LM7321/LM7321Q Single/
LM7322/LM7322Q Dual Rail-
to-Rail Input/Output
January 5, 2012
±15V, High Output Current and Unlimited Capacitive Load
Operational Amplifier
General Description
The LM7321/LM7321Q/LM7322/LM7322Q are rail-to-rail in-
put and output amplifiers with wide operating voltages and
high output currents. The LM7321/LM7321Q/LM7322/
LM7322Q are efficient, achieving 18 V/µs slew rate and 20
MHz unity gain bandwidth while requiring only 1 mA of supply
current per op amp. The LM7321/LM7321Q/LM7322/
LM7322Q performance is fully specified for operation at 2.7V,
±5V and ±15V.
The LM7321/LM7321Q/LM7322/LM7322Q are designed to
drive unlimited capacitive loads without oscillations. All
LM7321/LM7321Q and LM7322/LM732Q parts are tested at
−40°C, 125°C, and 25°C, with modern automatic test equip-
ment. High performance from −40°C to 125°C, detailed spec-
ifications, and extensive testing makes them suitable for
industrial, automotive, and communications applications.
Greater than rail-to-rail input common mode voltage range
with 50 dB of common mode rejection across this wide voltage
range, allows both high side and low side sensing. Most de-
vice parameters are insensitive to power supply voltage, and
this makes the parts easier to use where supply voltage may
vary, such as automotive electrical systems and battery pow-
ered equipment. These amplifiers have true rail-to-rail output
and can supply a respectable amount of current (15 mA) with
minimal head- room from either rail (300 mV) at low distortion
(0.05% THD+Noise). There are several package options for
each part. Standard SOIC versions of both parts make up-
grading existing designs easy. LM7322LM7322Q are offered
in a space saving 8-Pin MSOP package. The LM7321/
LM7321Q are offered in small SOT23-5 package, which
makes it easy to place this part close to sensors for better
circuit performance.
Features
(VS = ±15, TA = 25°C, Typical values unless specified.)
Wide supply voltage range 2.5V to 32V
Output current +65 mA/−100 mA
Gain bandwidth product 20 MHz
Slew rate 18 V/µs
Capacitive load tolerance Unlimited
Input common mode voltage 0.3V beyond rails
Input voltage noise 15 nV/Hz
Input current noise 1.3 pA/Hz
Supply current/channel 1.1 mA
Distortion THD+Noise −86 dB
Temperature range −40°C to 125°C
Tested at −40°C, 25°C and 125°C at 2.7V, ±5V, ±15V.
LM7321Q/LM7322Q are Automotive Grade products that
are AEC-Q100 Grade 1 qualified.
Applications
Driving MOSFETs and power transistors
Capacitive proximity sensors
Driving analog optocouplers
High side sensing
Below ground current sensing
Photodiode biasing
Driving varactor diodes in PLLs
Wide voltage range power supplies
Automotive
International power supplies
Typical Performance Characteristics
Output Swing vs. Sourcing Current
20205736
Large Signal Step Response
20205749
© 2012 Texas Instruments Incorporated 202057 SNOSAW8C www.ti.com
LM7321/LM7321Q Single/ LM7322/LM7322Q Dual Rail-to-Rail Input/Output, ±15V, High Output
Current and Unlimited Capacitive Load Operational Amplifier
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the Texas Instruments Sales Office/
Distributors for availability and specifications.
ESD Tolerance (Note 2)
Human Body Model 2 kV
Machine Model 200V
Charge-Device Model 1 kV
VIN Differential ±10V
Output Short Circuit Current (Note 3)
Supply Voltage (VS = V+ - V)35V
Voltage at Input/Output pins V+ +0.8V, V −0.8V
Storage Temperature Range −65°C to 150°C
Junction Temperature (Note 4) 150°C
Soldering Information:
Infrared or Convection (20 sec.) 235°C
Wave Soldering (10 sec.) 260°C
Operating Ratings
Supply Voltage (VS = V+ - V)2.5V to 32V
Temperature Range (Note 4) −40°C to 125°C
Package Thermal Resistance, θJA,(Note 4)
5-Pin SOT-23 325°C/W
8-Pin MSOP 235°C/W
8-Pin SOIC 165°C/W
2.7V Electrical Characteristics (Note 5)
Unless otherwise specified, all limits guaranteed for TA = 25°C, V+ = 2.7V, V = 0V, VCM = 0.5V, VOUT = 1.35V, and
RL > 1 M to 1.35V. Boldface limits apply at the temperature extremes.
