LM6142 and LM6144
17 MHz Rail-to-Rail Input-Output Operational Amplifiers
General Description
Using patent pending new circuit topologies, the LM6142/44
provides new levels of performance in applications where
low voltage supplies or power limitations previously made
compromise necessary. Operating on supplies of 1.8V to
over 24V, the LM6142/44 is an excellent choice for battery
operated systems, portable instrumentation and others.
The greater than rail-to-rail input voltage range eliminates
concern over exceeding the common-mode voltage range.
The rail-to-rail output swing provides the maximum possible
dynamic range at the output. This is particularly important
when operating on low supply voltages.
High gain-bandwidth with 650 µA/Amplifier supply current
opens new battery powered applications where previous
higher power consumption reduced battery life to unaccept-
able levels. The ability to drive large capacitive loads without
oscillating functionally removes this common problem.
Features
At V
S
= 5V. Typ unless noted.
nRail-to-rail input CMVR −0.25V to 5.25V
nRail-to-rail output swing 0.005V to 4.995V
nWide gain-bandwidth: 17 MHz at 50 kHz (typ)
nSlew rate:
Small signal, 5V/µs
Large signal, 30V/µs
nLow supply current 650 µA/Amplifier
nWide supply range 1.8V to 24V
nCMRR 107 dB
nGain 108 dB with R
L
= 10k
nPSRR 87 dB
Applications
nBattery operated instrumentation
nDepth sounders/fish finders
nBarcode scanners
nWireless communications
nRail-to-rail in-out instrumentation amps
Connection Diagrams
8-Pin CDIP
DS012057-14
Top View
8-Pin DIP/SO
DS012057-1
Top View
14-Pin DIP/SO
DS012057-2
Top View
August 2000
LM6142 l and LM6144 17 MHz Rail-to-Rail Input-Output Operational Amplifiers
© 2000 National Semiconductor Corporation DS012057 www.national.com
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance (Note 2) 2500V
Differential Input Voltage 15V
Voltage at Input/Output Pin (V+) + 0.3V, (V−) − 0.3V
Supply Voltage (V+ − V−) 35V
Current at Input Pin ±10 mA
Current at Output Pin (Note 3) ±25 mA
Current at Power Supply Pin 50 mA
Lead Temperature
(soldering, 10 sec) 260˚C
Storage Temp. Range −65˚C to +150˚C
Junction Temperature (Note 4) 150˚C
Operating Ratings (Note 1)
Supply Voltage 1.8V ≤V+ ≤24V
Junction Temperature Range
LM6142, LM6144 −40˚C ≤T
J
≤+85˚C
Thermal Resistance (θ
JA
)
N Package, 8-Pin Molded DIP 115˚C/W
M Package, 8-Pin Surface Mount 193˚C/W
N Package, 14-Pin Molded DIP 81˚C/W
M Package, 14-Pin Surface Mount 126˚C/W
5.0V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V+ = 5.0V, V− = 0V, V
CM
=V
O
= V+/2 and R
L
>1MΩto
V+/2. Boldface limits apply at the temperature extremes.
LM6144AI LM6144BI
Symbol Parameter Conditions Typ LM6142AI LM6142BI Units
(Note 5) Limit Limit
(Note 6) (Note 6)
V
OS
Input Offset Voltage 0.3 1.0 2.5 mV
2.2 3.3 max
TCV
OS
Input Offset Voltage 3µV/˚C
Average Drift
I
B
Input Bias Current 170 250 300 nA
max
0V ≤V
CM
≤5V 180 280
526 526
I
OS
Input Offset Current 3 30 30 nA
80 80 max
R
IN
Input Resistance, C
M
126 MΩ
CMRR Common Mode 0V ≤V
CM
≤4V 107 84 84
dB
min
Rejection Ratio 78 78
0V ≤V
CM
≤5V 82 66 66
79 64 64
PSRR Power Supply 5V ≤V
+
≤24V 87 80 80
Rejection Ratio 78 78
V
CM
Input Common-Mode −0.25 00V
Voltage Range 5.25 5.0 5.0
A
V
Large Signal R
L
= 10k 270 100 80 V/mV
Voltage Gain 70 33 25 min
V
O
Output Swing R
L
= 100k 0.005 0.01 0.01 V
0.013 0.013 max
4.995 4.98 4.98 V
4.93 4.93 min
R
L
= 10k 0.02 V max
4.97 V min
R
L
= 2k 0.06 0.1 0.1 V
0.133 0.133 max
4.90 4.86 4.86 V
4.80 4.80 min
LM6142 and LM6144
www.national.com 2
5.0V DC Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for T
J
= 25˚C, V+ = 5.0V, V− = 0V, V
CM
=V
O
= V+/2 and R
L
>1MΩto
V+/2. Boldface limits apply at the temperature extremes.
