National Semiconductor LM7321 Technical data

September 5, 2008

LM7321 Single/ LM7322 Dual Rail-to-Rail Input/Output
±15V, High Output Current and Unlimited Capacitive Load
Operational Amplifier

LM7321 Single/ LM7322 Dual Rail-to-Rail Input/Output, ±15V, High Output Current and Unlimited

Capacitive Load Operational Amplifier

General Description

The LM7321/LM7322 are rail-to-rail input and output ampli­fiers with wide operating voltages and high output currents.
The LM7321/LM7322 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/LM7322 per­formance is fully specified for operation at 2.7V, ±5V and
±15V.

The LM7321/LM7322 are designed to drive unlimited capac­itive loads without oscillations. All LM7321 and LM7322 parts
are tested at −40°C, 125°C, and 25°C, with modern automatic
test equipment. High performance from −40°C to 125°C, de­tailed specifications, 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 de­vice 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 pow­ered 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 up­grading existing designs easy. LM7322 is offered in a space
saving 8-Pin MSOP package. The LM7321 is 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.

■

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

© 2008 National Semiconductor Corporation 202057 www.national.com

Large Signal Step Response

20205749

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

ESD Tolerance (Note 2)

LM7321/LM7322

Human Body Model 2 kV
Machine Model 200V
Charge-Device Model 1 kV
VIN Differential

Output Short Circuit Current (Note 3)
Supply Voltage (VS = V+ - V−)

Voltage at Input/Output pins V+ +0.8V, V− −0.8V

Storage Temperature Range −65°C to 150°C

±10V

35V

Junction Temperature (Note 4) 150°C
Soldering Information:

Infrared or Convection (20 sec.)
 Wave Soldering (10 sec.)

Operating Ratings

Supply Voltage (VS = V+ - V−)

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, V
RL > 1 MΩ to 1.35V. Boldface limits apply at the temperature extremes.

Symbol Parameter Condition Min

(Note 7)

V

OS

TC V

I

B

I

OS

CMRR Common Mode Rejection Ratio

PSRR Power Supply Rejection Ratio

CMVR Common Mode Voltage Range CMRR > 50 dB −0.3 −0.1

A

VOL

V

OUT

Input Offset Voltage VCM = 0.5V & VCM = 2.2V −5

−6

Input Offset Voltage Temperature Drift VCM = 0.5V & VCM = 2.2V

OS

Input Bias Current VCM = 0.5V

Input Offset Current VCM = 0.5V and VCM = 2.2V 20 200

Open Loop Voltage Gain

Output Voltage Swing
High

Output Voltage Swing
Low

(Note 8)

(Note 9)

VCM = 2.2V
(Note 9)

0V ≤ VCM ≤ 1.0V

0V ≤ VCM ≤ 2.7V

2.7V ≤ VS ≤ 30V

0.5V ≤ VO ≤ 2.2V

RL = 10 kΩ to 1.35V

0.5V ≤ VO ≤ 2.2V

RL = 2 kΩ to 1.35V

RL = 10 kΩ to 1.35V
VID = 100 mV

RL = 2 kΩ to 1.35V
VID = 100 mV

RL = 10 kΩ to 1.35V
VID = −100 mV

RL = 2 kΩ to 1.35V
VID = −100 mV

−2.0

−2.5

70

60

55

50

78

74

2.8

2.7

65

62

59

55

= 1.35V, and

OUT

Typ

(Note 6)

±0.7 +5

±2 µV/C

−1.2

0.45 1.0

100

70

104

3.0

72

66

50 150

100 250

20 120

40 120

2.5V to 32V

Max

(Note 7)

+6

1.5

300

0.0

160

280

150

150

235°C

260°C

Units

mV

µA

nA

dB

dB

V

dB

mV from

either rail

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LM7321/LM7322

Symbol Parameter Condition Min

(Note 7)

I

OUT

Output Current Sourcing

VID = 200 mV, V

= 0V (Note 3)

OUT

Sinking
VID = −200 mV, V

I

S

Supply Current LM7321 0.95 1.3

= 2.7V (Note 3)

