Amplifier

LMC6462 Dual/LMC6464 Quad Micropower, Rail-to-Rail Input and Output CMOS Operational
May 1999

LMC6462 Dual/LMC6464 Quad

Micropower, Rail-to-Rail Input and Output CMOS
Operational Amplifier
General Description Features
The LMC6462/4 is a micropower version of the popular (Typical unless otherwise noted)
LMC6482/4, combining Rail-to-Rail Input and Output Range n Ultra Low Supply Current 20 µA/Amplifier
with very low power consumption. n Guaranteed Characteristics at 3V and 5V
The LMC6462/4 provides an input common-mode voltage n Rail-to-Rail Input Common-Mode Voltage Range
range that exceeds both rails. The rail-to-rail output swing of n Rail-to-Rail Output Swing
the amplifier, guaranteed for loads down to 25 kΩ, assures (within 10 mV of rail, VS = 5V and RL = 25 kΩ)
maximum dynamic sigal range. This rail-to-rail performance n Low Input Current 150 fA
of the amplifier, combined with its high voltage gain makes it
n Low Input Offset Voltage 0.25 mV
unique among rail-to-rail amplifiers. The LMC6462/4 is an
excellent upgrade for circuits using limited common-mode
range amplifiers. Applications
The LMC6462/4, with guaranteed specifications at 3V and n Battery Operated Circuits
5V, is especially well-suited for low voltage applications. A n Transducer Interface Circuits
quiescent power consumption of 60 µW per amplifier (at VS n Portable Communication Devices
= 3V) can extend the useful life of battery operated systems. n Medical Applications
The amplifier’s 150 fA input current, low offset voltage of n Battery Monitoring
0.25 mV, and 85 dB CMRR maintain accuracy in
battery-powered systems.

8-Pin DIP/SO 14-Pin DIP/SO

DS012051-1

Top View
DS012051-2

Top View

© 1999 National Semiconductor Corporation DS012051 www.national.com

 Ordering Information
Package Temperature Range NSC Transport
Military Industrial Drawing Media
−55˚C to +125˚C −40˚C to +85˚C
8-Pin Molded DIP LMC6462AMN LMC6462AIN, LMC6462BIN N08E Rails
8-Pin SO-8 LMC6462AIM, LMC6462BIM M08A Rails
LMC6462AIMX, LMC6462BIMX M08A Tape and Reel
14-Pin Molded DIP LMC6464AMN LMC6464AIN, LMC6464BIN N14A Rails
14-Pin SO-14 LMC6464AIM, LMC6464BIM M14A Rails
LMC6464AIMX, LMC6464BIMX M14A Tape and Reel
8-Pin Ceramic DIP LMC6462AMJ-QML J08A Rails
14-Pin Ceramic DIP LMC6464AMJ-QML J14A Rails
14-Pin Ceramic SOIC LMC6464AMWG-QML WG14A Trays

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 Absolute Maximum Ratings (Note 1) Operating Ratings (Note 1)
If Military/Aerospace specified devices are required, Supply Voltage 3.0V ≤ V+ ≤ 15.5V
please contact the National Semiconductor Sales Office/
Junction Temperature Range
Distributors for availability and specifications.
LMC6462AM, LMC6464AM −55˚C ≤ TJ ≤ +125˚C
ESD Tolerance (Note 2) 2.0 kV LMC6462AI, LMC6464AI −40˚C ≤ TJ ≤ +85˚C
Differential Input Voltage ± Supply Voltage LMC6462BI, LMC6464BI −40˚C ≤ TJ ≤ +85˚C
Voltage at Input/Output Pin (V+) + 0.3V, (V−) − 0.3V Thermal Resistance (θJA)
Supply Voltage (V+ − V−) 16V N Package, 8-Pin Molded DIP 115˚C/W
Current at Input Pin (Note 12) ± 5 mA M Package, 8-Pin Surface Mount 193˚C/W
Current at Output Pin N Package, 14-Pin Molded DIP 81˚C/W
(Notes 3, 8) ± 30 mA M Package, 14-Pin
Current at Power Supply Pin 40 mA Surface Mount 126˚C/W
Lead Temp. (Soldering, 10 sec.) 260˚C
Storage Temperature Range −65˚C to +150˚C
Junction Temperature (Note 4) 150˚C

