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| LF444 Quad Low Power JFET Input Operational Amplifier December 1994 LF444 Quad Low Power JFET Input Operational Amplifier General Description The LF444 quad low power operational amplifier provides many of the same AC characteristics as the industry standard LM148 while greatly improving the DC characteristics of the LM148 The amplifier has the same bandwidth slew rate and gain (10 kX load) as the LM148 and only draws one fourth the supply current of the LM148 In addition the well matched high voltage JFET input devices of the LF444 reduce the input bias and offset currents by a factor of 10 000 over the LM148 The LF444 also has a very low equivalent input noise voltage for a low power amplifier The LF444 is pin compatible with the LM148 allowing an immediate 4 times reduction in power drain in many applications The LF444 should be used wherever low power dissipation and good electrical characteristics are the major considerations Features Y Y Y Y Y Y Y Y supply current of a LM148 200 mA Amplifier (max) Low input bias current 50 pA (max) High gain bandwidth 1 MHz High slew rate 1 V ms Low noise voltage for low power 35 nV 0Hz Low input noise current 0 01 pA 0Hz High input impedance 1012X High gain VO e g10V RL e 10k 50k (min) Simplified Schematic Quad Connection Diagram Dual-In-Line Package TL H 9156 - 2 TL H 9156 - 1 Top View Order Number LF444AMD LF444CM LF444ACN LF444CN or LF444MD 883 See NS Package Number D14E M14A or N14A Ordering Information LF444XYZ X indicates electrical grade Y indicates temperature range ``M'' for military ``C'' for commercial Z indicates package type ``D'' ``M'' or ``N'' BI-FETTM and BI-FET IITM are trademarks of National Semiconductor Corporation C1995 National Semiconductor Corporation TL H 9156 RRD-B30M115 Printed in U S A Absolute Maximum Ratings If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications LF444A Supply Voltage Differential Input Voltage Input Voltage Range (Note 1) Output Short Circuit Duration (Note 2) Power Dissipation (Notes 3 and 9) Tj max ijA (Typical) g22V g38V g19V LF444 g18V g30V g15V Operating Temperature Range Storage Temperature Range ESD Tolerance (Note 10) LF444A LF444 (Note 4) b 65 C s TA s 150 C Rating to be determined Continuous D Package 900 mW 150 C 100 C W Continuous N M Packages 670 mW 115 C 85 C W Soldering Information Dual-In-Line Packages (Soldering 10 sec ) 260 C Small Outline Package Vapor Phase (60 sec ) 215 C Infrared (15 sec ) 220 C See AN-450 ``Surface Mounting Methods and Their Effect on Product Reliability'' for other methods of soldering surface mount devices DC Electrical Characteristics (Note 5) LF444A Symbol VOS Parameter Input Offset Voltage Conditions Min RS e 10k TA e 25 C 0 C s TA s a 70 C b 55 C s TA s a 125 C LF444 Units Max 5 65 8 Min Typ 3 Max 10 12 mV mV mV 10 25 15 10 5 50 15 mV C pA nA nA 10 100 3 pA nA nA 1012 25 15 100 X V mV V mV g13 Typ 2 DVOS DT IOS Average TC of Input Offset Voltage Input Offset Current RS e 10 kX VS e g15V (Notes 5 6) Tj e 25 C Tj e 70 C Tj e 125 C 10 5 IB Input Bias Current VS e g15V (Notes 5 6) Tj e 25 C Tj e 70 C Tj e 125 C 10 50 3 20 RIN AVOL Input Resistance Large Signal Voltage Gain Tj e 25 C VS e g15V VO e g10V RL e 10 kX TA e 25 C Over Temperature 50 25 g12 g16 1012 100 VO VCM CMRR PSRR IS Output Voltage Swing Input Common-Mode Voltage Range Common-Mode Rejection Ratio Supply Voltage Rejection Ratio Supply Current VS e g15V RL e 10 kX g13 g12 g11 V V V dB dB 10 mA a 18 b 17 a 14 b 12 RS s 10 kX (Note 7) 80 80 100 100 06 08 70 70 95 90 06 2 AC Electrical Characteristics (Note 5) Symbol Parameter Amplifier-to-Amplifier Coupling SR GBW en in Slew Rate Gain-Bandwidth Product Equivalent Input Noise Voltage Equivalent Input Noise Current VS e g15V TA e 25 C VS e g15V TA e 25 C TA e 25 C RS e 100X f e 1 kHz TA e 25 C f e 1 kHz Conditions Min LF444A Typ b 120 LF444 Max Min Typ b 120 Units