TL H 7758
LM108LM208LM308
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 C to
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 C to
a
125 C the
LM208 from
b
25 C to
a
85 C and the LM308 from 0 C to
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
C1995 National Semiconductor Corporation
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
(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 C to
a
125 C
0 C to
a
70 C
(LM208)
b
25 C to
a
85 C
Storage Temperature Range
b
65 C to
a
150 C
b
65 C to
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
30
70
10
40
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
m
V 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
e a
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
Typical Performance Characteristics
LM108 LM208
Input Currents
Offset Error
Drift Error
Input Noise Voltage
Power Supply Rejection
Output Impedance
Closed Loop
Voltage Gain
Output Swing
Supply Current
Frequency Response
Open Loop
Frequency Response
Large Signal
Pulse Response
Voltage Follower
TL H 7758 6
4
Typical Performance Characteristics
LM308
Input Currents
Offset Error
Drift Error
Input Noise Voltage
Power Supply Rejection
Output Impedance
Closed Loop
Voltage Gain
Output Swing
Supply Current
Frequency Response
Open Loop
Frequency Response
Large Signal
Pulse Response
Voltage Follower
TL H 7758 7
5
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