LF441 Low Power JFET Input Operational Amplifier General Description The LF441 low power operational amplifier provides many of the same AC characteristics as the industry standard LM741 while greatly improving the DC characteristics of the LM741. The amplifier has the same bandwidth, slew rate, and gain (10 kX load) as the LM741 and only draws one tenth the supply current of the LM741. In addition, the well matched high voltage JFET input devices of the LF441 reduce the input bias and offset currents by a factor of 10,000 over the LM741. A combination of careful layout design and internal trimming guarantees very low input offset voltage and voltage drift. The LF441 also has a very low equivalent input noise voltage for a low power amplifier. The LF441 is pin compatible with the LM741, allowing an immediate 10 times reduction in power drain in many applications. The LF441 should be used where low power dissipation and good electrical characteristics are the major considerations. Typical Connection Ordering Information Features Y Y Y Y Y Y Y Y Y Y 1/10 supply current of a LM741 Low input bias current Low input offset voltage Low input offset voltage drift High gain bandwidth High slew rate Low noise voltage for low power Low input noise current High input impedance High gain VO e g 10V, RL e 10k 200 mA (max) 50 pA (max) 0.5 mV (max) 10 mV/§ C (max) 1 MHz 1 V/ms 35 nV/ SHz 0.01 pA/ SHz 1012X 50k (min) LF441XYZ X indicates electrical grade Y indicates temperature range ‘‘M’’ for military, ‘‘C’’ for commercial Z indicates package type ‘‘H’’ or ‘‘N’’ TL/H/9297 – 1 Connection Diagrams Dual-In-Line Package Metal Can Package TL/H/9297 – 2 Top View Note: Pin 4 connected to case. Order Number LF441MH/883 See NS Package Number H08A TL/H/9297 – 4 Top View Order Number LF441ACN, LF441CM or LF441CN See NS Package Number M08A or N08E BI-FETTM is a trademark of National Semiconductor Corporation. C1995 National Semiconductor Corporation TL/H/9297 RRD-B30M115/Printed in U. S. A. LF441 Low Power JFET Input Operational Amplifier February 1995 Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. LF441A LF441 Supply Voltage g 22V g 18V Differential Input Voltage g 38V g 30V Operating Temp. Range Storage Temp. Range Lead Temperature (Soldering, 10 seconds) Soldering Information Dual-In-Line Package Soldering (10 sec.) Small Outline Package Vapor Phase (60 sec.) Infrared (15 sec.) LF441 g 19V g 15V Output Short Circuit Duration Continuous Continuous H Package N Package 670 mW 670 mW 150§ C 115§ C 130§ C/W Power Dissipation (Notes 2 and 9) Tj max ijA(Typical) Board Mount in still air Board Mount in 400 LF/ min air flow ijC LF441A Input Voltage Range (Note 1) M Package 185§ C/W 165§ C/W 65§ C/W 25§ C/W (Note 3) b 65§ C s TA s 150§ C 300§ C LF441A LF441 260§ C 260§ C 215§ C 220§ C 215§ C 220§ C (Note 3) b 65§ C s TA s 150§ C 260§ C See AN-450 ‘‘Surface Mounting Methods and Their Effect on Product Reliability’’ for other methods of soldering surface mount devices. ESD Tolerance (Note 10) Rating to be Determined DC Electrical Characteristics (Note 4) Symbol Parameter LF441A Conditions Min VOS Input Offset Voltage RS e 10 kX, TA e 25§ C DVOS/DT Average TC of Input Offset Voltage RS e 10 kX (Note 5) IOS Input Offset Current VS e g 15V (Notes 4 and 6) LF441 Typ Max 0.3 0.5 Min Max 1 5 mV 7.5 mV Over Temperature IB Input Bias Current VS e g 15V (Notes 4 and 6) Tj e 25§ C 7 10 10 5 25 5 Tj e 70§ C 1.5 Tj e 125§ C 10 Tj e 25§ C 10 Tj e 70§ C 50 10 Tj e 25§ C AVOL Large Signal Voltage Gain VS e g 15V, VO e g 10V, RL e 10 kX, TA e 25§ C VO Output Voltage Swing VCM Input Common-Mode Voltage Range CMRR Common-Mode Rejection Ratio Over Temperature 50 g 12 g 16 RS s 10 kX 80 2 pA 1.5 nA 100 pA 3 nA nA 100 25 g 13 g 12 25 VS e g 15V, RL e 10 kX 50 20 1012 Input Resistance mV/§ C nA 3 Tj e 125§ C RIN Units Typ 1012 X 100 V/mV 15 a 18, b 17 100 g 11 70 V/mV g 13 a 14, b 12 95 V V dB DC Electrical Characteristics (Note 4) (Continued) Symbol Parameter PSRR Supply Voltage Rejection Ratio IS Supply Current LF441A Conditions (Note 7) Min Typ 80 100 150 LF441 Max Min Typ 70 90 200 150 Units Max dB 250 mA AC Electrical Characteristics (Note 4) Symbol Parameter LF441A Conditions Min Typ LF441 Max Min Typ Units Max SR Slew Rate VS e g 15V, TA e 25§ C 0.8 1 0.6 1 V/ms GBW Gain-Bandwidth Product VS e g 15V, TA e 25§ C 0.8 1 0.6 1 MHz en Equivalent Input Noise Voltage TA e 25§ C, RS e 100X, f e 1 kHz in Equivalent Input Noise Current TA e 25§ C, f e 1 kHz 35 35 nV/0Hz 0.01 0.01 pA/0Hz Note 1: Unless otherwise specified the absolute maximum negative input voltage is equal to the negative power supply voltage. Note 2: For operating at elevated temperature, these devices must be derated based on a thermal resistance of ijA. Note 3: The temperature range is designated by the position just before the package type in the device number. A ‘‘C’’ indicates the commercial temperature range and an ‘‘M’’ indicates the military temperature range. The military temperature range is available in ‘‘H’’ package only. Note 4: Unless otherwise specified the specifications apply over the full temperature range and for VS e g 20V for the LF441A and for VS e g 15V for the LF441. VOS, IB, and IOS are measured at VCM e 0. Note 5: The LF441A is 100% tested to this specification. Note 6: The input bias currents are junction leakage currents which approximately double for every 10§ C increase in the junction temperature, Tj. Due to limited production test time, the input bias currents measured are correlated to junction temperature. In normal operation the junction temperature rises above the