Max dB V ms MHz nV 0Hz pA 0Hz 1 1 35 0 01 1 1 35 0 01 Note 1 Unless otherwise specified the absolute maximum negative input voltage is equal to the negative power supply voltage Note 2 Any of the amplifier outputs can be shorted to ground indefinitely however more than one should not be simultaneously shorted as the maximum junction temperature will be exceeded Note 3 For operating at elevated temperature these devices must be derated based on a thermal resistance of ijA Note 4 The LF444A is available in both the commercial temperature range 0 C s TA s 70 C and the military temperature range b 55 C s TA s 125 C The LF444 is available in the commercial temperature range only 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 ``D'' package only Note 5 Unless otherwise specified the specifications apply over the full temperature range and for VS e g20V for the LF444A and for VS e g15V for the LF444 VOS IB and IOS are measured at VCM e 0 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 ijAPD 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 g15V to g5V for the LF444 and from g20V to g5V for the LF444A Note 8 Refer to RETS444X for LF444MD 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 9156 - 3 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 9156 - 4 4 Typical Performance Characteristics Open Loop Voltage Gain (Continued) Inverter Settling Time Output Impedance TL H 9156 - 5 Pulse Response RL e 10 kX Small Signal Inverting CL e 10 pF Small Signal Non-Inverting TL H 9156 - 6 TL H 9156 - 7 Large Signal Inverting Large Signal Non-Inverting TL H 9156 - 8 TL H 9156 - 9 5 Application Hints This device is a quad low power op amp with JFET input devices (BI-FETTM ) 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 amplifiers 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 Each amplifier is individually biased to allow normal circuit operation with power supplies of g3 0V Supply voltages less than these may degrade the common-mode rejection and restrict the output voltage swing The amplifiers will drive a 10 kX load resistance to g10V over the full temperature range 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 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 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 Typical Application pH Probe Amplifier Temperature Compensator For R2 e 50k R4 e 330k g1% For R2 e 100k R4 e 75k g1% For R2 e 200k R4 e 56k g1% Polystyrene Film resistor type RN60C To calibrate insert probe in pH e 7 solution Set the ``TEMPERATURE ADJUST'' pot R2 to correspond to the solution temperature full clockwise for 0 C and proportionately for intermediate temperatures using a turns-counting dial Then set ``CALIBRATE'' pot so output reads 7V Typical probe e Ingold Electrodes 465-35 TL H 9156 - 10 6 Detailed Schematic Quad TL H 9156 - 11 7 8 Physical Dimensions inches (millimeters) Order Number LF444AMD or LF444MD 883 See NS Package Number D14E Order Number LF444CM See NS Package Number M14A 9 LF444 Quad Low Power JFET Input Operational Amplifier Physical Dimensions inches (millimeters) (Continued) Order Number LF444ACN or LF444CN See NS Package Number N14A 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 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 1111 West Bardin Road Arlington TX 76017 Tel 1(800) 272-9959 Fax 1(800) 737-7018 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 Europe Fax (a49) 0-180-530 85 86 Email cnjwge tevm2 nsc com Deutsch Tel (a49) 0-180-530 85 85 English Tel (a49) 0-180-532 78 32 Fran ais Tel (a49) 0-180-532 93 58 Italiano Tel (a49) 0-180-534 16 80 National Semiconductor Hong Kong Ltd 13th Floor Straight Block Ocean Centre 5 Canton Rd Tsimshatsui Kowloon Hong Kong Tel (852) 2737-1600 Fax (852) 2736-9960 National Semiconductor Japan Ltd Tel 81-043-299-2309 Fax 81-043-299-2408 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 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