Symbol Parameter Condition Min
(Note 7)
Typ
(Note 6)
Max
(Note 7)Units
VOS Input Offset Voltage VCM = 0.5V & VCM = 2.2V −5
−6 ±0.7 +5
+6 mV
TC VOS Input Offset Voltage Temperature Drift VCM = 0.5V & VCM = 2.2V
(Note 8) ±2 µV/C
IBInput Bias Current
VCM = 0.5V
(Note 9)
−2.0
−2.5
−1.2
µA
VCM = 2.2V
(Note 9)
0.45 1.0
1.5
IOS Input Offset Current VCM = 0.5V and VCM = 2.2V 20 200
300 nA
CMRR Common Mode Rejection Ratio
0V VCM 1.0V 70
60
100
dB
0V VCM 2.7V 55
50
70
PSRR Power Supply Rejection Ratio 2.7V VS 30V 78
74
104 dB
CMVR Common Mode Voltage Range CMRR > 50 dB
−0.3 −0.1
0.0 V
2.8
2.7
3.0
AVOL Open Loop Voltage Gain
0.5V VO 2.2V
RL = 10 k to 1.35V
65
62
72
dB
0.5V VO 2.2V
RL = 2 k to 1.35V
59
55
66
VOUT
Output Voltage Swing
High
RL = 10 k to 1.35V
VID = 100 mV
50 150
160
mV from
either rail
RL = 2 k to 1.35V
VID = 100 mV
100 250
280
Output Voltage Swing
Low
RL = 10 k to 1.35V
VID = −100 mV
20 120
150
RL = 2 k to 1.35V
VID = −100 mV
40 120
150
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LM7321/LM7321Q/LM7322/LM7322Q
Symbol Parameter Condition Min
(Note 7)
Typ
(Note 6)
Max
(Note 7)Units
IOUT Output Current
Sourcing
VID = 200 mV, VOUT = 0V (Note 3)
30
20
48
mA
Sinking
VID = −200 mV, VOUT = 2.7V (Note 3)
40
30
65
ISSupply Current
LM7321 0.95 1.3
1.9 mA
LM7322 2.0 2.5
3.8
SR Slew Rate (Note 10) AV = +1, VI = 2V Step 8.5 V/µs
fuUnity Gain Frequency RL = 2 k, CL = 20 pF 7.5 MHz
GBW Gain Bandwidth f = 50 kHz 16 MHz
enInput Referred Voltage Noise Density f = 2 kHz 11.9 nV/
inInput Referred Current Noise Density f = 2 kHz 0.5 pA/
THD+N Total Harmonic Distortion + Noise
V+ = 1.9V, V = −0.8V
f = 1 kHz, RL = 100 k, AV = +2
VOUT = 210 mVPP
−77 dB
CT Rej. Crosstalk Rejection f = 100 kHz, Driver RL = 10 k 60 dB
±5V Electrical Characteristics (Note 5)
Unless otherwise specified, all limited guaranteed for TA = 25°C, V+ = 5V, V = −5V, VCM = 0V, VOUT = 0V, and
RL > 1 M to 0V. Boldface limits apply at the temperature extremes.