LM6144AI LM6144BI
Symbol Parameter Conditions Typ LM6142AI LM6142BI Units
(Note 5) Limit Limit
(Note 6) (Note 6)
I
SC
Output Short Sourcing 13 10 8 mA
Circuit Current 4.9 4 min
LM6142 35 35 mA
max
Sinking 24 10 10 mA
5.3 5.3 min
35 35 mA
max
I
SC
Output Short Sourcing 8 6 6 mA
Circuit Current 33min
LM6144 35 35 mA
max
Sinking 22 8 8 mA
44min
35 35 mA
max
I
S
Supply Current Per Amplifier 650 800 800 µA
880 880 max
5.0V AC Electrical Characteristics
Unless Otherwise Specified, All Limits Guaranteed for T
J
= 25˚C, V+ = 5.0V, V− = 0V, V
CM
=V
O
= V+/2 and R
L
>1MΩto
V
S
/2. Boldface limits apply at the temperature extremes.
LM6144AI LM6144BI
Symbol Parameter Conditions Typ LM6142AI LM6142BI Units
(Note 5) Limit Limit
(Note 6) (Note 6)
SR Slew Rate 8 V
p-p
@V
CC
12V 25 15 13 V/µs
R
S
>1kΩ13 11 min
GBW Gain-Bandwidth Product f = 50 kHz 17 10 10 MHz
66min
φ
m
Phase Margin 38 Deg
Amp-to-Amp Isolation 130 dB
e
n
Input-Referred f = 1 kHz 16
Voltage Noise
i
n
Input-Referred f = 1 kHz 0.22
Current Noise
T.H.D. Total Harmonic Distortion f = 10 kHz, R
L
=10kΩ, 0.003 %
LM6142 and LM6144
www.national.com3
2.7V DC Electrical Characteristics
Unless Otherwise Specified, All Limits Guaranteed for T
J
= 25˚C, V+ = 2.7V, V− = 0V, V
CM
=V
O
= V+/2 and R
L
>1MΩto
V
+
/2. Boldface limits apply at the temperature extreme
LM6144AI LM6144BI
Symbol Parameter Conditions Typ LM6142AI LM6142BI Units
(Note 5) Limit Limit
(Note 6) (Note 6)
V
OS
Input Offset Voltage 0.4 1.8 2.5 mV
4.3 5 max
I
B
Input Bias Current 150 250 300 nA
526 526 max
I
OS
Input Offset Current 4 30 30 nA
80 80 max
R
IN
Input Resistance 128 MΩ
CMRR Common Mode 0V ≤V
CM
≤1.8V 90 dB
min
Rejection Ratio 0V ≤V
CM
≤2.7V 76
PSRR Power Supply 3V ≤V+ ≤5V 79
Rejection Ratio
V
CM
Input Common-Mode −0.25 0 0 V min
Voltage Range 2.95 2.7 2.7 V max
A
V
Large Signal R
L
= 10k 55 V/mV
Voltage Gain min
V
O
Output Swing R
L
= 100kΩ0.019 0.08 0.08 V
0.112 0.112 max
2.67 2.66 2.66 V
2.25 2.25 min
I
S
Supply Current Per Amplifier 510 800 800 µA
880 880 max
2.7V AC Electrical Characteristics
Unless Otherwise Specified, All Limits Guaranteed for T
J
= 25˚C, V+ = 2.7V, V− = 0V, V
CM
=V
O
= V+/2 and R
L
>1MΩto
V
+
/2. Boldface limits apply at the temperature extreme
LM6144AI LM6144BI
Symbol Parameter Conditions Typ LM6142AI LM6142BI Units
(Note 5) Limit Limit
(Note 6) (Note 6)
GBW Gain-Bandwidth Product f = 50 kHz 9 MHz
φ
m
Phase Margin 36 Deg
G
m
Gain Margin 6 dB
LM6142 and LM6144
www.national.com 4
24V Electrical Characteristics
Unless Otherwise Specified, All Limits Guaranteed for T
J
= 25˚C, V+ = 24V, V− = 0V, V
CM
=V
O
= V+/2 and R
L
>1MΩto
V
S
/2. Boldface limits apply at the temperature extreme
LM6144AI LM6144BI
Symbol Parameter Conditions Typ LM6142AI LM6142BI Units
(Note 5) Limit Limit
(Note 6) (Note 6)
V
OS
Input Offset Voltage 1.3 2 3.8 mV
