LT1012IN8

LT1012A/LT1012 Picoamp Input Current, Microvolt Offset, Low Noise Op Amp DESCRIPTIO The LT ®1012 is an internally compensated universal precision operational amplifier which can be used in practically all precision applications. The LT1012 combines picoampere bias currents (which are maintained over the full –55°C to 125°C temperature range), microvolt offset voltage (and low drift with time and temperature), low voltage and current noise, and low power dissipation. The LT1012 achieves precision operation on two Ni-Cad batteries with 1mW of power dissipation. Extremely high common mode and power supply rejection ratios, practically unmeasurable warm-up drift, and the ability to deliver 5mA load current with a voltage gain of one million round out the LT1012’s superb precision specifications. The all around excellence of the LT1012 eliminates the necessity of the time consuming error analysis procedure of precision system design in many applications; the LT1012 can be stocked as the universal internally compensated precision op amp. , LTC and LT are registered trademarks of Linear Technology Corporation. Protected by U. S. patents 4,575,685 and 4,775,884 FEATURES s s s s s s s s s OP-07 Type Performance: at 1/8th of OP-07’s Supply Current at 1/20th of OP-07’s Bias and Offset Currents Guaranteed Offset Voltage: 25µV Max Guaranteed Bias Current: 100pA Max Guaranteed Drift: 0.6µV/°C Max Low Noise, 0.1Hz to 10Hz: 0.5µVP-P Guaranteed Low Supply Current: 500µA Max Guaranteed CMRR: 114dB Min Guaranteed PSRR: 114dB Min Guaranteed Operation at ±1.2V Supplies APPLICATIO S s s s s s s s Replaces OP-07 While Saving Power Precision Instrumentation Charge Integrators Wide Dynamic Range Logarithmic Amplifiers Light Meters Low Frequency Active Filters Thermocouple Amplifiers TYPICAL APPLICATIO R1 1M –IN 3 R2 20k 2 R3 1M +IN 7 6 4 R5 975k ± 250V Common Mode Range Instrumentation Amplifier (AV = 1) 200 Typical Distribution of Input Offset Voltage 1140 UNITS FROM THREE RUNS VS = ±15V TA = 25°C VCM = 0V 1 6V TO 18V R6 25k 2 6 LT1012 3 OUT R1 TO R6: VISHAY 444 ACCUTRACT THIN FILM SIP NETWORK X : VISHAY 444 PIN NUMBERS VISHAY INTERTECHNOLOGY, INC 63 LINCOLN HIGHWAY MALVERN, PA 19355 50k OPTIONAL CMRR TRIM 160 – + 7 NUMBER OF UNITS 120 COMMON MODE INPUT ± 250V 4 80 5 R4 19.608k – 6V TO –18V 40 0 –40 COMMON MODE REJECTION RATIO = 74dB (RESISTOR LIMITED) WITH OPTIONAL TRIM = 130dB OUTPUT OFFSET (TRIMMABLE TO ZERO) = 500µV OUTPUT OFFSET DRIFT = 10µV/°C INPUT RESISTANCE = 1M LT1012A • TA01 U U U 20 40 –20 0 INPUT OFFSET VOLTAGE (µV) LT1012A • TA02 sn1012 1012afbs 1 LT1012A/LT1012 ABSOLUTE AXI U RATI GS Supply Voltage ...................................................... ± 20V Differential Input Current (Note 1) ...................... ± 10mA Input Voltage ......................................................... ± 20V Output Short Circuit Duration .......................... Indefinite PACKAGE/ORDER I FOR ATIO TOP VIEW VOS TRIM –IN +IN V– 1 2 3 4 – + 8 7 6 5 VOS TRIM V+ OUT OVER COMP VOS TRIM 1 –IN 2 +IN 3 S8 PACKAGE 8-LEAD PLASTIC SO TJMAX = 100°C, θJA = 170°C/W H PACKAGE 8-LEAD TO-5 METAL CAN TJMAX = 150°C, θJA = 150°C/W, θJC = 45°C/W ORDER PART NUMBER LT1012S8 LT1012IS8 LT1012ACS8 LT1012AIS8 S8 PART MARKING 1012 1012I 1012A 1012AI ORDER PART NUMBER LT1012AMH LT1012MH LT1012ACH LT1012CH LT1012DH OBSOLETE PACKAGE Consider the S8 or N8 Packages for Alternate Source Consult LTC Marketing for parts specified with wider operating temperature ranges. 