OUT

LM7322 2.0 2.5

30

20

40

30

Typ

(Note 6)

48

65

Max

(Note 7)

1.9

Units

mA

mA

3.8

SR Slew Rate (Note 10) AV = +1, VI = 2V Step 8.5 V/µs

f

u

Unity Gain Frequency

RL = 2 kΩ, CL = 20 pF

7.5 MHz

GBW Gain Bandwidth f = 50 kHz 16 MHz

e

n

i

n

THD+N Total Harmonic Distortion + Noise V+ = 1.9V, V− = −0.8V

Input Referred Voltage Noise Density f = 2 kHz 11.9

Input Referred Current Noise Density f = 2 kHz 0.5

−77 dB

nV/

pA/

f = 1 kHz, RL = 100 kΩ, AV = +2
V

= 210 mV

CT Rej. Crosstalk Rejection

OUT

f = 100 kHz, Driver RL = 10 kΩ

PP

60 dB

±5V Electrical Characteristics (Note 5)

Unless otherwise specified, all limited guaranteed for TA = 25°C, V+ = 5V, V− = −5V, VCM = 0V, V
RL > 1 MΩ to 0V. Boldface limits apply at the temperature extremes.

Symbol Parameter Condition Min

(Note 7)

V

OS

TC V

Input Offset Voltage VCM = −4.5V and VCM = 4.5V −5

Input Offset Voltage Temperature Drift VCM = −4.5V and VCM = 4.5V

OS

(Note 8)

I

B

Input Bias Current VCM = −4.5V

(Note 9)

−2.0

−2.5

VCM = 4.5V
(Note 9)

I

OS

CMRR Common Mode Rejection Ratio

Input Offset Current VCM = −4.5V and VCM = 4.5V 20 200

−5V ≤ VCM ≤ 3V

−5V ≤ VCM ≤ 5V

PSRR Power Supply Rejection Ratio

2.7V ≤ VS ≤ 30V, VCM = −4.5V

CMVR Common Mode Voltage Range CMRR > 50 dB −5.3 −5.1

A

VOL

Open Loop Voltage Gain

−4V ≤ VO ≤ 4V

RL = 10 kΩ to 0V

−4V ≤ VO ≤ 4V

RL = 2 kΩ to 0V

= 0V, and

OUT

Typ

(Note 6)

Max

(Note 7)

Units

±0.7 +5

−6

+6

±2 µV/°C

−1.2

0.45 1.0

1.5

300

80

100

70

65

80

62

78

104

74

−5.0

5.1

5.3

5.0

74

80

70

68

74

65

mV

µA

nA

dB

dB

V

dB

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Symbol Parameter Condition Min

V

OUT

Output Voltage Swing
High

RL = 10 kΩ to 0V
VID = 100 mV

RL = 2 kΩ to 0V

LM7321/LM7322

Output Voltage Swing
Low

VID = 100 mV

RL = 10 kΩ to 0V
VID = −100 mV

RL = 2 kΩ to 0V
VID = −100 mV

I

OUT

Output Current Sourcing

VID = 200 mV, V

= −5V (Note 3)

OUT

Sinking
VID = −200 mV, V

I

S

Supply Current VCM = −4.5V LM7321 1.0 1.3

= 5V (Note 3)

OUT

(Note 7)

100 250

160 350

35 200

80 200

35

20

50

30

Typ

(Note 6)

70

85

Max

(Note 7)

280

450

250

250

2

LM7322 2.3 2.8

3.8

SR Slew Rate (Note 10) AV = +1, VI = 8V Step 12.3

f

u

Unity Gain Frequency

RL = 2 kΩ, CL = 20 pF

9 MHz

GBW Gain Bandwidth f = 50 kHz 16 MHz

e

n

i

n

THD+N Total Harmonic Distortion + Noise

CT Rej. Crosstalk Rejection

Input Referred Voltage Noise Density f = 2 kHz 14.3

Input Referred Current Noise Density f = 2 kHz 1.35

f = 1 kHz, RL = 100 kΩ, AV = +2
V

= 8 V

OUT

PP

f = 100 kHz, Driver RL = 10 kΩ

−79 dB

60 dB

Units

mV from

either rail

mA

mA

V/µs

nV/

pA/

±15V Electrical Characteristics (Note 5)

Unless otherwise specified, all limited guaranteed for TA = 25°C, V+ = 15V, V− = −15V, VCM = 0V, V
RL > 1MΩ to 15V. Boldface limits apply at the temperature extremes.