5V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2 and RL > 1M. Boldface
limits apply at the temperature extremes.
LMC6462AI LMC6462BI LMC6462AM
Symbol Parameter Conditions Typ LMC6464AI LMC6464BI LMC6464AM Units
(Note 5) Limit Limit Limit
(Note 6) (Note 6) (Note 6)
VOS Input Offset Voltage 0.25 0.5 3.0 0.5 mV
1.2 3.7 1.5 max
TCVOS Input Offset Voltage 1.5 µV/˚C
Average Drift
IB Input Current (Note 13) 0.15 10 10 200 pA max
IOS Input Offset Current (Note 13) 0.075 5 5 100 pA max
CIN Common-Mode 3 pF
Input Capacitance
RIN Input Resistance > 10 Tera Ω
CMRR Common Mode 0V ≤ VCM ≤ 15.0V, 85 70 65 70 dB
Rejection Ratio V+ = 15V 67 62 65 min
0V ≤ VCM ≤ 5.0V 85 70 65 70
V+ = 5V 67 62 65
+PSRR Positive Power Supply 5V ≤ V+ ≤ 15V, 85 70 65 70 dB
Rejection Ratio V− = 0V, VO = 2.5V 67 62 65 min
−PSRR Negative Power Supply −5V ≤ V− ≤ −15V, 85 70 65 70 dB
Rejection Ratio V+ = 0V, VO = −2.5V 67 62 65 min
VCM Input Common-Mode V+ = 5V −0.2 −0.10 −0.10 −0.10 V
Voltage Range For CMRR ≥ 50 dB 0.00 0.00 0.00 max
5.30 5.25 5.25 5.25 V
5.00 5.00 5.00 min
V+ = 15V −0.2 −0.15 −0.15 −0.15 V
For CMRR ≥ 50 dB 0.00 0.00 0.00 max
15.30 15.25 15.25 15.25 V
15.00 15.00 15.00 min

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 5V DC Electrical Characteristics (Continued)

Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2 and RL > 1M. Boldface
limits apply at the temperature extremes.
LMC6462AI LMC6462BI LMC6462AM
Symbol Parameter Conditions Typ LMC6464AI LMC6464BI LMC6464AM Units
(Note 5) Limit Limit Limit
(Note 6) (Note 6) (Note 6)
AV Large Signal RL = 100 kΩ Sourcing 3000 V/mV
Voltage Gain (Note 7) min
Sinking 400 V/mV
min
RL = 25 kΩ Sourcing 2500 V/mV
(Note 7) min
Sinking 200 V/mV
min
VO Output Swing V+ = 5V 4.995 4.990 4.950 4.990 V
RL = 100 kΩ to V+/2 4.980 4.925 4.970 min
0.005 0.010 0.050 0.010 V
0.020 0.075 0.030 max
V+ = 5V 4.990 4.975 4.950 4.975 V
RL = 25 kΩ to V+/2 4.965 4.850 4.955 min
0.010 0.020 0.050 0.020 V
0.035 0.150 0.045 max
V+ = 15V 14.990 14.975 14.950 14.975 V
RL = 100 kΩ to V+/2 14.965 14.925 14.955 min
0.010 0.025 0.050 0.025 V
0.035 0.075 0.050 max
V+ = 15V 14.965 14.900 14.850 14.900 V
RL = 25 kΩ to V+/2 14.850 14.800 14.800 min
0.025 0.050 0.100 0.050 V
0.150 0.200 0.200 max
ISC Output Short Circuit Sourcing, VO = 0V 27 19 19 19 mA
Current 15 15 15 min
V+ = 5V Sinking, VO = 5V 27 22 22 22 mA
17 17 17 min
ISC Output Short Circuit Sourcing, VO = 0V 38 24 24 24 mA
Current 17 17 17 min
V+ = 15V Sinking, VO = 12V 75 55 55 55 mA
(Note 8) 45 45 45 min
IS Supply Current Dual, LMC6462 40 55 55 55 µA
V+ = +5V, VO = V+/2 70 70 75 max
Quad, LMC6464 80 110 110 110 µA
V+ = +5V, VO = V+/2 140 140 150 max
Dual, LMC6462 50 60 60 60 µA
V+ = +15V, VO = V+/2 70 70 75 max
Quad, LMC6464 90 120 120 120 µA
V+ = +15V, VO = V+/2 140 140 150 max

