NSC LMC6062AIM

LMC6062
Precision CMOS Dual Micropower Operational Amplifier
General Description
Features
The LMC6062 is a precision dual low offset voltage, micropower operational amplifier, capable of precision single
supply operation. Performance characteristics include ultra
low input bias current, high voltage gain, rail-to-rail output
swing, and an input common mode voltage range that includes ground. These features, plus its low power consumption, make the LMC6062 ideally suited for battery powered
applications.
Other applications using the LMC6062 include precision
full-wave rectifiers, integrators, references, sample-and-hold
circuits, and true instrumentation amplifiers.
This device is built with National’s advanced double-Poly
Silicon-Gate CMOS process.
For designs that require higher speed, see the LMC6082
precision dual operational amplifier.
PATENT PENDING
(Typical Unless Otherwise Noted)
n Low offset voltage 100 µV
n Ultra low supply current 16 µA/Amplifier
n Operates from 4.5V to 15V single supply
n Ultra low input bias current 10 fA
n Output swing within 10 mV of supply rail, 100k load
n Input common-mode range includes V−
n High voltage gain 140 dB
n Improved latchup immunity
Applications
n
n
n
n
n
n
n
Instrumentation amplifier
Photodiode and infrared detector preamplifier
Transducer amplifiers
Hand-held analytic instruments
Medical instrumentation
D/A converter
Charge amplifier for piezoelectric transducers
Connection Diagram
8-Pin DIP/SO
DS011298-1
Top View
Ordering Information
Temperature Range
Package
Military
−55˚C to +125˚C
8-Pin
LMC6062AMN
Molded DIP
Industrial
−40˚C to +85˚C
LMC6062AIN
Transport
Media
N08E
Rail
LMC6062IN
8-Pin
LMC6062AIM
Small Outline
LMC6062IM
8-Pin
NSC
Drawing
LMC6062AMJ/883
M08A
Rail
Tape and Reel
J08A
Rail
Ceramic DIP
© 1999 National Semiconductor Corporation
DS011298
www.national.com
LMC6062 Precision CMOS Dual Micropower Operational Amplifier
November 1994
Absolute Maximum Ratings (Note 1)
Differential Input Voltage
Voltage at Input/Output Pin
Supply Voltage (V+ − V−)
Output Short Circuit to V+
Output Short Circuit to V−
Lead Temperature
(Soldering, 10 sec.)
Storage Temp. Range
Junction Temperature
ESD Tolerance (Note 4)
± 10 mA
± 30 mA
Current at Input Pin
Current at Output Pin
Current at Power Supply Pin
Power Dissipation
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
± Supply Voltage
40 mA
(Note 3)
Operating Ratings (Note 1)
(V+) +0.3V,
(V−) −0.3V
16V
(Note 11)
(Note 2)
Temperature Range
LMC6062AM
LMC6062AI, LMC6082I
Supply Voltage
Thermal Resistance (θJA) (Note 12)
8-Pin Molded DIP
8-Pin SO
Power Dissipation
260˚C
−65˚C to +150˚C
150˚C
2 kV
−55˚C ≤ TJ ≤ +125˚C
−40˚C ≤ TJ ≤ +85˚C
4.5V ≤ V+ ≤ 15.5V
115˚C/W
193˚C/W
(Note 10)
DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. Boldface limits apply at the temperature extremes. V+ = 5V,
V− = 0V, VCM = 1.5V, VO = 2.5V and RL > 1M unless otherwise specified.
