LM6142QML
17 MHz Rail-to-Rail Input-Output Operational Amplifiers
General Description
Using patented new circuit topologies, the LM6142 provides
new levels of performance in applications where low voltage
supplies or power limitations previously made compromise
necessary. Operating on supplies of 2.7V to over 24V, the
LM6142 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 650µA/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: 17MHz (typ)
nSlew rate:
Small signal, 5V/µs
Large signal, 30V/µs
nLow supply current 650µA/Amplifier
nWide supply range 2.8V to 24V
nCMRR 107dB
nGain 108dB with R
L
= 10k
nPSRR 87dB
Applications
nBattery operated instrumentation
nPortable sonar
nBarcode scanners
nWireless communications
nRail-to-rail in-out instrumentation amps
Ordering Information
NS Part Number JAN Part Number NS Package Number Package Description
LM6142AMJ-QML 5962–9550301QPA J08A 8LD CERDIP
Connection Diagram
8-Pin CDIP
20144014
Top View
November 2005
LM6142QML 17 MHz Rail-to-Rail Input-Output Operational Amplifiers
© 2005 National Semiconductor Corporation DS201440 www.national.com
Absolute Maximum Ratings (Note 1)
Differential Input Voltage 15V
Voltage at Input/Output Pin (V
+
) + 0.3V, (V
−
) − 0.3V
Supply Voltage (V
+
−V
−
) 35V
Current at Input Pin ±10mA
Current at Output Pin (Note 4) ±25mA
Current at Power Supply Pin 50mA
Lead Temperature (soldering, 10 sec) 260˚C
Storage Temp. Range −65˚C ≤T
A
≤+150˚C
Maximum Junction Temperature (T
Jmax
)(Note 2) 150˚C
Thermal Resistance
θ
JA
still Air 125˚C/W
500LF / Min Air Flow 63˚C/W
θ
JC
12˚C/W
ESD Tolerance (Note 3) 3KV
Recommended Operating Conditions(Note 1)
Supply Voltage 2.8V ≤V
+
≤24V
Operating Temperature Range −55˚C ≤T
A
≤+125˚C
Quality Conformance Inspection
Mil-Std-883, Method 5005 - Group A
Subgroup Description Temp ˚C
1 Static tests at 25
2 Static tests at 125
3 Static tests at -55
4 Dynamic tests at 25
5 Dynamic tests at 125
6 Dynamic tests at -55
7 Functional tests at 25
8A Functional tests at 125
8B Functional tests at -55
9 Switching tests at 25
10 Switching tests at 125
11 Switching tests at -55
12 Settling time at 25
13 Settling time at 125
14 Settling time at -55
LM6142QML
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5.0V Electrical Characteristics
DC Parameters
The following conditions apply to all the following parameters, unless otherwise specified.
DC: V
+
= 5.0V, V
−
= 0V, V
CM
=V
O
=V
+
/2 and R
L
≥100KΩto V
+
/2
Symbol Parameter Conditions Notes Min Max µnit Sub-
group
V
IO
Input Offset Voltage 1.0 mV 1
2.5 mV 2, 3
I
IB
Input Bias Current 0V ≤V
CM
≤5V 280 nA 1
526 nA 2, 3
I
IO
Input Offset Current 30 nA 1
80 nA 2, 3
CMRR Common Mode Rejection Ratio 0V ≤V
CM
≤4V 84 dB 1
78 dB 2, 3
0V ≤V
CM
≤5V 66 dB 1
64 dB 2, 3
PSRR Power Supply Rejection Ratio 5V ≤V+ ≤24V 80 dB 1
78 dB 2, 3
V
CM
Input Common-Mode Voltage
Range
(Note 5) 0 5.0 V 1, 2, 3
A
V
Large Signal Voltage Gain R
L
= 10KΩ100 V/mV 4
33 V/mV 5, 6
V
O
Output Swing R
L
= 100KΩ4.98 0.01 V 4
4.93 0.014 V 5, 6
Output Swing R
L
=2KΩ4.86 0.1 V 4
4.77 0.133 V 5
4.8 0.133 V 6
I
SC
Output Short Circuit Current Sourcing 10 mA 1
2.0 35 mA 2, 3
Sinking 10 mA 1
4.0 35 mA 2, 3
I
S
Supply Current Per Amplifier 800 µA 1
880 µA 2, 3
AC Parameters
The following conditions apply to all the following parameters, unless otherwise specified.
