LT1008S8#TRPBF [Linear]
LT1008 - Picoamp Input Current, Microvolt Offset, Low Noise Op Amp; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C;
| 型号： | LT1008S8#TRPBF |
| 厂家： | 
Linear |
| 描述： | LT1008 - Picoamp Input Current, Microvolt Offset, Low Noise Op Amp; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C 运算放大器 放大器电路 光电二极管 |
| 文件： | 总16页 (文件大小：272K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1008
Picoamp Input Current,
Microvolt Offset,
Low Noise Op Amp
U
FEATURES
DESCRIPTIO
The LT®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 –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. 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.
■
Guaranteed Bias Current
TA = 25°C: 100pA Max
TA = –55°C to 125°C: 600pA Max
■
Guaranteed Offset Voltage: 120μV Max
■
Guaranteed Drift: 1.5μV/°C Max
■
Low Noise, 0.1Hz to 10Hz: 0.5μVP-P
■
Guaranteed Low Supply Current: 600μA Max
■
Guaranteed CMRR: 114dB Min
■
Guaranteed PSRR: 114dB Min
Guaranteed Voltage Gain with 5mA Load Current
Available in 8-Lead PDIP and SO Packages
■
■
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.
U
APPLICATIO S
■
Precision Instrumentation
Charge Integrators
Wide Dynamic Range Logarithmic Amplifiers
Light Meters
Low Frequency Active Filters
Standard Cell Buffers
Thermocouple Amplifiers
The LT1008 is externally compensated with a single ca-
pacitor 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.
U
TYPICAL APPLICATIO
Input Amplifier for 4.5 Digit Voltmeter
Input Bias Current vs Temperature
100
1000pF
50
1
15V
UNDERCANCELLED UNIT
–
2
3
0.1V
1V
8
INPUT
7
0.1V
1V
0
6
100k
5%
LT1008
OVERCANCELLED UNIT
+
10V
9k*
1k*
4
100V
1000V
–50
9M
10V
900k
100V
90k
1000V
10k
–15V
TO 1V FULL-SCALE
ANALOG-TO-DIGITAL
CONVERTER
–100
*RATIO MATCH 0.01%
–150
–50
0
25
50
75 100 125
–25
TEMPERATURE (°C)
THIS APPLICATION REQUIRES LOW
BIAS CURRENT AND OFFSET VOLTAGE,
LOW NOISE AND LOW DRIFT WITH
FN507
ALLEN BRADLEY
DECADE VOLTAGE DIVIDER
1008 TA02
TIME AND TEMPERATURE
1008 TA01
1008fb
1
LT1008
W W
U W
ABSOLUTE AXI U RATI GS (Note 1)
Supply Voltage ...................................................... 20V
Differential Input Current (Note 2) ..................... 10mA
Input Voltage ........................................................ 20V
Output Short-Circuit Duration......................... Indefinite
Storage Temperature Range ................. –65°C to 150°C
Operating Temperature Range
LT1008M (OBSOLETE) ............... –55°C to 125°C
LT1008C................................................. 0°C to 70°C
LT1008I ............................................. –40°C to 85°C
Lead Temperature (Soldering, 10 sec).................. 300°C
U W
U
PACKAGE/ORDER I FOR ATIO
TOP VIEW
COMP2
TOP VIEW
TOP VIEW
COMP1
–IN
1
COMP2
8
7
6
5
8
+
COMP1
–IN
1
2
3
4
8
7
6
5
COMP2
+
V
7
5
COMP1
–IN
+IN
1
3
2
V
+
V
–
+
+IN
3
4
OUT
NC
2
6
OUT
+IN
OUT
NC
–
V
–
NC
V
4
N8 PACKAGE
8-LEAD PDIP
–
V
(CASE)
S8 PACKAGE
8-LEAD PLASTIC SO
H PACKAGE
TJMAX = 150°C, θJA = 130°C/W
8-LEAD TO-5 METAL CAN
TJMAX = 150°C, θJA = 190°C/W
J8 PACKAGE 8-LEAD CERDIP
TJMAX = 150°C, θJA = 100°C/W
TJMAX = 150°C, θJA = 150°C/W, θJC = 45°C/W
ORDER PART
NUMBER
ORDER PART
NUMBER
ORDER PART
NUMBER
ORDER PART
NUMBER
S8 PART
MARKING
LT1008MH
LT1008CH
LT1008MJ8
LT1008CJ8
LT1008CN8
LT1008IN8
LT1008S8
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/
OBSOLETE PACKAGES
Consider N8 or S8 Package for Alternate Source
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
VS = 15V, VCM = 0V, TA = 25°C, unless otherwise noted.
