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LT1008 Picoamp Input Current, Microvolt Offset, Low Noise Op Amp DESCRIPTIO
The LT(R)1008 is a universal precision operational amplifier that can be used in practically all precision applications. The LT1008 combines for the first time, picoampere bias currents (which are maintained over the full - 55C to 125C temperature range), microvolt offset voltage (and low drift with time and temperature), low voltage and current noise, and low power dissipation. Extremely high common mode and power supply rejection ratios, and the ability to deliver 5mA load current with high voltage gain round out the LT1008's superb precision specifications. The all around excellence of the LT1008 eliminates the necessity of the time consuming error analysis procedure of precision system design in many applications; the LT1008 can be stocked as the universal precision op amp. The LT1008 is externally compensated with a single capacitor for additional flexibility in shaping the frequency response of the amplifier. It plugs into and upgrades all standard LM108A/LM308A applications. For an internally compensated version with even lower offset voltage but otherwise similar performance see the LT1012.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
FEATURES

Guaranteed Bias Current TA = 25C: 100pA Max TA = - 55C to 125C: 600pA Max Guaranteed Offset Voltage: 120V Max Guaranteed Drift: 1.5V/C Max Low Noise, 0.1Hz to 10Hz: 0.5VP-P Guaranteed Low Supply Current: 600A Max Guaranteed CMRR: 114dB Min Guaranteed PSRR: 114dB Min Guaranteed Voltage Gain with 5mA Load Current Available in 8-Lead PDIP and SO Packages
APPLICATIO S

Precision Instrumentation Charge Integrators Wide Dynamic Range Logarithmic Amplifiers Light Meters Low Frequency Active Filters Standard Cell Buffers Thermocouple Amplifiers
TYPICAL APPLICATIO
Input Amplifier for 4.5 Digit Voltmeter
100
Input Bias Current vs Temperature
1000pF 1 INPUT 0.1V 1V 9M 10V 900k 100V 90k 1000V 10k FN507 ALLEN BRADLEY DECADE VOLTAGE DIVIDER 100k 5% 15V 8 7 LT1008 6 9k* 0.1V 1V 10V 100V 1k* 1000V TO 1V FULL-SCALE ANALOG-TO-DIGITAL CONVERTER
INPUT BIAS CURRENT (pA)
50 UNDERCANCELLED UNIT 0 OVERCANCELLED UNIT -50
+
3
-
2
4 -15V
-100
*RATIO MATCH 0.01% THIS APPLICATION REQUIRES LOW BIAS CURRENT AND OFFSET VOLTAGE, LOW NOISE AND LOW DRIFT WITH TIME AND TEMPERATURE 1008 TA01
-150 -50 -25
U
U
U
50 25 0 75 TEMPERATURE (C)
100
125
1008 TA02
1008fb
1
LT1008
ABSOLUTE
AXI U
RATI GS (Note 1)
Operating Temperature Range LT1008M (OBSOLETE) ............... - 55C to 125C LT1008C ................................................. 0C to 70C LT1008I ............................................. - 40C to 85C Lead Temperature (Soldering, 10 sec).................. 300C
Supply Voltage ...................................................... 20V Differential Input Current (Note 2) ..................... 10mA Input Voltage ........................................................ 20V Output Short-Circuit Duration ......................... Indefinite Storage Temperature Range ................. - 65C to 150C
PACKAGE/ORDER I FOR ATIO
TOP VIEW COMP2 8 COMP1 1 -IN 2 +IN 3 4 V H PACKAGE 8-LEAD TO-5 METAL CAN
TJMAX = 150C, JA = 150C/W, JC = 45C/W
- (CASE)
COMP1 1
7 V+ 6 OUT 5 NC
-IN 2 +IN 3 V- 4
- +
N8 PACKAGE 8-LEAD PDIP TJMAX = 150C, JA = 130C/W
J8 PACKAGE 8-LEAD CERDIP TJMAX = 150C, JA = 100C/W
ORDER PART NUMBER LT1008MH LT1008CH
ORDER PART NUMBER LT1008MJ8 LT1008CJ8
OBSOLETE PACKAGES
Consider N8 or S8 Package for Alternate Source
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL VOS PARAMETER Input Offset Voltage
VS = 15V, VCM = 0V, TA = 25C, unless otherwise noted.