AC: V
+
= 5.0V, V
−
= 0V, V
CM
=V
O
=V
+
/2 and R
L
≥100KΩto V
+
/2
Symbol Parameter Conditions Notes Min Max µnit Sub-
group
+SR Slew Rate -4V ≤V
I
≤+4V,
+V
CC
= 6V, -V
CC
-6V,
R
S
=1KΩ,R
L
=2KΩC
O
=0F
15 V/µS 4
9.5 V/µS 5
11 V/µS 6
-SR Slew Rate +4V ≥V
I
≥-4V,
+V
CC
= 6V, -V
CC
-6V,
R
S
=1KΩ,R
L
=2KΩC
O
=0F
15 V/µS 4
9.5 V/µS 5
11 V/µS 6
GBW Gain-Bandwidth Product ƒ = 50Khz 10 MHz 4
6.0 MHz 5, 6
LM6142QML
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2.8V Electrical Characteristics
DC Parameters
The following conditions apply to all the following parameters, unless otherwise specified.
DC: V
+
= 2.8V, V
−
= 0V, V
CM
=V
O
=V
+
/2 and R
L
≥100KΩto V
+
/2
Symbol Parameter Conditions Notes Min Max µnit Sub-
group
V
IO
Input Offset Voltage 1.8 mV 1
4.3 mV 2, 3
I
IB
Input Bias Current 250 nA 1
526 nA 2, 3
I
IO
Input Offset Current 30 nA 1
80 nA 2, 3
CMRR Common Mode Rejection Ratio 0V ≤V
CM
≤1.9V 72 dB 1
63 dB 2, 3
0V ≤V
CM
≤2.8V 62 dB 1
58 dB 2, 3
PSRR Power Supply Rejection Ratio 3V ≤V
+
≤5V 72 dB 1
58 dB 2, 3
V
CM
Input Common-Mode Voltage
Range
(Note 5) 0.0 2.8 V 1, 2, 3
A
V
Large Signal Voltage Gain R
L
= 100KΩ,V
O
=±1.1V 10 V/mV 4
1.5 V/mV 5, 6
V
O
Output Swing R
L
= 100KΩ2.76 0.08 V 4
2.35 0.112 V 5, 6
I
S
Supply Current Per Amplifier 800 µA 1
880 µA 2, 3
AC Parameters
The following conditions apply to all the following parameters, unless otherwise specified.
AC: V
+
= 2.8V, V
−
= 0V, V
CM
=V
O
=V
+
/2 and R
L
≥100KΩto V
+
/2
Symbol Parameter Conditions Notes Min Max µnit Sub-
group
GBW Gain-Bandwidth Product ƒ = 50KHz 3 MHz 4
1.5 MHz 5, 6
LM6142QML
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24V Electrical Characteristics
DC Parameters
The following conditions apply to all the following parameters, unless otherwise specified.
DC: V
+
= 24V, V
−
= 0V, V
CM
=V
O
=V
+
/2 and R
L
≥100KΩto V
+
/2
Symbol Parameter Conditions Notes Min Max µnit Sub-
group
V
IO
Input Offset Voltage 2.0 mV 1
4.8 mV 2, 3
V
O
Output Swing R
L
= 10KΩ23.81 0.15 V 4
23.62 0.185 V 5, 6
I
S
Supply Current Per Amplifier 1100 µA 1
1150 µA 2, 3
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
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. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJmax (maximum junction temperature), θJA (package junction
to ambient thermal resistance), and TA(ambient temperature). The maximum allowable power dissipation at any temperature is PDmax =(T
Jmax -T
A)/θJA or the
number given in the Absolute Maximum Ratings, whichever is lower.
Note 3: Human body model, 1.5kΩin series with 100pF.
Note 4: 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 5: Input common-mode voltage range is guaranteed by CMRR.