ambient temperature as a result of internal power dissipation, PD. Tj e TA a ijA PD where ijA is the thermal resistance from junction to ambient. Use of a heat sink is recommended if input bias current is to be kept to a minimum. Note 7: Supply voltage rejection ratio is measured for both supply magnitudes increasing or decreasing simultaneously in accordance with common practice. From g 15V to g 5V for the LF441 and from g 20V to g 5V for the LF441A. Note 8: Refer to RETS441X for LF441MH military specifications. Note 9: Max. Power Dissipation is defined by the package characteristics. Operating the part near the Max. Power Dissipation may cause the part to operate outside guaranteed limits. Note 10: Human body model, 1.5 kX in series with 100 pF. Typical Performance Characteristics Input Bias Current Input Bias Current Supply Current Positive Common-Mode Input Voltage Limit Negative Common-Mode Input Voltage Limit Positive Current Limit TL/H/9297 – 5 3 Typical Performance Characteristics (Continued) Negative Current Limit Output Voltage Swing Output Voltage Swing Gain Bandwidth Bode Plot Slew Rate Distortion vs Frequency Undistorted Output Voltage Swing Open Loop Frequency Response Common-Mode Rejection Ratio Power Supply Rejection Ratio Equivalent Input Noise Voltage TL/H/9297 – 6 4 Typical Performance Characteristics (Continued) Open Loop Voltage Gain Output Impedance Inverter Settling Time TL/H/9297 – 7 Simplified Schematic TL/H/9297 – 3 Pulse Response RL e 10 kX, CL e 10 pF Small Signal Inverting TL/H/9297 – 8 5 Pulse Response RL e 10 kX, CL e 10 pF (Continued) Small Signal Non-Inverting TL/H/9297 – 9 Large Signal Inverting TL/H/9297 – 10 Large Signal Non-Inverting TL/H/9297 – 11 6 Application Hints The amplifier will drive a 10 kX load resistance to g 10V over the full temperature range. Precautions should be taken to ensure that the power supply for the integrated circuit never becomes reversed in polarity or that the unit is not inadvertently installed backwards in a socket, as an unlimited current surge through the resulting forward diode within the IC could cause fusing of the internal conductors and result in a destroyed unit. As with most amplifiers, care should be taken with lead dress, component placement and supply decoupling in order to ensure stability. For example, resistors from the output to an input should be placed with the body close to the input to minimize ‘‘pick-up’’ and maximize the frequency of the feedback pole by minimizing the capacitance from the input to ground. A feedback pole is created when the feedback around any amplifier is resistive. The parallel resistance and capacitance from the input of the device (usually the inverting input to AC ground) set the frequency of this pole. In many instances the frequency of this pole is much greater than the expected 3 dB frequency, of the closed loop gain and consequently there is negligible effect on stability margin. However, if the feedback pole is less than approximately 6 times the expected 3 dB frequency, a lead capacitor should be placed from the output to the input of the op amp. The value of the added capacitor should be such that the RC time constant of this capacitor and the resistance it parallels is greater than or equal to the original feedback pole time constant. This device is a low power op amp with an internally trimmed input offset voltage and JFET input devices (BI-FET II). These JFETs have large reverse breakdown voltages from gate to source and drain, eliminating the need for clamps across the inputs. Therefore, large differential input voltages can easily be accommodated without a large increase in input current. The maximum differential input voltage is independent of the supply voltages. However, neither of the input voltages should be allowed to exceed the negative supply as this will cause large currents to flow which can result in a destroyed unit. Exceeding the negative common-mode limit on either input will force the output to a high state, potentially causing a reversal of phase to the output. Exceeding the negative common-mode limit on both inputs will force the amplifier output to a high state. In neither case does a latch occur since raising the input back within the common-mode range again puts the input stage and thus the amplifier in a normal operating mode. Exceeding the positive common-mode limit on a single input will not change the phase of the output; however, if both inputs exceed the limit, the output of the amplifier will be forced to a high state. The amplifier will operate with a common-mode input voltage equal to the positive supply; however, the gain bandwidth and slew rate may be decreased in this condition. When the negative common-mode voltage swings to within 3V of the negative supply, an increase in input offset voltage may occur. The amplifier is biased to allow normal circuit operation with power supplies of g 3V. Supply voltages less than these may degrade the common-mode rejection and restrict the output voltage swing. Detailed Schematic TL/H/9297 – 13 7 8 Physical Dimensions inches (millimeters) Metal Can Package (H) Order Number LF441MH/883 NS Package Number H08A Dual-In-Line Package(M) Order Number LF441CM NS Package Number M08A 9 LF441 Low Power JFET Input Operational Amplifier Physical Dimensions inches (millimeters) (Continued) Molded Dual-In-Line Package (N) Order Number LF441ACN or LF441CN NS Package Number N08E 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 OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. 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