2 U U W WW U W (Note 1) Operating Temperature Range LT1012AM/LT1012M (OBSOLETE)....– 55°C to 125°C LT1012I/LT1012AI ............................. – 40°C to 85°C LT1012AC/LT1012C LT1012D/LT1012S8 ................................ 0°C to 70°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C TOP VIEW VOS TRIM 8 – + 4 TOP VIEW 7V + VOS TRIM –IN +IN V– 1 2 3 4 N8 PACKAGE 8-LEAD PDIP – + 8 7 6 5 VOS TRIM V+ OUT OVER COMP 6 OUT 5 OVER COMP – (CASE) V TJMAX = 100°C, θJA = 130°C/W ORDER PART NUMBER LT1012ACN8 LT1012AIN8 LT1012CN8 LT1012DN8 LT1012IN8 sn1012 1012afbs LT1012A/LT1012 ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER VOS Input Offset Voltage (Note 3) Long Term lnput Offset Voltage Stability IOS IB en en in AVOL CMRR PSRR Input Offset Current (Note 3) Input Bias Current (Note 3) Input Noise Voltage Input Noise Voltage Density Input Noise Current Density Large Signal Voltage Gain Common Mode Rejection Ratio 0.1Hz to 10Hz fO = 10Hz (Note 4) fO = 1000Hz (Note 5) fO = 10Hz VOUT = ±12V, RL ≥ 10kΩ VOUT = ±10V, RL ≥ 2kΩ VCM = ±13.5V CONDITIONS VS = ± 15V, VCM = OV, TA = 25°C, unless otherwise noted. LT1O12AM/AC/AI MIN TYP MAX 8 20 0.3 15 25 ± 25 ± 35 0.5 17 14 20 300 300 114 114 ±13.5 ±13 0.1 2000 1000 132 132 ±14 ±14 0.2 370 380 500 600 300 200 114 114 ±13.5 ±13 0.1 30 22 100 150 ±100 ±150 25 90 MIN LT1O12M/I TYP MAX 8 20 0.3 15 25 ± 25 ± 35 0.5 17 14 20 2000 1000 132 132 ±14 ±14 0.2 380 380 600 200 200 110 110 ±13.5 ±13 0.1 30 22 100 150 ±100 ±150 35 90 MIN LT1O12C TYP MAX 10 25 0.3 20 30 ± 30 ± 40 0.5 17 14 20 2000 1000 132 132 ±14 ±14 0.2 380 380 600 30 22 150 200 ±150 ±200 50 120 UNITS µV µV µV/month pA pA pA pA µVP-P nV√Hz nV√Hz fA/√Hz V/mV V/mV dB dB V V V/µs µA µA Power SuppIy Rejection Ratio VS = ±1.2V to ±20V Input Voltage Range RL = 10kΩ VOUT Output Voltage Swing Slew Rate IS Supply Current (Note 3) sn1012 1012afbs 3 LT1012A/LT1012 ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER VOS Input Offset Voltage (Note 3) Long Term Input Offset Voltage Stability lOS IB en en in AVOL CMRR PSRR Input Offset Current (Note 3) Input Bias Current (Note 3) Input Noise Voltage Input Noise Voltage Density lnput Noise Current Density Large-Signal Voltage Gain 0.1Hz to 10Hz fO = 10Hz (Note 5) fO = 1000Hz (Note 5) fO = 10Hz VOUT = ±12V,RL ≥ 10kΩ VOUT = ±10V,RL ≥ 2kΩ VS = ±1.2V to ± 20V RL = 10kΩ CONDITIONS VS = ± 15V, VCM = 0V, TA = 25°C, unless otherwise noted. MIN LT1012D TYP 12 25 0.3 20 30 ± 30 ± 40 0.5 17 14 20 200 200 110 110 ±13.5 ±13 0.1 2000 1000 132 132 ±14.0 ±14 0.2 380 600 200 120 110 110 ±13.5 ±13 0.1 30 22 150 ± 150 MAX 60 MIN LT1012S8 TYP 15 25 0.4 50 60 ± 80 ±120 0.5 17 14 20 2000 1000 132 132 ±14.0 ±14 0.2 380 600 30 22 280 380 ± 300 ± 400 MAX 120 180 