Symbol
VOS
TCVOS
Parameter
Conditions
Input Offset Voltage
Typ
LMC6062AM
LMC6062AI
(Note 5)
Limit
Limit
Limit
(Note 6)
(Note 6)
(Note 6)
100
Input Offset Voltage
LMC6062I
Units
350
350
800
µV
1200
900
1300
Max
1.0
µV/˚C
Average Drift
IB
IOS
Input Bias Current
Input Offset Current
RIN
Input Resistance
CMRR
Common Mode
−PSRR
5V ≤ V+ ≤ 15V
VO = 2.5V
85
Rejection Ratio
Negative Power Supply
0V ≤ V− ≤ −10V
100
Rejection Ratio
VCM
Input Common-Mode
V+ = 5V and 15V
Voltage Range
for CMRR ≥ 60 dB
−0.4
V+ − 1.9
AV
Large Signal
RL = 100 kΩ
Voltage Gain
(Note 7)
RL = 25 kΩ
Sourcing
4000
4
Max
100
2
2
Max
75
75
66
dB
70
72
63
Min
75
75
66
dB
70
72
63
Min
84
84
74
dB
70
81
71
Min
−0.1
−0.1
−0.1
V
0
0
0
Max
pA
Tera Ω
V+ − 2.3
V+ − 2.3
V+ − 2.3
V
V+ − 2.6
V+ − 2.5
V+ − 2.5
Min
400
400
300
V/mV
200
300
200
Min
180
90
V/mV
Sinking
3000
180
70
100
60
Min
Sourcing
3000
400
400
200
V/mV
150
150
80
Min
Sinking
2000
100
100
70
V/mV
35
50
35
Min
(Note 7)
www.national.com
4
> 10
85
Positive Power Supply
pA
100
0.005
0V ≤ VCM ≤ 12.0V
V+ = 15V
Rejection Ratio
+PSRR
0.010
2
DC Electrical Characteristics
(Continued)
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. Boldface limits apply at the temperature extremes. V+ = 5V,
V− = 0V, VCM = 1.5V, VO = 2.5V and RL > 1M unless otherwise specified.
Symbol
VO
Parameter
Output Swing
Conditions
V+ = 5V
RL = 100 kΩ to 2.5V
Typ
LMC6062AM
LMC6062AI
(Note 5)
Limit
Limit
Limit
(Note 6)
(Note 6)
(Note 6)
4.990
4.990
4.950
V
4.970
4.980
4.925
Min
4.995
0.005
V+ = 5V
RL = 25 kΩ to 2.5V
4.990
0.010
V+ = 15V
RL = 100 kΩ to 7.5V
14.990
0.010
V+ = 15V
RL = 25 kΩ to 7.5V
14.965
0.025
IO
Output Current
V+ = 5V
Sourcing, VO = 0V
22
Sinking, VO = 5V
IO
Output Current
V+ = 15V
21
Sourcing, VO = 0V
25
Sinking, VO = 13V
35
(Note 11)
IS
Supply Current
Both Amplifiers
V+ = +5V, VO = 1.5V
32
Both Amplifiers
V+ = +15V, VO = 7.5V
40
3
LMC6062I
Units
0.010
0.010
0.050
V
0.030
0.020
0.075
Max
4.975
4.975
4.950
V
4.955
4.965
4.850
Min
0.020
0.020
0.050
V
0.045
0.035
0.150
Max
14.975
14.975
14.950
V
14.955
14.965
14.925
Min
0.025
0.025
0.050
V
0.050
0.035
0.075
Max
14.900
14.900
14.850
V
14.800
14.850
14.800
Min
0.050
0.050
0.100
V
0.200
0.150
0.200
Max
16
16
13
mA
8
10
8
Min
16
16
16
mA
7
8
8
Min
15
15
15
mA
9
10
10
Min
24
24
24
mA
7
8
8
Min
38
38
46
µA
60
46
56
Max
47
47
57
µA
70
55
66
Max
www.national.com
AC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C, Boldface limits apply at the temperature extremes. V+ = 5V,
V− = 0V, VCM = 1.5V, VO = 2.5V and RL > 1M unless otherwise specified.
Symbol
SR
Parameter
Slew Rate
GBW
Gain-Bandwidth Product
θm
Phase Margin
Conditions
Typ
LMC6062AM
LMC6062AI
(Note 5)
Limit
Limit
Limit
(Note 6)
(Note 6)
(Note 6)
20
20
15
8
10
7
(Note 8)
35
LMC6062I
Units
V/ms
Min
100
kHz
50
Deg
Amp-to-Amp Isolation
(Note 9)
155
dB
en
Input-Referred Voltage Noise
F = 1 kHz
83
nV/√Hz
in
Input-Referred Current Noise
F = 1 kHz
0.0002
pA/√Hz
T.H.D.
Total Harmonic Distortion
F = 1 kHz, AV = −5
0.01
%
RL = 100 kΩ, VO = 2 VPP
± 5V Supply
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The
guaranteed specifications apply only for the test conditions listed.