LT1008M/I MIN TYP MAX 30 40 0.3 30 40 120 180 100 150 MIN LT1008C TYP MAX 30 40 0.3 30 40 100 150 120 180 UNITS V V V/Month pA pA pA pA VP-P 30 22 nVHz nV/Hz fA/Hz V/mV V/mV
1008fb
CONDITIONS (Note 3)
Long-Term Input Offset Voltage Stability IOS IB en Input Offset Current (Note 3) Input Bias Current (Note 3) Input Noise Voltage Input Noise Voltage Density in AVOL Input Noise Current Density Large-Signal Voltage Gain 0.1Hz to 10Hz fO = 10Hz (Note 4) fO = 1000Hz (Note 5) fO = 10Hz VOUT = 12V, RL 10k VOUT = 10V, RL 2k 200 120
2
U
U
W
WW U
W
TOP VIEW
TOP VIEW
8 7 6 5
COMP2 V+ OUT NC
COMP1 1 -IN 2 +IN 3 V- 4 8 7 6 5 COMP2 V+ OUT NC
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 150C, JA = 190C/W
ORDER PART NUMBER LT1008CN8 LT1008IN8
ORDER PART NUMBER LT1008S8
S8 PART MARKING 1008
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/
30 100 40 150 0.5 17 14 20 2000 600 200 120 30 22
30 100 40 150 0.5 17 14 20 2000 600
LT1008
ELECTRICAL CHARACTERISTICS
SYMBOL CMRR PSRR VOUT IS PARAMETER Common Mode Rejection Ratio Power Supply Rejection Ratio Input Voltage Range Output Voltage Swing Slew Rate Supply Current
VS = 15V, VCM = 0V, TA = 25C, unless otherwise noted.
LT1008M/I MIN TYP MAX 114 114 13 0.1 132 132 14 0.2 380 600 MIN 114 114 13 0.1 LT1008C TYP MAX 132 132 14 0.2 380 600 UNITS dB dB V V V/s A
CONDITIONS VCM = 13.5V VS = 2V to 20V RL = 10k CF = 30pF (Note 3)
13.5 14
13.5 14
The indicates specifications which apply over the full operating temperature range of - 55C TA 125C for the LT1008M, - 40C TA 85C for the LT1008I and 0C TA 70C for the LT1008C. VS = 15V, VCM = 0V, unless otherwise noted.
SYMBOL VOS PARAMETER 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 VOUT IS Large-Signal Voltage Gain Common Mode Rejection Ratio Power Supply Rejection Ratio Input Voltage Range Output Voltage Swing Supply Current RL = 10k VOUT = 12V, RL 10k VCM = 13.5V VS = 2.5V to 20V CONDITIONS

LT1008M/I MIN TYP MAX 50 60 0.2 60 80 0.4 250 320 1.5 250 350 2.5
MIN
LT1008C TYP MAX 40 50 0.2 40 50 0.4 180 250 1.5 180 250 2.5
UNITS V V V/C pA pA pA/C pA pA pA/C V/mV dB dB V V
80 600 150 800 0.6 100 108 108 13.5 13 14 400 800 1000 128 126 6 110 110 13.5 13
40 180 50 250 0.4 150 1500 130 128 14 400 800 2.5
A
(LT1008S8 only) VS = 15V, VCM = 0V, TA = 25C, unless otherwise noted.
SYMBOL VOS PARAMETER Input Offset Voltage (Note 3) Long-Term Input Offset Voltage Stability IOS IB en Input Offset Current (Note 3) Input Bias Current (Note 3) Input Noise Voltage Input Noise Voltage Density 0.1Hz to 10Hz fO = 10Hz (Note 5) fO = 1000Hz (Note 5) CONDITIONS MIN TYP 30 40 0.3 100 120 100 120 0.5 17 14 30 22 280 380 300 400 MAX 200 250 UNITS V V V/Month pA pA pA pA VP-P nV/Hz nV/Hz
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3
LT1008
ELECTRICAL CHARACTERISTICS
SYMBOL in AVOL CMRR PSRR VOUT IS PARAMETER Input Noise Current Density Large-Signal Voltage Gain Common Mode Rejection Ratio Power Supply Rejection Ratio Input Voltage Range Output Voltage Swing Slew Rate Supply Current
(LT1008S8 only) VS = 15V, VCM = 0V, TA = 25C, unless otherwise noted.
