LT1351CS8_技术文档

LT1351

250µA, 3MHz, 200V/µs

Operational Amplifier

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FEATURES

DESCRIPTION

The LT^®1351 is a low power, high speed, high slew rate

operational amplifier with outstanding AC and DC perfor-

mance. The LT1351 features lower supply current, lower

input offset voltage, lower input bias current and higher

DC gain than devices with comparable bandwidth. The

circuit combines the slewing performance of a current

feedback amplifier in a true operational amplifier with

matched high impedance inputs. The high slew rate en-

sures thatthe large-signalbandwidth is notdegraded. The

amplifier is a single gain stage with outstanding settling

characteristics which make the circuit an ideal choice for

data acquisition systems. The output drives a 1kΩ load to

±13Vwith±15Vsuppliesanda500Ωloadto±3.4Von±5V

supplies. The amplifier is also stable with any capacitive

load which makes it useful in buffer or cable driver

applications.

■

3MHz Gain Bandwidth

■

200V/µs Slew Rate

■

250µA Supply Current

■

Available in Tiny MSOP Package

C-Load^TMOp Amp Drives All Capacitive Loads

■

Unity-Gain Stable

■

Power Saving Shutdown Feature

■

Maximum Input Offset Voltage: 600µV

■

Maximum Input Bias Current: 50nA

■

Maximum Input Offset Current: 15nA

■

Minimum DC Gain, R_L= 2k: 30V/mV

■

Input Noise Voltage: 14nV/√Hz

■

Settling Time to 0.1%, 10V Step: 700ns

■

Settling Time to 0.01%, 10V Step: 1.25µs

■

Minimum Output Swing into 1k: ±13V

■

Minimum Output Swing into 500Ω: ±3.4V

■

Specified at ±2.5V, ±5V and ±15V

The LT1351 is a member of a family of fast, high perfor-

mance amplifiers using this unique topology and employ-

ing Linear Technology Corporation’s advanced

complementary bipolar processing. For dual and quad

amplifier versions of the LT1351 see the LT1352/LT1353

data sheet. For higher bandwidth devices with higher

supplycurrentseetheLT1354throughLT1365datasheets.

Singles, duals and quads of each amplifier are available.

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APPLICATIONS

■

Battery-Powered Systems

■

Wideband Amplifiers

■

Buffers

Active Filters

Data Acquisition Systems

Photodiode Amplifiers

■

, LTC and LT are registered trademarks of Linear Technology Corporation.

C-Load is a trademark of Linear Technology Corporation.

■

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TYPICAL APPLICATION

Instrumentation Amplifier

Large-Signal Response

R1

50k

R2

5k

R5

1.1k

R4

50k

R3

5k

–

LT1351

–

V

+

LT1351

–

IN

OUT

V

+

GAIN = [R4/R3][1 + (1/2)(R2/R1 + R3/R4) + (R2 + R3)/R5] = 102

TRIM R5 FOR GAIN

TRIM R1 FOR COMMON MODE REJECTION

BW = 30kHz

A_V= –1

1351 TA02

1351 TA01

1

LT1351

W W

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ABSOLUTE MAXIMUM RATINGS

Total Supply Voltage (V⁺to V^–) .............................. 36V

Differential Input Voltage (Transient Only, Note 1)... ±10V

Input Voltage .......................................................... ±V_S

Output Short-Circuit Duration (Note 2) ........... Indefinite

Operating Temperature Range ................ –40°C to 85°C

Specified Temperature Range (Note 6) .....–40°C to 85°C

Maximum Junction Temperature (See Below)

Plastic Package ................................................ 150°C

Storage Temperature Range ................. –65°C to 150°C

Lead Temperature (Soldering, 10 sec).................. 300°C

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PACKAGE/ORDER INFORMATION

ORDER PART

TOP VIEW

NUMBER

NULL

–IN

1

2

3

4

NULL

NULL 1

–IN 2

8 NULL

7 V

8

7

6

5

+

V

LT1351CN8

LT1351CS8

+IN 3

6 V

5 SHDN

LT1351CMS8

OUT

–

V

4

+IN

V

OUT

–

MS8 PACKAGE

8-LEAD PLASTIC MSOP

V

SHDN

S8 PART MARKING

1351

MS8 PART MARKING

LTBT

N8 PACKAGE

S8 PACKAGE

T_JMAX= 150°C, θ_JA= 250°C/ W

8-LEAD PDIP 8-LEAD PLASTIC SO

T_JMAX= 150°C, θ_JA= 130°C/ W (N8)

_JMAX= 150°C, θ_JA= 190°C/ W (S)

T

Consult factory for Industrial and Military grade parts.