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 5V AC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2 and RL > 1M. Boldface
limits apply at the temperature extremes.
LMC6462AI LMC6462BI LMC6462AM
Symbol Parameter Conditions Typ LMC6464AI LMC6464BI LMC6464AM Units
(Note 5) Limit Limit Limit
(Note 6) (Note 6) (Note 6)
SR Slew Rate (Note 9) 28 15 15 15 V/ms
8 8 8 min
GBW Gain-Bandwidth Product V+ = 15V 50 kHz
φm Phase Margin 50 Deg
Gm Gain Margin 15 dB
Amp-to-Amp Isolation (Note 10) 130 dB
en Input-Referred f = 1 kHz 80
Voltage Noise VCM = 1V
in Input-Referred f = 1 kHz 0.03
Current Noise

3V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C, V+ = 3V, V− = 0V, VCM = VO = V+/2 and RL > 1M. Boldface
limits apply at the temperature extremes.
LMC6462AI LMC6462BI LMC6462AM
Symbol Parameter Conditions Typ LMC6464AI LMC6464BI LMC6464AM Units
(Note 5) Limit Limit Limit
(Note 6) (Note 6) (Note 6)
VOS Input Offset Voltage 0.9 2.0 3.0 2.0 mV
2.7 3.7 3.0 max
TCVOS Input Offset Voltage 2.0 µV/˚C
Average Drift
IB Input Current (Note 13) 0.15 10 10 200 pA
IOS Input Offset Current (Note 13) 0.075 5 5 100 pA
CMRR Common Mode 0V ≤ VCM ≤ 3V 74 60 60 60 dB
Rejection Ratio min
PSRR Power Supply 3V ≤ V+ ≤ 15V, V− = 0V 80 60 60 60 dB
Rejection Ratio min
VCM Input Common-Mode For CMRR ≥ 50 dB −0.10 0.0 0.0 0.0 V
Voltage Range max
3.0 3.0 3.0 3.0 V
min
VO Output Swing RL = 25 kΩ to V+/2 2.95 2.9 2.9 2.9 V
min
0.15 0.1 0.1 0.1 V
max
IS Supply Current Dual, LMC6462 40 55 55 55 µA
VO = V+/2 70 70 70
Quad, LMC6464 80 110 110 110 µA
VO = V+/2 140 140 140 max

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 3V AC Electrical Characteristics
Unless otherwise specified, V+ = 3V, V− = 0V, VCM = VO = V+/2 and RL > 1M. Boldface limits apply at the temperature ex-
tremes.
LMC6462AI LMC6462BI LMC6462AM
Symbol Parameter Conditions Typ LMC6464AI LMC6464BI LMC6464AM Units
(Note 5) Limit Limit Limit
(Note 6) (Note 6) (Note 6)
SR Slew Rate (Note 11) 23 V/ms
GBW Gain-Bandwidth Product 50 kHz
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is in-
tended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.
Note 2: Human body model, 1.5 kΩ in series with 100 pF. All pins rated per method 3015.6 of MIL-STD-883. This is a class 2 device rating.
Note 3: Applies to both single supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the maxi-
mum allowed junction temperature of 150˚C. Output currents in excess of ± 30 mA over long term may adversely affect reliability.
Note 4: 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. All numbers apply for packages soldered directly into a PC board.
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, 3.5V ≤ VO ≤ 7.5V.
Note 8: Do not short circuit output to V+, when V+ is greater than 13V or reliability will be adversely affected.
Note 9: V+ = 15V. Connected as Voltage Follower with 10V step input. Number specified is the slower of either the positive or negative slew rates.
Note 10: Input referred, V+ = 15V and RL = 100 kΩ connected to 7.5V. Each amp excited in turn with 1 kHz to produce VO = 12 VPP.
Note 11: Connected as Voltage Follower with 2V step input. Number specified is the slower of either the positive or negative slew rates.
Note 12: Limiting input pin current is only necessary for input voltages that exceed absolute maximum input voltage ratings.
Note 13: Guaranteed limits are dictated by tester limitations and not device performance. Actual performance is reflected in the typical value.
Note 14: For guaranteed Military Temperature Range parameters see RETSMC6462/4X.