LT1008M/I
LT1008C
SYMBOL PARAMETER
Input Offset Voltage
CONDITIONS
MIN TYP MAX
MIN TYP MAX
UNITS
V
OS
30
40
120
180
30
40
120
180
μV
μV
(Note 3)
Long-Term Input Offset Voltage Stability
Input Offset Current
0.3
0.3
μV/Month
I
I
30
40
100
150
30
40
100
150
pA
pA
OS
(Note 3)
Input Bias Current
30
40
100
150
30
40
100
150
pA
pA
B
(Note 3)
e
Input Noise Voltage
0.1Hz to 10Hz
0.5
0.5
μV
P-P
n
Input Noise Voltage Density
f = 10Hz (Note 4)
f = 1000Hz (Note 5)
O
17
14
30
22
17
14
30
22
nV√Hz
nV/√Hz
O
i
Input Noise Current Density
Large-Signal Voltage Gain
f = 10Hz
20
20
fA/√Hz
n
O
A
V
OUT
V
OUT
= 12V, R ≥ 10k
= 10V, R ≥ 2k
200 2000
120 600
200 2000
120 600
V/mV
V/mV
VOL
L
L
1008fb
2
LT1008
ELECTRICAL CHARACTERISTICS
VS = 15V, VCM = 0V, TA = 25°C, unless otherwise noted.
LT1008M/I
MIN TYP MAX
LT1008C
MIN TYP MAX
SYMBOL PARAMETER
CONDITIONS
= 13.5V
UNITS
dB
CMRR
PSRR
Common Mode Rejection Ratio
V
114 132
114 132
13.5 14
114 132
114 132
13.5 14
CM
Power Supply Rejection Ratio
Input Voltage Range
Output Voltage Swing
Slew Rate
V = 2V to 20V
S
dB
V
V
I
R = 10k
L
13
14
13
14
V
OUT
C = 30pF
F
0.1
0.2
0.1
0.2
V/μs
μA
Supply Current
(Note 3)
380 600
380 600
S
The ● indicates specifications which apply over the full operating temperature range of –55°C ≤ TA ≤ 125°C for the LT1008M, –40°C
≤ TA ≤ 85°C for the LT1008I and 0°C ≤ TA ≤ 70°C for the LT1008C. VS = 15V, VCM = 0V, unless otherwise noted.
LT1008M/I
LT1008C
SYMBOL PARAMETER
Input Offset Voltage
CONDITIONS
MIN TYP MAX
MIN TYP MAX
UNITS
V
●
●
50
60
250
320
40
50
180
250
μV
μV
OS
(Note 3)
Average Temperature Coefficient of
Input Offset Voltage
●
0.2
1.5
0.2
1.5
μV/°C
I
I
Input Offset Current
●
●
60
80
250
350
40
50
180
250
pA
pA
OS
(Note 3)
(Note 3)
Average Temperature Coefficient of
Input Offset Current
●
0.4
80
150 800
2.5
0.4
2.5
pA/°C
Input Bias Current
●
●
600
40
50
180
250
pA
pA
B
Average Temperature Coefficient of
Input Bias Current
●
●
●
●
●
●
●
0.6
100 1000
108 128
108 126
13.5
6
0.4
150 1500
110 130
110 128
13.5
2.5
pA/°C
V/mV
dB
A
Large-Signal Voltage Gain
Common Mode Rejection Ratio
Power Supply Rejection Ratio
Input Voltage Range
V
V
= 12V, R ≥ 10k
L
VOL
OUT
CM
CMRR
PSRR
= 13.5V
V = 2.5V to 20V
dB
S
V
V
I
Output Voltage Swing
R = 10k
13
14
400 800
13
14
V
OUT
L
Supply Current
400 800
μA
S
(LT1008S8 only) VS = 15V, VCM = 0V, TA = 25°C, unless otherwise noted.