UNITS µV µV µV/month pA pA pA pA µVP-P nV√Hz nV√Hz fA/√Hz V/mV V/mV dB dB V V V/µs µA Common Mode Rejection Ratio VCM = ±13.5V Power Supply Rejection Ratio Input Voltage Range VOUT Output Voltage Swing Slew Rate IS Supply Current (Note 3) sn1012 1012afbs 4 LT1012A/LT1012 ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER VOS Input Offset Voltage (Note 3) Average Temperature Coefficient of Input Offset Voltage IOS Input Offset Current (Note 3) Average Temperature Coefficient of Input Offset Current IB Input Bias Current (Note 3) Average Temperature Coefficient of Input Bias Current AVOL CMRR PSRR Large-Signal Voltage Gain Common Mode Rejection Ratio Power Supply Rejection Ratio Input Voltage Range VOUT IS Output Voltage Swing Supply Current RL = 10kΩ The q denotes the specifications which apply over the full operating temperature range of –55°C ≤ TA ≤ 125°C for LT1012AM and LT1012M, and –40°C ≤ TA≤ 85°C for LT1012AI and LT1012I. VS = ± 15V, VCM = 0V, unless otherwise noted. CONDITIONS q q q MIN LT1012AM/AI TYP MAX 30 40 0.2 30 70 0.3 ± 80 ±150 0.6 60 180 0.6 250 350 2.5 ± 600 ± 800 6.0 MIN LT1012M/I TYP 30 40 0.2 30 70 0.3 ± 80 ±150 0.6 MAX 180 250 1.5 250 350 2.5 ± 600 ± 800 6.0 UNITS µV µV µV/°C pA pA pA/°C pA pA pA/°C V/mV V/mV dB dB V q q q q q q VOUT = ±12V, RL ≥ 10kΩ VOUT = ±10V, RL ≥ 2kΩ VCM = ±13.5V VS = ±1.5V to ± 20V q q q q q q q 200 200 110 110 ±13.5 ±13 1000 600 128 126 ±14 400 650 150 100 108 108 ±13.5 ±13 1000 600 128 126 ±14 400 800 V µA sn1012 1012afbs 5 LT1012A/LT1012 The q denotes the specifications which apply over the full operating temperature range of 0°C ≤ TA ≤ 70°C. VS = ± 15V, VCM = 0V, unless otherwise noted. SYMBOL PARAMETER VOS Input Offset Voltage (Note 3) Average Temperature Coefficient of Input Offset Voltage IOS Input Offset Current (Note 3) Average Temperature Coefficient of Input Offset Current IB Input Bias Current (Note 3) Average Temperature Coefficient of Input Bias Current AVOL CMRR PSRR Large-Signal Voltage Gain Common Mode Rejection Ratio Power Supply Rejection Ratio Input Voltage Range VOUT IS Output Voltage Swing Supply Current RL = 10kΩ VOUT = ±12V, RL ≥ 10kΩ VOUT = ±10V, RL ≥ 2kΩ VCM = 13.5V VS = ±1.3V to ± 20V CONDITIONS q q q q q q q q q q q q q q q q ELECTRICAL CHARACTERISTICS MIN LT1012AC TYP 20 30 0.2 25 40 0.3 ± 35 ± 50 0.3 MAX 60 160 0.6 230 300 2.5 ± 230 ± 300 2.5 MIN LT1012C TYP 20 30 0.2 35 45 0.3 ± 35 ± 50 0.3 MAX 100 200 1.0 230 300 2.5 ± 230 ± 300 2.5 UNITS µV µV µV/°C pA pA pA/°C pA pA pA/°C V/mV V/mV dB dB V 200 200 110 110 ±13.5 ±13 1500 1000 130 128 150 150 108 108 ±13.5 1500 800 130 128 ±14 400 600 ±13 ±14 400 800 V µA sn1012 1012afbs 6 LT1012A/LT1012 ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER VOS Input Offset Voltage (Note 3) Average Temperature Coefficient of Input Offset Voltage IOS Input Offset Current (Note 3) Average Temperature Coefficient of Input Offset Current IB Input Bias Current (Note 3) Average Temperature Coefficient of Input Bias Current AVOL CMRR PSRR Large-Signal Voltage Gain Common Mode Rejection Ratio Power Supply Rejection Ratio Input Voltage Range