NSC LMV932 1.8v, rrio operational amplifier Datasheet

LMV931 Single / LMV932 Dual / LMV934 Quad
1.8V, RRIO Operational Amplifiers
General Description
Features
The LMV931/LMV932/LMV934 are low voltage, low power
operational amplifiers. LMV931/LMV932/LMV934 are guaranteed to operate from +1.8V to +5.0V supply voltages and
have rail-to-rail input and output. LMV931/LMV932/LMV934
input common mode voltage extends 200mV beyond the
supplies which enables user enhanced functionality beyond
the supply voltage range. The output can swing rail-to-rail
unloaded and within 105mV from the rail with 600Ω load at
1.8V supply. The LMV931/LMV932/LMV934 are optimized to
work at 1.8V which make them ideal for portable two-cell
battery powered systems and single cell Li-Ion systems.
(Typical 1.8V Supply Values; Unless Otherwise Noted)
n Guaranteed 1.8V, 2.7V and 5V specifications
n Output swing
— w/600Ω load
80mV from rail
— w/2kΩ load
30mV from rail
n VCM
200mV beyond rails
n Supply current (per channel)
100µA
n Gain bandwidth product
1.4MHz
n Maximum VOS
4.0mV
n Ultra tiny packages
n Temperature range
−40˚C to 125˚C
LMV931/LMV932/LMV934 exhibit excellent speed-power ratio, achieving 1.4MHz gain bandwidth product at 1.8V supply
voltage with very low supply current. The LMV931/LMV932/
LMV934 are capable of driving a 600Ω load and up to
1000pF capacitive load with minimal ringing. LMV931/
LMV932/LMV934 have a high DC gain of 101dB, making
them suitable for low frequency applications.
The single LMV931 is offered in space saving SC70-5 and
SOT23-5 packages. The dual LMV932 are in MSOP-8 and
SOIC-8 packages and the quad LMV934 are in TSSOP-14
and SOIC-14 packages. These small packages are ideal
solutions for area constrained PC boards and portable electronics such as cellular phones and PDAs.
Applications
n
n
n
n
n
n
n
Consumer communication
Consumer computing
PDAs
Audio pre-amp
Portable/battery-powered electronic equipment
Supply current monitoring
Battery monitoring
Typical Application
200326H0
© 2002 National Semiconductor Corporation
DS200326
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LMV931 Single / LMV932 Dual / LMV934 Quad 1.8V, RRIO Operational Amplifiers
December 2002
LMV931 Single / LMV932 Dual / LMV934 Quad
Absolute Maximum Ratings
Infrared or Convection (20 sec)
(Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Operating Ratings (Note 1)
Supply Voltage Range
ESD Tolerance (Note 2)
Machine Model
1.8V to 5.0V
Temperature Range
200V
Human Body Model
235˚C
−40˚C to 125˚C
Thermal Resistance (θJA)
2000V
SC70-5
414˚C/W
SOT23-5
265˚C/W
Output Short Circuit to V+ (Note 3)
MSOP-8
235˚C/W
Output Short Circuit to V− (Note 3)
SOIC-8
175˚C/W
Storage Temperature Range
TSSOP-14
155˚C/W
SOIC-14
127˚C/W
Differential Input Voltage
+
−
Supply Voltage (V –V )
Junction Temperature (Note 4)
± Supply Voltage
5.5V
−65˚C to 150˚C
150˚C
Mounting Temp.