SYMBOL PARAMETER
Input Offset Voltage
CONDITIONS
MIN
TYP
MAX
UNITS
V
30
40
200
250
μV
μV
OS
(Note 3)
Long-Term Input Offset Voltage Stability
Input Offset Current
0.3
μV/Month
I
I
100
120
280
380
pA
pA
OS
(Note 3)
Input Bias Current
100
120
300
400
pA
pA
B
(Note 3)
e
Input Noise Voltage
0.1Hz to 10Hz
0.5
μV
n
P-P
Input Noise Voltage Density
f = 10Hz (Note 5)
f = 1000Hz (Note 5)
O
17
14
30
22
nV/√Hz
nV/√Hz
O
1008fb
3
LT1008
ELECTRICAL CHARACTERISTICS
(LT1008S8 only) VS = 15V, VCM = 0V, TA = 25°C, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
f = 10Hz
MIN
TYP
MAX
UNITS
i
Input Noise Current Density
20
fA/√Hz
n
O
A
Large-Signal Voltage Gain
V
V
= 12V, R ≥ 10k
200
120
2000
600
V/mV
V/mV
VOL
OUT
OUT
L
=
10V, R ≥ 2k
L
CMRR
PSRR
Common Mode Rejection Ratio
Power Supply Rejection Ratio
Input Voltage Range
Output Voltage Swing
Slew Rate
V
= 13.5V
110
110
13.5
13
132
132
14
dB
dB
V
CM
V = 2V to 20V
S
V
I
R = 10k
14
V
OUT
L
C = 30pF
0.1
0.2
380
V/μs
μA
F
Supply Current
(Note 3)
600
S
(LT1008S8 only) The ● indicates specifications which apply over the full operating temperature range of 0°C ≤ TA ≤ 70°C.
VS = 15V, VCM = 0V, unless otherwise noted.
SYMBOL PARAMETER
Input Offset Voltage
CONDITIONS
MIN
TYP
MAX
UNITS
V
●
●
40
50
280
340
μV
μV
OS
(Note 3)
Average Temperature Coefficient of
Input Offset Voltage
●
0.2
1.8
μV/°C
I
I
Input Offset Current
●
●
120
140
380
500
pA
pA
OS
(Note 3)
(Note 3)
Average Temperature Coefficient of
Input Offset Current
●
0.4
4
pA/°C
Input Bias Current
●
●
120
140
420
550
pA
pA
B
Average Temperature Coefficient of
Input Bias Current
●
0.4
5
pA/°C
A
Large-Signal Voltage Gain
Common Mode Rejection Ratio
Power Supply Rejection Ratio
Input Voltage Range
V
V
= 12V, R ≥ 10k
●
●
●
●
●
●
150
108
108
13.5
13
1500
130
V/mV
dB
dB
V
VOL
OUT
CM
L
CMRR
PSRR
= 13.5V
V = 2.5V to 20V
128
S
V
I
Output Voltage Swing
R = 10k
14
V
OUT
L
Supply Current
400
800
μA
S
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 3: These specifications apply for 2V ≤ V ≤ 20V
S
( 2.5V ≤ V ≤ 20V over the temperature range) and
S
–13.5V ≤ V ≤ 13.5V (for V = 15V).
CM
S
Note 4: 10Hz noise voltage density is sample tested on every lot. Devices
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.
100% tested at 10Hz are available on request.
Note 5: This parameter is tested on a sample basis only.