LM6142QML
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Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise Specified
Supply Current vs. Supply Voltage Offset Voltage vs. Supply Voltage
20144015 20144016
Bias Current vs. Supply Voltage Offset Voltage vs. V
CM
20144017 20144018
Offset Voltage vs. V
CM
Offset Voltage vs. V
CM
20144019 20144020
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Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise
Specified (Continued)
Bias Current vs. V
CM
Bias Current vs. V
CM
20144021 20144022
Bias Current vs. V
CM
Open-Loop Transfer Function
20144023 20144024
Open-Loop Transfer Function Open-Loop Transfer Function
20144025 20144026
LM6142QML
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Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise
Specified (Continued)
Output Voltage vs. Source Current Output Voltage vs. Source Current
20144027 20144029
Output Voltage vs. Source Current Output Voltage vs. Sink Current
20144028 20144030
Output Voltage vs. Sink Current Output Voltage vs. Sink Current
20144031 20144032
LM6142QML
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Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise
Specified (Continued)
Gain and Phase vs. Load Gain and Phase vs. Load
20144033 20144034
Distortion + Noise vs. Frequency GBW vs. Supply
20144035 20144036
Open Loop Gain vs. Load, 3V Supply Open Loop Gain vs. Load, 5V Supply
20144037 20144038
LM6142QML
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Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise
Specified (Continued)
Open Loop Gain vs. Load, 24V Supply Unity Gain Frequency vs. V
S
20144039 20144040
CMRR vs. Frequency Crosstalk vs. Frequency
20144041 20144042
PSRR vs. Frequency Noise Voltage vs. Frequency
20144043 20144044
LM6142QML
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Typical Performance Characteristics T
A
= 25˚C, R
L
=10kΩUnless Otherwise
Specified (Continued)
Noise Current vs. Frequency NF vs. R
Source
20144045 20144012
LM6142 Application Ideas
The LM6142 brings a new level of ease of use to op amp
system 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 op amps, 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
amplitude.
Figure 2 shows how excess input signal, is routed around
the input collector-base junctions, directly to the current
mirrors.
The LM6142 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
additional transistors, (Q5, Q6), directly into the current mir-
rors.
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 op amp reacts better than a
conventional op amp. 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 op amps when they are overdriven.
This speed-up action adds stability to the system when
driving large capacitive loads.
DRIVING CAPACITIVE LOADS
Capacitive loads decrease the phase margin of all op amps.
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 op amps with a
fixed maximum slew-rate will lag further and further behind
when driving capacitive loads even though the differential
input voltage raises. With the LM6142, the lag causes the
slew rate to raise. The increased slew-rate keeps the output
following the input much better. This effectively reduces
phase lag. After the output has caught up with the input, the
differential input voltage drops down and the amplifier settles
rapidly.
Slew Rate vs. ∆V
IN
V
S
=±5V
20144007
FIGURE 1.
LM6142QML
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LM6142 Application Ideas (Continued)
These features allow the LM6142 to drive capacitive loads
as large as 1000pF at unity gain and not oscillate. The scope
photos (Figure 3 and Figure 4) above show the LM6142
driving a l000pF load. In Figure 3, the upper trace is with no
capacitive load and the lower trace is with a 1000pF load.
Here we are operating on ±12V supplies with a 20 V
PP
pulse. Excellent response is obtained with a C
f
of l0pF. In
Figure 4, the supplies have been reduced to ±2.5V, the
pulse is 4 V
PP
and C
f
is 39pF. The best value for the
compensation 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 op amps is the phase
shift caused by the feedback resistor and the input capaci-
tance. This phase shift also reduces phase margin. This
effect is taken care of at the same time as the effect of the
capacitive load when the capacitor is placed across the
feedback resistor.
The circuit shown in Figure 5 was used for these scope
photos.
20144006
FIGURE 2.
20144008
FIGURE 3.
20144009
FIGURE 4.
LM6142QML
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LM6142 Application Ideas (Continued)
Typical Applications
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
LM6142a good choice for buffering the inputs of A to D
converters.
3 OP AMP INSTRUMENTATION AMP WITH
RAIL-TO-RAIL INPUT AND OUTPUT
Using two LM6142 amplifiers,a3opampinstrumentation
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
input 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 two LM6142
amplifiers, all of these problems are eliminated.
In this example, amplifiers A and B act as buffers to the
differential stage (Figure 6). These buffers assure that the
input impedance is over 100MΩand they eliminate the
requirement 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
limiting will occur.
SPICE MACROMODEL
A SPICE macromodel of this and many other National Semi-
conductor op amps is available at no charge from the NSC
Customer Response Group at 800-272-9959.
20144010
FIGURE 5.
20144013
FIGURE 6.
LM6142QML
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Revision History Section
Date
Released
Revision Section Originator Changes
11/08/05 A New release to the corporate format L. Lytle 1 MDS datasheet converted into standard
corporate format. MNLM6142-X Rev 4A1 to
be archived.
LM6142QML
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Physical Dimensions inches (millimeters) unless otherwise noted
8-Pin Cerdip
Dual-In-Line Package
NS Package Number J08A
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.
For the most current product information visit us at www.national.com.
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LM6142QML 17 MHz Rail-to-Rail Input-Output Operational Amplifiers