T_A= 25°C, V_CM= 0V unless otherwise noted.

ELECTRICAL CHARACTERISTICS

SYMBOL

PARAMETER

CONDITIONS

V

MIN

TYP

MAX

UNITS

SUPPLY

V

Input Offset Voltage

±15V

±5V

±2.5V

0.2

0.3

0.6

0.8

mV

OS

I

Input Offset Current

Input Bias Current

Input Noise Voltage

Input Noise Current

Input Resistance

±2.5V to ±15V

5

15

50

nA

OS

20

14

0.5

B

e

f = 10kHz

nV/√Hz

pA/√Hz

n

i

n

R

V

CM

= ±12V

±15V

300

600

20

MΩ

IN

Differential

C

Input Capacitance

±15V

3

pF

IN

Positive Input Voltage Range

±15V

±5V

±2.5V

12.0

2.5

0.5

13.5

3.5

1.0

V

Negative Input Voltage Range

Common Mode Rejection Ratio

Power Supply Rejection Ratio

±15V

±5V

±2.5V

–13.5 –12.0

V

–3.5

–1.0

–2.5

–0.5

CMRR

PSRR

V

= ±12V

= ±2.5V

= ±0.5V

±15V

±5V

±2.5V

80

78

68

94

86

77

dB

CM

V = ±2.5V to ±15V

S

90

106

dB

2

LT1351

ELECTRICAL CHARACTERISTICS ^T_A^{= 25°C, V}_CM= 0V unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

V

MIN

TYP

MAX

UNITS

SUPPLY

A

Large-Signal Voltage Gain

V

= ±12V, R = 5k

±15V

±5V

40

30

20

30

25

15

20

80

60

40

60

50

30

40

V/mV

VOL

OUT

L

= ±10V, R = 2k

L

= ±10V, R = 1k

L

= ±2.5V, R = 5k

L

= ±2.5V, R = 2k

L

= ±2.5V, R = 1k

L

= ±1V, R = 5k

±2.5V

L

V

Output Swing

Output Current

R = 5k, V = ±10mV

±15V

±5V

±2.5V

13.5

13.4

13.0

3.5

3.4

1.3

14.0

13.8

13.4

4.0

3.8

1.7

±V

OUT

L

IN

R = 2k, V = ±10mV

L

IN

R = 1k, V = ±10mV

L

IN

R = 1k, V = ±10mV

L

IN

R = 500Ω, V = ±10mV

L

IN

R = 5k, V = ±10mV

L

IN

I

V

= ±13V

= ±3.4V

±15V

±5V

13.0

6.8

13.4

7.6

mA

OUT

SC

OUT

Short-Circuit Current

Slew Rate

V

= 0V, V = ±3V

±15V

30

45

mA

OUT

IN

SR

A = –1, R = 5k (Note 3)

±15V

±5V

120

30

200

50

V/µs

V

L

Full-Power Bandwidth

Gain Bandwidth

10V Peak (Note 4)

3V Peak (Note 4)

±15V

±5V

3.2

2.6

MHz

GBW

f = 200kHz, R = 10k

±15V

± 5V

± 2.5V

2.0

1.8

3.0

2.7

2.5

MHz

L

t , t

r

Rise Time, Fall Time

Overshoot

A = 1, 10% to 90%, 0.1V

±15V

±5V

46

53

ns

f

V

A = 1, 0.1V

V

±15V

±5V

13

16

%

Propagation Delay

Settling Time

50% V to 50% V , 0.1V

±15V

±5V

41

52

ns

IN

OUT

t

10V Step, 0.1%, A = –1

±15V

±5V

700

1250

950

ns

s

V

10V Step, 0.01%, A = –1

V

5V Step, 0.1%, A = –1

V

5V Step, 0.01%, A = –1

±5V

1400

V

R

Output Resistance

A = 1, f = 20kHz

V

±15V

1.5

Ω

O

I

Shutdown Input Current

SHDN = V + 0.1V

±15V

–10

0.1

µA

SHDN

EE

SHDN = V

2

CC

I

Supply Current

±15V

±5V

250

220

10

330

300

µA

S

SHDN = V + 0.1V

EE

0°C ≤ T_A≤ 70°C, V_CM= 0V unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

V

MIN

TYP

MAX

UNITS

SUPPLY

V

Input Offset Voltage

±15V

±5V

±2.5V

0.8

1.0

mV

OS

Input V Drift

(Note 5)

±2.5V to ±15V

3

8

µV/°C

nA

OS

I

Input Offset Current

Input Bias Current

20

75

OS

nA

B

3

LT1351

0°C ≤ T_A≤ 70°C, V_CM= 0V unless otherwise noted.