Note 2: Applies to both single-supply and split-supply operation. Continous short circuit operation at elevated ambient temperature can result in exceeding the maximum allowed junction temperature of 150˚C. Output currents in excess of ± 30 mA over long term may adversely affect reliability.
Note 3: The maximum power dissipation is a function of TJ(Max), θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(Max)
− TA)/θJA.
Note 4: Human body model, 1.5 kΩ in series with 100 pF.
Note 5: Typical values represent the most likely parametric norm.
Note 6: All limits are guaranteed by testing or statistical analysis.
Note 7: V+ = 15V, VCM = 7.5V and RL connected to 7.5V. For Sourcing tests, 7.5V ≤ VO ≤ 11.5V. For Sinking tests, 2.5V ≤ VO ≤ 7.5V.
Note 8: V+ = 15V. Connected as Voltage Follower with 10V step input. Number specified is the slower of the positive and negative slew rates.
Note 9: Input referred V+ = 15V and RL = 100 kΩ connected to 7.5V. Each amp excited in turn with 100 Hz to produce VO = 12 VPP.
Note 10: For operating at elevated temperatures the device must be derated based on the thermal resistance θJA with PD = (TJ–TA)/θJA.
Note 11: Do not connect output to V+, when V+ is greater than 13V or reliability witll be adversely affected.
Note 12: All numbers apply for packages soldered directly into a PC board.
Note 13: For guaranteed Military Temperature Range parameters, see RETSMC6062X.
www.national.com
4
Typical Performance Characteristics
Distribution of LMC6062
Input Offset Voltage
(TA = +25˚C)
VS = ± 7.5V, TA = 25˚C, Unless otherwise specified
Distribution of LMC6062
Input Offset Voltage
(TA = −55˚C)
DS011298-15
Input Bias Current
vs Temperature
Distribution of LMC6062
Input Offset Voltage
(TA = +125˚C)
DS011298-16
Supply Current
vs Supply Voltage
DS011298-18
Common Mode
Rejection Ratio
vs Frequency
DS011298-17
Input Voltage
vs Output Voltage
DS011298-19
Power Supply Rejection
Ratio vs Frequency
DS011298-20
Input Voltage Noise
vs Frequency
DS011298-22
DS011298-23
DS011298-21
5
www.national.com
Typical Performance Characteristics
VS = ± 7.5V, TA = 25˚C, Unless otherwise
specified (Continued)
Output Characteristics
Sourcing Current
Output Characteristics
Sinking Current
Gain and Phase Response
vs Temperature
(−55˚C to +125˚C)
DS011298-24
DS011298-25
Gain and Phase
Response vs Capacitive Load
with RL = 20 kΩ
Gain and Phase
Response vs Capacitive Load
with RL = 500 kΩ
DS011298-26
Open Loop
Frequency Response
DS011298-29
DS011298-27
Inverting Small Signal
Pulse Response
DS011298-28
Inverting Large Signal
Pulse Response
DS011298-30
www.national.com
Non-Inverting Small
Signal Pulse Response
DS011298-31
6
DS011298-32
Typical Performance Characteristics
VS = ± 7.5V, TA = 25˚C, Unless otherwise
specified (Continued)
Non-Inverting Large
Signal Pulse Response
Crosstalk Rejection
vs Frequency
DS011298-33
Stability vs Capacitive
Load, RL = 20 kΩ
DS011298-34
DS011298-35
Stability vs Capacitive
Load RL = 1 MΩ
DS011298-36
duce leakage, but lowers stray input capacitance as well.
(See Printed-Circuit-Board Layout for High Impedance
Work).
Applications Hints
AMPLIFIER TOPOLOGY
The LMC6062 incorporates a novel op-amp design topology
that enables it to maintain rail-to-rail output swing even when
driving a large load. Instead of relying on a push-pull unity
gain output buffer stage, the output stage is taken directly
from the internal integrator, which provides both low output
impedance and large gain. Special feed-forward compensation design techniques are incorporated to maintain stability
over a wider range of operating conditions than traditional
micropower op-amps. These features make the LMC6062
both easier to design with, and provide higher speed than
products typically found in this ultra-low power class.
