LMV321 [NSC]
General Purpose, Low Voltage, Rail-to-Rail Output Operational Amplifiers; 通用型，低电压，轨到轨输出运算放大器
| 型号： | LMV321 |
| 厂家： | 
National Semiconductor |
| 描述： | General Purpose, Low Voltage, Rail-to-Rail Output Operational Amplifiers |
| 文件： | 总27页 (文件大小：1142K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
June 2003
LMV321/LMV358/LMV324 Single/Dual/Quad
General Purpose, Low Voltage, Rail-to-Rail Output
Operational Amplifiers
General Description
The LMV358/324 are low voltage (2.7–5.5V) versions of the
dual and quad commodity op amps, LM358/324, which cur-
rently operate at 5–30V. The LMV321 is the single version.
Features
(For V+ = 5V and V− = 0V, Typical Unless Otherwise Noted)
n Guaranteed 2.7V and 5V Performance
n No Crossover Distortion
The LMV321/358/324 are the most cost effective solutions
for the applications where low voltage operation, space sav-
ing and low price are needed. They offer specifications that
meet or exceed the familiar LM358/324. The LMV321/358/
324 have rail-to-rail output swing capability and the input
common-mode voltage range includes ground. They all ex-
hibit excellent speed-power ratio, achieving 1MHz of band-
width and 1V/µs of slew rate with low supply current.
n Space Saving Package
n Industrial Temp. Range
n Gain-Bandwidth Product
n Low Supply Current
— LMV321
— LMV358
— LMV324
n Rail-to-Rail Output Swing 10kΩ
SC70-5 2.0x2.1x1.0mm
−40˚C to +85˚C
1MHz
130µA
210µA
410µA
V+ −10mV
@
The LMV321 is available in space saving SC70-5, which is
approximately half the size of SOT23-5. The small package
saves space on pc boards, and enables the design of small
portable electronic devices. It also allows the designer to
place the device closer to the signal source to reduce noise
pickup and increase signal integrity.
V− +65mV
n VCM
−0.2V to V+−0.8V
Applications
n Active Filters
n General Purpose Low Voltage Applications
n General Purpose Portable Devices
The chips are built with National’s advanced submicron
silicon-gate BiCMOS process. The LMV321/358/324 have
bipolar input and output stages for improved noise perfor-
mance and higher output current drive.
Output Voltage Swing vs. Supply Voltage
Gain and Phase vs. Capacitive Load
10006045
10006067
© 2003 National Semiconductor Corporation
DS100060
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Absolute Maximum Ratings (Note 1)
Storage Temp. Range
−65˚C to 150˚C
150˚C
Junction Temperature(Note 5)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Operating Ratings (Note 1)
ESD Tolerance (Note 2)
Supply Voltage
2.7V to 5.5V
Machine Model
100V
Temperature Range
LMV321, LMV358, LMV324
Thermal Resistance (θ JA)(Note 10)
5-pin SC70-5
Human Body Model
LMV358/324
−40˚C to +85˚C
2000V
900V
LMV321
478˚C/W
265˚C/W
190˚C/W
235˚C/W
145˚C/W
155˚C/W
Differential Input Voltage
Supply Voltage (V+–V −)
Output Short Circuit to V +
Output Short Circuit to V −
Soldering Information
Infrared or Convection (20 sec)
Supply Voltage
5.5V
5-pin SOT23-5
8-Pin SOIC
(Note 3)
8-Pin MSOP
(Note 4)
14-Pin SOIC
14-Pin TSSOP
235˚C
2.7V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T J = 25˚C, V+ = 2.7V, V− = 0V, VCM = 1.0V, VO = V+/2 and RL 1MΩ.