ELECTRICAL CHARACTERISTICS

SYMBOL

PARAMETER

CONDITIONS

V

MIN

TYP

MAX

UNITS

SUPPLY

CMRR

Common Mode Rejection Ratio

V

CM

V

CM

V

CM

= ±12V

= ±2.5V

= ±0.5V

±15V

±5V

±2.5V

78

77

67

dB

PSRR

Power Supply Rejection Ratio

Large-Signal Voltage Gain

V = ±2.5V to ±15V

89

dB

S

A

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

= ±12V, R = 5k

±15V

±5V

25

20

15

10

15

V/mV

VOL

OUT

L

= ±10V, R = 2k

L

= ±2.5V, R = 5k

L

= ±2.5V, R = 2k

L

= ±2.5V, R = 1k

L

= ±1V, R = 5k

±2.5V

L

V

Output Swing

Output Current

R = 5k, V = ±10mV

±15V

±5V

±2.5V

13.4

13.3

12.0

3.4

3.3

1.2

±V

L

IN

R = 2k, V = ±10mV

L

IN

R = 1k, V = ±10mV

L

IN

R = 1k, V = ±10mV

L

IN

R = 500Ω, V = ±10mV

L

IN

R = 5k, V = ±10mV

L

IN

I

V

OUT

V

OUT

= ±12V

= ±3.3V

±15V

±5V

12.0

6.6

mA

OUT

SC

Short-Circuit Current

Slew Rate

V

OUT

= 0V, V = ±3V

±15V

24

mA

IN

SR

A = –1, R = 5k (Note 3)

±15V

±5V

100

21

V/µs

V

L

GBW

Gain Bandwidth

f = 200kHz, R = 10k

±15V

± 5V

1.8

1.6

MHz

L

I

Shutdown Input Current

Supply Current

SHDN = V + 0.1V

±15V

– 20

µA

SHDN

S

EE

SHDN = V

3

CC

±15V

±5V

380

355

µA

SHDN = V + 0.1V

20

EE

–40°C ≤ T_A≤ 85°C, V_CM= 0V unless otherwise noted (Note 6).

SYMBOL

PARAMETER

CONDITIONS

V

MIN

TYP

MAX

UNITS

SUPPLY

V

Input Offset Voltage

±15V

±5V

±2.5V

1.0

1.2

mV

OS

Input V Drift

(Note 5)

±2.5V to ±15V

3

8

µV/°C

nA

OS

I

Input Offset Current

30

OS

Input Bias Current

100

nA

B

CMRR

Common Mode Rejection Ratio

V

CM

V

CM

V

CM

= ±12V

= ±2.5V

= ±0.5V

±15V

±5V

±2.5V

76

66

dB

PSRR

Power Supply Rejection Ratio

Large-Signal Voltage Gain

V = ±2.5V to ±15V

87

dB

S

A

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

= ±12V, R = 5k

±15V

±5V

20

15

10

8

V/mV

VOL

L

= ±10V, R = 2k

L

= ±2.5V, R = 5k

L

= ±2.5V, R = 2k

L

= ±2.5V, R = 1k

L

= ±1V, R = 5k

±2.5V

10

L

4

LT1351

ELECTRICAL CHARACTERISTICS ^{–40°C ≤ T}_A^{≤ 85°C, V}_CM= 0V unless otherwise noted (Note 6).