MIN 200 120 110 110 13.5 13 0.1 TYP 20 2000 600 132 132 14 14 0.2 380 600 MAX UNITS fA/Hz V/mV V/mV dB dB V V V/s A
CONDITIONS fO = 10Hz VOUT = 12V, RL 10k VOUT = 10V, RL 2k VCM = 13.5V VS = 2V to 20V RL = 10k CF = 30pF (Note 3)
(LT1008S8 only) The indicates specifications which apply over the full operating temperature range of 0C TA 70C. VS = 15V, VCM = 0V, unless otherwise noted.
SYMBOL VOS PARAMETER 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 VOUT IS Large-Signal Voltage Gain Common Mode Rejection Ratio Power Supply Rejection Ratio Input Voltage Range Output Voltage Swing Supply Current RL = 10k VOUT = 12V, RL 10k VCM = 13.5V VS = 2.5V to 20V CONDITIONS

MIN
TYP 40 50 0.2 120 140 0.4 120 140 0.4
MAX 280 340 1.8 380 500 4 420 550 5
UNITS V V V/C pA pA pA/C pA pA pA/C V/mV dB dB V V
150 108 108 13.5 13
1500 130 128 14 400 800
A
Note 1:Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Differential input voltages greater than 1V will cause excessive current to flow through the input protection diodes unless current limiting resistors are used.
Note 3: These specifications apply for 2V VS 20V (2.5V VS 20V over the temperature range) and -13.5V VCM 13.5V (for VS = 15V). 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.
1008fb
4
LT1008
FREQUE CY CO PE SATIO CIRCUITS
Standard Compensation Circuit
R1 -VIN R2
+VIN
1 CF**
R1CO R1 + R2 CO = 30pF CF
1008 FCC01
+VIN
FOR
R2 > 200, NO EXTERNAL FREQUENCY COMPENSATION IS NECESSARY R1
TYPICAL PERFOR A CE CHARACTERISTICS
Offset Voltage Drift vs Source Resistance (Balanced or Unbalanced)
100
OFFSET VOLTAGE DRIFT WITH TEMPERATURE (V/C)
Offset Voltage vs Source Resistance (Balanced or Unbalanced)
10 VS = 15V TA = 25C INPUT BIAS CURRENT (pA)
60 40
INPUT OFFSET VOLTAGE (mV)
10
1
MAXIMUM 1
MAXIMUM 0.1 TYPICAL
IB
TYPICAL 0.1 1k 10k 100k 1M 10M SOURCE RESISTANCE () 100M
1008 G01
-40 -60 -15
VCM
0.01 1k 100k 1M 10M 10k SOURCE RESISTANCE () 100M
1008 G02
10 -5 0 5 -10 COMMON MODE INPUT VOLTAGE (V)
Warm-Up Drift
5
Long-Term Stability of Four Representative Units
10 CHANGE IN OFFSET VOLTAGE (V) 8 6 4 2 0 -2 -4 -6 -8 OFFSET VOLTAGE (V)
40 20 0 -20 -40 60
Offset Voltage Drift with Temperature of Four Representative Units
CHANGE IN OFFSET VOLTAGE (V)
VS = 15V TA = 25C
4
3
2
METAL CAN (H) PACKAGE DUAL-IN-LINE PACKAGE PLASTIC (N) OR CERDIP (J)
1
0
0
1 3 4 2 TIME AFTER POWER ON (MINUTES)
5
-10
0
1
3 2 TIME (MONTHS)
4
5
1008 G05
-60 -50
-25
50 25 75 0 TEMPERATURE (C)
1008 G04
+ -
+
UW
+
R3
LT1008 3 8
6
VOUT
3
-
-
2
**BANDWIDTH AND SLEW RATE ARE PROPORTIONAL TO 1/CF
U
UW
U
Alternate* Frequency Compensation
R1 -VIN 2 R2 *IMPROVES REJECTION OF POWER SUPPLY NOISE BY A FACTOR OF 5 **BANDWIDTH AND SLEW RATE ARE PROPORTIONAL TO 1/CS VOUT
LT1008 8
6
CS** 100pF
1008 FCC02
Input Bias Current vs Common Mode Range
VS = 15V TA = 25C DEVICE WITH POSITIVE INPUT CURRENT
20 RINCM = 2 x 1012 0 -20 DEVICE WITH NEGATIVE INPUT CURRENT
15
1008 G03
100
125
1008 G06
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5
LT1008 TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
500
SHORT-CIRCUIT CURRENT (mA) SINKING SOURCING
SUPPLY CURRENT (A)
450
400 25C 125C 350 -55C
300
0
10 15 5 SUPPLY VOLTAGE (V)