>
Typ
(Note 6)
1.7
Limit
(Note 7)
7
Symbol
VOS
Parameter
Conditions
Units
mV
Input Offset Voltage
max
TCVOS
IB
Input Offset Voltage Average
Drift
5
11
µV/˚C
Input Bias Current
250
50
nA
max
nA
IOS
Input Offset Current
5
max
dB
CMRR
PSRR
VCM
Common Mode Rejection Ratio 0V ≤ VCM ≤ 1.7V
63
50
min
dB
Power Supply Rejection Ratio
2.7V ≤ V+ ≤ 5V
VO = 1V
60
50
min
V
Input Common-Mode Voltage
Range
For CMRR≥50dB
−0.2
1.9
V+ -10
60
0
min
V
1.7
max
mV
min
mV
max
µA
VO
Output Swing
RL = 10kΩ to 1.35V
V+ -100
180
170
340
680
IS
Supply Current
LMV321
80
max
µA
LMV358
140
260
Both amplifiers
LMV324
max
µA
All four amplifiers
max
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2.7V AC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T J = 25˚C, V+ = 2.7V, V− = 0V, VCM = 1.0V, VO = V+/2 and RL 1MΩ.
>
Typ
(Note 6)
1
Limit
(Note 7)
Symbol
Parameter
Conditions
CL = 200pF
Units
GBWP
Φm
Gain-Bandwidth Product
Phase Margin
MHz
Deg
dB
60
Gm
Gain Margin
10
en
Input-Referred Voltage Noise
f = 1kHz
f = 1kHz
46
in
Input-Referred Current Noise
0.17
5V DC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T J = 25˚C, V+ = 5V, V− = 0V, VCM = 2.0V, VO = V+/2 and R L 1MΩ.
Boldface limits apply at the temperature extremes.
>
Typ
(Note 6)
1.7
Limit
(Note 7)
Symbol
VOS
Parameter
Conditions
Units
mV
Input Offset Voltage
7
9
max
TCVOS
IB
Input Offset Voltage Average
Drift
5
15
µV/˚C
Input Bias Current
250
500
50
nA
max
nA
IOS
Input Offset Current
5
150
50
max
dB
CMRR
PSRR
VCM
Common Mode Rejection Ratio 0V ≤ VCM ≤ 4V
65
min
dB
Power Supply Rejection Ratio
2.7V ≤ V+ ≤ 5V
60
50
0
VO = 1V VCM = 1V
min
V
Input Common-Mode Voltage
Range
For CMRR≥50dB
−0.2
4.2
min
V
4
max
V/mV
min
mV
min
mV
max
mV
min
mV
max
m
AV
VO
Large Signal Voltage Gain (Note RL = 2kΩ
8)
100
V+ -40
120
V+ -10
65
15
10
V+ -300
V+ -400
300
Output Swing
RL = 2kΩ to 2.5V
400
RL = 10kΩ to 2.5V
V+ -100
V+ -200
180
280
IO
Output Short Circuit Current
Supply Current
Sourcing, VO = 0V
Sinking, VO = 5V
LMV321
60
5
min
mA
min
µA
160
130
210
410
10
IS
250
350
440
615
830
1160
max
µA
LMV358
Both amplifiers
LMV324
max
µA
All four amplifiers
max
3
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5V AC Electrical Characteristics
Unless otherwise specified, all limits guaranteed for T J = 25˚C, V+ = 5V, V− = 0V, VCM = 2.0V, VO = V+/2 and R L 1MΩ.
Boldface limits apply at the temperature extremes.
>
Typ
(Note 6)
Limit
(Note 7)
Symbol
SR
Parameter
Conditions
Units
Slew Rate
(Note 9)
1
V/µs
MHz
Deg
dB
GBWP
Φm
Gain-Bandwidth Product
Phase Margin
CL = 200pF
1
60
10
39
Gm
Gain Margin
en
Input-Referred Voltage Noise
f = 1kHz
f = 1kHz
in
Input-Referred Current Noise
0.21
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, 0Ω in series with 200pF.
+
Note 3: Shorting output to V will adversely affect reliability.
-
Note 4: Shorting output to V will adversely affect reliability.