Typical Performance Characteristics VS = +5V, Single Supply, TA = 25˚C unless otherwise specified

Supply Current vs Sourcing Current vs Sourcing Current vs

Supply Voltage Output Voltage Output Voltage

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DS012051-31 DS012051-32

Sourcing Current vs Sinking Current vs Sinking Current vs

Output Voltage Output Voltage Output Voltage

DS012051-33 DS012051-34 DS012051-35

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Typical Performance Characteristics VS = +5V, Single Supply, TA = 25˚C unless otherwise
specified (Continued)

Sinking Current vs Input Voltage Input Voltage Noise

Output Voltage Noise vs Frequency vs Input Voltage

DS012051-36 DS012051-37 DS012051-38

Input Voltage Noise Input Voltage Noise ∆VOS vs CMR

vs Input Voltage vs Input Voltage

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DS012051-39 DS012051-40

Input Voltage vs Open Loop Open Loop Frequency

Output Voltage Frequency Response Response vs Temperature

DS012051-43
DS012051-42
DS012051-44

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 Typical Performance Characteristics VS = +5V, Single Supply, TA = 25˚C unless otherwise
specified (Continued)

Gain and Phase vs Slew Rate vs Non-Inverting Large

Capacitive Load Supply Voltage Signal Pulse Response

DS012051-46 DS012051-47
DS012051-45

Non-Inverting Large Non-Inverting Large Non-Inverting Small

Signal Pulse Response Signal Pulse Response Signal Pulse Response

DS012051-48 DS012051-49 DS012051-50

Non-Inverting Small Non-Inverting Small Inverting Large

Signal Pulse Response Signal Pulse Response Signal Pulse Response

DS012051-51 DS012051-52 DS012051-53

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Typical Performance Characteristics VS = +5V, Single Supply, TA = 25˚C unless otherwise
specified (Continued)

Inverting Large Signal Inverting Large Signal Inverting Small Signal

Pulse Response Pulse Response Pulse Response

DS012051-54 DS012051-55 DS012051-56

Inverting Small Signal Inverting Small Signal

Pulse Response Pulse Response

DS012051-57 DS012051-58

Application Information pins, possibly affecting reliability. The input current can be
externally limited to ± 5 mA, with an input resistor, as shown
in Figure 3.
1.0 Input Common-Mode Voltage Range
The LMC6462/4 has a rail-to-rail input common-mode volt-
age range. Figure 1 shows an input voltage exceeding both
supplies with no resulting phase inversion on the output.

DS012051-6

FIGURE 2. A ± 7.5V Input Signal Greatly Exceeds

the 3V Supply in Figure 3 Causing
No Phase Inversion Due to RI
DS012051-5

FIGURE 1. An Input Voltage Signal Exceeds

the LMC6462/4 Power Supply Voltage
with No Output Phase Inversion

The absolute maximum input voltage at V+ = 3V is 300 mV

beyond either supply rail at room temperature. Voltages
greatly exceeding this absolute maximum rating, as in Figure
2, can cause excessive current to flow in or out of the input

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 Application Information (Continued) Another circuit, shown in Figure 6, is also used to indirectly
drive capacitive loads. This circuit is an improvement to the
circuit shown in Figure 4 because it provides DC accuracy as
well as AC stability. R1 and C1 serve to counteract the loss
of phase margin by feeding the high frequency component of
the output signal back to the amplifiers inverting input,
thereby preserving phase margin in the overall feedback
loop. The values of R1 and C1 should be experimentally de-
termined by the system designer for the desired pulse re-
DS012051-7 sponse. Increased capacitive drive is possible by increasing
the value of the capacitor in the feedback loop.
FIGURE 3. Input Current Protection for Voltages
Exceeding the Supply Voltage

2.0 Rail-to-Rail Output

The approximated output resistance of the LMC6462/4 is
180Ω sourcing, and 130Ω sinking at VS = 3V, and 110Ω
sourcing and 83Ω sinking at VS = 5V. The maximum output
swing can be estimated as a function of load using the calcu-
lated output resistance.

3.0 Capacitive Load Tolerance

The LMC6462/4 can typically drive a 200 pF load with VS =
5V at unity gain without oscillating. The unity gain follower is
the most sensitive configuration to capacitive load. Direct ca-
DS012051-10
pacitive loading reduces the phase margin of op-amps. The
combination of the op-amp’s output impedance and the ca- FIGURE 6. LMC6462 Non-Inverting Amplifier,
pacitive load induces phase lag. This results in either an un- Compensated to Handle a 300 pF Capacitive
derdamped pulse response or oscillation. and 100 kΩ Resistive Load
Capacitive load compensation can be accomplished using
resistive isolation as shown in Figure 4. If there is a resistive
component of the load in parallel to the capacitive compo-
nent, the isolation resistor and the resistive load create a
voltage divider at the output. This introduces a DC error at
the output.

