.national.com LMV951 Typical Performance Characteristics Unless otherwise specified, all limits are guaranteed for TA = 25˚C, V+ = 1V, V− = 0V, VCM = V+/2 = VO. Boldface limits apply at the temperature extremes. (Continued) LMV951 Application Information CIRCUIT DESCRIPTION AND ADVANTAGE OF THE LMV951 The LMV951 utilizes an internal voltage generator which allows for rail to rail input and output operation from 1 to 3V supplies. An internal switching frequency between 10 MHz and 15 MHz is used for generating the internal voltages. The bipolar input stage provides rail to rail input operation with no input bias current phase reversal and a constant input offset voltage over the entire input common mode range. The CMOS output stage provides a gain that is virtually independent of resistive loads and an output drive current in excess of 35 mA at 1V. A further benefit of the output stage is that the LMV951 is stable in positive unity gain at capacitive loads in excess of 1000 pF. 20123156 FIGURE 1. Snubber Network to Improve Phase Margin The chart below gives recommended values for some common values of large capacitors. For these values RL = 2 kΩ; Battery Operated Systems The maximum operating voltage is 3V and the operating characteristics are guaranteed down to 1V which makes the LMV951 an excellent choice for battery operated systems using one or two NiCd or NiMH cells. The LMV951 is also functional at 0.9V making it an appropriate choice for a single cell alkaline battery. CL RS CS 500 pF 330Ω 6800 pF 680 pF 270Ω 8200 pF 1000 pF 220Ω .015 µF Shutdown Capability While in shutdown mode, the LMV951 typically consumes less than 50 nA of supply current making it ideal for power conscious applications. Full functionality is restored within 3 µs of enable. Small Size The small footprint of the LMV951 package is ideal for high density board systems. By using the small 6-Pin SOT23 package, the amplifier can be placed closer to the signal source, reducing noise pickup and increasing signal integrity. Power Supply Bypassing As in any high performance IC, proper power supply bypassing is necessary for optimizing the performance of the LMV951. The internal voltage generator needs proper bypassing for optimum operation. A surface mount ceramic .01 µF capacitor must be located as close as possible to the V+ and V− pins (pins 2 and 6). This capacitor needs to have low ESR and a self resonant frequency above 15 MHz. A small tantalum or electrolytic capacitor with a value between 1 µF and 10 µF also needs to be located close to the LMV951. 20123160 FIGURE 2. 1000 pF and no Snubber DRIVING CAPACITIVE LOAD The unity gain follower is the most sensitive op amp configuration to capacitive loading; the LMV951 can drive up to 10,000 pF in this configuration without oscillation. If the application requires a phase margin greater than those shown in the datasheet graphs, a snubber network is recommended. The snubber offers the advantage of reducing the output signal ringing while maintaining the output swing which ensures a wider dynamic range; this is especially important at lower supply voltages. 20123161 FIGURE 3. 1000 pF with Snubber www.national.com 14 Some applications may benefit from doubling the voltage across the load. With V+ = 1V a bridge configuration can provide a 2 VPP output to the load with a resistance as low as 300Ω. The output stage of the LMV951 enables it to drive a load of 120Ω and still swing at least 70% of the supply rails. Resistor values have been selected to keep the current consumption to a minimum and voltage errors due to bias currents negligible. Using the selected resistor values makes this circuit quite practical in a battery operated design. R1, R2 and R5, R6 set up a virtual ground that is half of V+. Note that the accuracy of the resistor values will establish how well the two virtual grounds match. Any errors in the virtual grounds will show as current across RL when there is no input signal. The bridge configuration shown in Figure 4 enables the amplifier to maintain a low dropout voltage thus maximizing its dynamic range. It has been configured in a gain of 1 and uses the fewest number of parts. AC coupling the input signal sets the DC bias point of this signal to the virtual ground of the circuit. Using the large resistor values with a 1 µF capacitor (C1) sets the frequency rolloff of this circuit below 10 Hz. (Continued) BRIDGE CONFIGURATION AMPLIFIER 20123144 FIGURE 4. Bridge Amplifier • C2 and C3 are .01 µF ceramic capacitors that must be located as close as possible to pin 6, the V+ pin. As covered in the power supply bypassing section these capacitors must have low ESR and a self resonant frequency above 15 MHz. • C4 is a 1 µF tantalum or electrolytic capacitor that should also be located close to the supply pin. • To use the shutdown feature tie pin 5 of the two parts together and connect through a 470 kΩ resistor to V+. Add a switch between pin 5 and ground. Closing the switch keeps the parts in the active mode, opening the switch sets the parts in the shutdown mode without adding any additional current to V+. R3 and R4 are used to set the voltage of the virtual ground. To maintain low noise the values should be between 1 kΩ and 10 kΩ. C1 and C2 provide the recommended bypassing for the LMV951. These caps must be placed as close as possible to pins 2 and 6. TWO WIRE LINE TRANSMISSION The robust output stage of the LMV951 makes it an excellent choice for driving long cables. The circuit shown below in Figure 5 can drive a long cable using only two wires; power and ground. When many sensors are located remotely from the control area the wiring becomes a significant expense. Using only two wires helps minimize the wiring expense in a large project such as an industrial plant. Figure 6 shows a 25 kHz signal after passing though 1000 ft. of twisted pair cable. Figure 7 shows a 200 kHz signal after passing through 50 ft. of twisted pair cable. VIRTUAL GROUND CIRCUIT The front page of this data sheet shows the LMV951 being used in a system establishing a virtual ground. Having a buffered output stage gives this part the ability to handle load currents higher than 35 mA at 1V. 15 www.national.com LMV951 Application Information LMV951 Application Information (Continued) 20123157 FIGURE 5. Two Wire Line Driver 20123159 FIGURE 6. 25 kHz Through 1000 ft. 20123158 FIGURE 7. 200 kHz Through 50 ft. the correct DC operating point at the input of A1. C4 along with R5 and R6 are used to setup the correct DC operating point for A2. C1, C3, and C4 have been selected to give about a 20% droop with a 1 kHz square wave input. The power supply of 3V is recommended to power this system. A1 and A2 are set up as unity gain buffers. It is easy to configure A1 with the required gain if a gain of greater than one is required. C1 along with R1 and R2 are used to ensure www.national.com 16 inches (millimeters) unless otherwise noted 6-Pin SOT23 NS Package Number MK06A 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. 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