Note 5: The maximum power dissipation is a function of T
, θ , and T . The maximum allowable power dissipation at any ambient temperature is P =
A D
J(MAX) JA
(T
–T )/θ . All numbers apply for packages soldered directly into a PC board.
J(MAX)
A JA
Note 6: Typical values represent the most likely parametric norm.
Note 7: All limits are guaranteed by testing or statistical analysis.
-
Note 8: R is connected to V . The output voltage is 0.5V ≤ V ≤ 4.5V.
L
O
Note 9: Connected as voltage follower with 3V step input. Number specified is the slower of the positive and negative slew rates.
Note 10: All numbers are typical, and apply for packages soldered directly onto a PC board in still air.
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Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C.
Supply Current vs. Supply Voltage (LMV321)
Input Current vs. Temperature
10006073
100060A9
Sourcing Current vs. Output Voltage
Sourcing Current vs. Output Voltage
10006069
10006068
Sinking Current vs. Output Voltage
Sinking Current vs. Output Voltage
10006070
10006071
5
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Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
Output Voltage Swing vs. Supply Voltage
Input Voltage Noise vs. Frequency
10006056
10006067
Input Current Noise vs. Frequency
Input Current Noise vs. Frequency
10006060
10006058
Crosstalk Rejection vs. Frequency
PSRR vs. Frequency
10006061
10006051
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Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
CMRR vs. Frequency
CMRR vs. Input Common Mode Voltage
10006064
10006062
CMRR vs. Input Common Mode Voltage
∆VOS vs. CMR
10006063
10006053
∆V
vs. CMR
Input Voltage vs. Output Voltage
OS
10006054
10006050
7
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Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
Input Voltage vs. Output Voltage
Open Loop Frequency Response
10006052
10006042
Open Loop Frequency Response
Open Loop Frequency Response vs. Temperature
10006041
10006043
Gain and Phase vs. Capacitive Load
Gain and Phase vs. Capacitive Load
10006045
10006044
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Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
Slew Rate vs. Supply Voltage
Non-Inverting Large Signal Pulse Response
10006088
10006057
Non-Inverting Large Signal Pulse Response
Non-Inverting Large Signal Pulse Response
100060A1
100060A0
Non-Inverting Small Signal Pulse Response
Non-Inverting Small Signal Pulse Response
10006089
100060A2
9
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Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
Non-Inverting Small Signal Pulse Response
Inverting Large Signal Pulse Response
100060A3
10006090
Inverting Large Signal Pulse Response
Inverting Large Signal Pulse Response
100060A4
100060A5
Inverting Small Signal Pulse Response
Inverting Small Signal Pulse Response
10006091
100060A6
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Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
Inverting Small Signal Pulse Response
Stability vs. Capacitive Load
Stability vs. Capacitive Load
THD vs. Frequency
100060A7
10006046
Stability vs. Capacitive Load
10006049
10006047
Stability vs. Capacitive Load
10006059
10006048
11
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Typical Performance Characteristics Unless otherwise specified, VS = +5V, single supply,
TA = 25˚C. (Continued)
Open Loop Output Impedance vs. Frequency
Short Circuit Current vs. Temperature (Sinking)
10006055
10006065
Short Circuit Current vs. Temperature (Sourcing)
10006066
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Application Notes
1.0 BENEFITS OF THE LMV321/358/324
Size: The small footprints of the LMV321/358/324 packages
save space on printed circuit boards, and enable the design
of smaller electronic products, such as cellular phones, pag-
ers, or other portable systems. The low profile of the
LMV321/358/324 make them possible to use in PCMCIA
type III cards.
Signal Integrity
Signals can pick up noise between the signal source and the
amplifier. By using a physically smaller amplifier package,
the LMV321/358/324 can be placed closer to the signal
source, reducing noise pickup and increasing signal integrity.
Time (50µs/div)
10006097
Simplified Board Layout
These products help you to avoid using long pc traces in
your pc board layout. This means that no additional compo-
nents, such as capacitors and resistors, are needed to filter
out the unwanted signals due to the interference between
the long pc traces.