1008fb
4
LT1008
U
W U
U
FREQUE CY CO PE SATIO CIRCUITS
Standard Compensation Circuit
Alternate* Frequency Compensation
R1
R2
R1
R2
–V
IN
–V
IN
*IMPROVES REJECTION OF POWER
SUPPLY NOISE BY A FACTOR OF 5
**BANDWIDTH AND SLEW RATE
**BANDWIDTH AND SLEW RATE ARE
–
+
–
+
2
3
ARE PROPORTIONAL TO 1/C
2
3
F
PROPORTIONAL TO 1/C
S
6
6
V
V
LT1008
1
LT1008
8
OUT
OUT
R3
8
+V
+V
IN
IN
R1C
O
R1 + R2
= 30pF
C ≥
F
C **
100pF
S
C
O
1008 FCC02
C **
F
1008 FCC01
R2
R1
FOR
> 200, NO EXTERNAL FREQUENCY COMPENSATION IS NECESSARY
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Offset Voltage Drift vs Source
Resistance (Balanced or
Unbalanced)
Offset Voltage vs Source
Resistance (Balanced or
Unbalanced)
Input Bias Current vs
Common Mode Range
60
40
100
10
10
1
V
T
=
15V
V
T
=
15V
S
A
S
A
= 25°C
= 25°C
DEVICE WITH POSITIVE INPUT CURRENT
20
R
= 2 × 1012Ω
INCM
0
DEVICE WITH NEGATIVE INPUT CURRENT
–
MAXIMUM
TYPICAL
MAXIMUM
TYPICAL
1
0.1
–20
–40
–60
I
B
+
V
CM
0.1
0.01
–15
–5
0
5
10
15
1k
10k
100k
1M
10M
100M
1k
10k
100k
1M
10M
100M
–10
SOURCE RESISTANCE (Ω)
SOURCE RESISTANCE (Ω)
COMMON MODE INPUT VOLTAGE (V)
1008 G03
1008 G01
1008 G02
Offset Voltage Drift with
Temperature of Four
Representative Units
Long-Term Stability of Four
Representative Units
Warm-Up Drift
5
10
8
60
40
20
0
V
= 15V
= 25°C
S
A
T
4
3
2
1
0
6
4
2
0
–2
–4
–6
–8
–10
METAL CAN (H) PACKAGE
–20
–40
–60
DUAL-IN-LINE PACKAGE
PLASTIC (N) OR CERDIP (J)
0
1
2
3
4
5
0
1
3
4
5
50
TEMPERATURE (°C)
100 125
2
–50 –25
0
25
75
TIME AFTER POWER ON (MINUTES)
TIME (MONTHS)
1008 G04
1008 G05
1008 G06
1008fb
5
LT1008
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
Output Short-Circuit Current vs Time
15
500
450
400
350
300
12
9
–55°C
6
125°C
25°C
3
0
25°C
–3
–6
–9
–12
–15
125°C
125°C
25°C
–55°C
–55°C
0
1.0 1.5 2.0
2.5 3.0 3.5
0.5
10
15
0
20
5
TIME FROM OUTPUT SHORT (MINUTES)
SUPPLY VOLTAGE ( V)
1008 G08
1008 G07
0.1Hz to 10Hz Noise
Noise Spectrum
Total Noise vs Source Resistance
1000
10
1
T
= 25°C
T = 25°C
A
A
S
T
= 25°C
A
S
V
= 2V TO 20V
V
S
= 2V TO 20V
V
=
2V TO 20V
AT 10Hz
AT 1Hz
100
10
1
R
–
+
R
CURRENT NOISE
R
= 2R
S
VOLTAGE NOISE
0.1
0.01
1/f CORNER
2.5Hz
AT 1Hz
1/f CORNER
120Hz
AT 10Hz
2
RESISTOR NOISE ONLY
3
4
5
6
7
10
8
10
1
10
100
1000
10
10
10
10
10
0
2
4
6
8
10
FREQUENCY (Hz)
SOURCE RESISTANCE (Ω)
TIME (SECONDS)
1008 G10
1008 G11
1008 G09
Gain, Phase Shift vs Frequency
with Standard (Feedback)
Compensation
Gain, Phase Shift vs Frequency
with Alternate Compensation
Voltage Gain vs Frequency
40
30
20
10
0
100
120
140
160
180
200
40
30
20
10
0
100
120
140
160
180
200
140
120
100
80
GAIN
φ
C
C
= 10pF
S
GAIN
= 3pF
= 30pF
F
C
F
C
= 3pF
F
φ
C
φ
C
= 3pF
C
= 10pF
= 100pF
S
F
S
φ
C
= 10pF
GAIN
= 30pF
S
C
= 100pF
C
S
GAIN
= 100pF
F
60
C
S
C
= 30pF
F
40
20
PHASE MARGIN
PHASE MARGIN
WITH C = 100pF = 56°
WITH C = 30pF = 60°
F
S
0
T
= 25°C
T
= 25°C
A
S
A
S
V
= 15V
V
= 15V
–10
–10
–20
0.01
0.1
1
10
0.01
0.1
1
10
100 1k
10k 100k 1M 10M
0.01 0.1
1
10
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (Hz)
1008 G13
1008 G14
1008 G12
1008fb
6
LT1008