VOUT IS Output Voltage Swing Supply Current RL = 10kΩ The q denotes the specifications which apply over the full operating temperature range of 0°C ≤ TA ≤ 70°C. VS = ± 15V, VCM = 0V, unless otherwise noted. CONDITIONS q q q q q q q q q MIN LT1012D TYP 25 40 0.3 35 45 0.35 ± 50 ± 65 0.4 MAX 140 1.7 380 4.0 ± 420 5.0 MIN LT1012S8 TYP 30 45 0.3 60 80 0.4 ±100 ±150 0.5 MAX 200 270 1.8 380 500 4.0 ± 420 ± 550 5.0 UNITS µV µV µV/°C pA pA pA/°C pA pA pA/°C V/mV V/mV dB dB V VOUT = ±12V, RL ≥ 10kΩ VOUT = ±10V, RL ≥ 2kΩ VCM = ±13.5V VS = ±1.3V to ± 20V q q q q q q q 150 150 108 108 ±13.5 ±13 1500 800 130 128 150 100 108 108 ±13.5 1500 800 130 128 ±14 400 800 ±13 ±14 400 800 V µA Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Differential input voltages greater than 1V will cause excessive current to flow through the input protection diodes unless limiting resistance is used. Note 3: These specifications apply for VMIN ≤ VS ≤ ± 20V and –13.5V ≤ VCM ≤ 13.5V (for VS = ± 15V). VMIN = ±1.2V at 25°C, ± 1.3V from 0°C to 70°C, ± 1.5V from – 55°C to 125°C. Note 4: 10Hz noise voltage density is sample tested on every lot. Devices 100% tested at 10Hz are available on request. Note 5: This parameter is tested on a sample basis only. V+ 5k TO 100k POT 1 2 Optional Offset Nulling and Overcompensation Circuits Input offset voltage can be adjusted over a ± 800µV range with a 5k to 100k potentiometer. – LT1012 8 7 5 6 OUT 3 + 4 V– CS LT1012A • EC01 The LT1012 is internally compensated for unity gain stability. The overcompensation capacitor, CS, can be used to improve capacitive load handling capability, to narrow noise bandwidth, or to stabilize circuits with gain in the feedback loop. sn1012 1012afbs 7 LT1012A/LT1012 TYPICAL PERFOR A CE CHARACTERISTICS Offset Voltage vs Source Resistance (Balanced or Unbalanced) 1000 VS = ±15V INPUT OFFSET VOLTAGE (µV) 100 NUMBER OF UNITS – 55°C TO 125°C 25°C 120 NUMBER OF UNITS 10 1 1k 3k 10k 30k 100k 300k 1M SOURCE RESISTANCE (Ω) 3M 10M LT1012A • TPC01 100 60 40 UNDERCANCELLED UNIT OFFSET VOLTAGE DRIFT WITH TEMPERATURE (µV/ °C) Input Bias Current vs Temperature INPUT BIAS CURRENT (pA) INPUT BIAS CURRENT (pA) 50 0 OVERCANCELLED UNIT –50 –100 –150 –50 –25 50 75 0 25 TEMPERATURE (°C) Warm-Up Drift 5 CHANGE IN OFFSET VOLTAGE (µV) CHANGE IN OFFSET VOLTAGE (µV) VS = ±15V TA = 25°C 4 4 2 0 –2 –4 –6 –8 OFFSET VOLTAGE (µV) 3 2 METAL CAN (H) PACKAGE DUAL-IN-LINE PACKAGE PLASTIC (N) OR SO (S) 1 0 0 1 3 4 2 TIME AFTER POWER ON (MINUTES) 8 UW 100 Typical Distribution of Input Bias Current 200 VS = ±15V TA = 25°C VCM = 0V 1020 UNITS FROM THREE RUNS 200 Typical Distribution of Input Offset Current VS = ±15V TA = 25°C VCM = 0V 1020 UNITS FROM THREE RUNS 160 160 120 80 80 40 40 0 –120 60 – 60 0 INPUT BIAS CURRENT (pA) 120 0 –120 60 120 –60 0 INPUT OFFSET CURRENT (pA) LT1012A • TPC03 LT1012A • TPC02 Input Bias Current Over Common Mode Range VS = ±15V TA = 25oC DEVICE WITH POSITIVE INPUT CURRENT RIN CM = 2 X 1012Ω DEVICE WITH NEGATIVE INPUT CURRENT IB VCM Offset Voltage Drift vs Source Resistance (Balanced or Unbalanced) 100 20 0 –20 –40 –60 –15 10 – + 