FIGURE 1. Output Swing of LMV324
Low Supply Current
These devices will help you to maximize battery life. They
are ideal for battery powered systems.
Low Supply Voltage
National provides guaranteed performance at 2.7V and 5V.
These guarantees ensure operation throughout the battery
lifetime.
Rail-to-Rail Output
Rail-to-rail output swing provides maximum possible dy-
namic range at the output. This is particularly important
when operating on low supply voltages.
Time (50µs/div)
10006098
FIGURE 2. Output Swing of LM324
2.0 CAPACITIVE LOAD TOLERANCE
Input Includes Ground
Allows direct sensing near GND in single supply operation.
The differential input voltage may be larger than V+ without
damaging the device. Protection should be provided to pre-
vent the input voltages from going negative more than −0.3V
(at 25˚C). An input clamp diode with a resistor to the IC input
terminal can be used.
The LMV321/358/324 can directly drive 200pF in unity-gain
without oscillation. The unity-gain follower is the most sensi-
tive configuration to capacitive loading. Direct capacitive
loading reduces the phase margin of amplifiers. The combi-
nation of the amplifier’s output impedance and the capacitive
load induces phase lag. This results in either an under-
damped pulse response or oscillation. To drive a heavier
capacitive load, circuit in Figure 3 can be used.
Ease Of Use & Crossover Distortion
The LMV321/358/324 offer specifications similar to the fa-
miliar LM324. In addition, the new LMV321/358/324 effec-
tively eliminate the output crossover distortion. The scope
photos in Figure 1 and Figure 2 compare the output swing of
the LMV324 and the LM324 in a voltage follower configura-
tion, with V S
=
2.5V and RL (= 2kΩ) connected to GND. It
is apparent that the crossover distortion has been eliminated
in the new LMV324.
10006004
FIGURE 3. Indirectly Driving A Capacitive Load Using
Resistive Isolation
13
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input bias current will be reduced. The circuit in Figure 6
shows how to cancel the error caused by input bias current.
Application Notes (Continued)
In Figure 3 , the isolation resistor RISO and the load capacitor
CL form a pole to increase stability by adding more phase
margin to the overall system. The desired performance de-
pends on the value of RISO. The bigger the RISO resistor
value, the more stable VOUT will be. Figure 4 is an output
waveform of Figure 3 using 620Ω for RISO and 510pF for CL..
10006006
FIGURE 6. Cancelling the Error Caused by Input Bias
Current
4.0 TYPICAL SINGLE-SUPPLY APPLICATION CIRCUITS
4.1 Difference Amplifier
Time (2µs/div)
The difference amplifier allows the subtraction of two volt-
ages or, as a special case, the cancellation of a signal
common to two inputs. It is useful as a computational ampli-
fier, in making a differential to single-ended conversion or in
rejecting a common mode signal.
10006099
FIGURE 4. Pulse Response of the LMV324 Circuit in
Figure 3
The circuit in Figure 5 is an improvement to the one in Figure
3 because it provides DC accuracy as well as AC stability. If
there were a load resistor in Figure 3, the output would be
voltage divided by RISO and the load resistor. Instead, in
Figure 5, RF provides the DC accuracy by using feed-
forward techniques to connect VIN to RL. Caution is needed
in choosing the value of RF due to the input bias current of
the LMV321/358/324. CF and RISO serve to counteract the
loss of phase margin by feeding the high frequency compo-
nent of the output signal back to the amplifier’s inverting
input, thereby preserving phase margin in the overall feed-
back loop. Increased capacitive drive is possible by increas-
ing the value of C . This in turn will slow down the pulse
F
10006007
response.
10006019
FIGURE 7. Difference Amplifier
4.2 Instrumentation Circuits
The input impedance of the previous difference amplifier is
set by the resistors R1, R2, R3, and R4. To eliminate the
problems of low input impedance, one way is to use a
voltage follower ahead of each input as shown in the follow-
ing two instrumentation amplifiers.