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Common Mode Rejection
vs Frequency
Power Supply Rejection
vs Frequency
Voltage Gain vs Load Resistance
140
120
100
80
10M
140
120
100
80
V
S
V
O
=
=
15V
10V
V
T
=
15V
V
T
=
15V
S
A
S
A
= 25°C
= 25°C
C = 30pF
F
–55°C
NEGATIVE
SUPPLY
3M
1M
C
S
= 100pF
25°C
POSITIVE
SUPPLY
F
125°C
C = 30pF
60
POSITIVE
60
40
20
SUPPLY
= 100pF
40
C
300k
100k
S
20
0
10k
FREQUENCY (Hz)
1M
1
10
100
1k
100k
1
2
5
10
20
0.1
100 1k
10k 100k 1M
1
10
LOAD RESISTANCE (kΩ)
FREQUENCY (Hz)
1008 G15
1008 G16
1008 G17
Slew Rate
vs Compensation Capacitance
Large-Signal Transient Response
Large-Signal Transient Response
10
V
=
15V
S
A
T
= 25°C
1
C
S
C
F
AV = 1
CS = 100pF
20μs/DIV
1008 G18
AV = 1
CF = 30pF
20μs/DIV
1008 G20
0.1
20
40
60
80
100
0
COMPENSATION CAPACITOR (pF)
108 G19
Small-Signal Transient Response
Small-Signal Transient Response
Small-Signal Transient Response
AV = 1
CS = 100pF
CLOAD = 100pF
5μs/DIV
1008 G21
AV = 1
CS = 100pF
CLOAD = 600pF
5μs/DIV
1008 G22
AV = 1
CF = 30pF
CLOAD = 100pF
5μs/DIV
1008 G23
1008fb
7
LT1008
W U U
U
APPLICATIO S I FOR ATIO
Achieving Picoampere/Microvolt Performance
TheLT1008isspecifiedoverawiderangeofpowersupply
voltagesfrom 2Vto 18V. Operationwithlowersupplies
is possible down to 1.2V (two Ni-Cad batteries).
In order to realize the picoampere—microvolt level accu-
racy 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
residueswillprobablyberequired.Surfacecoatingmaybe
necessary to provide a moisture barrier in high humidity
environments.
Test Circuit for Offset Voltage and Its Drift with Temperature
50k*
15V
*RESISTORS MUST HAVE LOW
–
2
3
THERMOELECTRIC POTENTIAL
7
THIS CIRCUIT IS ALSO USED AS
THE BURN-IN CONFIGURATION
FOR THE LT1008 WITH SUPPLY
VOLTAGES INCREASED TO 20V
6
100Ω*
LT1008
V
O
+
4
50k*
V
= 1000V
OS
O
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
ringshouldbetiedtoground, innoninvertingconnections
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 leak-
age into the compensation terminals can affect offset
voltage and drift with temperature.
–15V
1008 AI02
Noise Testing
The 0.1Hz to 10Hz peak-to-peak noise of the LT1008 is
measured in the test circuit shown. The frequency re-
sponse of this noise tester indicates that the 0.1Hz corner
isdefinedbyonlyonezero. Thetesttimetomeasure0.1Hz
to 10Hz noise should not exceed 10 seconds, as this time
limit acts as an additional zero to eliminate noise contribu-
tions from the frequency band below 0.1Hz.
COMPENSATION
+
V
A noise voltage density test is recommended when mea-
suring 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.
8
OUTPUT
7
1
6
2
5
4
3
Current noise is measured in the circuit shown and calcu-
lated by the following formula where the noise of the
source resistors is subtracted.
–
V
GUARD
1008 AI01
1/2
2
⎡
⎤
e2 – 820nV
REFERENCE ONLY—OBSOLETE PACKAGE
(
)
⎥
⎦
no
⎢
⎣
in =
Microvolt level error voltages can also be generated in the
external circuitry. Thermocouple effects caused by tem-
perature gradients across dissimilar metals at the con-
tacts 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.