Symbol Parameter Condition Min
(Note 7)
Typ
(Note 6)
Max
(Note 7)Units
VOS Input Offset Voltage VCM = −4.5V and VCM = 4.5V −5
−6
±0.7 +5
+6 mV
TC VOS Input Offset Voltage Temperature Drift VCM = −4.5V and VCM = 4.5V
(Note 8) ±2 µV/°C
IBInput Bias Current
VCM = −4.5V
(Note 9)
−2.0
−2.5
−1.2
µA
VCM = 4.5V
(Note 9)
0.45 1.0
1.5
IOS Input Offset Current VCM = −4.5V and VCM = 4.5V 20 200
300 nA
CMRR Common Mode Rejection Ratio
−5V VCM 3V 80
70
100
dB
−5V VCM 5V 65
62
80
PSRR Power Supply Rejection Ratio 2.7V VS 30V, VCM = −4.5V 78
74
104 dB
CMVR Common Mode Voltage Range CMRR > 50 dB
−5.3 −5.1
−5.0 V
5.1
5.0
5.3
AVOL Open Loop Voltage Gain
−4V VO 4V
RL = 10 k to 0V
74
70
80
dB
−4V VO 4V
RL = 2 k to 0V
68
65
74
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LM7321/LM7321Q/LM7322/LM7322Q
Symbol Parameter Condition Min
(Note 7)
Typ
(Note 6)
Max
(Note 7)Units
VOUT
Output Voltage Swing
High
RL = 10 k to 0V
VID = 100 mV
100 250
280
mV from
either rail
RL = 2 k to 0V
VID = 100 mV
160 350
450
Output Voltage Swing
Low
RL = 10 k to 0V
VID = −100 mV
35 200
250
RL = 2 k to 0V
VID = −100 mV
80 200
250
IOUT Output Current
Sourcing
VID = 200 mV, VOUT = −5V (Note 3)
35
20
70
mA
Sinking
VID = −200 mV, VOUT = 5V (Note 3)
50
30
85
ISSupply Current VCM = −4.5V
LM7321 1.0 1.3
2mA
LM7322 2.3 2.8
3.8
SR Slew Rate (Note 10) AV = +1, VI = 8V Step 12.3 V/µs
fuUnity Gain Frequency RL = 2 k, CL = 20 pF 9 MHz
GBW Gain Bandwidth f = 50 kHz 16 MHz
enInput Referred Voltage Noise Density f = 2 kHz 14.3 nV/
inInput Referred Current Noise Density f = 2 kHz 1.35 pA/
THD+N Total Harmonic Distortion + Noise f = 1 kHz, RL = 100 k, AV = +2
VOUT = 8 VPP
−79 dB
CT Rej. Crosstalk Rejection f = 100 kHz, Driver RL = 10 k 60 dB
±15V Electrical Characteristics (Note 5)
Unless otherwise specified, all limited guaranteed for TA = 25°C, V+ = 15V, V = −15V, VCM = 0V, VOUT = 0V, and
RL > 1M to 15V. Boldface limits apply at the temperature extremes.
Symbol Parameter Condition Min
(Note 7)
Typ
(Note 6)
Max
(Note 7)Units
VOS Input Offset Voltage VCM = −14.5V and VCM = 14.5V −6
−8
±0.7 +6
+8 mV
TC VOS Input Offset Voltage Temperature Drift VCM = −14.5V and VCM = 14.5V
(Note 8)
±2 µV/°C
IBInput Bias Current
VCM = −14.5V
(Note 9)
−2
−2.5
−1.1
µA
VCM = 14.5V
(Note 9)
0.45 1.0
1.5
IOS Input Offset Current VCM = −14.5V and VCM = 14.5V 30 300
500 nA
CMRR Common Mode Rejection Ratio
−15V VCM 12V 80
75
100
dB
−15V VCM 15V 72
70
80
PSRR Power Supply Rejection Ratio 2.7V VS 30V, VCM = −14.5V 78
74
100 dB
CMVR Common Mode Voltage Range CMRR > 50 dB
−15.3 −15.1
−15 V
15.1
15
15.3
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LM7321/LM7321Q/LM7322/LM7322Q
Symbol Parameter Condition Min
(Note 7)
Typ
(Note 6)
Max
(Note 7)Units
AVOL Open Loop Voltage Gain
−13V VO 13V
RL = 10 k to 0V
75
70
85
dB
−13V VO 13V
RL = 2 k to 0V
70
65
78
VOUT
Output Voltage Swing
High
RL = 10 k to 0V
VID = 100 mV
150 300
350
mV from
either rail
RL = 2 k to 0V
VID = 100 mV
250 550
650
Output Voltage Swing
Low
RL = 10 k to 0V
VID = −100 mV
60 200
250
RL = 2 k to 0V
VID = −100 mV
130 300
400
IOUT Output Current
Sourcing
VID = 200 mV, VOUT = −15V (Note 3)
40 65
mA
Sinking
VID = −200 mV, VOUT = 15V (Note 3)
60 100
ISSupply Current VCM = −14.5V
LM7321 1.1 1.7
2.4 mA
LM7322 2.5 4
5.6
SR Slew Rate
(Note 10)
AV = +1, VI = 20V Step 18 V/µs
fuUnity Gain Frequency RL = 2 k, CL = 20 pF 11.3 MHz
GBW Gain Bandwidth f = 50 kHz 20 MHz
enInput Referred Voltage Noise Density f = 2 kHz 15 nV/
inInput Referred Current Noise Density f = 2 kHz 1.3 pA/
THD+N Total Harmonic Distortion +Noise f = 1 kHz, RL 100 kΩ,
AV = +2, VOUT = 23 VPP
−86 dB
CT Rej. Crosstalk Rejection f = 100 kHz, Driver RL = 10 k 60 dB
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Rating 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, applicable std. MIL-STD-883, Method 3015.7. Machine Model, applicable std. JESD22-A115-A (ESD MM std. of JEDEC)
Field-Induced Charge-Device Model, applicable std. JESD22-C101-C (ESD FICDM std. of JEDEC).