0.1Hz to 10Hz Noise
1000
VOLTAGE NOISE DENSITY (nV/Hz) CURRENT NOISE DENSITY (fA/Hz)
TA = 25C VS = 2V TO 20V
NOISE VOLTAGE (400nV/DIV)
TOTAL NOISE DENSITY (V/Hz)
CURRENT NOISE VOLTAGE NOISE 10 1/f CORNER 2.5Hz 1/f CORNER 120Hz 1 1 10 100 FREQUENCY (Hz) 1000
1008 G10
R
0.1 AT 1Hz AT 10Hz 0.01 RESISTOR NOISE ONLY 102 103 104 105 106 107 SOURCE RESISTANCE () 108
0
2
6 4 TIME (SECONDS)
8
10
1008 G09
Voltage Gain vs Frequency
140 120 CF = 3pF
Gain, Phase Shift vs Frequency with Alternate Compensation
40 GAIN CS = 10pF CS = 100pF 140 100 40
Gain, Phase Shift vs Frequency with Standard (Feedback) Compensation
GAIN CF = 3pF CF = 30pF CF = 3pF GAIN CF = 30pF 100
30 CS = 10pF GAIN CS = 100pF
120 PHASE SHIFT (DEG)
30
VOLTAGE GAIN (dB)
100 CS = 10pF
GAIN (dB)
CS = 100pF 60 40 20 0 -20 0.01 0.1 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz)
1008 G12
CF = 30pF
10 PHASE MARGIN WITH CS = 100pF = 56 TA = 25C VS = 15V 0.1 1 FREQUENCY (MHz) 10
1008 G13
160
GAIN (dB)
80
20
20
10
0
180
-10 0.01
200
PHASE MARGIN 0 WITH C = 30pF = 60 F TA = 25C VS = 15V -10 0.1 1 0.01 FREQUENCY (MHz)
6
+ -
UW
Output Short-Circuit Current vs Time
15 12 9 6 3 0 -3 -6 -9 125C 25C -55C 0 2.5 3.0 3.5 0.5 1.0 1.5 2.0 TIME FROM OUTPUT SHORT (MINUTES)
1008 G08
-55C
25C
125C
-12 -15
20
1008 G07
Noise Spectrum
TA = 25C VS = 2V TO 20V 10
Total Noise vs Source Resistance
TA = 25C VS = 2V TO 20V AT 10Hz AT 1Hz 1
R
100
RS = 2R
1008 G11
120 PHASE SHIFT (DEG)
140
160
180
200 10
1008 G14
1008fb
LT1008 TYPICAL PERFOR A CE CHARACTERISTICS
Voltage Gain vs Load Resistance
10M COMMON MODE REJECTION RATIO (dB) VS = 15V VO = 10V -55C 25C 1M 125C
120 100
POWER SUPPLY REJECTION RATIO (dB)
3M
VOLTAGE GAIN
300k
100k 1 10 2 5 LOAD RESISTANCE (k) 20
1008 G15
Large-Signal Transient Response
10
SLEW RATE (V/s)
2V/DIV
1 CS CF
AV = 1 CS = 100pF
20s/DIV
2V/DIV
Small-Signal Transient Response
20mV/DIV
20mV/DIV
AV = 1 CS = 100pF CLOAD = 100pF
5s/DIV
1008 G21
AV = 1 CS = 100pF CLOAD = 600pF
5s/DIV
20mV/DIV
UW
1008 G18
Common Mode Rejection vs Frequency
140 VS = 15V TA = 25C CF = 30pF CS = 100pF 80 60 40 20 0 1 10 10k 1k 100 FREQUENCY (Hz) 100k 1M
Power Supply Rejection vs Frequency
140 120 100 80 60 40 20 0.1 POSITIVE SUPPLY CF = 30pF POSITIVE SUPPLY CS = 100pF NEGATIVE SUPPLY VS = 15V TA = 25C
1
10
100 1k 10k FREQUENCY (Hz)
100k
1M
1008 G16
1008 G17
Slew Rate vs Compensation Capacitance
VS = 15V TA = 25C
Large-Signal Transient Response
AV = 1 CF = 30pF
0.1 0 20 40 60 80 COMPENSATION CAPACITOR (pF) 100
108 G19
20s/DIV
1008 G20
Small-Signal Transient Response
Small-Signal Transient Response
1008 G22
AV = 1 CF = 30pF CLOAD = 100pF
5s/DIV
1008 G23
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7
LT1008
APPLICATIO S I FOR ATIO
Achieving Picoampere/Microvolt Performance In order to realize the picoampere--microvolt level accuracy of the LT1008, 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., TeflonTM, 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 noninverting 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 compensation terminals can affect offset voltage and drift with temperature.
COMPENSATION V+
100*
50k* -15V