40MΩ ×100
10k
10M* 10M*
2
–
+
6
100Ω
e
no
LT1008
10M* 10M*
3
*METAL FILM
1008 AI04
1008fb
8
LT1008
W U U
U
APPLICATIO S I FOR ATIO
0.1Hz to 10Hz Noise Test Circuit
0.1μF
100k
10Ω
–
2k
LT1008*
+
22μF
SCOPE
4.3k
2.2μF
+
4.7μF
×1
LT1001
R
= 1M
VOLTAGE
GAIN: 50,000
IN
110k
–
100k
*DEVICE UNDER TEST
24.3k
NOTE: ALL CAPACITOR VALUES ARE FOR
NONPOLARIZED CAPACITORS ONLY
0.1μF
1008 AI03
Frequency Compensation
In the voltage follower configuration, when the input is
drivenbyafast, large-signalpulse(>1V), theinputprotec-
tion 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 LT1008 is externally frequency compensated with a
single capacitor. The two standard compensation circuits
shown earlier are identical to the LM108A/LM308A fre-
quency compensation schemes. Therefore, the LT1008
operational amplifiers can be inserted directly into
LM108A/LM308A sockets, with similar AC and upgraded
DC performance.
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,resultinginfasterrecoveryandsettlingoftheoutput.
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
of1.2V/μscanberealized. Forclosed-loopgainsinexcess
of 200, no external compensation is necessary, and slew
rate increases to 4V/μs. The LT1008 can also be overcom-
pensated (i.e.,CF>30pForCS >100pF)toimprovecapaci-
tiveloadhandlingcapabilityortonarrownoisebandwidth.
In many applications, the feedback loop around the ampli-
fier has gain (e.g., logarithmic amplifiers); overcompen-
sation can stabilize these circuits with a single capacitor.
Inverter Feedforward Compensation
C2
5pF
R1
10k
R2
2
3
10k
INPUT
–
+
6
V
OUT
LT1008
1
8
R3
3k
C3
10pF
C1
500pF
1008 AI05
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/μs. The voltage
follower feedforward scheme bypasses the amplifier’s
gain stages and slews at nearly 10V/μs.
The inputs of the LT1008 are protected with back-to-back
diodes.Currentlimitingresistorsarenotused,becausethe
leakage of these resistors would prevent the realization of
picoampere level bias currents at elevated temperatures.
5μs/DIV
1008 AI07
1008fb
9
LT1008
APPLICATIO S I FOR ATIO
W U U
U
Follower Feedforward Compensation
30pF
10k
2
3
–
6
OUTPUT
LT1008
10k
INPUT*
+
8
1000pF
1008 AI06
*SOURCE RESISTANCE ≤15k FOR STABILITY
5μs/DIV
1008 AI07
U
TYPICAL APPLICATIO S
Logarithmic Amplifier
Q1A
2N2979
Q1B
2N2979
124k*
5.1k
15V
15V
LT1004C
1.2V
–
+
2
3
2k
100pF
330pF
10k*
2
3
7
INPUT
–
+
6
15.7k
LM107
6
4
LT1008
1k
TEL. LABS
TYPE Q81
8
1
–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
Saturated Standard Cell Amplifier
15V
R5
56M
+
3
2
7
V
+
–
C1
30pF
2N3609
1.018235V
SATURATED
STANDARD
CELL #101
6
OUTPUT
LT1008
S1
100k
T
4
R3
510k
R1
8
1
100k
1
2
3
–15V
+
–
+
8
6
R4
510k
LT1008
OUTPUT
EPPLEY LABS
NEWPORT, R.I.
1000pF
R2
S2
100k
R2
100k
R6
56M
T
VOLTAGE GAIN ≈ 100
R1
1008 TA04
1008 TA05
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
LT1008
U
TYPICAL APPLICATIO S
Amplifier for Photodiode Sensor
Five Decade Kelvin-Varley Divider Buffered by the LT1008
R1
5M
1%
15V
7
2
3
10V
–
+
6
100k
KELVIN-VARLEY
DIVIDER
OUTPUT
LT1008
2
4
–
8
6
ESI #DP311
λ
S1
LT1008
8
OUTPUT
1
00000 – 99999 + 1
–15V
3
+
R2
V
OUT
= 10V/μA
C1
5M
1%
100pF
1000pF
1008 TA06
APPROXIMATE ERROR DUE TO NOISE, BIAS CURRENT,
COMMON MODE REJECTION. VOLTAGE GAIN OF THE
AMPLIFIER IS 1/5 OF A LEAST SIGNIFICANT BIT
1008 TA07
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
15V
1.8k
OPTIONAL 0.01Hz TRIM
22M
50k
1000pF
(POLYSTYRENE)
–15V
1μF
2
V
IN
0V TO 10V
–
10k*
6
3
+
–
63.4k*
10k*
LT1008
8
1k
6
3
+
LM301A
100k
750k
10k*
2
100pF
LM329
22k
10k
15V
+
–
2
3
10k
10k
15V
LT1004C
1.2V
7
LT311A
–15V
1
4
5pF
–15V
FREQUENCY OUPUT
0.01Hz TO 10kHz
1008 TA08
*1% METAL FILM RESISTOR
ALL DIODES 1N4148
1008fb
11
LT1008
U
TYPICAL APPLICATIO S
Precision, Fast Settling, Lowpass Filter
Thiscircuitisusefulwherefastsignalacquisitionandhigh
precision are required, as in electronic scales.
