Document
LM108A LM208A LM308A Operational Amplifiers
May 1989
LM108A LM208A LM308A Operational Amplifiers
General Description
The LM108 LM108A series are precision operational amplifiers having specifications about a factor of ten better than FET amplifiers over their operating temperature range In addition to low input currents these devices have extremely low offset voltage making it possible to eliminate offset adjustments in most cases and obtain performance approaching chopper stabilized amplifiers The devices operate with supply voltages from g 2V to g 18V and have sufficient supply rejection to use unregulated 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 bypass capacitors unnecessary The low current error of the LM108A series makes possible many designs that are not practical with conventional amplifiers 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 using capacitors no larger than 1 mF The LM208A is identical to the LM108A except that the LM208A has its performance guaranteed over a b25 C to a 85 C temperature range instead of b 55 C to a 125 C The LM308A devices have slightly-relaxed specifications and performances over a 0 C to a 70 C temperature range
Features
Y Y Y Y Y
Offset voltage guaranteed less than 0 5 mV Maximum input bias current of 3 0 nA over temperature Offset current less than 400 pA over temperature Supply current of only 300 mA even in saturation Guaranteed 5 mV C drift
Compensation Circuits
Standard Compensation Circuit Alternate Frequency Compensation
Cf t
R1 CO R1 a R2
CO e 30 pF
TL H 7759 – 1
Improves rejection of power supply noise by a factor of ten
TL H 7759 – 2
Bandwidth and slew rate are proportional to 1 Cf
Bandwidth and slew rate are proportional to 1 Cs
Feedforward Compensation
TL H 7759 – 3
C1995 National Semiconductor Corporation
TL H 7759
RRD-B30M115 Printed in U S A
LM108A LM208A Absolute Maximum Ratings
If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications (Note 5) g 20V Supply Voltage Power Dissipation (Note 1) 500 mW g 10 mA Differential Input Current (Note 2) g 15V Input Voltage (Note 3) Output Short-Circuit Duration Continuous Operating Free Air Temperature Range b 55 C to a 125 C LM108A b 25 C to a 85 C LM208A
b 65 C to a 150 C Storage Temperature Range Lead Temperature (Soldering 10 sec ) (DIP) 260 C
Soldering Information Dual-In-Line Package Soldering (10 sec ) Small Outline Package Vapor Phase (60 sec ) Infrared (15 sec )
260 C
215 C 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 Input Offset Voltage Input Offset Current Input Bias Current Input Resistance Supply Current Large Signal Voltage Gain Input Offset Voltage Average Temperature Coefficient of Input Offset Voltage Input Offset Current Average Temperature Coefficient of Input Offset Current Input Bias Current Supply Current Large Signal Voltage Gain Output Voltage Swing Input Voltage Range Common Mode Rejection Ratio Supply Voltage Rejection Ratio TA e 125 C VS e g 15V VOUT e g 10V RL t 10 kX VS e g 15V RL e 10 kX VS e g 15V 40
g 13 g 13 5 g 14
Conditions TA e 25 C TA e 25 C TA e 25 C TA e 25 C TA e 25 C TA e 25 C VS e g 15V VOUT e g 10V RL t 10 kX
Min
Typ 03 0 05 08
Max 05 02 20
Units mV nA nA MX
30
70 03 06
mA V mV
80
300 10 10 50 04 05 25 30 0 15 04
mV mV C nA pA C nA mA V mV V V
96 96
110 110
dB dB
Note 1 The maximum junction temperature of the LM108A is 150 C while that of the LM208A is 100 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 VS s g 20V and b 55 C s TA s 125 C unless otherwise specified With the LM208A however all temperature specifications are limited to b 25 C s TA s 85 C Note 5 Refer to RETS108AX for LM108AH and LM108AJ-8 military specifications Note 6 Human body model 1 5 kX in series with 100 pF
2
LM308A Absolute Maximum Ratings
If Military Aerospace specifi.