TL081 Wide Bandwidth JFET Input Operational Amplifier General Description The TL081 is a low cost high speed JFET input operational amplifier with an internally trimmed input offset voltage (BI-FET IITM technology). The device requires a low supply current and yet maintains a large gain bandwidth product and a fast slew rate. In addition, well matched high voltage JFET input devices provide very low input bias and offset currents. The TL081 is pin compatible with the standard LM741 and uses the same offset voltage adjustment circuitry. This feature allows designers to immediately upgrade the overall performance of existing LM741 designs. The TL081 may be used in applications such as high speed integrators, fast D/A converters, sample-and-hold circuits and many other circuits requiring low input offset voltage, low input bias current, high input impedance, high slew rate and wide bandwidth. The devices has low noise and offset voltage drift, but for applications where these requirements are critical, the LF356 is recommended. If maximum supply current is important, however, the TL081C is the better choice. Features Y Y Y Y Y Y Y Y Y Y Y Internally trimmed offset voltage Low input bias current Low input noise voltage Low input noise current Wide gain bandwidth High slew rate Low supply current High input impedance Low total harmonic distortion AV e 10, RL e 10k, VO e 20 Vp-p, BW e 20 Hzb20 kHz Low 1/f noise corner Fast settling time to 0.01% 15 mV 50 pA 25 nV/0Hz 0.01 pA/0Hz 4 MHz 13 V/ms 1.8 mA 1012X k 0.02% 50 Hz 2 ms Simplified Schematic Typical Connection TL/H/8358 – 1 Connection Diagram TL/H/8358 – 2 Dual-In-Line Package TL/H/8358 – 4 Order Number TL081CP See NS Package Number N08E BI-FET IITM is a trademark of National Semiconductor Corp. C1995 National Semiconductor Corporation TL/H/8358 RRD-B30M125/Printed in U. S. A. TL081 Wide Bandwidth JFET Input Operational Amplifier December 1995 Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Supply Voltage g 18V Power Dissipation (Notes 1 and 6) Operating Temperature Range Tj(MAX) Differential Input Voltage Input Voltage Range (Note 2) g 15V Output Short Circuit Duration Continuous Storage Temperature Range b 65§ C to a 150§ C Lead Temp. (Soldering, 10 seconds) ijA 670 mW 0§ C to a 70§ C 115§ C g 30V 260§ C 120§ C/W ESD rating to be determined. DC Electrical Characteristics (Note 3) Symbol Parameter TL081C Conditions Min Units Typ Max 5 15 20 VOS Input Offset Voltage RS e 10 kX, TA e 25§ C Over Temperature DVOS/DT Average TC of Input Offset Voltage RS e 10 kX IOS Input Offset Current Tj e 25§ C, (Notes 3, 4) Tj s 70§ C 25 100 4 pA nA IB Input Bias Current Tj e 25§ C, (Notes 3, 4) Tj s 70§ C 50 200 8 pA nA RIN Input Resistance Tj e 25§ C Large Signal Voltage Gain VS e g 15V, TA e 25§ C VO e g 10V, RL e 2 kX 25 Over Temperature 15 AVOL VO Output Voltage Swing VCM Input Common-Mode Voltage Range CMRR VS e g 15V, RL e 10 kX 10 mV mV mV/§ C 1012 X 100 V/mV V/mV g 12 g 13.5 V VS e g 15V g 11 a 15 b 12 V V Common-Mode Rejection Ratio RS s 10 kX 70 100 dB PSRR Supply Voltage Rejection Ratio (Note 5) 70 100 IS Supply Current 1.8 dB 2.8 mA AC Electrical Characteristics (Note 3) Symbol Parameter TL081C Conditions Min Typ Units Max SR Slew Rate VS e g 15V, TA e 25§ C 13 V/ms GBW Gain Bandwidth Product VS e g 15V, TA e 25§ C 4 MHz en Equivalent Input Noise Voltage TA e 25§ C, RS e 100X, f e 1000 Hz 25 nV/0Hz in Equivalent Input Noise Current Tj e 25§ C, f e 1000 Hz 0.01 pA/0Hz Note 1: For operating at elevated temperature, the device must be derated based on a thermal resistance of 120§ C/W junction to ambient for N package. Note 2: Unless otherwise specified the absolute maximum negative input voltage is equal to the negative power supply voltage. Note 3: These specifications apply for VS e g 15V and 0§ C s TA s a 70§ C. VOS, IB and IOS are measured at VCM e 0. Note 4: The input bias currents are junction leakage currents which approximately double for every 10§ C increase in the junction temperature, Tj. Due to the 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 5: Supply voltage rejection ratio is measured for both supply magnitudes increasing or decreasing simultaneously in accordance with common practice from VS e g 5V to g 15V. Note 6: 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. 2 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 Negative Current Limit Voltage Swing Output Voltage Swing Gain Bandwidth Bode Plot Slew Rate TL/H/8358 – 5 3 Typical Performance Characteristics Distortion vs Frequency (Continued) Undistorted Output Voltage Swing Common-Mode Rejection Ratio Power Supply Rejection Ratio Open Loop Voltage Gain (V/V) Output Impedance Open Loop Frequency Response Equivalent Input Noise Voltage Inverter Settling Time TL/H/8358 – 6 4 Pulse Response Small Signal Inverting Small Signal Non-Inverting TL/H/8358 – 7 TL/H/8358 – 13 Large Signal Inverting Large Signal Non-Inverting TL/H/8358 – 14 TL/H/8358 – 15 Current Limit (RL e 100X) TL/H/8358 – 16 Application Hints 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 The TL081 is an 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 5 Application Hints (Continued) resulting forward diode within the IC could cause fusing of the internal conductors and result in a destroyed unit. 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 TL081 is biased by a zener reference which allows normal circuit operation on g 4V power supplies. Supply voltages less than these may result in lower gain bandwidth and slew rate. The TL081 will drive a 2 kX load resistance to g 10V over the full temperature range of 0§ C to a 70§ C. If the amplifier is forced to drive heavier load currents, however, an increase in input offset voltage may occur on the negative voltage swing and finally reach an active current limit on both positive and negative swings. 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 Because these amplifiers are JFET rather than MOSFET input op amps they do not require special handling. 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 the 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. Detailed Schematic TL/H/8358 – 8 6 Typical Applications Supply Current Indicator/Limiter Hi-ZIN Inverting Amplifier TL/H/8358 – 9 TL/H/8358 – 10 # VOUT switches high when RSIS l VD Parasitic input capacitance C1 j (3 pF for TL081 plus any additional layout capacitance) interacts with feedback elements and creates undesirable high frequency pole. To compensate, add C2 such that: R2C2 j R1C1. Ultra-Low (or High) Duty Cycle Pulse Generator Long Time Integrator TL/H/8358–11 # tOUTPUT HIGH & R1C fin 4.8 b 2VS 4.8 b VS TL/H/8358 – 12 * Low leakage capacitor 2V b 7.8 # tOUTPUT LOW & R2C fin S VS b 7.8 # 50k pot used for less sensitive VOS adjust where VS e V a a l Vb l *low leakage capacitor 7 TL081 Wide Bandwidth JFET Input Operational Amplifier Physical Dimensions inches (millimeters) Molded Dual-In-Line Package (N) Order Number TL081CP 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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