1.8V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 1.8V, V − = 0V, VCM = V+/2, VO = V+/2 and
RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
VOS
Parameter
Input Offset Voltage
Condition
Min
(Note 6)
Typ
(Note 5)
Max
(Note 6)
Units
LMV931 (Single)
1
4
6
mV
LMV932 (Dual)
LMV934 (Quad)
1
5.5
7.5
mV
TCVOS
Input Offset Voltage Average
Drift
5.5
IB
Input Bias Current
15
35
50
nA
IOS
Input Offset Current
13
25
40
nA
IS
Supply Current (per channel)
103
185
205
CMRR
Common Mode Rejection
Ratio
LMV931, 0 ≤ VCM ≤ 0.6V
1.4V ≤ VCM ≤ 1.8V (Note 8)
60
55
78
LMV932 and LMV934
0 ≤ VCM ≤ 0.6V
1.4V ≤ VCM ≤ 1.8V (Note 8)
55
50
76
−0.2V ≤ VCM ≤ 0V
1.8V ≤ VCM ≤ 2.0V
50
72
75
70
100
V− −0.2
−0.2 to 2.1
PSRR
Power Supply Rejection
Ratio
1.8V ≤ V+ ≤ 5V
CMVR
Input Common-Mode Voltage
Range
For CMRR
Range ≥ 50dB
AV
Large Signal Voltage Gain
LMV931 (Single)
Large Signal Voltage Gain
LMV932 (Dual)
LMV934 (Quad)
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TA = 25˚C
V
TA = 125˚C
V− +0.2
dB
V+ +0.2
V+
V
V+ −0.2
RL = 600Ω to 0.9V,
VO = 0.2V to 1.6V, VCM = 0.5V
77
73
101
RL = 2kΩ to 0.9V,
VO = 0.2V to 1.6V, VCM = 0.5V
80
75
105
RL = 600Ω to 0.9V,
VO = 0.2V to 1.6V, VCM = 0.5V
75
72
90
RL = 2kΩ to 0.9V,
VO = 0.2V to 1.6V, VCM = 0.5V
78
75
100
2
µA
dB
−
TA −40˚C to
85˚C
µV/˚C
dB
dB
(Continued)
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 1.8V, V − = 0V, VCM = V+/2, VO = V+/2 and
RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
VO
Parameter
Output Swing
Condition
RL = 600Ω to 0.9V
VIN = ± 100mV
Min
(Note 6)
Typ
(Note 5)
1.65
1.63
1.72
0.077
1.75
1.74
RL = 2kΩ to 0.9V
VIN = ± 100mV
Output Short Circuit Current
0.105
0.120
1.77
0.024
IO
Max
(Note 6)
Sourcing, VO = 0V
VIN = 100mV
4
3.3
8
Sinking, VO = 1.8V
VIN = −100mV
7
5
9
Units
V
0.035
0.04
mA
1.8V AC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 1.8V, V
Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
Parameter
Conditions
−
= 0V, VCM = V+/2, VO = V+/2 and RL > 1 MΩ.
Min
(Note 6)
(Note 7)
Typ
(Note 5)
Max
(Note 6)
Units
SR
Slew Rate
0.35
V/µs
GBW
Gain-Bandwidth Product
1.4
MHz
Φm
Phase Margin
67
deg
Gm
Gain Margin
7
dB
en
Input-Referred Voltage Noise
f = 1kHz, VCM = 0.5V
in
Input-Referred Current Noise
f = 1kHz
0.06
THD
Total Harmonic Distortion
f = 1kHz, AV = +1
RL = 600Ω, VIN = 1 VPP
0.023
%
Amp-to-Amp Isolation
(Note 9)
123
dB
60
2.7V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V − = 0V, VCM = V+/2, VO = V+/2 and
RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
VOS
Parameter
Input Offset Voltage
Condition
Min
(Note 6)
Typ
(Note 5)
Max
(Note 6)
Units
LMV931 (Single)
1
4
6
mV
LMV932 (Dual)
LMV934 (Quad)
1
5.5
7.5
mV
TCVOS
Input Offset Voltage Average
Drift
5.5
IB
Input Bias Current
15
35
50
nA
IOS
Input Offset Current
8
25
40
nA
IS
Supply Current (per channel)
105
190
210
3
µV/˚C
µA
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LMV931 Single / LMV932 Dual / LMV934 Quad
1.8V DC Electrical Characteristics
LMV931 Single / LMV932 Dual / LMV934 Quad
2.7V DC Electrical Characteristics
(Continued)
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V − = 0V, VCM = V+/2, VO = V+/2 and
RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
CMRR
Parameter
Common Mode Rejection
Ratio
Condition
Min
(Note 6)
Typ