4.8 4.8 max
I
B
Input Bias Current 174 nA
max
I
OS
Input Offset Current 5 nA
max
R
IN
Input Resistance 288 MΩ
CMRR Common Mode 0V ≤V
CM
≤23V 114 dB
min
Rejection Ratio 0V ≤V
CM
≤24V 100
PSRR Power Supply 0V ≤V
CM
≤24V 87
Rejection Ratio
V
CM
Input Common-Mode −0.25 0 0 V min
Voltage Range 24.25 24 24 V max
A
V
Large Signal R
L
= 10k 500 V/mV
Voltage Gain min
V
O
Output Swing R
L
=10kΩ0.07 0.15 0.15 V
0.185 0.185 max
23.85 23.81 23.81 V
23.62 23.62 min
I
S
Supply Current Per Amplifier 750 1100 1100 µA
1150 1150 max
GBW Gain-Bandwidth Product f = 50 kHz 18 MHz
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 Charactenstics.
Note 2: Human body model, 1.5 kΩin series with 100 pF.
Note 3: Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the
maximum allowed junction temperature of 150˚C.
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=(T
j(max)
−T
A
)/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: For guaranteed military specifications see military datasheet MNLM6142AM-X.
LM6142 and LM6144
www.national.com5
Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise Specified
Supply Current vs
Supply Voltage
DS012057-15
Offset Voltage vs
Supply Voltage
DS012057-16
Bias Current vs
Supply Voltage
DS012057-17
Offset Voltage vs V
CM
DS012057-18
Offset Voltage vs V
CM
DS012057-19
Offset Voltage vs V
CM
DS012057-20
Bias Current vs V
CM
DS012057-21
Bias Current vs V
CM
DS012057-22
Bias Current vs V
CM
DS012057-23
Open-Loop Transfer
Function
DS012057-24
Open-Loop Transfer
Function
DS012057-25
Open-Loop Transfer
Function
DS012057-26
LM6142 and LM6144
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Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise
Specified (Continued)
Output Voltage vs
Source Current
DS012057-27
Output Voltage vs
Source Current
DS012057-28
Output Voltage vs
Source Current
DS012057-29
Output Voltage vs
Sink Current
DS012057-30
Output Voltage vs
Sink Current
DS012057-31
Output Voltage vs
Sink Current
DS012057-32
Gain and Phase vs Load
DS012057-33
Gain and Phase vs Load
DS012057-34
Distortion + Noise
vs Frequency
DS012057-35
LM6142 and LM6144
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Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise
Specified (Continued)
GBW vs Supply
DS012057-36
Open Loop Gain vs
Load, 3V Supply
DS012057-37
Open Loop Gain vs
Load, 5V Supply
DS012057-38
Open Loop Gain vs
Load, 24V Supply
DS012057-39
Unity Gain Freq vs V
S
DS012057-40
CMRR vs Frequency
DS012057-41
Crosstalk vs Frequency
DS012057-42
PSRR vs Frequency
DS012057-43
Noise Voltage vs Frequency
DS012057-44
LM6142 and LM6144
www.national.com 8
Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise
Specified (Continued)
LM6142/44 Application Ideas
The LM6142 brings a new level of ease of use to opamp sys-
tem design.