SYMBOL

PARAMETER

CONDITIONS

V

MIN

TYP

MAX

UNITS

SUPPLY

V

Output Swing

R = 5k, V = ±10mV

±15V

±5V

±2.5V

13.3

13.2

10.0

3.3

3.2

1.1

±V

OUT

L

IN

R = 2k, V = ±10mV

L

IN

R = 1k, V = ±10mV

L

IN

R = 1k, V = ±10mV

L

IN

R = 500Ω, V = ±10mV

L

IN

R = 5k, V = ±10mV

L

IN

I

Output Current

V

= ±10V

= ±3.2V

±15V

±5V

10.0

6.4

mA

OUT

SC

OUT

Short-Circuit Current

Slew Rate

V

= 0V, V = ±3V

±15V

20

mA

OUT

IN

SR

A = –1, R = 5k (Note 3)

±15V

±5V

50

15

V/µs

V

L

GBW

Gain Bandwidth

f = 200kHz, R = 10k

±15V

± 5V

1.6

1.4

MHz

L

I

Shutdown Input Current

Supply Current

SHDN = V + 0.1V

±15V

– 30

30

µA

SHDN

S

EE

SHDN = V

5

CC

±15V

±5V

390

380

µA

SHDN = V + 0.1V

EE

Note 1: Differential inputs of ±10V are appropriate for transient operation

only, such as during slewing. Large, sustained differential inputs will cause

excessive power dissipation and may damage the part. See Input

Considerations in the Applications Information section of this data sheet

for more details.

Note 4: Full-power bandwidth is calculated from the slew rate

measurement: FPBW = (Slew Rate)/2πV .

P

Note 5: This parameter is not 100% tested.

Note 6: The LT1351 is designed, characterized and expected to meet these

extended temperature limits, but is not tested at –40°C and at 85°C.

Guaranteed I grade parts are available; consult factory.

Note 2: A heat sink may be required to keep the junction temperature

below absolute maximum when the output is shorted indefinitely.

Note 3: Slew rate is measured between ±8V on the output with ±12V

input for ±15V supplies and ±2V on the output with ±3V input for ±5V

supplies.

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TYPICAL PERFORMANCE CHARACTERISTICS

Supply Current vs Supply Voltage

and Temperature

Input Common Mode Range

vs Supply Voltage

Input Bias Current

vs Input Common Mode Voltage

+

V

30

20

10

0

350

300

250

200

150

100

T

= 25°C

OS

T

= 25°C

= ±15V

+

A

S

–0.5

–1.0

–1.5

–2.0

∆V = 1mV

V

–

I

+ I

2

B

I

=

B

125°C

25°C

2.0

1.5

1.0

0.5

–55°C

–10

–20

–

V

0

10

15

20

–15

–10

–5

0

5

10

15

5

10

SUPPLY VOLTAGE (±V)

15

5

0

20

INPUT COMMON MODE VOLTAGE (V)

SUPPLY VOLTAGE (±V)

1351 G03

1351 G02

1351 G01

5

LT1351

TYPICAL PERFORMANCE CHARACTERISTICS

W

U

Input Bias Current vs Temperature

Input Noise Spectral Density

Open-Loop Gain vs Resistive Load

40

36

32

28

24

20

16

12

8

110

100

90

100

10

1

10

V

= ±15V

T

= 25°C

T = 25°C

A

S

B

A

S

V

+

–

V

A

= ±15V

= 101

I

B

+ I

2

B

I

=

V

= ±15V

S

R

= 100k

S

V

S

= ±5V

e

n

1

80

i

n

70

4

0

60

0.1

–50

0

25

50

75 100 125

–25

10

100

1k

10k

1

10

1k

10k

100

FREQUENCY (Hz)

TEMPERATURE (°C)

LOAD RESISTANCE (Ω)

1351 G04

1351 G06

1351 G05

Output Voltage Swing

vs Supply Voltage

Output Voltage Swing

vs Load Current

Open-Loop Gain vs Temperature

+

V

100

99

V

= ±15V

= ±12V

= 5k

V

= ±5V

IN

S

O

L

S

–0.5

–1.0

–1.5

–2.0

85°C

= 10mV

R

= 2k

25°C

L

–1

–2

R

–40°C

25°C

–40°C 85°C

= 1k

98

–3

3

T

= 25°C

IN

A

97

V

= ±10mV

25°C

85°C

2.0

1.5

1.0

0.5

96

95

94

R

= 1k

= 2k

2

L

–40°C

25°C

85°C

1

–

V

–20 –15

0

10

15

50

TEMPERATURE (°C)

100 125

–5

20

–50 –25

0

25

75

5

10

SUPPLY VOLTAGE (V)

20

–10

5

0

15

OUTPUT CURRENT (mA)