The effect of input capacitance can be compensated for by
adding a capacitor. Place a capacitor, Cf, around the feedback resistor (as in Figure 1 ) such that:
or
R1 CIN ≤ R2 Cf
Since it is often difficult to know the exact value of CIN, Cf can
be experimentally adjusted so that the desired pulse response is achieved. Refer to the LMC660 and the LMC662
for a more detailed discussion on compensating for input
capacitance.
COMPENSATING FOR INPUT CAPACITANCE
It is quite common to use large values of feedback resistance for amplifiers with ultra-low input current, like the
LMC6062.
Although the LMC6062 is highly stable over a wide range of
operating conditions, certain precautions must be met to
achieve the desired pulse response when a large feedback
resistor is used. Large feedback resistors and even small
values of input capacitance, due to transducers, photodiodes, and circuit board parasitics, reduce phase margins.
When high input impedances are demanded, guarding of the
LMC6062 is suggested. Guarding input lines will not only re-
7
www.national.com
Applications Hints
fier with respect to the desired output swing. Open loop gain
of the amplifier can also be affected by the pull up resistor
(see Electrical Characteristics).
(Continued)
DS011298-14
FIGURE 3. Compensating for Large Capacitive Loads
with a Pull Up Resistor
DS011298-4
PRINTED-CIRCUIT-BOARD LAYOUT
FOR HIGH-IMPEDANCE WORK
It is generally recognized that any circuit which must operate
with less than 1000 pA of leakage current requires special
layout of the PC board. When one wishes to take advantage
of the ultra-low bias current of the LMC6062, typically less
than 10 fA, it is essential to have an excellent layout. Fortunately, the techniques of obtaining low leakages are quite
simple. First, the user must not ignore the surface leakage of
the PC board, even though it may sometimes appear acceptably low, because under conditions of high humidity or dust
or contamination, the surface leakage will be appreciable.
To minimize the effect of any surface leakage, lay out a ring
of foil completely surrounding the LMC6062’s inputs and the
terminals of capacitors, diodes, conductors, resistors, relay
terminals etc. connected to the op-amp’s inputs, as in Figure
4. To have a significant effect, guard rings should be placed
on both the top and bottom of the PC board. This PC foil
must then be connected to a voltage which is at the same
voltage as the amplifier inputs, since no leakage current can
flow between two points at the same potential. For example,
a PC board trace-to-pad resistance of 1012Ω, which is normally considered a very large resistance, could leak 5 pA if
the trace were a 5V bus adjacent to the pad of the input. This
would cause a 100 times degradation from the LMC6062’s
actual performance. However, if a guard ring is held within
5 mV of the inputs, then even a resistance of 1011Ω would
cause only 0.05 pA of leakage current. See Figure 5 for typical connections of guard rings for standard op-amp
configurations.
FIGURE 1. Canceling the Effect of Input Capacitance
CAPACITIVE LOAD TOLERANCE
All rail-to-rail output swing operational amplifiers have voltage gain in the output stage. A compensation capacitor is
normally included in this integrator stage. The frequency location of the dominate pole is affected by the resistive load
on the amplifier. Capacitive load driving capability can be optimized by using an appropriate resistive load in parallel with
the capacitive load (see typical curves).
Direct capacitive loading will reduce the phase margin of
many op-amps. A pole in the feedback loop is created by the
combination of the op-amp’s output impedance and the capacitive load. This pole induces phase lag at the unity-gain
crossover frequency of the amplifier resulting in either an oscillatory or underdamped pulse response. With a few external components, op amps can easily indirectly drive capacitive loads, as shown in Figure 2.
DS011298-5
FIGURE 2. LMC6062 Noninverting Gain of 10 Amplifier,
Compensated to Handle Capacitive Loads
In the circuit of Figure 2, R1 and C1 serve to counteract the
loss of phase margin by feeding the high frequency component of the output signal back to the amplifier’s inverting input, thereby preserving phase margin in the overall feedback
loop.