(Note 5)
LMV931, 0 ≤ VCM ≤ 1.5V
2.3V ≤ VCM ≤ 2.7V (Note 8)
60
55
81
LMV932 and LMV934
0 ≤ VCM ≤ 1.5V
2.3V ≤ VCM ≤ 2.7V (Note 8)
55
50
80
−0.2V ≤ VCM ≤ 0V
2.7V ≤ VCM ≤ 2.9V
50
74
1.8V ≤ V+ ≤ 5V
VCM = 0.5V
75
70
100
V− −0.2
−0.2 to 3.0
PSRR
Power Supply Rejection
Ratio
VCM
Input Common-Mode Voltage For CMRR
Range
Range ≥ 50dB
TA = 25˚C
TA = −40˚C to
85˚C
TA = 125˚C
AV
VO
−
V− +0.2
V+ −0.2
104
RL = 2kΩ to 1.35V,
VO = 0.2V to 2.5V
92
91
110
Large Signal Voltage Gain
LMV932 (Dual)
LMV934 (Quad)
RL = 600Ω to 1.35V,
VO = 0.2V to 2.5V
78
75
90
RL = 2kΩ to 1.35V,
VO = 0.2V to 2.5V
81
78
100
Output Swing
RL = 600Ω to 1.35V
VIN = ± 100mV
2.55
2.53
2.62
2.65
2.64
Sourcing, VO = 0V
VIN = 100mV
20
15
30
Sinking, VO = 0V
VIN = −100mV
18
12
25
V
dB
dB
0.110
0.130
2.675
0.025
Output Short Circuit Current
V+ +0.2
V+
0.083
IO
dB
V
87
86
RL = 2kΩ to 1.35V
VIN = ± 100mV
Units
dB
RL = 600Ω to 1.35V,
VO = 0.2V to 2.5V
Large Signal Voltage Gain
LMV931 (Single)
Max
(Note 6)
V
0.04
0.045
mA
2.7V AC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V − = 0V, VCM = 1.0V, VO = 1.35V and
RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
Parameter
Conditions
Typ
(Note 5)
Max
(Note 6)
Units
SR
Slew Rate
0.4
V/µs
GBW
Gain-Bandwidth Product
1.4
MHz
Φm
Phase Margin
70
deg
Gm
Gain Margin
7.5
dB
en
Input-Referred Voltage Noise
f = 1kHz, VCM = 0.5V
in
Input-Referred Current Noise
f = 1kHz
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(Note 7)
Min
(Note 6)
57
0.082
4
(Continued)
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 2.7V, V − = 0V, VCM = 1.0V, VO = 1.35V and
RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
THD
Parameter
Conditions
Total Harmonic Distortion
f = 1kHz, AV = +1
RL = 600kΩ, VIN = 1VPP
Amp-to-Amp Isolation
(Note 9)
Min
(Note 6)
Typ
(Note 5)
Max
(Note 6)
Units
0.022
%
123
dB
5V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5V, V − = 0V, VCM = V+/2, VO = V+/2 and
RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
VOS
Parameter
Input Offset Voltage
Condition
Min
(Note 6)
Typ
(Note 5)
Max
(Note 6)
Units
LMV931 (Single)
1
4
6
mV
LMV932 (Dual)
LMV934 (Quad)
1
5.5
7.5
mV
TCVOS
Input Offset Voltage Average
Drift
5.5
IB
Input Bias Current
14
35
50
nA
IOS
Input Offset Current
9
25
40
nA
IS
Supply Current (per channel)
116
210
230
CMRR
Common Mode Rejection
Ratio
0 ≤ VCM ≤ 3.8V
4.6V ≤ VCM ≤ 5.0V (Note 8)
60
55
86
−0.2V ≤ VCM ≤ 0V
5.0V ≤ VCM ≤ 5.2V
50
78
75
70
100
V− −0.2
−0.2 to 5.3
PSRR
Power Supply Rejection
Ratio
1.8V ≤ V+ ≤ 5V
VCM = 0.5V
CMVR
Input Common-Mode Voltage
Range
For CMRR
Range ≥ 50dB
TA = 25˚C
TA = −40˚C to
85˚C
TA = 125˚C
AV
VO
V+ −0.3
RL = 2kΩ to 2.5V,
VO = 0.2V to 4.8V
94
93
113
Large Signal Voltage Gain
LMV932 (Dual)
LMV934 (Quad)
RL = 600Ω to 2.5V,
VO = 0.2V to 4.8V
81
78
90
RL = 2kΩ to 2.5V,
VO = 0.2V to 4.8V
85
82
100
Output Swing
RL = 600Ω to 2.5V
VIN = ± 100mV
4.855
4.835
4.890
0.120
4.945
4.935
V
dB
dB
0.160
0.180
4.967
0.037
5
V+ +0.2
V− +0.3
102
RL = 2kΩ to 2.5V
VIN = ± 100mV
dB
V+
88
87
µA
dB
V−
RL = 600Ω to 2.5V,
VO = 0.2V to 4.8V
Large Signal Voltage Gain
LMV931 (Single)
µV/˚C
V
0.065
0.075
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LMV931 Single / LMV932 Dual / LMV934 Quad
2.7V AC Electrical Characteristics
LMV931 Single / LMV932 Dual / LMV934 Quad