10006005
FIGURE 5. Indirectly Driving A Capacitive Load with
DC Accuracy
3.0 INPUT BIAS CURRENT CANCELLATION
The LMV321/358/324 family has a bipolar input stage. The
typical input bias current of LMV321/358/324 is 15nA with 5V
supply. Thus a 100kΩ input resistor will cause 1.5mV of error
voltage. By balancing the resistor values at both inverting
and non-inverting inputs, the error caused by the amplifier’s
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4.3 Single-Supply Inverting Amplifier
Application Notes (Continued)
There may be cases where the input signal going into the
amplifier is negative. Because the amplifier is operating in
single supply voltage, a voltage divider using R3 and R4 is
implemented to bias the amplifier so the input signal is within
the input common-mode voltage range of the amplifier. The
capacitor C1 is placed between the inverting input and resis-
tor R1 to block the DC signal going into the AC signal source,
VIN. The values of R1 and C1 affect the cutoff frequency, fc =
1/2πR1C1.
4.2.1 Three-Op-Amp Instrumentation Amplifier
The quad LMV324 can be used to build a three-op-amp
instrumentation amplifier as shown in Figure 8.
As a result, the output signal is centered around mid-supply
(if the voltage divider provides V+/2 at the non-inverting
input). The output can swing to both rails, maximizing the
signal-to-noise ratio in a low voltage system.
10006085
FIGURE 8. Three-op-amp Instrumentation Amplifier
The first stage of this instrumentation amplifier is a
differential-input, differential-output amplifier, with two volt-
age followers. These two voltage followers assure that the
input impedance is over 100 MΩ. The gain of this instrumen-
tation amplifier is set by the ratio of R2/R1. R3 should equal
R1, and R4 equal R2. Matching of R3 to R1 and R4 to R2
affects the CMRR. For good CMRR over temperature, low
drift resistors should be used. Making R4 slightly smaller
than R2 and adding a trim pot equal to twice the difference
between R2 and R4 will allow the CMRR to be adjusted for
optimum.
10006013
10006020
FIGURE 10. Single-Supply Inverting Amplifier
4.4 ACTIVE FILTER
4.2.2 Two-op-amp Instrumentation Amplifier
4.4.1 Simple Low-Pass Active Filter
A two-op-amp instrumentation amplifier can also be used to
make a high-input-impedance dc differential amplifier (Fig-
ure 9) . As in the three-op-amp circuit, this instrumentation
amplifier requires precise resistor matching for good CMRR.
R4 should equal to R1 and R3 should equal R2.
The simple low-pass filter is shown in Figure 11. Its low-
→
frequency gain (ω
0) is defined by -R3/R1. This allows
low-frequency gains other than unity to be obtained. The
filter has a -20dB/decade roll-off after its corner frequency fc.
R2 should be chosen equal to the parallel combination of R1
and R3 to minimize errors due to bias current. The frequency
response of the filter is shown in Figure 12.
10006011
10006035
FIGURE 9. Two-Op-amp Instrumentation Amplifier
15
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Its transfer function is
Application Notes (Continued)
(2)
10006014
10006016
FIGURE 13. Sallen-Key 2nd-Order Active Low-Pass
Filter
10006037
The following paragraphs explain how to select values for
R1, R2, R3, R4, C1, and C 2 for given filter requirements, such
as ALP, Q, and f c.