Noise Testing The 0.1Hz to 10Hz peak-to-peak noise of the LT1008 is measured in the test circuit shown. The frequency response of this noise tester indicates that the 0.1Hz corner is defined by only one zero. The test time to measure 0.1Hz to 10Hz noise should not exceed 10 seconds, as this time limit acts as an additional zero to eliminate noise contributions from the frequency band below 0.1Hz. A noise voltage density test is recommended when measuring noise on a large number of units. A 10Hz noise voltage density measurement will correlate well with a 0.1Hz to 10Hz peak-to-peak noise reading since both results are determined by the white noise and the location of the 1/f corner frequency. Current noise is measured in the circuit shown and calculated by the following formula where the noise of the source resistors is subtracted.
OUTPUT 6 5
7
8 1
2 4 3
V- GUARD
IN
PU TS
1008 AI01
REFERENCE ONLY--OBSOLETE PACKAGE
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.
e2no - (820nV )2 in = 40M x 100
100
8
+
3
-
U
The LT1008 is specified over a wide range of power supply voltages from 2V to 18V. Operation with lower supplies is possible down to 1.2V (two Ni-Cad batteries).
Test Circuit for Offset Voltage and Its Drift with Temperature
50k* 15V 2 7 LT1008 4 6 VO *RESISTORS MUST HAVE LOW THERMOELECTRIC POTENTIAL THIS CIRCUIT IS ALSO USED AS THE BURN-IN CONFIGURATION FOR THE LT1008 WITH SUPPLY VOLTAGES INCREASED TO 20V VO = 1000VOS
1008 AI02
W
UU
1/ 2
10k 10M* 10M* 2
-
LT1008 6 eno
10M* 10M* 3 *METAL FILM
+
1008 AI04
1008fb
LT1008
APPLICATIO S I FOR ATIO
0.1F 100k 10
0.1Hz to 10Hz Noise Test Circuit
LT1008* 4.7F VOLTAGE GAIN: 50,000
*DEVICE UNDER TEST NOTE: ALL CAPACITOR VALUES ARE FOR NONPOLARIZED CAPACITORS ONLY
Frequency Compensation The LT1008 is externally frequency compensated with a single capacitor. The two standard compensation circuits shown earlier are identical to the LM108A/LM308A frequency compensation schemes. Therefore, the LT1008 operational amplifiers can be inserted directly into LM108A/LM308A sockets, with similar AC and upgraded DC performance. External frequency compensation provides the user with additional flexibility in shaping the frequency response of the amplifier. For example, for a voltage gain of ten and CF = 3pF, a gain bandwidth product of 5MHz and slew rate of 1.2V/s can be realized. For closed-loop gains in excess of 200, no external compensation is necessary, and slew rate increases to 4V/s. The LT1008 can also be overcompensated (i.e., CF > 30pF or CS > 100pF) to improve capacitive load handling capability or to narrow noise bandwidth. In many applications, the feedback loop around the amplifier has gain (e.g., logarithmic amplifiers); overcompensation can stabilize these circuits with a single capacitor. The availability of the compensation terminals permits the use of feedforward frequency compensation to enhance slew rate in low closed-loop gain configurations. The inverter slew rate is increased to 1.4V/s. The voltage follower feedforward scheme bypasses the amplifier's gain stages and slews at nearly 10V/s. The inputs of the LT1008 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.