1.0 MAXIMUM TYPICAL 0.1 1k 10k 100k 1M 10M SOURCE RESISTANCE (Ω) 100M 125 –10 –5 0 5 10 15 LT1012A • TPC04 COMMON MODE INPUT VOLTAGE LT1012A * TPC5 LT1012 • TPC06 Long Term Stability of Four Representative Units 10 8 6 40 20 0 –20 –40 60 Offset Voltage Drift with Temperature of Four Representative Units 5 –10 0 1 3 2 TIME (MONTHS) 4 5 –60 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 LT1012A • TPC07 LT1012A • TPC08 LT1012A • TPC09 sn1012 1012afbs LT1012A/LT1012 TYPICAL PERFOR A CE CHARACTERISTICS 0.1Hz to 10Hz Noise VOLTAGE NOISE DENSITY (nV√Hz) CURRENT NOISE DENSITY (fA√Hz) TA = 25°C VS = ± 1.2V TO ± 20V NOISE VOLTAGE 400nV/DIVISION TOTAL NOISE DENSITY (µV/√Hz) 0 2 6 4 TIME (SECONDS) Supply Current vs Supply Voltage 500 COMMON MODE REJECTION RATIO (dB) 120 100 80 60 40 20 0 1 VS = ±15V TA = 25°C 10 10k 1k 100 FREQUENCY (Hz) 100k 1M POWER SUPPLY REJECTION RATIO (dB) SUPPLY CURRENT (µA) 400 25°C 125°C –55°C 300 0 ± 10 ± 15 ±5 SUPPLY VOLTAGE (V) Voltage Gain vs Frequency 140 120 40 VOLTAGE GAIN (dB) 100 VOLTAGE GAIN GAIN (dB) 80 60 40 20 0 VS = ±15V TA = 25°C 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz) LT1012A • TPC16 –20 0.01 0.1 UW 8 10 LT1012A • TPC10 LT1012A • TPC13 Noise Spectrum 1000 TA = 25°C VS = ±1.2 TO ± 20V Total Noise vs Source Resistance 10.0 TA = 25°C VS = ± 1.2V TO ± 20V AT 10Hz AT 1kHz 100 CURRENT NOISE VOLTAGE NOISE 10 1/f CORNER 2.5Hz 1/f CORNER 120Hz 1 1 10 100 FREQUENCY (Hz) 1000 LT1012A • TPC11 1.0 R – + R RS = 2R 0.1 AT 10Hz AT 1kHz RESISTOR NOISE ONLY 0.01 102 103 104 105 106 107 SOURCE RESISTANCE (Ω) 108 LT1012A • TPC12 Common Mode Rejection vs Frequency 140 140 120 100 Power Supply Rejection vs Frequency NEGATIVE SUPPLY 80 60 40 POSITIVE SUPPLY VS = ±15V TA = 25°C 1 10 100 1k 10k FREQUENCY (Hz) 100k 1M ± 20 20 0.1 LT1012A • TPC14 LT1012A • TPC15 Gain, Phase Shift vs Frequency 100 Voltage Gain vs Load Resistance 10M VS = ± 15V V0 = ± 10V 3M – 55°C 25°C 1M 125°C 30 PHASE 120 PHASE SHIFT (DEGREES) 20 GAIN 10 PHASE MARGIN = 70°C 0 VS = ±15V TA = 25°C 0.1 1 FREQUENCY (MHz) 10 LT1012A • TPC17 140 160 300k 180 –10 0.01 200 100k 1 2 5 10 LOAD RESISTANCE (kΩ) 20 LT1012A • TPC18 sn1012 1012afbs 9 LT1012A/LT1012 TYPICAL PERFOR A CE CHARACTERISTICS Small-Signal Transient Response Small-Signal Transient Response Large-Signal Transient Response 20mV/DIV 20mV/DIV AV = +1 CLOAD = 100pF 5µs/DIV AV = +1 CLOAD = 1000pF 5µs/DIV 2V/DIV Output Short-Circuit Current vs Time 20 SHORT-CIRCUIT CURRENT (mA) SINKING SOURCING 1 –55°C GAIN BANDWIDTH PRODUCT (kHz) 15 10 25°C SLEW RATE (V/µs) 5 0 –5 –10 –15 –20 0 125°C VS = ±15V 125°C 25°C –55°C 0.1 SLEW 100 OUTPUT IMPEDANCE (Ω) 2 1 TIME FROM OUTPUT SHORT (MINUTES) Common Mode Range and Voltage Swing at Minimum Supply Voltage COMMON MODE RANGE OR OUTPUT VOLTAGE (V) V+ ± 1.8 V+ – 0.3 V + – 0.6 MINIMUM SUPPLY VOLTAGE (V) V+ – 0.9 V+ – 1.2 V – + 1.2 V – + 0.9 V – + 0.6 V– + 0.3 V– –50 –25 CM RANGE 0 25 75 50 TEMPERATURE (°C) 10 UW AV = +1 20µs/DIV Slew Rate, Gain Bandwidth Product vs Overcompensation Capacitor 1000 Closed-Loop Output Impedance 1000 100 10 AV = 1000 1 AV = +1 0.1 0.01 0.001 1 