With greater than rail-to-rail input voltage range concern
over exceeding the common-mode voltage range is elimi-
nated.
Rail-to-rail output swing provides the maximum possible dy-
namic range at the output. This is particularly important
when operating on low supply voltages.
The high gain-bandwidth with low supply current opens new
battery powered applications, where high power consump-
tion, previously reduced battery life to unacceptable levels.
To take advantage of these features, some ideas should be
kept in mind.
ENHANCED SLEW RATE
Unlike most bipolar opamps, the unique phase reversal
prevention/speed-up circuit in the input stage causes the
slew rate to be very much a function of the input signal am-
plitude.
Figure 2
shows how excess input signal, is routed around
the input collector-base junctions, directly to the current mir-
rors.
The LM6142/44 input stage converts the input voltage
change to a current change. This current change drives the
current mirrors through the collectors of Q1–Q2, Q3–Q4
when the input levels are normal.
If the input signal exceeds the slew rate of the input stage,
the differential input voltage rises above two diode drops.
This excess signal bypasses the normal input transistors,
(Q1–Q4), and is routed in correct phase through the two ad-
ditional transistors, (Q5, Q6), directly into the current mirrors.
This rerouting of excess signal allows the slew-rate to in-
crease by a factor of 10 to 1 or more. (See
Figure 1
.)
As the overdrive increases, the opamp reacts better than a
conventional opamp. Large fast pulses will raise the slew-
rate to around 30V to 60V/µs.
This effect is most noticeable at higher supply voltages and
lower gains where incoming signals are likely to be large.
This new input circuit also eliminates the phase reversal
seen in many opamps when they are overdriven.
This speed-up action adds stability to the system when driv-
ing large capacitive loads.
DRIVING CAPACITIVE LOADS
Capacitive loads decrease the phase margin of all opamps.
This is caused by the output resistance of the amplifier and
the load capacitance forming an R-C phase lag network.
This can lead to overshoot, ringing and oscillation. Slew rate
limiting can also cause additional lag. Most opamps with a
fixed maximum slew-rate will lag further and further behind
when driving capacitive loads even though the differential in-
put voltage raises. With the LM6142, the lag causes the slew
rate to raise. The increased slew-rate keeps the output fol-
lowing the input much better. This effectively reduces phase
lag. After the output has caught up with the input, the differ-
ential input voltage drops down and the amplifier settles
rapidly.
Noise Current vs Frequency
DS012057-45
NE vs R Source
DS012057-12
Slew Rate vs ∆V
IN
V
S
=±5V
DS012057-7
FIGURE 1.
LM6142 and LM6144
www.national.com9
LM6142/44 Application Ideas (Continued)
These features allow the LM6142 to drive capacitive loads
as large as 1000 pF at unity gain and not oscillate. The
scope photos (
Figure 3
and
Figure 4
) above show the
LM6142 driving a l000 pF load. In
Figure 3
, the upper trace
is with no capacitive load and the lower trace is with a 1000
pF load. Here we are operating on ±12V supplies with a 20
Vp-p pulse. Excellent response is obtained with a C
f
of l0 pF.
In
Figure 4
, the supplies have been reduced to ±2.5V, the
pulse is 4 Vp-p and C
f
is 39 pF. The best value for the com-
pensation capacitor is best established after the board layout
is finished because the value is dependent on board stray
capacity, the value of the feedback resistor, the closed loop
gain and, to some extent, the supply voltage.
Another effect that is common to all opamps is the phase
shift caused by the feedback resistor and the input capaci-
tance. This phase shift also reduces phase margin. This ef-
fect is taken care of at the same time as the effect of the ca-
pacitive load when the capacitor is placed across the
feedback resistor.
The circuit shown in
Figure 5
was used for these scope
photos.
Typical Applications
FISH FINDER/ DEPTH SOUNDER.
The LM6142/44 is an excellent choice for battery operated
fish finders. The low supply current, high gain-bandwidth and
full rail to rail output swing of the LM6142 provides an ideal
combination for use in this and similar applications.
DS012057-6
FIGURE 2.