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. Short circuit test is a momentary test. Output short circuit duration is infinite for VS 6V at room temperature
and below. For VS > 6V, allowable short circuit duration is 1.5 ms.
Note 4: The maximum power dissipation is a function of TJ(MAX), θJA. The maximum allowable power dissipation at any ambient temperature is
PD = (TJ(MAX)) - TA)/ θJA. All numbers apply for packages soldered directly onto a PC board.
Note 5: 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.
Note 6: Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may vary over time and will
also depend on the application and configuration. The typical values are not tested and are not guaranteed on shipped production material.
Note 7: All limits are guaranteed by testing or statistical analysis.
Note 8: Offset voltage temperature drift determined by dividing the change in VOS at temperature extremes into the total temperature change.
Note 9: Positive current corresponds to current flowing into the device.
Note 10: Slew rate is the slower of the rising and falling slew rates. Connected as a Voltage Follower.
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LM7321/LM7321Q/LM7322/LM7322Q
Connection Diagrams
5-Pin SOT-23
20205705
Top View
8-Pin SOIC
20205703
Top View
8-Pin MSOP/SOIC
20205706
Top View
Ordering Information
Package Part Number Package
Marking Media Transport NSC Drawing
5-Pin SOT-23
LM7321MF
AU4A
1k Units Tape and Reel
MF05A
LM7321MFE 250 Units Tape and Reel
LM7321MFX 3k Units Tape and Reel
LM7321QMF
AR8A
1k Units Tape and Reel
LM7321QMFE 250 Units Tape and Reel
LM7321QMFX 3k Units Tape and Reel
8-Pin MSOP
LM7322MM
AZ4A
1k Units Tape and Reel
MUA08ALM7322MME 250 Units Tape and Reel
LM7322MMX 3.5k Units Tape and Reel
8-Pin SOIC
LM7321MA LM7321MA 95 Units/Rail
M08A
LM7321MAX 2.5k Units Tape and Reel
LM7322MA LM7322MA 95 Units/Rail
LM7322MAX 2.5k Units Tape and Reel
LM7322QMA LM7322QMA 95 Units/Rail
LM7322QMAX 2.5k Units Tape and Reel
Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including
defect detection methodologies. Reliability qualification is compliant with the requirements and temperature grades defined in the
AEC-Q100 standard. Automotive Grade products are identified with the letter Q. PPAP (Production Part Approval Process) doc-
umentation of the device technology, process and qualification is available from Texas Instruments upon request.
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LM7321/LM7321Q/LM7322/LM7322Q
Typical Performance Characteristics Unless otherwise specified: TA = 25°C.