DS012051-8
DS012051-11
FIGURE 4. Resistive Isolation of
a 300 pF Capacitive Load FIGURE 7. Pulse Response of
LMC6462 Circuit in Figure 6

The pulse response of the circuit shown in Figure 6 is shown

in Figure 7.

4.0 Compensating for Input Capacitance

It is quite common to use large values of feedback resis-
tance with amplifiers that have ultra-low input current, like
the LMC6462/4. Large feedback resistors can react with
small values of input capacitance due to transducers, photo-
diodes, and circuits board parasitics to reduce phase
margins.

DS012051-9

FIGURE 5. Pulse Response of the LMC6462

Circuit Shown in Figure 4

Figure 5 displays the pulse response of the LMC6462/4 cir-

cuit in Figure 4.

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Application Information (Continued)

DS012051-14

FIGURE 10. Non-Inverting Configuration

Offset Voltage Adjustment
DS012051-12

FIGURE 8. Canceling the Effect of Input Capacitance 6.0 Spice Macromodel

The effect of input capacitance can be compensated for by A Spice macromodel is available for the LMC6462/4. This
adding a feedback capacitor. The feedback capacitor (as in model includes a simulation of:
Figure 8 ), CF, is first estimated by: • Input common-mode voltage range
• Frequency and transient response
• GBW dependence on loading conditions
• Quiescent and dynamic supply current
or • Output swing dependence on loading conditions
R1 CIN ≤ R2 CF and many more characteristics as listed on the macromodel
disk.
which typically provides significant overcompensation.
Contact the National Semiconductor Customer Response
Printed circuit board stray capacitance may be larger or
Center to obtain an operational amplifier Spice model library
smaller than that of a breadboard, so the actual optimum
disk.
value for CF may be different. The values of CF should be
checked on the actual circuit. (Refer to the LMC660 quad
7.0 Printed-Circuit-Board Layout
CMOS amplifier data sheet for a more detailed discussion.)
for High-Impedance Work
5.0 Offset Voltage Adjustment It is generally recognized that any circuit which must operate
with less than 1000 pA of leakage current requires special
Offset voltage adjustment circuits are illustrated in Figure 9
layout of the PC board. When one wishes to take advantage
and Figure 10. Large value resistances and potentiometers
of the ultra-low input current of the LMC6462/4, typically 150
are used to reduce power consumption while providing typi-
fA, it is essential to have an excellent layout. Fortunately, the
cally ± 2.5 mV of adjustment range, referred to the input, for
techniques of obtaining low leakages are quite simple. First,
both configurations with VS = ± 5V.
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 LMC6462’s inputs and the
terminals of capacitors, diodes, conductors, resistors, relay
terminals, etc. connected to the op-amp’s inputs, as in Fig-
ure 11. To have a significant effect, guard rings should be
placed in 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
DS012051-13 flow between two points at the same potential. For example,
a PC board trace-to-pad resistance of 1012Ω, which is nor-
FIGURE 9. Inverting Configuration
mally considered a very large resistance, could leak 5 pA if
Offset Voltage Adjustment
the trace were a 5V bus adjacent to the pad of the input. This
would cause a 30 times degradation from the LMC6462/4’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 12 for
typical connections of guard rings for standard op-amp
configurations.

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 Application Information (Continued) board at all, but bend it up in the air and use only air as an in-
sulator. Air is an excellent insulator. In this case you may
have to forego some of the advantages of PC board con-
struction, but the advantages are sometimes well worth the
effort of using point-to-point up-in-the-air wiring. See Figure
13.

DS012051-19

(Input pins are lifted out of PC board and soldered directly to components.
All other pins connected to PC board.)
FIGURE 13. Air Wiring

DS012051-15

FIGURE 11. Example of Guard Ring in P.C. Board

Layout

DS012051-16

Inverting Amplifier

DS012051-17

Non-Inverting Amplifier

DS012051-18

Follower
FIGURE 12. 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

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Application Information (Continued) cations that benefit from these features include analytic
medical instruments, magnetic field detectors, gas detectors,
8.0 Instrumentation Circuits and silicon-based transducers.
The LMC6464 has the high input impedance, large A small valued potentiometer is used in series with Rg to set
common-mode range and high CMRR needed for designing the differential gain of the three op-amp instrumentation cir-
instrumentation circuits. Instrumentation circuits designed cuit in Figure 14. This combination is used instead of one
with the LMC6464 can reject a larger range of large valued potentiometer to increase gain trim accuracy
common-mode signals than most in-amps. This makes in- and reduce error due to vibration.
strumentation circuits designed with the LMC6464 an excel-
lent choice for noisy or industrial environments. Other appli-

DS012051-20

FIGURE 14. Low Power Three Op-Amp Instrumentation Amplifier

A two op-amp instrumentation amplifier designed for a gain Higher frequency and larger common-mode range applica-
of 100 is shown in Figure 15. Low sensitivity trimming is tions are best facilitated by a three op-amp instrumentation
made for offset voltage, CMRR and gain. Low cost and low amplifier.
power consumption are the main advantages of this two
op-amp circuit.