DS011298-6
FIGURE 4. Example of Guard Ring in P.C. Board
Layout
Capacitive load driving capability is enhanced by using a pull
up resistor to V+ (Figure 3). Typically a pull up resistor conducting 10 µA or more will significantly improve capacitive
load responses. The value of the pull up resistor must be determined based on the current sinking capability of the ampliwww.national.com
8
Applications Hints
Latchup
(Continued)
CMOS devices tend to be susceptible to latchup due to their
internal parasitic SCR effects. The (I/O) input and output pins
look similar to the gate of the SCR. There is a minimum current required to trigger the SCR gate lead. The LMC6062
and LMC6082 are designed to withstand 100 mA surge current on the I/O pins. Some resistive method should be used
to isolate any capacitance from supplying excess current to
the I/O pins. In addition, like an SCR, there is a minimum
holding current for any latchup mode. Limiting current to the
supply pins will also inhibit latchup susceptibility.
DS011298-7
(a) Inverting Amplifier
DS011298-10
DS011298-8
(Input pins are lifted out of PC board and soldered directly to components.
All other pins connected to PC board).
(b) Non-Inverting Amplifier
FIGURE 6. Air Wiring
Typical Single-Supply
Applications
(V+ = 5.0 VDC)
The extremely high input impedance, and low power consumption, of the LMC6062 make it ideal for applications that
require battery-powered instrumentation amplifiers. Examples of these types of applications are hand-held pH
probes, analytic medical instruments, magnetic field detectors, gas detectors, and silicon based pressure transducers.
DS011298-9
(c) Follower
FIGURE 5. Typical Connections of Guard Rings
The designer should be aware that when it is inappropriate
to lay out a PC board for the sake of just a few circuits, there
is another technique which is even better than a guard ring
on a PC board: Don’t insert the amplifier’s input pin into the
board at all, but bend it up in the air and use only air as an insulator. Air is an excellent insulator. In this case you may
have to forego some of the advantages of PC board construction, but the advantages are sometimes well worth the
effort of using point-to-point up-in-the-air wiring. See Figure
6.
Figure 7 shows an instrumentation amplifier that features
high differential and common mode input resistance
( > 1014Ω), 0.01% gain accuracy at AV = 100, excellent
CMRR with 1 kΩ imbalance in bridge source resistance. Input current is less than 100 fA and offset drift is less than
2.5 µV/˚C. R2 provides a simple means of adjusting gain
over a wide range without degrading CMRR. R7 is an initial
trim used to maximize CMRR without using super precision
matched resistors. For good CMRR over temperature, low
drift resistors should be used.
9
www.national.com
Typical Single-Supply
Applications (Continued)
DS011298-11
If R1 = R5, R3 = R6, and R4 = R7; then
∴AV ≈ 100 for circuit shown (R2 = 9.822k).
FIGURE 7. Instrumentation Amplifier
DS011298-12
FIGURE 8. Low-Leakage Sample and Hold
DS011298-13
FIGURE 9. 1 Hz Square Wave Oscillator
www.national.com
10
Physical Dimensions
inches (millimeters) unless otherwise noted
8-Pin Ceramic Dual-In-Line Package
Order Number LMC6062AMJ/883
NS Package Number J08A
8-Pin Small Outline Package
Order Number LMC6062AIM or LMC6062IM
NS Package Number M08A
11
www.national.com
LMC6062 Precision CMOS Dual Micropower Operational Amplifier
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
8-Pin Molded Dual-In-Line Package
Order Number LMC6062AIN, LMC6062AMN or LMC6062IN
NS Package Number N08E
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
2. A critical component is any component of a life support
1. Life support devices or systems are devices or sysdevice or system whose failure to perform can be reatems which, (a) are intended for surgical implant into
sonably expected to cause the failure of the life support
the body, or (b) support or sustain life, and whose faildevice or system, or to affect its safety or effectiveness.
ure to perform when properly used in accordance
with instructions for use provided in the labeling, can
be reasonably expected to result in a significant injury
to the user.
National Semiconductor
Corporation
Americas
Tel: 1-800-272-9959
Fax: 1-800-737-7018
Email: [email protected]
www.national.com
National Semiconductor
Europe
Fax: +49 (0) 1 80-530 85 86
Email: [email protected]
Deutsch Tel: +49 (0) 1 80-530 85 85
English Tel: +49 (0) 1 80-532 78 32
Français Tel: +49 (0) 1 80-532 93 58
Italiano Tel: +49 (0) 1 80-534 16 80
National Semiconductor
Asia Pacific Customer
Response Group
Tel: 65-2544466
Fax: 65-2504466
Email: [email protected]
National Semiconductor
Japan Ltd.
Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.