10 100 1 FREQUENCY (Hz) 10 100 I0 = 1mA VS = ±15V TA = 25°C GBW 0.01 10 0.001 VS = ±15V TA = 25°C 1 3 1 10 100 1000 10,000 OVERCOMPENSATION CAPACITOR (pF) LT1012A • TPC20 LT1012A • TPC19 LT1012A • TPC21 Minimum Supply Voltage, Voltage Gain at VMIN ± 1.6 ± 1.4 ± 1.2 ± 1.0 ± 0.8 RL = 10k RL = 2k 200k 300k 400k CM RANGE VOLTAGE GAIN AT MINIMUM SUPPLY VOLTAGE (V/V) SWING R L = 2k SWING R L = 10k SWING R L = 2k 100k 100 125 –50 –25 50 25 0 75 TEMPERATURE (°C) 100 0 125 LT1012A • TPC22 LT1012A • TPC23 sn1012 1012afbs LT1012A/LT1012 APPLICATIO S I FOR ATIO The LT1012 may be inserted directly into OP-07, LM11, 108A or 101A sockets with or without removal of external frequency compensation or nulling components. The LT1012 can also be used in 741, LF411, LF156 or OP-15 applications provided that the nulling circuitry is removed. Although the OP-97 is a copy of the LT1012, the LT1012 directly replaces and upgrades OP-97 applications. The LT1012C and D have lower offset voltage and drift than the OP-97F. The LT1012A has lower supply current than the OP-97A/E. In addition, all LT1012 grades guarantee operation at ±1.2V supplies. Achieving Picoampere/Microvolt Performance In order to realize the picoampere/microvolt level accuracy of the LT1012, proper care must be exercised. For example, leakage currents in circuitry external to the op amp can significantly degrade performance. High quality insulation should be used (e.g. Teflon, Kel-F); cleaning of all insulating surfaces to remove fluxes and other residues will probably be required. Surface coating may be necessary to provide a moisture barrier in high humidity environments. Board leakage can be minimized by encircling the input circuitry with a guard ring operated at a potential close to that of the inputs: in inverting configurations the guard ring should be tied to ground, in non-inverting connections to the inverting input at Pin 2. Guarding both sides of the printed circuit board is required. Bulk leakage reduction depends on the guard ring width. Nanoampere level leakage into the offset trim terminals can affect offset voltage and drift with temperature. OFFSET TRIM V+ OUTPUT 6 OVER COMP 5 4 3 2 7 8 1 V– GUARD IN PU TS LT1012A * AI01 U Microvolt level error voltages can also be generated in the external circuitry. Thermocouple effects caused by temperature gradients across dissimilar metals at the contacts to the input terminals can exceed the inherent drift of the amplifier. Air currents over device leads should be minimized, package leads should be short, and the two input leads should be as close together as possible and maintained at the same temperature. Noise Testing For application information on noise testing and calculations, please see the LT1008 data sheet. Frequency Compensation The LT1012 can be overcompensated to improve capacitive load handling capability or to narrow noise bandwidth. In many applications, the feedback loop around the amplifier has gain (e.g. Iogarithmic amplifiers); overcompensation can stabilize these circuits with a single capacitor. The availability of the compensation