10k
The filter’s time constant is set by the 2k resistor and the
1μF capacitor until comparator 1 switches. The time
constant is then set by the 1.5M resistor and the 1μF
capacitor. Comparator 2 provides a quick reset.
2
–
1.5M
6
OUTPUT
LT1008
2k
3
8
INPUT
+
1μF
1
The circuit settles to a final value three times as fast as a
simple 1.5M-1μF filter with almost no DC error.
1000pF
OPTO-MOS*
15V
1k
15V
2
8
+
7
#1
LT311A
3
–
4
–15V
1
5
FILTER CUT
IN ADJUST
100Ω
10k
15V
*OPTO-MOS SWITCH
TYPE OFM1A
THETA-J CORP
3
2
8
–
+
7
#2
LT311A
4
–15V
1
1008 TA09
Fast Precision Inverters
2pF TO 8pF
10k*
10k*
10k*
10pF
INPUT
10k
1N4148 ×2
15V
1
300pF
2N4393
×2
2
3
10k*
5
–
+
15V
7
INPUT
7
1000pF
6
LT318A
OUTPUT
2
3
15V
7
–
6
2
3
4
LT318A
OUTPUT
–
+
15k
6
LT1008
+
4
4
8
–15V
–15V
1
10k
10k
–15V
1N4148 (4)
300pF
30pF
FULL POWER BANDWIDTH = 2MHz
SLEW RATE AT 50V/μs
SETTLING (10V STEP) = 12μs TO 0.01%
BIAS CURRENT DC = 30pA
OFFSET DRIFT = 0.3μV/°C
OFFSET VOLTAGE = 30μV
*1% METAL FILM
15V
7
10k
2
–
6
LT1008
4
3
+
8
SLEW RATE = 100V/μs
1
10k
–15V
SETTLING (10V STEP) = 5μs TO 0.01%
OFFSET VOLTAGE = 30μV
BIAS CURRENT DC = 30pA
*1% METAL FILM
30pF
1008 TA10
1008fb
12
LT1008
W
W
SCHE ATIC DIAGRA
COMP1
COMP2
8
+
1
V
7
1.3k
4.2k
Q20
Q14
Q30
22k
22k
Q29
3k
Q22
Q24
Q7
Q5
Q8
1.5k
Q43
Q25
Q21
Q6
Q27
Q28
Q37
Q38
S
Q16
Q4
60Ω
70Ω
OUTPUT
6
Q3
3k
Q13
Q23
Q11
3k
S
S
S
–INPUT
2
50k 1.5k
Q12
Q2
Q1
Q15
Q26
Q9
J1
Q42
Q32
Q31
Q33
Q10
Q39
+INPUT
3
16k
20k
Q35
3.3k
Q18
Q19
Q17
Q40
Q41
3.3k
3.3k
Q34
320Ω
40Ω
330Ω
–
4.3k
4.8k
V
4
1008fb
13
LT1008
U
PACKAGE DESCRIPTIO
H Package
8-Lead TO-5 Metal Can (.200 Inch PCD)
(Reference LTC DWG # 05-08-1320)
0.335 – 0.370
(8.509 – 9.398)
DIA
0.027 – 0.045
(0.686 – 1.143)
0.305 – 0.335
(7.747 – 8.509)
0.040
(1.016)
MAX
45°TYP
PIN 1
0.028 – 0.034
(0.711 – 0.864)
0.050
(1.270)
MAX
0.165 – 0.185
(4.191 – 4.699)
0.200
(5.080)
TYP
REFERENCE
PLANE
SEATING
PLANE
GAUGE
PLANE
0.500 – 0.750
(12.700 – 19.050)
0.010 – 0.045*
(0.254 – 1.143)
H8(TO-5) 0.200 PCD 1197
0.110 – 0.160
0.016 – 0.021**
(0.406 – 0.533)
(2.794 – 4.064)
INSULATING
STANDOFF
*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)
J8 Package
8-Lead CERDIP (Narrow .300 Inch, Hermetic)
(Reference LTC DWG # 05-08-1110)
0.405
(10.287)
MAX
CORNER LEADS OPTION
(4 PLCS)
0.005
(0.127)
MIN
6
5
8
7
2
0.023 – 0.045
(0.584 – 1.143)
HALF LEAD
OPTION
0.025
(0.635)
RAD TYP
0.220 – 0.310
(5.588 – 7.874)
0.045 – 0.068
(1.143 – 1.727)
FULL LEAD
OPTION
1
3
4
0.200
0.300 BSC
(5.080)
MAX
(0.762 BSC)
0.015 – 0.060
(0.381 – 1.524)
