LM321
LM321 Low Power Single Op Amp
Literature Number: SNOS935A
LM321
Low Power Single Op Amp
General Description
The LM321 brings performance and economy to low power
systems. With a high unity gain frequency and a guaranteed
0.4V/µs slew rate, the quiescent current is only
430µA/amplifier (5V). The input common mode range in-
cludes ground and therefore the device is able to operate in
single supply applications as well as in dual supply applica-
tions. It is also capable of comfortably driving large capaci-
tive loads.
The LM321 is available in the SOT23-5 package. Overall the
LM321 is a low power, wide supply range performance op
amp that can be designed into a wide range of applications
at an economical price without sacrificing valuable board
space.
Features
(V
CC
=5V,T
A
= 25˚C. Typical values unless specified).
nGain-Bandwidth product 1MHz
nLow supply current 430µA
nLow input bias current 45nA
nWide supply voltage range +3V to +32V
nStable with high capacitive loads
nSingle version of LM324
Applications
nChargers
nPower supplies
nIndustrial: controls, instruments
nDesktops
nCommunications infrastructure
Connection Diagram
SOT23-5
20007601
Top View
Application Circuit
DC Summing Amplifier
(V
IN’s
0V
DC
and V
O
V
DC
)
20007607
Where: V0=V
1+V
2-V
3-V
4
,(V
1
+V
2
)(V3+V
4
) to keep VO>0V
DC
Ordering Information
Package Part Number Package Marking Transport Media NSC Drawing
5-Pin SOT-23 LM321MF A63A 1k Units Tape and Reel MF05A
LM321MFX 3k Units Tape and Reel
April 2001
LM321 Low Power Single Op Amp
© 2001 National Semiconductor Corporation DS200076 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.
Differential Input Voltage ±Supply Voltage
Input Current (V
IN
<−0.3V) (Note 6) 50mA
Supply Voltage (V
+
-V
) 32V
Input Voltage −0.3V to +32V
Output Short Circuit to GND,
V
+
15V and T
A
= 25˚C (Note 2) Continuous
Storage Temperature Range −65˚C to 150˚C
Junction Temperature (Note 3) 150˚C
Mounting Temperature
Lead Temp (Soldering, 10 sec) 260˚C
Infrared (10 sec) 215˚C
Thermal Resistance to Ambient (θ
JA
) 265˚C/W
ESD Tolerance (Note 10) 300V
Operating Ratings (Note 1)
Temperature Range −40˚C to 85˚C
Supply Voltage 3V to 30V
Electrical Characteristics Unless otherwise specified, all limits guaranteed for at T
A
= 25˚C; V
+
= 5V, V
=
0V, V
O
= 1.4V. Boldface limits apply at temperature extremes.
Symbol Parameter Conditions Min
(Note 5) Typ
(Note 4) Max
(Note 5) Units
V
OS
Input Offset Voltage (Note 7) 2 7
9mV
I
OS
Input Offset Current 5 50
150 nA
I
B
Input Bias Current (Note 8) 45 250
500 nA
V
CM
Input Common-Mode Voltage Range V
+
= 30V (Note 9)
For CMRR >= 50dB 0V
+
- 1.5
V
+
-2 V
A
V
Large Signal Voltage Gain (V
+
= 15V, R
L
=2k
V
O
= 1.4V to 11.4V) 25
15 100 V/mV
PSRR Power Supply Rejection Ratio R
S
10k,
V
+
5V to 30V 65 100 dB
CMRR Common Mode Rejection Ratio R
S
10k65 85 dB
V
O
Output Swing V
OH
V
+
= 30V, R
L
=2k26 V
V
+
= 30V, R
L
= 10k27 28
V
OL
V
+
= 5V, R
L
= 10k520mV
I
S
Supply Current, No Load V
+
= 5V 0.430
0.7 1.15
1.2 mA
V
+
= 30V 0.660
1.5 2.85
3
I
SOURCE
Output Current Sourcing V
ID
= +1V, V
+
= 15V,
V
O
=2V 20
10 40
20 mA
I
SINK
Output Current Sinking V
ID
= −1V
V
+
= 15V, V
O
=2V 10
520
8mA
V
ID
= −1V
V
+
= 15V, V
O
= 0.2V 12 100 µA
I
O
Output Short Circuit to Ground
(Note 2) V
+
= 15V 40 85 mA
SR Slew Rate V
+
= 15V, R
L
=2k,
V
IN
= 0.5 to 3V
C
L
= 100pF, Unity Gain 0.4 V/µs
GBW Gain Bandwidth Product V
+
= 30V, f = 100kHz,