Symbol Parameter Condition

V

OS

Input Offset Voltage VCM = −14.5V and VCM = 14.5V −6

Min

(Note 7)

−8

TC V

Input Offset Voltage Temperature Drift VCM = −14.5V and VCM = 14.5V

OS

±2 µV/°C

(Note 8)

I

B

Input Bias Current VCM = −14.5V

(Note 9)

VCM = 14.5V

−2

−2.5

0.45 1.0

(Note 9)

I

OS

CMRR Common Mode Rejection Ratio

Input Offset Current VCM = −14.5V and VCM = 14.5V 30 300

−15V ≤ VCM ≤ 12V

80

75

−15V ≤ VCM ≤ 15V

72

70

PSRR Power Supply Rejection Ratio

2.7V ≤ VS ≤ 30V, VCM = −14.5V

78

74

CMVR Common Mode Voltage Range CMRR > 50 dB −15.3 −15.1

15.1

15

= 0V, and

OUT

Typ

(Note 6)

±0.7 +6

−1.1

100

80

100

15.3

Max

(Note 7)

+8

1.5

500

−15

Units

mV

µA

nA

dB

dB

V

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LM7321/LM7322

Symbol Parameter Condition

A

VOL

Open Loop Voltage Gain

−13V ≤ VO ≤ 13V

RL = 10 kΩ to 0V

−13V ≤ VO ≤ 13V

RL = 2 kΩ to 0V

V

OUT

Output Voltage Swing
High

RL = 10 kΩ to 0V
VID = 100 mV

RL = 2 kΩ to 0V
VID = 100 mV

Output Voltage Swing
Low

RL = 10 kΩ to 0V
VID = −100 mV

RL = 2 kΩ to 0V
VID = −100 mV

I

OUT

Output Current Sourcing

VID = 200 mV, V

OUT

Sinking
VID = −200 mV, V

I

S

Supply Current VCM = −14.5V LM7321 1.1 1.7

OUT

Min

(Note 7)

75

70

70

65

150 300

250 550

60 200

130 300

40 65

= −15V (Note 3)

60 100

= 15V (Note 3)

LM7322 2.5 4

Typ

(Note 6)

85

78

Max

(Note 7)

350

650

250

400

2.4

Units

dB

mV from

either rail

mA

mA

5.6

SR Slew Rate

(Note 10)

f

u

Unity Gain Frequency

AV = +1, VI = 20V Step 18

RL = 2 kΩ, CL = 20 pF

11.3 MHz

V/µs

GBW Gain Bandwidth f = 50 kHz 20 MHz

e

n

i

n

THD+N Total Harmonic Distortion +Noise

CT Rej. Crosstalk Rejection

Input Referred Voltage Noise Density f = 2 kHz 15

Input Referred Current Noise Density f = 2 kHz 1.3

f = 1 kHz,RL 100 kΩ,
AV = +2, V

OUT

= 23 V

PP

f = 100 kHz, Driver RL = 10 kΩ

−86 dB

60 dB

nV/

pA/

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 T
PD = (T

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.

) - TA)/ θJA. All numbers apply for packages soldered directly onto a PC board.