terminal permits the use of feedforward frequency compensation to enhance slew rate. The voltage follower feedforward scheme bypasses the amplifier’s gain stages and slews at nearly 10V/µs. The inputs of the LT1012 are protected with back-to-back diodes. Current limiting resistors are not used, because the leakage of these resistors would prevent the realization of picoampere level bias currents at elevated temperatures. In the voltage follower configuration, when the input is driven by a fast, large signal pulse (>1V), the input protection diodes effectively short the output to the input during slewing, and a current, limited only by the output short-circuit protection will flow through the diodes. The use of a feedback resistor, as shown in the voltage follower feedforward diagram, is recommended because this resistor keeps the current below the short-circuit limit, resulting in faster recovery and settling of the output. sn1012 1012afbs W UU 11 LT1012A/LT1012 APPLICATIO S I FOR ATIO Test Circuit for Offset Voltage and its Drift with Temperature 50k * Follower Feedforward Compensation 50pF 15V – + 5V/DIV 2 100Ω* 3 7 LT1012 4 6 V0 50k* 5k –15V V0 = 1000V0S IN *RESISTORS MUST HAVE LOW THERMOELECTRIC POTENTIAL LT1012A • AI02 TYPICAL APPLICATIO S Ampmeter with Six Decade Range 10k 15V Q3 100µA METER R1 2k 1.2k 0.1µF 100pA Q1 Q2 RANGE 1nA 2 549Ω 549Ω 549Ω Q4 PIN 13 CA3146 100nA 549Ω 1µA 549Ω 10µA Q1, Q2, Q3, Q4, RCA CA3146 TRANSISTOR ARRAY. CALIBRATION: ADJUST R1 FOR FULL-SCALE DEFLECTION WITH 1µA INPUT CURRENT AMPMETER MEASURES CURRENTS FROM 100pA TO 100µA WITHOUT THE USE OF EXPENSIVE HIGH VALUE RESISTORS. ACCURACY AT 100µA IS LIMITED BY THE OFFSET VOLTAGE BETWEEN Q1 AND Q2 AND, AT 100pA, BY THE INVERTING BIAS CURRENT OF THE LT1012 549Ω 100µA LT1004C 10k CURRENT INPUT 10k – + LT1012 3 4 –15V 12 U Pulse Response of Feedforward Compensation 10k W U UU Photoo 2 – LT1012 6 5 OUT 3 + 0.01µF 5µs/DIV LT1012A • AI03 15V 7 6 33k 10nA LT1012A • TA03 sn1012 1012afbs LT1012A/LT1012 TYPICAL APPLICATIO S Saturated Standard Cell Amplifier 15V 2N3609 3 7 6 OUT 1.018235V U + – LT1012 LT1008 2 4 –15V SATURATED STANDARD CELL #101 EPPLEY LABS NEWPORT, R.I. + R2 R1 THE TYPICAL 30pA BIAS CURRENT OF THE LT1012 WILL DEGRADE THE STANDARD CELL BY ONLY 1ppm/YEAR. NOISE IS A FRACTION OF A ppm. UNPROTECTED GATE MOSFET ISOLATES STANDARD CELL ON POWER DOWN LT1012A • TA05 Amplifier for Bridge Transducers R5 56M V+ S1 100k T R3 510k R4 510k 2 R1 100k – LT1012 6 OUT 3 + VOLTAGE GAIN ≈ 100 S2 T 100k R2 100k R6 56M LT1012A • TA06 sn1012 1012afbs 13 LT1012A/LT1012 TYPICAL APPLICATIO S Amplifier for Photodiode Sensor R1 5M 1% 15V 7k 3 200 S1 λ 2 – LT1012 6 OUT LM399 3 + VOUT = 10V/µA 6.5k 1k R2 5M 1% Instrumentation Amplifier with ±100V Common Mode Range 10M 100Ω 15V 100M – IN 100M +IN 2 7 LT1012 3 6 – + 4 –5V LT1012A • TA10 10M –15V A V = 100 ALL RESISTORS 1% OR BETTER LT1012A • TA09 14 U Buffered Reference for A-to-D Converters + – 7 6 1k 2N3904 LT1012 2 4 3k OUT 10V 1k* LT1012A • TA07 *THE 1k PRELOAD MINIMIZES GLITCHES INDUCED BY TRANSIENT LOADS LT1012A • TA08 Low Power Comparator with