DS012057-8
FIGURE 3.
DS012057-9
FIGURE 4.
DS012057-10
FIGURE 5.
LM6142 and LM6144
www.national.com 10
Typical Applications (Continued)
ANALOG TO DIGITAL CONVERTER BUFFER
The high capacitive load driving ability, rail-to-rail input and
output range with the excellent CMR of 82 dB, make the
LM6142/44 a good choice for buffering the inputs of A to D
converters.
3 OPAMP INSTRUMENTATION AMP WITH
RAIL-TO-RAIL INPUT AND OUTPUT
Using the LM6144, a 3 opamp instrumentation amplifier with
rail-to-rail inputs and rail to rail output can be made. These
features make these instrumentation amplifiers ideal for
single supply systems.
Some manufacturers use a precision voltage divider array of
5 resistors to divide the common-mode voltage to get an in-
put range of rail-to-rail or greater. The problem with this
method is that it also divides the signal, so to even get unity
gain, the amplifier must be run at high closed loop gains.
This raises the noise and drift by the internal gain factor and
lowers the input impedance. Any mismatch in these preci-
sion resistors reduces the CMR as well. Using the LM6144,
all of these problems are eliminated.
In this example, amplifiers A and B act as buffers to the dif-
ferential stage (
Figure 6
). These buffers assure that the input
impedance is over 100 MΩand they eliminate the require-
ment for precision matched resistors in the input stage. They
also assure that the difference amp is driven from a voltage
source. This is necessary to maintain the CMR set by the
matching of R1–R2 with R3–R4.
The gain is set by the ratio of R2/R1 and R3 should equal R1
and R4 equal R2. Making R4 slightly smaller than R2 and
adding a trim pot equal to twice the difference between R2
and R4 will allow the CMR to be adjusted for optimum.
With both rail to rail input and output ranges, the inputs and
outputs are only limited by the supply voltages. Remember
that even with rail-to-rail output, the output can not swing
past the supplies so the combined common mode voltage
plus the signal should not be greater than the supplies or lim-
iting will occur.
SPICE MACROMODEL
A SPICE macromodel of this and many other National Semi-
conductor opamps is available at no charge from the NSC
Customer Response Group at 800-272-9959.
Ordering Information
Package Temperature Range Temperature Range NSC
Drawing
Industrial Military
−40˚C to +85˚C −55˚C to +125˚C
8-Pin Molded DIP LM6142AIN, LM6142BIN N08E
8-Pin Small Outline LM6142AIM,
LM6142AIMX,LM6142BIM,LM6142BIMXLM6142BIMTX, M08A
14-Pin Molded DIP LM6144AIN, LM6144BIN N14A
14-Pin Small Outline LM6144AIM,
LM6144AIMX,LM6144BIM,LM6144BIMX M14A
8-Pin CDIP LM6142AMJ-QML J08A
DS012057-13
FIGURE 6.
LM6142 and LM6144
www.national.com11
Physical Dimensions inches (millimeters) unless otherwise noted
8-Pin Ceramic Sidebrazed
Dual-In-Line Package
Order Number LM6142AMJ-QML
NS Package Number D08C
8-Pin Small Outline Package
Order Number LM6142AIM, LM6142AIMX or LM6142BIM, LM6142BIMX
NS Package Number M08A
LM6142 and LM6144
www.national.com 12
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
14-Pin Small Outline Package
Order Number LM6144AIM, LM6144AIMX or LM6144BIM, LM6144BIMX
NS Package Number M14A
8-Pin Molded Dual-In-Line Package
Order Number LM6142AIN, LM6142BIN, LM6142BIMT or LM6142BIMTX
NS Package Number N08E
LM6142 and LM6144
www.national.com13
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
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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
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure 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.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
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Tel: 1-800-272-9959
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Email: support@nsc.com
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Tel: 81-3-5639-7560
Fax: 81-3-5639-7507
www.national.com
14-Pin Molded Dual-In-Line Package
Order Number LM6144AIN or LM6144BIN
NS Package Number N14A
LM6142 l and LM6144 17 MHz Rail-to-Rail Input-Output Operational Amplifiers
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.