1351 G09

1351 G07

1351 G08

Output Short-Circuit Current

vs Temperature

Settling Time vs Output Step

(Noninverting)

Settling Time vs Output Step

(Inverting)

10

8

60

55

10

8

V

S

= ±15V

6

10mV

1mV

50

45

40

35

30

4

10mV

1mV

SINK

SOURCE

2

0

–2

–4

–6

–8

–2

–4

–6

–8

–10

V

S

A

V

= ±15V

= 1

10mV

1mV

10mV

1mV

V

A

= ±15V

S

V

= –1

OUTPUT

FILTER:

1.6MHz

LPF

R

= R = 2k

G

F

C

= 5pF

= 2k

R

L

–10

25

0.7 0.8 0.9

1

1.1 1.2 1.3

1.4 1.5

1.6

50

TEMPERATURE (°C)

100 125

–50 –25

0

25

75

0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5

SETTLING TIME (µs)

1351 G11

1351 G10

1351 G12

6

LT1351

W

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TYPICAL PERFORMANCE CHARACTERISTICS

Frequency Response

vs Capacitive Load

Gain and Phase vs Frequency

Output Impedance vs Frequency

10

8

70

60

50

40

30

20

10

0

120

100

80

1000

100

10

T

= 25°C

= ±15V

T

= 25°C

= ±15V

= –1

T

= 25°C

A

S

A

V

F

A

S

V

A

= –1

PHASE

= ±15V

R = R = 5k

G

6

R

= R = 5k

C = 5000pF

C = 1000pF

FB

G

A

V

= 100

C = 500pF

C = 100pF

4

V

= ±15V

A

= 10

S

A = 1

V

60

2

0

V

= ±5V

V

S

= ±5V

S

40

C = 10pF

GAIN

–2

–4

1

20

0

–6

0.1

0.01

–20

–40

–8

–10

1k

10k

100k

1M

10M

100M

1k

10k

100k

FREQUENCY (Hz)

1M

10M

10k

100k

1M

10M

FREQUENCY (Hz)

1351 G14

1351 G13

1351 G15

Gain Bandwidth and Phase Margin

vs Temperature

Frequency Response

vs Supply Voltage (A_V= 1)

Frequency Response

vs Supply Voltage (A_V= –1)

4.50

4.25

4.00

3.75

3.50

3.25

3.00

2.75

2.50

2.25

2.00

50

48

46

44

42

40

38

36

34

32

30

5

4

3

2

T

= 25°C

= 1

= 5k

T

= 25°C

A

V

= ±15V

= ±5V

A

V

L

S

4

3

2

A

= –1

V

R

= R = 5k

L G

V

S

PHASE MARGIN

1

0

1

0

GAIN BANDWIDTH

–1

–2

–3

–4

–5

–1

–2

–3

–4

–5

V

= ±15V

= ±5V

S

±15V

±5V

±2.5V

±15V

±5V

±2.5V

V

S

–50

0

25

50

75 100 125

10k

100k

1M

10M

10k

100k

1M

10M

–25

TEMPERATURE (°C)

FREQUENCY (Hz)

1351 G17

1351 G18

1351 G16

Gain Bandwidth and Phase Margin

vs Supply Voltage

Common Mode Rejection Ratio

vs Frequency

Power Supply Rejection Ratio

vs Frequency

4.50

4.25

4.00

3.75

3.50

3.25

3.00

2.75

2.50

2.25

2.00

50

48

46

44

42

40

38

36

34

32

30

120

100

80

60

40

20

0

120

100

T

= 25°C

= ±15V

T

= 25°C

= ±15V

A

S

A

S

T

A

= 25°C

V

PHASE MARGIN

80

60

–PSRR = +PSRR

40

20

0

GAIN BANDWIDTH

0

10

15

20

10

100

1k

10k 100k

1M

10M

100

1k

10k

100k

1M

10M

5

FREQUENCY (Hz)

SUPPLY VOLTAGE (±V)