FIGURE 11. Simple Low-Pass Active Filter
The standard form for a 2nd-order low pass filter is
(3)
where
Q: Pole Quality Factor
ωC: Corner Frequency
Comparison between the Equation (2) and Equation (3)
10006015
yields
FIGURE 12. Frequency Response of Simple Low-Pass
Active Filter in Figure 11
Note that the single-op-amp active filters are used in to the
applications that require low quality factor, Q( ≤ 10), low
frequency (≤ 5 kHz), and low gain (≤ 10), or a small value for
the product of gain times Q (≤ 100). The op amp should have
an open loop voltage gain at the highest frequency of inter-
est at least 50 times larger than the gain of the filter at this
frequency. In addition, the selected op amp should have a
slew rate that meets the following requirement:
Slew Rate ≥ 0.5 x (ω HVOPP) x 10−6 V/µsec
where ωH is the highest frequency of interest, and Vopp is the
output peak-to-peak voltage.
(4)
(5)
To reduce the required calculations in filter design, it is
convenient to introduce normalization into the components
and design parameters. To normalize, let ωC = ωn = 1rad/s,
and C1 = C2 = Cn = 1F, and substitute these values into
Equation (4) and Equation (5). From Equation (4), we obtain
4.4.2 Sallen-Key 2nd-Order Active Low-Pass Filter
The Sallen-Key 2nd-order active low-pass filter is illustrated
(6)
in Figure 13. The dc gain of the filter is expressed as
From Equation (5), we obtain
(1)
(7)
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An adjustment to the scaling may be made in order to have
realistic values for resistors and capacitors. The actual value
used for each component is shown in the circuit.
Application Notes (Continued)
For minimum dc offset, V+ = V−, the resistor values at both
inverting and non-inverting inputs should be equal, which
means
4.4.3 2nd-order High Pass Filter
A 2nd-order high pass filter can be built by simply inter-
changing those frequency selective components (R1, R
,
2
C1, C2) in the Sallen-Key 2nd-order active low pass filter. As
shown in Figure 14, resistors become capacitors, and ca-
pacitors become resistors. The resulted high pass filter has
the same corner frequency and the same maximum gain as
the previous 2nd-order low pass filter if the same compo-
nents are chosen.
(8)
From Equation (1) and Equation (8), we obtain
(9)
(10)
The values of C1 and C2 are normally close to or equal to
As a design example:
Require: ALP = 2, Q = 1, fc = 1KHz
Start by selecting C1 and C2. Choose a standard value that
is close to
10006083
FIGURE 14. Sallen-Key 2nd-Order Active High-Pass
Filter
From Equations (6), (7), (9), (10),
R1= 1Ω
R2= 1Ω
R3= 4Ω
R4= 4Ω
4.4.4 State Variable Filter
A state variable filter requires three op amps. One conve-
nient way to build state variable filters is with a quad op amp,
such as the LMV324 (Figure 15).
The above resistor values are normalized values with ωn =
1rad/s and C1 = C2 = Cn = 1F. To scale the normalized cut-off
frequency and resistances to the real values, two scaling
factors are introduced, frequency scaling factor (kf) and im-
pedance scaling factor (km).
This circuit can simultaneously represent a low-pass filter,
high-pass filter, and bandpass filter at three different outputs.
The equations for these functions are listed below. It is also
called "Bi-Quad" active filter as it can produce a transfer
function which is quadratic in both numerator and
denominator.
Scaled values:
R2 = R1 = 15.9 kΩ
R3 = R4 = 63.6 kΩ
C1 = C2 = 0.01 µF
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Application Notes (Continued)
10006039
FIGURE 15. State Variable Active Filter
A design example for a bandpass filter is shown below:
Assume the system design requires a bandpass filter with f O
= 1kHz and Q = 50. What needs to be calculated are
capacitor and resistor values.
First choose convenient values for C1, R1 and R2:
C1 = 1200pF
2R2 = R1 = 30kΩ
Then from Equation (11),
From Equation (12),
where for all three filters,
(11)
(12)
From the above calculated values, the midband gain is H 0
R3/R2 = 100 (40dB). The nearest 5% standard values have
been added to Figure 15.
=
4.5 PULSE GENERATORS AND OSCILLATORS
A pulse generator is shown in Figure 16. Two diodes have
been used to separate the charge and discharge paths to
capacitor C.