Output Swing vs. Sourcing Current
20205734
Output Swing vs. Sinking Current
20205731
Output Swing vs. Sourcing Current
20205735
Output Swing vs. Sinking Current
20205732
Output Swing vs. Sourcing Current
20205736
Output Swing vs. Sinking Current
20205733
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LM7321/LM7321Q/LM7322/LM7322Q
VOS Distribution
20205730
VOS vs. VCM (Unit 1)
20205707
VOS vs. VCM (Unit 2)
20205708
VOS vs. VCM (Unit 3)
20205709
VOS vs. VCM (Unit 1)
20205710
VOS vs. VCM (Unit 2)
20205711
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LM7321/LM7321Q/LM7322/LM7322Q
VOS vs. VCM (Unit 2)
20205712
VOS vs. VCM (Unit 1)
20205713
VOS vs. VCM (Unit 2)
20205714
VOS vs. VCM (Unit 3)
20205715
VOS vs. VS (Unit 1)
20205750
VOS vs. VS (Unit 2)
20205751
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LM7321/LM7321Q/LM7322/LM7322Q
VOS vs. VS (Unit 3)
20205752
VOS vs. VS (Unit 1)
20205753
VOS vs. VS (Unit 2)
20205754
VOS vs. VS (Unit 3)
20205755
IBIAS vs. VCM
20205723
IBIAS vs. VCM
20205724
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LM7321/LM7321Q/LM7322/LM7322Q
IBIAS vs. VCM
20205725
IBIAS vs. VS
20205722
IBIAS vs. VS
20205721
IS vs. VCM (LM7321)
20205718
IS vs. VCM (LM7322)
20205775
IS vs. VCM (LM7321)
20205719
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LM7321/LM7321Q/LM7322/LM7322Q
IS vs. VCM (LM7322)
20205776
IS vs. VCM (LM7321)
20205720
IS vs. VCM (LM7322)
20205777
IS vs. VS (LM7321)
20205717
IS vs. VS (LM7322)
20205779
IS vs. VS (LM7321)
20205716
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LM7321/LM7321Q/LM7322/LM7322Q
IS vs. VS (LM7322)
20205778
Positive Output Swing vs. Supply Voltage
20205727
Positive Output Swing vs. Supply Voltage
20205726
Negative Output Swing vs. Supply Voltage
20205728
Negative Output Swing vs. Supply Voltage
20205729
Open Loop Frequency Response with Various Capacitive
Load
20205782
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LM7321/LM7321Q/LM7322/LM7322Q
Open Loop Frequency Response with Various Resistive
Load
20205783
Open Loop Frequency Response with Various Supply
Voltage
20205784
Phase Margin vs. Capacitive Load
20205738
CMRR vs. Frequency
20205739
+PSRR vs. Frequency
20205740
−PSRR vs. Frequency
20205741
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LM7321/LM7321Q/LM7322/LM7322Q
Small Signal Step Response
20205737
Large Signal Step Response
20205749
Input Referred Noise Density vs. Frequency
20205742
Input Referred Noise Density vs. Frequency
20205743
Input Referred Noise Density vs. Frequency
20205744
THD+N vs. Frequency
20205745
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LM7321/LM7321Q/LM7322/LM7322Q
THD+N vs. Output Amplitude
20205746
THD+N vs. Output Amplitude
20205747
THD+N vs. Output Amplitude
20205748
Crosstalk Rejection vs. Frequency
20205768
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LM7321/LM7321Q/LM7322/LM7322Q
Application Information
DRIVING CAPACITIVE LOADS
The LM7321/LM7321Q/LM7322/LM7322Q are specifically
designed to drive unlimited capacitive loads without oscilla-
tions as shown in Figure 1.
20205769
FIGURE 1. ±5% Settling Time vs. Capacitive Load
In addition, the output current handling capability of the device
allows for good slewing characteristics even with large ca-
pacitive loads as shown in Figure 2 and Figure 3.
20205770
FIGURE 2. +SR vs. Capacitive Load
20205771
FIGURE 3. −SR vs. Capacitive Load
The combination of these features is ideal for applications
such as TFT flat panel buffers, A/D converter input amplifiers,
etc.
However, as in most op amps, addition of a series isolation
resistor between the op amp and the capacitive load improves
the settling and overshoot performance.
Output current drive is an important parameter when driving
capacitive loads. This parameter will determine how fast the
output voltage can change. Referring to the Slew Rate vs.
Capacitive Load Plots (typical performance characteristics
section), two distinct regions can be identified. Below about
10,000 pF, the output Slew Rate is solely determined by the
op amp’s compensation capacitor value and available current
into that capacitor. Beyond 10 nF, the Slew Rate is deter-
mined by the op amp’s available output current. Note that
because of the lower output sourcing current compared to the
sinking one, the Slew Rate limit under heavy capacitive load-
ing is determined by the positive transitions. An estimate of
positive and negative slew rates for loads larger than 100 nF
can be made by dividing the short circuit current value by the
capacitor.