J(MAX)

, θJA. The maximum allowable power dissipation at any ambient temperature is

J(MAX)

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Connection Diagrams

5-Pin SOT-23

LM7321/LM7322

Top View

Ordering Information

Package Part Number Package

5-Pin SOT-23

8-Pin MSOP

8-Pin SOIC

8-Pin SOIC

20205705

Top View

Marking

LM7321MF

AU4A

LM7321MFX 3k Units Tape and Reel

LM7322MM

AZ4A

LM7322MMX 3.5k Units Tape and Reel

LM7321MA

LM7321MAX 2.5k Units Tape and Reel

LM7322MA LM7322MA 95 Units/Rail

LM7322MAX 2.5k Units Tape and Reel

LM7321MA

20205703

Media Transport NSC Drawing

1k Units Tape and Reel

1k Units Tape and Reel

95 Units/Rail

8-Pin MSOP/SOIC

Top View

20205706

MF05ALM7321MFE 250 Units Tape and Reel

MUA08ALM7322MME 250 Units Tape and Reel

M08A

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LM7321/LM7322

Typical Performance Characteristics Unless otherwise specified: T

Output Swing vs. Sourcing Current

20205734

Output Swing vs. Sourcing Current

Output Swing vs. Sinking Current

Output Swing vs. Sinking Current

= 25°C.

A

20205731

Output Swing vs. Sourcing Current

20205735

20205736

20205732

Output Swing vs. Sinking Current

20205733

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LM7321/LM7322

VOS Distribution

VOS vs. VCM (Unit 1)

VOS vs. VCM (Unit 2)

VOS vs. VCM (Unit 1)

20205730

20205708

20205707

VOS vs. VCM (Unit 3)

20205709

VOS vs. VCM (Unit 2)

20205710

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20205711

LM7321/LM7322

VOS vs. VCM (Unit 2)

VOS vs. VCM (Unit 2)

20205712

VOS vs. VCM (Unit 1)

20205713

VOS vs. VCM (Unit 3)

VOS vs. VS (Unit 1)

20205714

20205750

20205715

VOS vs. VS (Unit 2)

20205751

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LM7321/LM7322

VOS vs. VS (Unit 3)

VOS vs. VS (Unit 1)

VOS vs. VS (Unit 2)

I

vs. V

BIAS

CM

20205752

20205754

VOS vs. VS (Unit 3)

I

vs. V

BIAS

CM

20205753

20205755

20205723

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20205724

I

BIAS

vs. V

CM

I

BIAS

vs. V

LM7321/LM7322

S

I

vs. V

BIAS

S

IS vs. VCM (LM7322)

20205725

20205721

20205722

IS vs. VCM (LM7321)

20205718

IS vs. VCM (LM7321)

20205775

20205719

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LM7321/LM7322

IS vs. VCM (LM7322)

IS vs. VCM (LM7321)

IS vs. VCM (LM7322)

IS vs. VS (LM7322)

20205776

20205777

20205720

IS vs. VS (LM7321)

20205717

IS vs. VS (LM7321)

20205779

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20205716

LM7321/LM7322

IS vs. VS (LM7322)

20205778

Positive Output Swing vs. Supply Voltage

Positive Output Swing vs. Supply Voltage

20205727

Negative Output Swing vs. Supply Voltage

20205726

Negative Output Swing vs. Supply Voltage

20205729

20205728

Open Loop Frequency Response with Various Capacitive

Load

20205782

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Open Loop Frequency Response with Various Resistive

Load

LM7321/LM7322

Open Loop Frequency Response with Various Supply

Voltage

Phase Margin vs. Capacitive Load

+PSRR vs. Frequency

20205783

20205738

20205784

CMRR vs. Frequency

20205739

−PSRR vs. Frequency

20205740

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20205741

LM7321/LM7322

Small Signal Step Response

20205737

Input Referred Noise Density vs. Frequency

Large Signal Step Response

20205749

Input Referred Noise Density vs. Frequency

Input Referred Noise Density vs. Frequency

20205742

20205744

20205743

THD+N vs. Frequency

20205745

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LM7321/LM7322

THD+N vs. Output Amplitude

THD+N vs. Output Amplitude

THD+N vs. Output Amplitude

20205746

20205748

20205747

Crosstalk Rejection vs. Frequency

20205768

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Application Information

DRIVING CAPACITIVE LOADS

The LM7321/LM7322 are specifically designed to drive un­limited capacitive loads without oscillations 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 ca­pacitive loads as shown in Figure 2 and Figure 3.