2V/DIV
U
2k
W
+
-
UU
+
LT1001
4.3k 2.2F 100k
22F 110k
-
24.3k 0.1F
SCOPE x1 RIN = 1M
1008 AI03
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 shortcircuit 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.
Inverter Feedforward Compensation
C2 5pF
R1 10k INPUT
2
-
LT1008
R2 10k 6 8 1 R3 3k C3 10pF
1008 AI05
VOUT
3
+
C1 500pF
5s/DIV
1008 AI07
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9
LT1008
APPLICATIO S I FOR ATIO
30pF 10k 2
Follower Feedforward Compensation
10k INPUT*
LT1008 3
6
OUTPUT
+
8
1000pF *SOURCE RESISTANCE 15k FOR STABILITY
1008 AI06
5V/DIV
-
TYPICAL APPLICATIO S
Logarithmic Amplifier
Q1A 2N2979 15V 10k* INPUT 2 Q1B 2N2979 2k 15.7k 100pF 6 1k TEL. LABS TYPE Q81 LM107 3 2 124k* 5.1k 15V LT1004C 1.2V
- +
1
7 LT1008
330pF 6 4
3
8 -15V OUTPUT
*1% FILM RESISTOR 30pF LOW BIAS CURRENT AND OFFSET VOLTAGE OF THE LT1008 ALLOW 4.5 DECADES OF VOLTAGE INPUT LOGGING
Amplifier for Bridge Transducers
R5 56M C1 30pF R3 510k R4 510k S2 T 100k R2 100k R6 56M 1 2
Saturated Standard Cell Amplifier
15V 3 2N3609 2 1.018235V SATURATED STANDARD CELL #101 EPPLEY LABS NEWPORT, R.I. R1
V+ S1 T 100k R1 100k
-
LT1008
8
+
6 OUTPUT
3
+
VOLTAGE GAIN 100
1008 TA04
THE TYPICAL 30pA BIAS CURRENT OF THE LT1008 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
1008fb
10
-
+
U
5s/DIV
1008 AI07
W
U
UU
+ -
1
7 LT1008 4 8 -15V 6 OUTPUT
1000pF
R2
1008 TA05
LT1008
TYPICAL APPLICATIO S
Amplifier for Photodiode Sensor
R1 5M 1% 2 S1 3 R2 5M 1%
100k KELVIN-VARLEY DIVIDER ESI #DP311 00000 - 99999 + 1
-
LT1008 6 OUTPUT VOUT = 10V/A
+
8
C1 100pF
The LT1008 integrator extends low frequency range. Total dynamic range is 0.01Hz to 10kHz (or 120dB) with 0.01% linearity.