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Application Notes (Continued)
10006081
FIGURE 16. Pulse Generator
10006086
When the output voltage VO is first at its high, VOH, the
capacitor C is charged toward VOH through R2. The voltage
across C rises exponentially with a time constant τ = R2C,
and this voltage is applied to the inverting input of the op
amp. Meanwhile, the voltage at the non-inverting input is set
at the positive threshold voltage (VTH+) of the generator. The
FIGURE 17. Waveforms of the Circuit in Figure 16
As shown in the waveforms in Figure 17, the pulse width (T1)
is set by R2, C and VOH, and the time between pulses (T2) is
set by R 1, C and VOL. This pulse generator can be made to
have different frequencies and pulse width by selecting dif-
ferent capacitor value and resistor values.
capacitor voltage continually increases until it reaches VTH+
,
at which point the output of the generator will switch to its
low, VOL (= 0V in this case). The voltage at the non-inverting
input is switched to the negative threshold voltage (VTH-) of
the generator. The capacitor then starts to discharge toward
VOL exponentially through R1, with a time constant τ = R1C.
When the capacitor voltage reaches VTH-, the output of the
pulse generator switches to V OH. The capacitor starts to
charge, and the cycle repeats itself.
Figure 18 shows another pulse generator, with separate
charge and discharge paths. The capacitor is charged
through R1 and is discharged through R2.
10006077
FIGURE 18. Pulse Generator
Figure 19 is a squarewave generator with the same path for
charging and discharging the capacitor.
19
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Application Notes (Continued)
4.6.2 High Compliance Current Sink
A current sink circuit is shown in Figure 21. The circuit
requires only one resistor (RE) and supplies an output cur-
rent which is directly proportional to this resistor value.
10006076
FIGURE 19. Squarewave Generator
4.6 CURRENT SOURCE AND SINK
10006082
FIGURE 21. High Compliance Current Sink
The LMV321/358/324 can be used in feedback loops which
regulate the current in external PNP transistors to provide
current sources or in external NPN transistors to provide
current sinks.
4.7 POWER AMPLIFIER
A power amplifier is illustrated in Figure 22. This circuit can
provide a higher output current because a transistor follower
is added to the output of the op amp.
4.6.1 Fixed Current Source
A multiple fixed current source is show in Figure 20. A
voltage (VREF = 2V) is established across resistor R3 by the
voltage divider (R3 and R ). Negative feedback is used to
4
cause the voltage drop across R 1 to be equal to VREF. This
controls the emitter current of transistor Q1 and if we neglect
the base current of Q1 and Q2, essentially this same current
is available out of the collector of Q1.
Large input resistors can be used to reduce current loss and
a Darlington connection can be used to reduce errors due to
the β of Q1.
The resistor, R2, can be used to scale the collector current of
Q2 either above or below the 1mA reference value.
10006079
FIGURE 22. Power Amplifier
4.8 LED DRIVER
The LMV321/358/324 can be used to drive an LED as shown
in Figure 23.
10006084
10006080
FIGURE 20. Fixed Current Source
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FIGURE 23. LED Driver
20
The differential voltage at the input of the op amp should not
exceed the specified absolute maximum ratings. For real
comparators that are much faster, we recommend you to use
National’s LMV331/393/339, which are single, dual and quad
general purpose comparators for low voltage operation.
Application Notes (Continued)
4.9 COMPARATOR WITH HYSTERESIS
The LMV321/358/324 can be used as a low power compara-
tor. Figure 24 shows a comparator with hysteresis. The
hysteresis is determined by the ratio of the two resistors.
VTH+ = VREF/(1+R 1/R2)+VOH/(1+R2/R1)
VTH− = VREF/(1+R 1/R2)+VOL/(1+R2/R1)
VH = (VOH−VOL)/(1+R 2/R1)
where
VTH+: Positive Threshold Voltage
VTH−: Negative Threshold Voltage
VOH: Output Voltage at High
V
OL: Output Voltage at Low
10006078
VH: Hysteresis Voltage
FIGURE 24. Comparator with Hysteresis
Since LMV321/358/324 have rail-to-rail output, the
(VOH−VOL) equals to VS, which is the supply voltage.