5V DC Electrical Characteristics
(Continued)
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5V, V − = 0V, VCM = V+/2, VO = V+/2 and
RL > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
IO
Parameter
Output Short Circuit Current
Condition
Min
(Note 6)
Typ
(Note 5)
LMV931, Sourcing, VO = 0V
VIN = 100mV
80
68
100
Sinking, VO = 5V
VIN = −100mV
58
45
65
Max
(Note 6)
Units
mA
5V AC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for TJ = 25˚C. V+ = 5V, V − = 0V, VCM = V+/2, VO = 2.5V and
R L > 1 MΩ. Boldface limits apply at the temperature extremes. See (Note 10)
Symbol
Parameter
Conditions
Min
(Note 6)
Max
(Note 6)
Units
SR
Slew Rate
0.42
V/µs
GBW
Gain-Bandwidth Product
1.5
MHz
Φm
Phase Margin
71
deg
Gm
Gain Margin
8
dB
en
Input-Referred Voltage Noise
f = 1kHz, VCM = 1V
in
Input-Referred Current Noise
f = 1kHz
THD
Total Harmonic Distortion
f = 1kHz, AV = +1
RL = 600Ω, VO = 1 V
Amp-to-Amp Isolation
(Note 7)
Typ
(Note 5)
50
0.07
0.022
%
123
dB
PP
(Note 9)
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 specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.
Note 2: Human body model, 1.5kΩ in series with 100pF. Machine model, 200Ω in series with 100pF.
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. Output currents in excess of 45mA 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)–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: V+ = 5V. Connected as voltage follower with 5V step input. Number specified is the slower of the positive and negative slew rates.
Note 8: For guaranteed temperature ranges, see Input Common-Mode Voltage Range specifications.
Note 9: Input referred, V+ = 5V and RL = 100kΩ connected to 2.5V. Each amp excited in turn with 1kHz to produce VO = 3VPP.
Note 10: Electrical Table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating
of the device such that TJ = TA. No guarantee of parametric performance is indicated in the electrical tables under conditions of internal self-heating where TJ > TA.
See Applications section for information of temperature derating of the device. Absolute Maximum Ratings indicated junction temperature limits beyond which the
device may be permanently degraded, either mechanically or electrically.
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6
5-Pin SC70-5/SOT23-5
(LMV931)
8-Pin MSOP/SOIC
(LMV932)
14-Pin TSSOP/SOIC
(LMV934)
200326AO
Top View
200326G13
200326G12
Top View
Top View
Ordering Information
Package
5-Pin SC70
5-Pin SOT23
8-Pin MSOP
8-Pin SOIC
14-Pin TSSOP
14-Pin SOIC
Part Number
LMV931MG
LMV931MGX
LMV931MF
LMV931MFX
LMV932MM
LMV932MMX
LMV932MA
LMV932MAX
LMV934MT
LMV934MTX
LMV934MA
LMV934MAX
Packaging Marking
A74
A79A
A86A
LMV932MA
LMV934MT
LMV934MA
7
Transport Media
1k Units Tape and Reel
3k Units Tape and Reel
1k Units Tape and Reel
3k Units Tape and Reel
1k Units Tape and Reel
3.5k Units Tape and Reel
Rails
2.5k Units Tape and Reel
Rails
2.5k Units Tape and Reel
Rails
2.5k Units Tape and Reel
NSC
Drawing
MAA05A
MF05A
MUA08A
M08A
MTC14
M14A
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LMV931 Single / LMV932 Dual / LMV934 Quad
Connection Diagrams
LMV931 Single / LMV932 Dual / LMV934 Quad
Typical Performance Characteristics
Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C.