Extended Range Charge Pump Voltage to Frequency Converter
15V 50k -15V OPTIONAL 0.01Hz TRIM 22M 15V 1.8k 1000pF (POLYSTYRENE)
VIN 0V TO 10V
LT1008 3
+
8 100pF
22k 10k 2 15V LT1004C 1.2V 3 7 1 4 5pF -15V *1% METAL FILM RESISTOR ALL DIODES 1N4148
1008 TA08
LT311A
-
100k 750k
10k* 2
+
10k*
63.4k*
-
+
U
Five Decade Kelvin-Varley Divider Buffered by the LT1008
15V 10V 2
- +
1
7 LT1008 6 4 8 -15V OUTPUT
3
1000pF
1008 TA06
APPROXIMATE ERROR DUE TO NOISE, BIAS CURRENT, COMMON MODE REJECTION. VOLTAGE GAIN OF THE 1008 TA07 AMPLIFIER IS 1/5 OF A LEAST SIGNIFICANT BIT
1F
2
-
6
10k*
3
LM301A
6
1k
LM329
10k -15V
10k 15V
FREQUENCY OUPUT 0.01Hz TO 10kHz
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11
LT1008
TYPICAL APPLICATIO S
Precision, Fast Settling, Lowpass Filter
10k
2 1.5M 2k INPUT 1F 3
-
LT1008 6 8 1 1000pF OUTPUT
+
1k 15V
OPTO-MOS* 15V 8 7 4 -15V 100
#1 LT311A
1
*OPTO-MOS SWITCH TYPE OFM1A THETA-J CORP
15V 8 7 4 -15V
5
#2 LT311A
1
1008 TA09
2pF TO 8pF 10k* INPUT 10k* 10k 1N4148 x2 10pF 10k*
10k* INPUT
2N4393 x2
15k
-15V 1N4148 (4)
10k
10k
12
U
+ - - +
2 3 2 3
This circuit is useful where fast signal acquisition and high precision are required, as in electronic scales. The filter's time constant is set by the 2k resistor and the 1F capacitor until comparator 1 switches. The time constant is then set by the 1.5M resistor and the 1F capacitor. Comparator 2 provides a quick reset. The circuit settles to a final value three times as fast as a simple 1.5M-1F filter with almost no DC error.
2
3 FILTER CUT IN ADJUST 10k 3
2
Fast Precision Inverters
1
15V 5 76
300pF 1000pF OUTPUT 2 15V 2 15V
- +
LT318A 4
- +
7 LT318A 6 OUTPUT
- +
1
7 LT1008 6 4 8 -15V 10k 3
3 10k
4 -15V
30pF 300pF FULL POWER BANDWIDTH = 2MHz SLEW RATE AT 50V/s SETTLING (10V STEP) = 12s TO 0.01% BIAS CURRENT DC = 30pA OFFSET DRIFT = 0.3V/C OFFSET VOLTAGE = 30V *1% METAL FILM 6 4 8 1 -15V SLEW RATE = 100V/s SETTLING (10V STEP) = 5s TO 0.01% OFFSET VOLTAGE = 30V BIAS CURRENT DC = 30pA *1% METAL FILM
15V
- +
7 LT1008
30pF
1008 TA10
1008fb
LT1008
SCHE ATIC DIAGRA
COMP1 1
22k Q7 Q8
22k
Q5
Q6 S Q16 Q3 Q13 Q11 Q23 S Q15 50k 1.5k Q12 J1 Q4 3k Q24
-INPUT 2
S Q1 Q9 Q2
S
+INPUT 3
Q10
Q39
Q17
V- 4
4.3k
W
COMP2 8 V+ 7 1.3k Q14 Q22 Q21 3k 4.2k Q20 Q29 1.5k Q25 Q27 Q37 60 OUTPUT 6 70 Q28 3k Q38 Q43 Q30 Q26 Q42 Q31 Q32 Q33 16k Q18 Q19 Q35 20k 3.3k 3.3k Q34 4.8k 3.3k 320 40 330 Q41 Q40
1008fb
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13
LT1008
PACKAGE DESCRIPTIO
0.335 - 0.370 (8.509 - 9.398) DIA 0.305 - 0.335 (7.747 - 8.509) 0.040 (1.016) MAX 0.050 (1.270) MAX GAUGE PLANE 0.010 - 0.045* (0.254 - 1.143) 0.016 - 0.021** (0.406 - 0.533) *LEAD DIAMETER IS UNCONTROLLED BETWEEN THE REFERENCE PLANE AND 0.045" BELOW THE REFERENCE PLANE 0.016 - 0.024 **FOR SOLDER DIP LEAD FINISH, LEAD DIAMETER IS (0.406 - 0.610) 0.165 - 0.185 (4.191 - 4.699) REFERENCE PLANE 0.500 - 0.750 (12.700 - 19.050)
SEATING PLANE
CORNER LEADS OPTION (4 PLCS)
0.045 - 0.068 (1.143 - 1.727) FULL LEAD OPTION 0.300 BSC (0.762 BSC)
0.008 - 0.018 (0.203 - 0.457)
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS
14
U