VH = VS/(1+R2/R 1)
Connection Diagrams
5-Pin SC70-5/SOT23-5
8-Pin SO/MSOP
14-Pin SO/TSSOP
10006001
Top View
10006002
Top View
10006003
Top View
Ordering Information
Temperature Range
Package
5-Pin SC70-5
Industrial
−40˚C to +85˚C
LMV321M7
LMV321M7X
LMV321M5
LMV321M5X
LMV358M
Packaging Marking
Transport Media
NSC Drawing
MAA05
A12
A12
1k Units Tape and Reel
3k Units Tape and Reel
1k Units Tape and Reel
3k Units Tape and Reel
Rails
5-Pin SOT23-5
8-Pin Small Outline
8-Pin MSOP
A13
MA05B
A13
LMV358M
LMV358M
LMV358
LMV358
LMV324M
LMV324M
LMV324MT
LMV324MT
M08A
MUA08A
M14A
LMV358MX
LMV358MM
LMV358MMX
LMV324M
2.5k Units Tape and Reel
1k Units Tape and Reel
3.5k Units Tape and Reel
Rails
14-Pin Small Outline
14-Pin TSSOP
LMV324MX
LMV324MT
LMV324MTX
2.5k Units Tape and Reel
Rails
MTC14
2.5k Units Tape and Reel
21
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SC70-5 Tape and Reel
Specification
100060B3
SOT-23-5 Tape and Reel
Specification
TAPE FORMAT
#
Tape Section
Leader
Cavities
Cavity Status
Empty
Cover Tape Status
Sealed
0 (min)
(Start End)
Carrier
75 (min)
3000
Empty
Sealed
Filled
Sealed
250
Filled
Sealed
Trailer
125 (min)
0 (min)
Empty
Sealed
(Hub End)
Empty
Sealed
TAPE DIMENSIONS
100060B1
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22
SOT-23-5 Tape and Reel Specification (Continued)
8 mm
0.130
(3.3)
0.124
(3.15)
0.130
(3.3)
0.126
(3.2)
0.138 0.002
(3.5 0.05)
DIM F
0.055 0.004
(1.4 0.11)
DIM Ko
0.157
(4)
0.315 0.012
(8 0.3)
Tape Size
DIM A
DIM Ao
DIM B
DIM Bo
DIM P1
DIM W
REEL DIMENSIONS
100060B2
8 mm
7.00 0.059 0.512 0.795 2.165 0.331 + 0.059/−0.000 0.567
W1+ 0.078/−0.039
W1 + 2.00/−1.00
W3
330.00 1.50 13.00 20.20 55.00
8.40 + 1.50/−0.00
14.40
Tape Size
A
B
C
D
N
W1
W2
23
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Physical Dimensions inches (millimeters)
unless otherwise noted
5-Pin SC70-5
NS Package Number MAA05A
5-Pin SOT23-5
NS Package Number MA05B
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24
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
8-Pin SOIC
NS Package Number M08A
8-Pin MSOPNS Package Number MUA08A
25
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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
14-Pin SOIC
NS Package Number M14A
14-Pin TSSOPNS Package Number MTC14
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26
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
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.
National Semiconductor
Americas Customer
Support Center
National Semiconductor
Europe Customer Support Center
Fax: +49 (0) 180-530 85 86
National Semiconductor
Asia Pacific Customer
Support Center
National Semiconductor
Japan Customer Support Center
Fax: 81-3-5639-7507
Email: new.feedback@nsc.com
Tel: 1-800-272-9959
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
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Email: ap.support@nsc.com
Email: jpn.feedback@nsc.com
Tel: 81-3-5639-7560
www.national.com
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.
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