Supply Current vs. Supply Voltage (LMV931)
Sourcing Current vs. Output Voltage
20032622
20032625
Sinking Current vs. Output Voltage
Output Voltage Swing vs. Supply Voltage
20032628
20032649
Output Voltage Swing vs. Supply Voltage
Gain and Phase vs. Frequency
20032650
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200326G8
8
LMV931 Single / LMV932 Dual / LMV934 Quad
Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
Gain and Phase vs. Frequency
Gain and Phase vs. Frequency
200326G9
200326G10
Gain and Phase vs. Frequency
CMRR vs. Frequency
20032639
200326G11
PSRR vs. Frequency
Input Voltage Noise vs. Frequency
20032658
20032656
9
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LMV931 Single / LMV932 Dual / LMV934 Quad
Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
Input Current Noise vs. Frequency
THD vs. Frequency
20032666
20032667
THD vs. Frequency
Slew Rate vs. Supply Voltage
20032669
20032668
Small Signal Non-Inverting Response
Small Signal Non-Inverting Response
20032670
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20032671
10
Small Signal Non-Inverting Response
Large Signal Non-Inverting Response
20032672
20032673
Large Signal Non-Inverting Response
Large Signal Non-Inverting Response
20032674
20032675
Short Circuit Current vs. Temperature (Sinking)
Short Circuit Current vs. Temperature (Sourcing)
20032676
20032677
11
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LMV931 Single / LMV932 Dual / LMV934 Quad
Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
LMV931 Single / LMV932 Dual / LMV934 Quad
Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
Offset Voltage vs. Common Mode Range
Offset Voltage vs. Common Mode Range
20032636
20032637
Offset Voltage vs. Common Mode Range
20032638
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LMV931 Single / LMV932 Dual / LMV934 Quad
Application Note
1.0 INPUT AND OUTPUT STAGE
The rail-to-rail input stage of this family provides more flexibility for the designer. The LMV931/LMV932/LMV934 use a
complimentary PNP and NPN input stage in which the PNP
stage senses common mode voltage near V− and the NPN
stage senses common mode voltage near V+. The transition
from the PNP stage to NPN stage occurs 1V below V+. Since
both input stages have their own offset voltage, the offset of
the amplifier becomes a function of the input common mode
voltage and has a crossover point at 1V below V+.
This VOS crossover point can create problems for both DC
and AC coupled signals if proper care is not taken. Large
input signals that include the VOS crossover point will cause
distortion in the output signal. One way to avoid such distortion is to keep the signal away from the crossover. For
example, in a unity gain buffer configuration and with VS =
5V, a 5V peak-to-peak signal will contain input-crossover
distortion while a 3V peak-to-peak signal centered at 1.5V
will not contain input-crossover distortion as it avoids the
crossover point. Another way to avoid large signal distortion
is to use a gain of −1 circuit which avoids any voltage
excursions at the input terminals of the amplifier. In that
circuit, the common mode DC voltage can be set at a level
away from the VOS cross-over point. For small signals, this
transition in VOS shows up as a VCM dependent spurious
signal in series with the input signal and can effectively
degrade small signal parameters such as gain and common
mode rejection ratio. To resolve this problem, the small
signal should be placed such that it avoids the VOS crossover point. In addition to the rail-to-rail performance, the
output stage can provide enough output current to drive
600Ω loads. Because of the high current capability, care
should be taken not to exceed the 150˚C maximum junction
temperature specification.
20032659
FIGURE 1. Canceling the Offset Voltage due to Input
Bias Current
Typical Applications
3.0 HIGH SIDE CURRENT SENSING
The high side current sensing circuit (Figure 2) is commonly
used in a battery charger to monitor charging current to
prevent over charging. A sense resistor RSENSE is connected
to the battery directly. This system requires an op amp with
rail-to-rail input. The LMV931/LMV932/LMV934 are ideal for
this application because its common mode input range goes
up to the rail.