0.008 – 0.018
(0.203 – 0.457)
0° – 15°
0.045 – 0.065
(1.143 – 1.651)
0.125
3.175
MIN
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS
0.014 – 0.026
(0.360 – 0.660)
0.100
(2.54)
BSC
J8 1298
OBSOLETE PACKAGES
1008fb
14
LT1008
U
PACKAGE DESCRIPTIO
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
4
3
.130 .005
.300 – .325
.045 – .065
(3.302 0.127)
(1.143 – 1.651)
(7.620 – 8.255)
.065
(1.651)
TYP
.008 – .015
(0.203 – 0.381)
.120
.020
(0.508)
MIN
(3.048)
MIN
+.035
.325
–.015
.018 .003
(0.457 0.076)
.100
(2.54)
BSC
+0.889
8.255
(
)
N8 1002
–0.381
NOTE:
INCHES
1. DIMENSIONS ARE
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 .005
.050 BSC
7
5
8
6
.245
MIN
.160 .005
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 .005
TYP
1
2
3
4
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
(0.254 – 0.508)
× 45°
.053 – .069
(1.346 – 1.752)
.004 – .010
(0.101 – 0.254)
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
NOTE:
INCHES
1. DIMENSIONS IN
(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)
SO8 0303
1008fb
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 represen-
tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LT1008
U
TYPICAL APPLICATIO
Ammeter measures currents from 100pA to 100μA with-
out 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 LT1008.
Ammeter with Six Decade Range
10k
15V
Q3
100μA
METER
R1
2k
1.2k
100pA
Q1
15V
549Ω
549Ω
549Ω
549Ω
549Ω
549Ω
RANGE 1nA
10k
2
3
7
CURRENT
INPUT
Q2
–
+
33k
6
LT1008
4
10nA
100nA
1μA
LT1004C-1.2
Q4
8
1
PIN 13
CA3146
–15V
0.01μF
Q1 TO Q4: RCA CA3146 TRANSISTOR ARRAY
CALIBRATION: ADJUST R1 FOR FULL SCALE
DEFLECTION WITH 1μA INPUT CURRENT
10μA
100μA
1008 TA11
RELATED PARTS
PART NUMBER DESCRIPTION
COMMENTS
LT1012
LT1112
LT1880
Picoamp Input Current, Microvolt Offset, Low Noise Op Amp
Dual Low Power, Precision, Picoamp Input Op Amp
Internally Compensated LT1008
Dual LT1012
SOT-23, Rail-to-Rail Output, Picoamp Input Current Precision Op Amp
Single SOT-23 Version of LT1884
LT1881/LT1882 Dual and Quad Rail-to-Rail Output, Picoamp Input Precision Op Amps
LT1884/LT1885 Dual and Quad Rail-to-Rail Output, Picoamp Input Precision Op Amps
Dual/Quad C
Stable
LOAD
Dual/Quad Faster LT1881/LT1882
1008fb
LT 0607 REV B • PRINTED IN THE USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
© LINEAR TECHNOLOGY CORPORATION 1991
相关型号：
LT1009CH#PBF
IC TWO TERM VOLTAGE REFERENCE, MBCY3, LEAD FREE, METAL CAN, TO-46, 3 PIN, Voltage Reference
Linear
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