20205770

FIGURE 2. +SR vs. Capacitive Load

LM7321/LM7322

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 deter­mined 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 load­ing 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/LM7322, 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 conditions while the
fed back output has not quite caught up with the input, there
will be an overdrive imposed on the input allowing 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 minimum, 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/LM7322

FIGURE 4. Output Short Circuit Sourcing Current vs.

Input Overdrive

20205774

FIGURE 6. Buffer Amplifier Scope Photo

20205772

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 kΩ load can accommodate an output swing to
within 250 mV of V− and to 330 mV of V+ (VS = ±15V) corre­sponding to a typical 29.3 VPP unclipped swing.

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 over­drive 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 neg­ative transition is faster than the positive one.

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20205756

FIGURE 7. Output Sourcing Characteristics with Load

Lines

20205759

LM7321/LM7322

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/LM7322 is used as a buffer amplifier for the V
signal employed in a TFT LCD flat panel:

FIGURE 9. V

Driver Application Schematic

COM

COM

20205758

Figure 10 shows the time domain response of the amplifier
when used as a V
application, the op amp loop will try and maintain its output

buffer/driver with V

COM

at ground. In this

REF

voltage based on the voltage on its non-inverting input
(V

) despite the current injected into the TFT simulated

REF

load. As long as this load current is within the range tolerable
by the LM7321/LM7322 (45 mA sourcing and 65 mA sinking
for ±5V supplies), the output will settle to its final value within
less than 2 μs.

FIGURE 10. V

Driver Performance Scope Photo

COM

OUTPUT SHORT CIRCUIT CURRENT AND DISSIPATION ISSUES

The LM7321/LM7322 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 conditions 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 compo­nent. 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 out­put is maintained somewhere in the range of linear operation.

Therefore:

P

= PQ + PDC + P

TOTAL

PQ = IS · V

S

AC

Op 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

19 www.national.com

Table 1 below shows the maximum AC component of the load
power dissipated by the op amp for standard Sinusoidal, Tri­angular, and Square Waveforms:

TABLE 1. Normalized AC Power Dissipated in the Output

Stage for Standard Waveforms

LM7321/LM7322

PAC (W.Ω/V2)

Sinusoidal Triangular Square

50.7 x 10

−3

46.9 x 10

The table entries are normalized to V
AC load current component of power dissipation, simply mul-

−3

62.5 x 10

2

/RL. To figure out the

S

tiply the table entry corresponding to the output waveform by

2

the factor V
load, and triangular waveform power dissipation in the output

/RL. For example, with ±12V supplies, a 600Ω

S

stage is calculated as:

PAC = (46.9 x 10−3) · [242/600] = 45.0 mW

The maximum power dissipation allowed at a certain temper­ature is a function of maximum die junction temperature (T

) allowed, ambient temperature TA, and package thermal

(MAX)

resistance from junction to ambient, θJA.

For the LM7321/LM7322, the maximum junction temperature
allowed is 150°C at which no power dissipation is allowed.
The power capability at 25°C is given by the following calcu­lations:

For MSOP package:

For SOIC package:

−3

20205765

FIGURE 11. Power Capability vs. Temperature

J

When high power is required and ambient temperature can't
be reduced, providing air flow is an effective approach to re­duce thermal resistance therefore to improve power capabil­ity.

Other Application Hints

The use of supply decoupling is mandatory in most applica­tions. 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 capac­itor (∼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 neces­sary. 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 pro­vide supply decoupling and will help keep the op amp oscil­lation free under any load.

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 P
less than P
below 150°C. If the intersection of ambient temperature and

, the device junction temperature will remain

D(MAX)

TOTAL

is

package power is above the maximum thermal capability line,
the junction temperature will exceed 150°C and this should
be strictly prohibited.

www.national.com 20

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 ca­pacitive 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.

Physical Dimensions inches (millimeters) unless otherwise noted

LM7321/LM7322

NS Package Number MF05A

5-Pin SOT-23

NS Package Number MUA08A

8-Pin MSOP

21 www.national.com

LM7321/LM7322

NS Package Number M08A

8-Pin SOIC

www.national.com 22

Notes

LM7321/LM7322

23 www.national.com

Notes

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