2.0 INPUT BIAS CURRENT CONSIDERATION
The LMV931/LMV932/LMV934 family has a complementary
bipolar input stage. The typical input bias current (IB) is
15nA. The input bias current can develop a significant offset
voltage. This offset is primarily due to IB flowing through the
negative feedback resistor, RF. For example, if IB is 50nA
and RF is 100kΩ, then an offset voltage of 5mV will develop
(VOS = IB x RF). Using a compensation resistor (RC), as
shown in Figure 1, cancels this effect. But the input offset
current (IOS) will still contribute to an offset voltage in the
same manner.
200326H0
FIGURE 2. High Side Current Sensing
13
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LMV931 Single / LMV932 Dual / LMV934 Quad
Typical Applications
In Figure 3 the circuit is referenced to ground, while in Figure
4 the circuit is biased to the positive supply. These configurations implement the half wave rectifier since the LMV931/
LMV932/LMV934 can not respond to one-half of the incoming waveform. It can not respond to one-half of the incoming
because the amplifier can not swing the output beyond either
rail therefore the output disengages during this half cycle.
During the other half cycle, however, the amplifier achieves a
half wave that can have a peak equal to the total supply
voltage. RI should be large enough not to load the
LMV931/LMV932/LMV934.
(Continued)
4.0 HALF-WAVE RECTIFIER WITH RAIL-TO-GROUND
OUTPUT SWING
Since the LMV931/LMV932/LMV934 input common mode
range includes both positive and negative supply rails and
the output can also swing to either supply, achieving halfwave rectifier functions in either direction is an easy task. All
that is needed are two external resistors; there is no need for
diodes or matched resistors. The half wave rectifier can have
either positive or negative going outputs, depending on the
way the circuit is arranged.
200326C4
200326C2
200326C3
FIGURE 3. Half-Wave Rectifier with Rail-To-Ground Output Swing Referenced to Ground
200326C1
200326B9
200326C0
FIGURE 4. Half-Wave Rectifier with Negative-Going Output Referenced to VCC
voltages. Remember that even with rail-to-rail outputs, the
output can not swing past the supplies so the combined
common mode voltages plus the signal should not be
greater that the supplies or limiting will occur. For additional
applications, see National Semiconductor application notes
AN–29, AN–31, AN–71, and AN–127.
5.0 INSTRUMENTATION AMPLIFIER WITH
RAIL-TO-RAIL INPUT AND OUTPUT
Some manufactures make a non-“rail-to-rail”-op amp rail-torail by using a resistive divider on the inputs. The resistors
divide the input voltage to get a rail-to-rail input range. The
problem with this method is that it also divides the signal, so
in order to get the obtained gain, the amplifier must have a
higher closed loop gain. This raises the noise and drift by the
internal gain factor and lowers the input impedance. Any
mismatch in these precision resistors reduces the CMRR as
well. The LMV981/LMV982 is rail-to-rail and therefore
doesn’t have these disadvantages.
Using three of the LMV981/LMV982 amplifiers, an instrumentation amplifier with rail-to-rail inputs and outputs can be
made as shown in Figure 5.
In this example, amplifiers on the left side act as buffers to
the differential stage. These buffers assure that the input
impedance is very high and require no 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 CMRR set by the matching R1-R2 with R3-R4.
The gain is set by the ratio of R2/R1 and R3 should equal R1
and R4 equal R2. With both rail-to-rail input and output
ranges, the input and output are only limited by the supply
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200326G4
FIGURE 5. Rail-to-rail Instrumentation Amplifier
14
LMV931 Single / LMV932 Dual / LMV934 Quad
Simplified Schematic
200326A9
15
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LMV931 Single / LMV932 Dual / LMV934 Quad
Physical Dimensions
inches (millimeters)
unless otherwise noted
5-Pin SC70
NS Package Number MAA05A
5-Pin SOT23
NS Package Number MF05A
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16
LMV931 Single / LMV932 Dual / LMV934 Quad
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
8-Pin MSOP
NS Package Number MUA08A
8-Pin SOIC
NS Package Number M08A
17
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LMV931 Single / LMV932 Dual / LMV934 Quad
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
14-Pin TSSOP
NS Package Number MTC14
14-Pin SOIC
NS Package Number M14A
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18
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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.
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Email: [email protected]
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Email: [email protected]
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2. A critical component is any component of a life
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can be reasonably expected to cause the failure of
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Response Group
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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.
LMV931 Single / LMV932 Dual / LMV934 Quad 1.8V, RRIO Operational Amplifiers
Notes
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