For the LM7321/LM7321Q/LM7322/LM7322Q, the available
output current increases with the input overdrive. Referring to
Figure 4 and Figure 5, Output Short Circuit Current vs. Input
Overdrive, it can be seen that both sourcing and sinking short
circuit current increase as input overdrive increases. In a
closed loop amplifier configuration, during transient condi-
tions while the fed back output has not quite caught up with
the input, there will be an overdrive imposed on the input al-
lowing more output current than would normally be available
under steady state condition. Because of this feature, the op
amp’s output stage quiescent current can be kept to a mini-
mum, thereby reducing power consumption, while enabling
the device to deliver large output current when the need arises
(such as during transients).
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LM7321/LM7321Q/LM7322/LM7322Q
20205772
FIGURE 4. Output Short Circuit Sourcing Current vs.
Input Overdrive
20205773
FIGURE 5. Output Short Circuit Sinking Current vs. Input
Overdrive
Figure 6 shows the output voltage, output current, and the
resulting input overdrive with the device set for AV = +1 and
the input tied to a 1 VPP step function driving a 47 nF capacitor.
As can be seen, during the output transition, the input over-
drive reaches 1V peak and is more than enough to cause the
output current to increase to its maximum value (see Figure
4 and Figure 5 plots). Note that because of the larger output
sinking current compared to the sourcing one, the output neg-
ative transition is faster than the positive one.
20205774
FIGURE 6. Buffer Amplifier Scope Photo
ESTIMATING THE OUTPUT VOLTAGE SWING
It is important to keep in mind that the steady state output
current will be less than the current available when there is
an input overdrive present. For steady state conditions, the
Output Voltage vs. Output Current plot (Typical Performance
Characteristics section) can be used to predict the output
swing. Figure 7 and Figure 8 show this performance along
with several load lines corresponding to loads tied between
the output and ground. In each cases, the intersection of the
device plot at the appropriate temperature with the load line
would be the typical output swing possible for that load. For
example, a 1 k load can accommodate an output swing to
within 250 mV of V and to 330 mV of V+ (VS = ±15V) corre-
sponding to a typical 29.3 VPP unclipped swing.
20205756
FIGURE 7. Output Sourcing Characteristics with Load
Lines
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LM7321/LM7321Q/LM7322/LM7322Q
20205757
FIGURE 8. Output Sinking Characteristics with Load
Lines
SETTLING TIME WITH LARGE CAPACITIVE LOADS
Figure 9 below shows a typical application where the LM7321/
LM7321Q/LM7322/LM7322Q is used as a buffer amplifier for
the VCOM signal employed in a TFT LCD flat panel:
20205758
FIGURE 9. VCOM Driver Application Schematic
Figure 10 shows the time domain response of the amplifier
when used as a VCOM buffer/driver with VREF at ground. In this
application, the op amp loop will try and maintain its output
voltage based on the voltage on its non-inverting input
(VREF) despite the current injected into the TFT simulated
load. As long as this load current is within the range tolerable
by the LM7321/LM7321Q/LM7322/LM7322Q (45 mA sourc-
ing and 65 mA sinking for ±5V supplies), the output will settle
to its final value within less than 2 μs.
20205759
FIGURE 10. VCOM Driver Performance Scope Photo
OUTPUT SHORT CIRCUIT CURRENT AND DISSIPATION
ISSUES
The LM7321/LM7321Q/LM7322/LM7322Q output stage is
designed for maximum output current capability. Even though
momentary output shorts to ground and either supply can be
tolerated at all operating voltages, longer lasting short condi-
tions can cause the junction temperature to rise beyond the
absolute maximum rating of the device, especially at higher
supply voltage conditions. Below supply voltage of 6V, the
output short circuit condition can be tolerated indefinitely.
With the op amp tied to a load, the device power dissipation
consists of the quiescent power due to the supply current flow
into the device, in addition to power dissipation due to the load
current. The load portion of the power itself could include an
average value (due to a DC load current) and an AC compo-
nent. DC load current would flow if there is an output voltage
offset, or the output AC average current is non-zero, or if the
op amp operates in a single supply application where the out-
put is maintained somewhere in the range of linear operation.
