LM108
TL/H/7758
LM108/LM208/LM308 Operational Amplifiers
December 1994
LM108/LM208/LM308 Operational Amplifiers
General Description
The LM108 series are precision operational amplifiers hav-
ing specifications a factor of ten better than FET amplifiers
over a
b
55
§
Cto
a
125
§
C temperature range.
The devices operate with supply voltages from
g
2V to
g
20V and have sufficient supply rejection to use unregulat-
ed supplies. Although the circuit is interchangeable with and
uses the same compensation as the LM101A, an alternate
compensation scheme can be used to make it particularly
insensitive to power supply noise and to make supply by-
pass capacitors unnecessary.
The low current error of the LM108 series makes possible
many designs that are not practical with conventional ampli-
fiers. In fact, it operates from 10 MX source resistances,
introducing less error than devices like the 709 with 10 kX
sources. Integrators with drifts less than 500 mV/sec and
analog time delays in excess of one hour can be made us-
ing capacitors no larger than 1 mF.
The LM108 is guaranteed from
b
55
§
Cto
a
125
§
C, the
LM208 from
b
25
§
Cto
a
85
§
C, and the LM308 from 0
§
Cto
a
70
§
C.
Features
Y
Maximum input bias current of 3.0 nA over temperature
Y
Offset current less than 400 pA over temperature
Y
Supply current of only 300 mA, even in saturation
Y
Guaranteed drift characteristics
Compensation Circuits
Standard Compensation Circuit
C
f
t
R1 C
O
R1
a
R2
C
O
e
30 pF
TL/H/7758– 1
**Bandwidth and slew rate are proportional to 1/C
f
Alternate* Frequency Compensation
TL/H/7758– 2
*Improves rejection of power supply noise by a factor of ten.
**Bandwidth and slew rate are proportional to 1/C
s
Feedforward Compensation
TL/H/7758– 3
C
1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.
查询LM108A供应商
Absolute Maximum Ratings
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
(Note 5)
LM108/LM208 LM308
Supply Voltage
g
20V
g
18V
Power Dissipation (Note 1) 500 mW 500 mW
Differential Input Current (Note 2)
g
10 mA
g
10 mA
Input Voltage (Note 3)
g
15V
g
15V
Output Short-Circuit Duration Continuous Continuous
Operating Temperature Range (LM108)
b
55
§
Cto
a
125
§
C0
§
Cto
a
70
§
C
(LM208)
b
25
§
Cto
a
85
§
C
Storage Temperature Range
b
65
§
Cto
a
150
§
C
b
65
§
Cto
a
150
§
C
Lead Temperature (Soldering, 10 sec)
DIP 260
§
C 260
§
C
H Package Lead Temp
(Soldering 10 seconds) 300
§
C 300
§
C
Soldering Information
Dual-In-Line Package
Soldering (10 seconds) 260
§
C
Small Outline Package
Vapor Phase (60 seconds) 215
§
C
Infrared (15 seconds) 220
§
C
See AN-450 ‘‘Surface Mounting Methods and Their Effect on Product
Reliability’’ for other methods of soldering surface mount devices.
ESD Tolerance (Note 6) 2000V
Electrical Characteristics (Note 4)
Parameter Condition
LM108/LM208 LM308
Units
Min Typ Max Min Typ Max
Input Offset Voltage T
A
e
25
§
C 0.7 2.0 2.0 7.5 mV
Input Offset Current T
A
e
25
§
C 0.05 0.2 0.2 1 nA
Input Bias Current T
A
e
25
§
C 0.8 2.0 1.5 7 nA
Input Resistance T
A
e
25
§
C 3070 1040 MX
Supply Current T
A
e
25
§
C 0.3 0.6 0.3 0.8 mA
Large Signal Voltage T
A
e
25
§
C, V
S
e
g
15V
50 300 25 300 V/mV
Gain V
OUT
e
g
10V, R
L
t
10 kX
Input Offset Voltage 3.0 10 mV
Average Temperature
Coefficient of Input 3.0 15 6.0 30 mV/
§
C
Offset Voltage
Input Offset Current 0.4 1.5 nA
Average Temperature
Coefficient of Input 0.5 2.5 2.0 10 pA/
§
C
Offset Current
Input Bias Current 3.0 10 nA
Supply Current T
A
ea
125
§
C 0.15 0.4 mA
Large Signal Voltage V
S
e
g
15V, V
OUT
e
g
10V
25 15 V/mV
Gain R
L
t
10 kX
Output Voltage Swing V
S
e
g
15V, R
L
e
10 kX
g
13
g
14
g
13
g
14 V
2
Electrical Characteristics (Note 4) (Continued)
Parameter Condition
LM108/LM208 LM308
Units
Min Typ Max Min Typ Max
Input Voltage Range V
S
e
g
15V
g
13.5
g
14 V
Common Mode
85 100 80 100 dB
Rejection Ratio
Supply Voltage
80 96 80 96 dB
Rejection Ratio
Note 1: The maximum junction temperature of the LM108 is 150
§
C, for the LM208, 100
§
C and for the LM308, 85
§
C. For operating at elevated temperatures, devices
in the H08 package must be derated based on a thermal resistance of 160
§
C/W, junction to ambient, or 20
§
C/W, junction to case. The thermal resistance of the
dual-in-line package is 100
§
C/W, junction to ambient.
Note 2: The inputs are shunted with back-to-back diodes for overvoltage protection. Therefore, excessive current will flow if a differential input voltage in excess of
1V is applied between the inputs unless some limiting resistance is used.
Note 3: For supply voltages less than
g
15V, the absolute maximum input voltage is equal to the supply voltage.
Note 4: These specifications apply for
g
5V
s
V
S
s
g
20V and
b
55
§
C
s
T
A
s
a
125
§
C, unless otherwise specified. With the LM208, however, all temperature
specifications are limited to
b
25
§
C
s
T
A
s
85
§
C, and for the LM308 they are limited to 0
§
C
s
T
A
s
70
§
C.
Note 5: Refer to RETS108X for LM108 military specifications and RETs 108AX for LM108A military specifications.
Note 6: Human body model, 1.5 kX in series with 100 pF.
Schematic Diagram
TL/H/7758– 8
3
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