DS012051-21

FIGURE 15. Low-Power Two-Op-Amp Instrumentation Amplifier

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 Typical Single-Supply Applications
TRANSDUCER INTERFACE CIRCUITS

DS012051-25
DS012051-22

FIGURE 16. Photo Detector Circuit FIGURE 19. Full-Wave Rectifier

with Input Current Protection (RI)
Photocells can be used in portable light measuring instru-
ments. The LMC6462, which can be operated off a battery, is In Figure 18 Figure 19, RI limits current into the amplifier
an excellent choice for this circuit because of its very low in- since excess current can be caused by the input voltage ex-
put current and offset voltage. ceeding the supply voltage.

LMC6462 AS A COMPARATOR PRECISION CURRENT SOURCE

DS012051-23

FIGURE 17. Comparator with Hysteresis

Figure 17 shows the application of the LMC6462 as a com-
DS012051-26
parator. The hysteresis is determined by the ratio of the two
resistors. The LMC6462 can thus be used as a micropower FIGURE 20. Precision Current Source
comparator, in applications where the quiescent current is an
important parameter. The output current IOUT is given by:

HALF-WAVE AND FULL-WAVE RECTIFIERS

OSCILLATORS

DS012051-24

FIGURE 18. Half-Wave Rectifier with

Input Current Protection (RI)

DS012051-27

FIGURE 21. 1 Hz Square-Wave Oscillator

For single supply 5V operation, the output of the circuit will

swing from 0V to 5V. The voltage divider set up R2, R3 and
R4 will cause the non-inverting input of the LMC6462 to
move from 1.67V (1⁄3 of 5V) to 3.33V (2⁄3 of 5V). This voltage
behaves as the threshold voltage.
R1 and C1 determine the time constant of the circuit. The fre-
quency of oscillation, fOSC is

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Typical Single-Supply Applications LOW FREQUENCY NULL
(Continued)

where ∆t is the time the amplifier input takes to move from

1.67V to 3.33V. The calculations are shown below.

where τ = RC = 0.68 seconds

→ t1 = 0.27 seconds.
and

→ t2 = 0.75 seconds
Then,

DS012051-28

FIGURE 22. High Gain Amplifier

with Low Frequency Null
Output offset voltage is the error introduced in the output
= 1 Hz
voltage due to the inherent input offset voltage VOS, of an
amplifier.
Output Offset Voltage = (Input Offset Voltage) (Gain)
In the above configuration, the resistors R5 and R6 deter-
mine the nominal voltage around which the input signal, VIN
should be symmetrical. The high frequency component of
the input signal VIN will be unaffected while the low fre-
quency component will be nulled since the DC level of the
output will be the input offset voltage of the LMC6462 plus
the bias voltage. This implies that the output offset voltage
due to the top amplifier will be eliminated.

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 Physical Dimensions inches (millimeters) unless otherwise noted

8-Pin Small Outline Package

Order Number LMC6462AIM or LMC6462BIM
NS Package Number M08A

14-Pin Small Outline Package

Order Number LMC6464AIM or LMC6464BIM
NS Package Number M14A

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

8-Pin Molded Dual-In-Line Package

Order Number LMC6462AIN or LMC6462BIN
NS Package Number N08E

14-Pin Molded Dual-In-Line Pacakge

Order Number LMC6462AIN or LMC6464BIN
NS Package Number N14A

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LMC6462 Dual/LMC6464 Quad Micropower, Rail-to-Rail Input and Output CMOS Operational
Amplifier
Notes

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 AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or 2. A critical component is any component of a life
systems which, (a) are intended for surgical implant support device or system whose failure to perform
into the body, or (b) support or sustain life, and can be reasonably expected to cause the failure of
whose failure to perform when properly used in the life support device or system, or to affect its
accordance with instructions for use provided in the safety or effectiveness.
labeling, can be reasonably expected to result in a
significant injury to the user.
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