V
IN
= 10mV, R
L
=2k,
C
L
= 100pF 1 MHz
φm Phase Margin 60 deg
LM321
www.national.com 2
Electrical Characteristics Unless otherwise specified, all limits guaranteed for at T
A
= 25˚C; V
+
= 5V, V
=
0V, V
O
= 1.4V. Boldface limits apply at temperature extremes. (Continued)
Symbol Parameter Conditions Min
(Note 5) Typ
(Note 4) Max
(Note 5) Units
THD Total Harmonic Distortion f = 1kHz, A
V
= 20dB
R
L
=2k,V
O
=2V
PP
,
C
L
= 100pF, V
+
= 30V 0.015 %
e
n
Equivalent Input Noise Voltage f = 1kHz, R
S
= 100
V
+
= 30V 40 nV/
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: Short circuits from the output V+can cause excessive heating and eventual destruction. When considering short circuits to ground the maximum output
current is approximately 40mA independent of the magnitude of V+. At values of supply voltage in excess of +15V, continuous short circuits can exceed the power
dissipation ratings and cause eventual destruction.
Note 3: 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 onto a PC board.
Note 4: Typical values represent the most likely parametric norm.
Note 5: All limits are guaranteed by testing or statistical analysis.
Note 6: This input current will only exist when the voltage at any of the input leads is driven negative. It is due to the collector base junction of the input PNP
transistors becoming forward biased and thereby acting as input diode clamps. In addition to this diode action, there is also lateral NPN parasitic transistor action
on the IC chip. This transistor action can cause the output voltages of the op amps to go to the V+voltage level (or to ground for a large overdrive) for the time
duration that an input is driven negative. This is not destructive and normal output states will re-establish when the input voltage, which was negative, again returns
to a value greater than −0.36V (at 25˚C).
Note 7: VO1.4V, RS=0with V+from 5V to 30V; and over the full input common-mode range (0V to V+- 1.5V) at 25˚C.
Note 8: The direction of the input current is out of the IC due to the PNP input stage. This current is essentially constant, independent of the state of the outputso
no loading change exists on the input lines.
Note 9: The input common-mode voltage of either input signal voltage should not be allowed to go negative by more than 0.3V (at 25˚C). The upper end of the
common-mode voltage range is V+- 1.5V at 25˚C, but either or both inputs can go to +32V without damage, independent of the magnitude of V+.
Note 10: Human Body Model, 1.5kin series with 100pF.
Simplified Schematic
20007603
LM321
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Typical Performance Characteristics Unless otherwise specified, V
S
= +5V, single supply,
T
A
= 25˚C.
Small Signal Pulse Response Large Signal Pulse Response
20007604
20007605
Supply Current vs. Supply Voltage Sinking Current vs. Output Voltage
20007612 20007613
Source Current vs. Output Voltage Open Loop Frequency Response
20007617 20007614
LM321
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Application Hints
The LM321 op amp can operate with a single or dual power
supply voltage, has true-differential inputs, and remain in the
linear mode with an input common-mode voltage of 0 V
DC
.
This amplifier operates over a wide range of power supply
voltages, with little change in performance characteristics.At
25˚C amplifier operation is possible down to a minimum
supply voltage of 3V.