1351 G19

1351 G20

1351 G21

7

LT1351

TYPICAL PERFORMANCE CHARACTERISTICS

W

U

Slew Rate vs Supply Voltage

Slew Rate vs Temperature

Slew Rate vs Input Level

250

200

150

100

50

200

150

100

50

200

175

150

125

T

= 25°C

A = –1

V

T

= 25°C

= ±15V

= –1

A

V

F

A

S

V

A

= –1

R = R = R = 5k

F G L

V

A

+

–

R

= R = 5k

SR = (SR + SR )/2

G

+

–

SR = (SR + SR )/2

R

= R = 5k

FB

G

+

–

V

= ±15V

S

SR = (SR + SR )/2

100

75

V

S

= ±5V

50

25

0

5

10

15

50

125

4

8

16

–50 –25

0

25

75 100

0

20

24

12

SUPPLY VOLTAGE (±V)

TEMPERATURE (°C)

INPUT LEVEL (V

)

P-P

1351 G22

1351 G23

1351 G24

Total Harmonic Distortion

vs Frequency

Undistorted Output Swing

vs Frequency (±15V)

vs Frequency (±5V)

30

25

20

15

10

5

10

9

8

7

6

5

4

3

2

1

0

1

T

= 25°C

= ±15V

= 5k

A

S

L

O

A

= –1

V

R

V

A

= 1

= 2V

V

P-P

0.1

A

V

= 1

A

V

= –1

0.01

A

= –1

= 1

V

= ±15V

V

= ±5V

S

L

S

L

R

= 5k

R

= 5k

THD = 1%

A

THD = 1%

V

0.001

0

10k

100k

1M

10k

100k

1M

10

100

1k

FREQUENCY (Hz)

10k

100k

FREQUENCY (Hz)

1351 G27

1351 G26

1351 G25

2nd and 3rd Harmonic Distortion

vs Frequency

Shutdown Supply Current

vs Temperature

Capacitive Load Handling

100

90

80

70

60

50

40

30

20

10

0

100

90

–30

–40

–50

–60

–70

–80

–90

V

A

= ±15V

= 1

V = ±15V

S

T

= 25°C

= ±15V

= 5k

S

V

L

A

S

L

V

R

= 5k

R

80

V

= 2V

O

P-P

70

V

SHDN

= V + 0.2

EE

A

= 1

V

60

50

3RD HARMONIC

2ND HARMONIC

V

= V + 0.1

EE

SHDN

40

30

20

10

0

A

= –1

V

= V

EE

SHDN

25

100k

1M

50

125

10p

100p

1n

10n

0.1µ

1µ

–50

0

75 100

–25

FREQUENCY (Hz)

TEMPERATURE (°C)

CAPACITIVE LOAD (F)

1351 G28

1351 G30

1351 G29

8

LT1351

W

U

TYPICAL PERFORMANCE CHARACTERISTICS

Small-Signal Transient

(A_V= 1)

Small-Signal Transient

(A_V= –1)

Small-Signal Transient

(A_V= –1, C_L= 1000pF)

1351 G31

1351 G32

1351 G33

Large-Signal Transient

(A_V= 1)

Large-Signal Transient

(A_V= –1)

Large-Signal Transient

(A_V= 1, C_L= 10,000pF)

1351 G34

1351 G35

1351 G36

U

W U U

APPLICATIONS INFORMATION

The LT1351 may be inserted directly into many high

speed amplifier applications improving both DC and AC

performance, provided that the nulling circuitry is re-

moved. The suggested nulling circuit for the LT1351 is

shown in Figure 1.

Layout and Passive Components

The LT1351 amplifier is easy to apply and tolerant of less

than ideal layouts. For maximum performance (for ex-

ample fast settling time) use a ground plane, short lead

lengthsandRF-qualitybypasscapacitors(0.01µFto0.1µF).

For high drive current applications use low ESR bypass

capacitors (1µF to 10µF tantalum). For details see Design

Note 50.

+

V

0.1µF

3

+

7

The parallel combination of the feedback resistor and gain

setting resistor on the inverting input can combine with

the input capacitance to form a pole which can cause

peakingorevenoscillations.Forfeedbackresistorsgreater

than 10k, a parallel capacitor of value, C_F> (R_G)(C_IN/R_F)

should be used to cancel the input pole and optimize

dynamic performance. For applications where the DC

6

LT1351

2

4

–

8

1

0.1µF

100k

–

V

1351 F01

Figure 1. Offset Nulling

9

LT1351

U

W U U

APPLICATIONS INFORMATION

noise gain is one and a large feedback resistor is used, C_F

should be greater than or equal to C_IN. An example would

beanI-to-VconverterasshownintheTypicalApplications

section.

Shutdown

The LT1351 has a Shutdown pin for conserving power.