Therefore:
PTOTAL = PQ + PDC + PAC
PQ = IS · VSOp Amp Quiescent Power
Dissipation
PDC = IO · (Vr - Vo) DC Load Power
PAC = See Table 1 below AC Load Power
where:
IS: Supply Current
VS: Total Supply Voltage (V+ − V)
VO: Average Output Voltage
Vr: V+ for sourcing and V for sinking current
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LM7321/LM7321Q/LM7322/LM7322Q
Table 1 below shows the maximum AC component of the load
power dissipated by the op amp for standard Sinusoidal, Tri-
angular, and Square Waveforms:
TABLE 1. Normalized AC Power Dissipated in the Output
Stage for Standard Waveforms
PAC (W./V2)
Sinusoidal Triangular Square
50.7 x 10−3 46.9 x 10−3 62.5 x 10−3
The table entries are normalized to VS2/RL. To figure out the
AC load current component of power dissipation, simply mul-
tiply the table entry corresponding to the output waveform by
the factor VS2/RL. For example, with ±12V supplies, a 600
load, and triangular waveform power dissipation in the output
stage is calculated as:
PAC = (46.9 x 10−3) · (242/600) = 45.0 mW
The maximum power dissipation allowed at a certain temper-
ature is a function of maximum die junction temperature (TJ
(MAX)) allowed, ambient temperature TA, and package thermal
resistance from junction to ambient, θJA.
For the LM7321/LM7321Q/LM7322/LM7322Q, the maximum
junction temperature allowed is 150°C at which no power dis-
sipation is allowed. The power capability at 25°C is given by
the following calculations:
For MSOP package:
For SOIC package:
Similarly, the power capability at 125°C is given by:
For MSOP package:
For SOIC package:
Figure 11 shows the power capability vs. temperature for
MSOP and SOIC packages. The area under the maximum
thermal capability line is the operating area for the device.
When the device works in the operating area where PTOTAL is
less than PD(MAX), the device junction temperature will remain
below 150°C. If the intersection of ambient temperature and
package power is above the maximum thermal capability line,
the junction temperature will exceed 150°C and this should
be strictly prohibited.
20205765
FIGURE 11. Power Capability vs. Temperature
When high power is required and ambient temperature can't
be reduced, providing air flow is an effective approach to re-
duce thermal resistance therefore to improve power capabil-
ity.
Other Application Hints
The use of supply decoupling is mandatory in most applica-
tions. As with most relatively high speed/high output current
Op Amps, best results are achieved when each supply line is
decoupled with two capacitors; a small value ceramic capac-
itor (0.01 μF) placed very close to the supply lead in addition
to a large value Tantalum or Aluminum (> 4.7 μF). The large
capacitor can be shared by more than one device if neces-
sary. The small ceramic capacitor maintains low supply
impedance at high frequencies while the large capacitor will
act as the charge "bucket" for fast load current spikes at the
op amp output. The combination of these capacitors will pro-
vide supply decoupling and will help keep the op amp oscil-
lation free under any load.
SIMILAR HIGH OUTPUT DEVICES
The LM7332 is a dual rail-to-rail amplifier with a slightly lower
GBW capable of sinking and sourcing 100 mA. It is available
in SOIC and MSOP packages.
The LM4562 is dual op amp with very low noise and 0.7 mV
voltage offset.
The LME49870 and LME49860 are single and dual low noise
amplifiers that can work from ±22 volt supplies.
OTHER HIGH PERFORMANCE SOT-23 AMPLIERS
The LM7341 is a 4 MHz rail-to-rail input and output part that
requires only 0.6 mA to operate, and can drive unlimited ca-
pacitive load. It has a voltage gain of 97 dB, a CMRR of 93
dB, and a PSRR of 104 dB.
The LM6211 is a 20 MHz part with CMOS input, which runs
on ±12 volt or 24 volt single supplies. It has rail-to-rail output
and low noise.
The LM7121 has a gain bandwidth of 235 MHz.
Detailed information on these parts can be found at
www.national.com.
www.ti.com 20
LM7321/LM7321Q/LM7322/LM7322Q
Physical Dimensions inches (millimeters) unless otherwise noted
5-Pin SOT-23
NS Package Number MF05A
8-Pin MSOP
NS Package Number MUA08A
21 www.ti.com
LM7321/LM7321Q/LM7322/LM7322Q
8-Pin SOIC
NS Package Number M08A
www.ti.com 22
LM7321/LM7321Q/LM7322/LM7322Q
Notes
23 www.ti.com
LM7321/LM7321Q/LM7322/LM7322Q
Notes
LM7321/LM7321Q Single/ LM7322/LM7322Q Dual Rail-to-Rail Input/Output, ±15V, High Output
Current and Unlimited Capacitive Load Operational Amplifier
www.ti.com
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