Large differential input voltages can be easily accommo-
dated and, as input differential voltage protection diodes are
not needed, no large input currents result from large differ-
ential input voltages. The differential input voltage may be
larger than V
+
without damaging the device. Protection
should be provided to prevent the input voltages from going
negative more than −0.3 V
DC
(at 25˚C).An input clamp diode
with a resistor to the IC input terminal can be used.
To reduce the power supply drain, the amplifier has a class A
output stage for small signal levels which converts to class B
in a large signal mode. This allows the amplifiers to both
source and sink large output currents. Therefore both NPN
and PNP external current boost transistors can be used to
extend the power capability of the basic amplifiers. The
output voltage needs to raise approximately 1 diode drop
above ground to bias the on-chip vertical PNP transistor for
output current sinking applications.
For AC applications, where the load is capacitively coupled
to the output of the amplifier, a resistor should be used, from
the output of the amplifier to ground to increase the class A
bias current and to reduce distortion.
Capacitive loads which are applied directly to the output of
the amplifier reduce the loop stability margin. Values of 50pF
can be accommodated using the worst-case non-inverting
unity gain connection. Large closed loop gains or resistive
isolation should be used if large load capacitance must be
driven by the amplifier.
The bias network of the LM321 establishes a supply current
which is independent of the magnitude of the power supply
voltage over the range of from 3 V
DC
to 30 V
DC
.
Output short circuits either to ground or to the positive power
supply should be of short time duration. Units can be de-
stroyed, not as a result of the short circuit current causing
metal fusing, but rather due to the large increase in IC chip
dissipation which will cause eventual failure due to exces-
sive junction temperatures. The larger value of output source
current which is available at 25˚C provides a larger output
current capability at elevated temperatures than a standard
IC op amp.
The circuits presented in the section on typical applications
emphasize operation on only a single power supply voltage.
If complementary power supplies are available, all of the
standard op amp circuits can be used. In general, introduc-
ing a pseudo-ground (a bias voltage reference of V
+
/2) will
allow operation above and below this value in single power
supply systems. Many application circuits are shown which
take advantage of the wide input common-mode voltage
range which includes ground. In most cases, input biasing is
not required and input voltages which range to ground can
easily be accommodated.
Typical Applications
Non-Inverting DC Gain (0V Input = 0V Output)
20007606
LM321
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Typical Applications (Continued)
Amplitude Modulator Circuit DC Summing Amplifier
(V
IN’s
0V
DC
and V
O
V
DC
)
20007602
20007607
Where: V0=V
1+V
2-V
3-V
4
,(V
1
+V
2
)(V3+V
4
) to keep VO>0V
DC
Power Amplifier LED Driver
20007608
V0=0V
DC for VIN =0V
DC,A
V=10
20007609
Fixed Current Sources Lamp Driver
20007610
20007611
LM321
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SOT23-5 Tape and Reel Specification
TAPE DIMENSIONS
20007615
8mm 0.130
(3.3) 0.124
(3.15) 0.130
(3.3) 0.126
(3.2) 0.138 ±0.002
(3.5 ±0.05) 0.055 ±0.004
(1.4 ±0.11) 0.157
(4) 0.315 ±0.012
(8 ±0.3)
Tape Size DIM A DIM Ao DIM B DIM Bo DIM F DIM Ko DIM P1 DIM W
LM321
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SOT23-5 Tape and Reel Specification (Continued)
REEL DIMENSIONS
20007616
8mm 7.00
330.00 0.059
1.50 0.512
13.00 0.795
20.20 2.165
55.00 0.331 + 0.059/−0.000
8.40 + 1.50/−0.00 0.567
14.40 W1 + 0.078/−0.039
W1 + 2.00/−1.00
Tape Size A B C D N W1 W2 W3
LM321
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Physical Dimensions inches (millimeters) unless otherwise noted
5-Pin SOT23
NS Package Number MF05A
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www.national.com
LM321 Low Power Single Op Amp
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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