When this pin is open or 2V above the negative supply the

part operates normally. When pulled down to V^–the

supply current will drop to about 10µA. The current out of

the Shutdown pin is also typically 10µA. In shutdown the

amplifier output is not isolated from the inputs so the

LT1351 cannot be used in multiplexing applications using

the shutdown feature.

Capacitive Loading

The LT1351 is stable with any capacitive load. As the

capacitive load increases, both the bandwidth and phase

margin decrease so there will be peaking in the frequency

domain and in the transient response. Graphs of Fre-

quency Response vs Capacitive Load, Capacitive Load

Handling and the transient response photos clearly show

these effects.

A level shift application is shown in the Typical Applica-

tions section so that a ground-referenced logic signal can

control the Shutdown pin.

Circuit Operation

Input Considerations

The LT1351 circuit topology is a true voltage feedback

amplifier that has the slewing behavior of a current

feedback amplifier. The operation of the circuit can be

understood by referring to the simplified schematic.

Each of the LT1351 inputs is the base of an NPN and

a PNP transistor whose base currents are of opposite

polarity and provide first-order bias current cancellation.

Because of variation in the matching of NPN and PNP

beta, the polarity of the input bias current can be positive

or negative. The offset current does not depend on

NPN/PNP beta matching and is well controlled. The use of

balanced source resistance at each input is recommended

for applications where DC accuracy must be maximized.

The inputs are buffered by complementary NPN and PNP

emitter followers which drive R1, a 1k resistor. The input

voltage appears across the resistor generating currents

which are mirrored into the high impedance node and

compensation capacitor C_T. Complementary followers

form an output stage which buffers the gain node from

the load. The output devices Q19 and Q22 are connected

to form a composite PNP and composite NPN.

The inputs can withstand transient differential input volt-

ages up to 10V without damage and need no clamping or

source resistance for protection. Differential inputs, how-

ever, generate large supply currents (tens of mA) as

required for high slew rates. If the device is used with

sustained differential inputs, the average supply current

will increase, excessive power dissipation will result and

the part may be damaged. The part should not be used as

a comparator, peak detector or other open-loop applica-

tion with large, sustained differential inputs. Under

normal, closed-loop operation, an increase of power

dissipation is only noticeable in applications with large

slewing outputs and is proportional to the magnitude of

the differential input voltage and the percent of the time

that the inputs are apart. Measure the average supply

current for the application in order to calculate the power

dissipation.

The bandwidth is set by the input resistor and the

capacitance on the high impedance node. The slew rate

is determined by the current available to charge the

capacitance. This current is the differential input voltage

divided by R1, so the slew rate is proportional to the

input. Highest slew rates are therefore seen in the lowest

gain configurations. For example, a 10V output step in a

gain of 10 has only a 1V input step whereas the same

outputstepinunitygainhasa10timesgreaterinputstep.

The curve of Slew Rate vs Input Level illustrates this

relationship.

Capacitive load compensation is provided by the R_C, C_C

network which is bootstrapped across the output stage.

When the amplifier is driving a light load the network has

no effect. When driving a capacitive load (or a low value

10

LT1351

U

W U U

APPLICATIONS INFORMATION

resistive load) the network is incompletely bootstrapped which improve the phase margin. The design ensures

and adds to the compensation at the high impedance that even for very large load capacitances the total phase

node. The added capacitance slows down the amplifier lag can never exceed 180 degrees (zero phase margin)

and a zero is created by the RC combination, both of and the amplifier remains stable.

W

SI PLIFIED SCHE ATIC

+

V

R2

R3

Q11

Q10

Q12

Q17

Q20

Q21

C1

R6

Q9

Q19

Q3

Q4

Q7

Q8

R1

1k

C

R

C

Q5

Q1

–IN

+IN

Q2

OUTPUT

Q6

Q18

Q16

R7

Q22

R4

Q13

Q15

C2

C

T

Q14

Q23

Q24

R5

–

1351 SS

V

U

TYPICAL APPLICATIONS

20kHz, 4th Order Butterworth Filter

4.64k

5.49k

470pF

220pF

4.64k

13.3k

V

–

IN

5.49k

11.3k

LT1351

–

2200pF

V

OUT

+

LT1351

4700pF

+

1351 TA03

11

LT1351

U

TYPICAL APPLICATIONS

Shutdown Circuit

3

+

–

6

LT1351

5

2

1N4148

1M

S

G

SHDN

SST177

D

S

G

SST177

D

1M

–

1351 TA04

V

DAC I-to-V Converter

10pF

12

5k

DAC

–

INPUTS

V

LT1351

OUT

565A TYPE

+

V

A

5k

OUT

V + I (5kΩ) +

OS OS

< 0.5LSB

1351 TA05

VOL

12

LT1351

U

PACKAGE DESCRIPTION ^{Dimensions in inches (millimeters) unless otherwise noted.}