H Package 8-Lead TO-5 Metal Can (.200 Inch PCD)
(Reference LTC DWG # 05-08-1320)
0.027 - 0.045 (0.686 - 1.143) 45TYP 0.028 - 0.034 (0.711 - 0.864) PIN 1 0.200 (5.080) TYP
H8(TO-5) 0.200 PCD 1197
0.110 - 0.160 (2.794 - 4.064) INSULATING STANDOFF
J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic)
(Reference LTC DWG # 05-08-1110)
0.405 (10.287) MAX 8 7 6 5
0.005 (0.127) MIN
0.023 - 0.045 (0.584 - 1.143) HALF LEAD OPTION
0.025 (0.635) RAD TYP 1 2 3
0.220 - 0.310 (5.588 - 7.874)
4
0.200 (5.080) MAX 0.015 - 0.060 (0.381 - 1.524)
0 - 15
0.045 - 0.065 (1.143 - 1.651) 0.014 - 0.026 (0.360 - 0.660) 0.100 (2.54) BSC
0.125 3.175 MIN
J8 1298
OBSOLETE PACKAGES
1008fb
LT1008
PACKAGE DESCRIPTIO
.300 - .325 (7.620 - 8.255)
.008 - .015 (0.203 - 0.381) +.035 .325 -.015 8.255 +0.889 -0.381
(
)
INCHES MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
NOTE: 1. DIMENSIONS ARE
.050 BSC
8
.245 MIN
.030 .005 TYP
RECOMMENDED SOLDER PAD LAYOUT .010 - .020 x 45 (0.254 - 0.508) .008 - .010 (0.203 - 0.254) 0- 8 TYP
NOTE: 1. DIMENSIONS IN
INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
U
N8 Package 8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510)
.400* (10.160) MAX 8 7 6 5 .255 .015* (6.477 0.381) 1 2 3 4 .130 .005 (3.302 0.127) .045 - .065 (1.143 - 1.651) .065 (1.651) TYP .120 .020 (3.048) MIN (0.508) MIN .018 .003 (0.457 0.076)
N8 1002
.100 (2.54) BSC
S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.045 .005
.189 - .197 (4.801 - 5.004) NOTE 3 7 6 5
.160 .005 .228 - .244 (5.791 - 6.197)
.150 - .157 (3.810 - 3.988) NOTE 3
1
2
3
4
.053 - .069 (1.346 - 1.752)
.004 - .010 (0.101 - 0.254)
.016 - .050 (0.406 - 1.270)
.014 - .019 (0.355 - 0.483) TYP
.050 (1.270) BSC
SO8 0303
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LT1008
TYPICAL APPLICATIO
Ammeter measures currents from 100pA to 100A without the use of expensive high value resistors. Accuracy at
CURRENT INPUT
Q1 TO Q4: RCA CA3146 TRANSISTOR ARRAY CALIBRATION: ADJUST R1 FOR FULL SCALE DEFLECTION WITH 1A INPUT CURRENT
RELATED PARTS
PART NUMBER LT1012 LT1112 LT1880 LT1881/LT1882 LT1884/LT1885 DESCRIPTION Picoamp Input Current, Microvolt Offset, Low Noise Op Amp Dual Low Power, Precision, Picoamp Input Op Amp SOT-23, Rail-to-Rail Output, Picoamp Input Current Precision Op Amp Dual and Quad Rail-to-Rail Output, Picoamp Input Precision Op Amps Dual and Quad Rail-to-Rail Output, Picoamp Input Precision Op Amps COMMENTS Internally Compensated LT1008 Dual LT1012 Single SOT-23 Version of LT1884 Dual/Quad CLOAD Stable Dual/Quad Faster LT1881/LT1882
16
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507
U
100A is limited by the offset voltage between Q1 and Q2 and at 100pA by the inverting bias current of the LT1008.
Ammeter with Six Decade Range
10k 15V Q3 100A METER R1 2k 1.2k Q1 15V 10k 2 7 LT1008 3 6 4 8 1 -15V PIN 13 CA3146 Q4 100nA 549 0.01F 1A 549 10A 549 100A
1008 TA11
100pA RANGE 1nA Q2 549
- +
33k 10nA
549 LT1004C-1.2 549
1008fb LT 0607 REV B * PRINTED IN THE USA
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 1991

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