MS8 Package

8-Lead Plastic MSOP

(LTC DWG # 05-08-1660)

0.118 ± 0.004*

(3.00 ± 0.102)

8

7

6

5

0.118 ± 0.004**

(3.00 ± 0.102)

0.192 ± 0.004

(4.88 ± 0.10)

1

2

3

4

0.040 ± 0.006

(1.02 ± 0.15)

0.034 ± 0.004

(0.86 ± 0.102)

0.007

(0.18)

0° – 6° TYP

SEATING

PLANE

0.012

(0.30)

REF

0.021 ± 0.006

(0.53 ± 0.015)

0.006 ± 0.004

(0.15 ± 0.102)

MSOP (MS8) 1197

0.0256

(0.65)

TYP

*

DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,

PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

13

LT1351

U

PACKAGE DESCRIPTION ^{Dimensions in inches (millimeters) unless otherwise noted.}

N8 Package

8-Lead PDIP (Narrow 0.300)

(LTC DWG # 05-08-1510)

0.400*

(10.160)

MAX

8

7

6

5

4

0.255 ± 0.015*

(6.477 ± 0.381)

1

2

3

0.130 ± 0.005

0.300 – 0.325

0.045 – 0.065

(3.302 ± 0.127)

(1.143 – 1.651)

(7.620 – 8.255)

0.065

(1.651)

TYP

0.009 – 0.015

(0.229 – 0.381)

0.125

0.020

(0.508)

MIN

(3.175)

MIN

+0.035

0.325

–0.015

0.100 ± 0.010

(2.540 ± 0.254)

0.018 ± 0.003

(0.457 ± 0.076)

+0.889

8.255

(

)

N8 1197

–0.381

*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.

MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)

14

LT1351

U

PACKAGE DESCRIPTION ^{Dimensions in inches (millimeters) unless otherwise noted.}

S8 Package

8-Lead Plastic Small Outline (Narrow 0.150)

(LTC DWG # 05-08-1610)

0.189 – 0.197*

(4.801 – 5.004)

7

5

8

6

0.150 – 0.157**

(3.810 – 3.988)

0.228 – 0.244

(5.791 – 6.197)

1

3

4

2

0.010 – 0.020

(0.254 – 0.508)

× 45°

0.053 – 0.069

(1.346 – 1.752)

0.004 – 0.010

(0.101 – 0.254)

0.008 – 0.010

(0.203 – 0.254)

0°– 8° TYP

0.016 – 0.050

0.406 – 1.270

0.050

(1.270)

TYP

0.014 – 0.019

(0.355 – 0.483)

*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD

FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE

SO8 0996

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.

15

LT1351

TYPICAL APPLICATION

U

Low Power Sample-and-Hold

–

+

LTC201

LT1351

+

V

OUT

LT1351

2000pF

V

IN

DROOP: 20nA/2000pF = 10mV/ms

ACQUISITION TIME: 10V, 0.1% = 2µs

CHARGE INJECTION ERROR: 8pC/2000pF = 4mV

1351 TA06

RELATED PARTS

PART NUMBER

LT1352/LT1353

LT1354

DESCRIPTION

COMMENTS

Dual/Quad 250µA, 3MHz, 200V/µs Op Amp

1mA, 12MHz, 400V/µs Op Amp

Good DC Precision, Stable with All Capacitive Loads

1351fa LT/TP 0498 REV A 2K • PRINTED IN USA

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

16

●

(408)432-1900 FAX:(408)434-0507 www.linear-tech.com

LINEAR TECHNOLOGY CORPORATION 1996


型号：	LT1351CS8
厂家：	Linear
描述：	250uA, 3MHz, 200V/us Operational Amplifier 250uA ，为3MHz ， 200V / us的运算放大器运算放大器
文件：	总16页 (文件大小：345K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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