Datasheet LT1351 Datasheet (Linear Technology)

FEATURES

■

3MHz Gain Bandwidth

■

200V/µs Slew Rate

■

250µA Supply Current

■

Available in Tiny MSOP Package

■

C-LoadTM Op 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, RL = 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

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APPLICATIONS

■

Battery-Powered Systems

■

Wideband Amplifiers

■

Buffers

■

Active Filters

■

Data Acquisition Systems

■

Photodiode Amplifiers

LT1351

250µA, 3MHz, 200V/µs

Operational Amplifier

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DESCRIPTION

The LT®1351 is a low power, high speed, high slew rate operational amplifier with outstanding AC and DC performance. 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 ensures that the large-signal bandwidth is not degraded. 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 ±13V with ± 15V supplies and a 500Ω load to ±3.4V on ±5V supplies. The amplifier is also stable with any capacitive load which makes it useful in buffer or cable driver applications.

The LT1351 is a member of a family of fast, high performance amplifiers using this unique topology and employing 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 supply current see the LT1354 through LT1365 data sheets. Singles, duals and quads of each amplifier are available.

, 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

R1

50k

–

V

IN

+

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

–

LT1351

+

R2

5k

R5

1.1k

R3 5k

–

+

50k

LT1351

Large-Signal Response

R4

V

OUT

1351 TA01

AV = –1 1351 TA02

1

LT1351

1 2 3 4

8 7 6 5



TOP VIEW

NULL

–IN

+IN

V

–

NULL V

+



V

OUT



SHDN

N8 PACKAGE 8-LEAD PDIP

S8 PACKAGE

8-LEAD PLASTIC SO

WW

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

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

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

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W

PACKAGE/ORDER INFORMATION

TOP VIEW

NULL

1

–IN

2

+IN

3

–

V

4

MS8 PACKAGE

8-LEAD PLASTIC MSOP

T

= 150°C, θJA = 250°C/ W

JMAX

Consult factory for Industrial and Military grade parts.

8 7 6 5

NULL

+

V



V

OUT

SHDN



ORDER PART

NUMBER

LT1351CMS8

MS8 PART MARKING

LTBT

Specified Temperature Range (Note 6) .....

–40°C to 85°C

Maximum Junction Temperature (See Below)

S

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

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

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

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ORDER PART

NUMBER

LT1351CN8 LT1351CS8

S8 PART MARKING

T

= 150°C, θJA = 130°C/ W (N8)

JMAX

T

= 150°C, θJA = 190°C/ W (S)

JMAX

1351

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS V

V

OS

I

OS

I

B

e

n

i

n

R

IN

C

IN

CMRR Common Mode Rejection Ratio VCM = ±12V ±15V 80 94 dB

PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V 90 106 dB

2

Input Offset Voltage ±15V 0.2 0.6 mV

Input Offset Current ±2.5V to ±15V 5 15 nA Input Bias Current ±2.5V to ±15V 20 50 nA Input Noise Voltage f = 10kHz ±2.5V to ±15V 14 nV/√Hz Input Noise Current f = 10kHz ±2.5V to ±15V 0.5 pA/√Hz Input Resistance VCM = ±12V ±15V 300 600 MΩ

Differential ±15V 20 MΩ Input Capacitance ±15V 3 pF Positive Input Voltage Range ±15V 12.0 13.5 V

Negative Input Voltage Range ±15V –13.5 –12.0 V

VCM = ±2.5V ±5V 78 86 dB

V

TA = 25°C, VCM = 0V unless otherwise noted.

SUPPLY

±5V 0.2 0.6 mV

±2.5V 0.3 0.8 mV

±5V 2.5 3.5 V

±2.5V 0.5 1.0 V

±5V –3.5 –2.5 V

±2.5V –1.0 –0.5 V

= ±0.5V ±2.5V 68 77 dB

CM

MIN TYP MAX UNITS

LT1351

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS V

A

VOL

V

OUT

Large-Signal Voltage Gain V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

Output Swing RL = 5k, VIN = ±10mV ±15V 13.5 14.0 ±V

= 2k, VIN = ±10mV ±15V 13.4 13.8 ±V

R

L

TA = 25°C, VCM = 0V unless otherwise noted.

SUPPLY

= ±12V, RL = 5k ±15V 40 80 V/mV = ±10V, RL = 2k ±15V 30 60 V/mV = ±10V, RL = 1k ±15V 20 40 V/mV = ±2.5V, RL = 5k ±5V 30 60 V/mV = ±2.5V, RL = 2k ±5V 25 50 V/mV = ±2.5V, RL = 1k ±5V 15 30 V/mV = ±1V, RL = 5k ±2.5V 20 40 V/mV

MIN TYP MAX UNITS

RL = 1k, VIN = ±10mV ±15V 13.0 13.4 ±V

= 1k, VIN = ±10mV ±5V 3.5 4.0 ±V

R

L

= 500Ω, VIN = ±10mV ±5V 3.4 3.8 ±V

R

L

= 5k, VIN = ±10mV ±2.5V 1.3 1.7 ±V

R

L

I

OUT

I

SC

Output Current V

Short-Circuit Current V

= ±13V ±15V 13.0 13.4 mA

OUT

= ±3.4V ±5V 6.8 7.6 mA

V

OUT

= 0V, VIN = ±3V ±15V 30 45 mA

OUT

SR Slew Rate AV = –1, RL = 5k (Note 3) ±15V 120 200 V/µs

±5V 30 50 V/µs

Full-Power Bandwidth 10V Peak (Note 4) ±15V 3.2 MHz

3V Peak (Note 4) ±5V 2.6 MHz

GBW Gain Bandwidth f = 200kHz, RL = 10k ±15V 2.0 3.0 MHz

±5V 1.8 2.7 MHz

±2.5V 2.5 MHz

tr, t

f

Rise Time, Fall Time AV = 1, 10% to 90%, 0.1V ±15V 46 ns

±5V 53 ns

Overshoot AV = 1, 0.1V ±15V 13 %

±5V 16 %

Propagation Delay 50% VIN to 50% V

, 0.1V ±15V 41 ns

OUT

±5V 52 ns

t

s

Settling Time 10V Step, 0.1%, AV = –1 ±15V 700 ns

10V Step, 0.01%, A 5V Step, 0.1%, A

= –1 ±15V 1250 ns

V

= –1 ±5V 950 ns

V

5V Step, 0.01%, AV = –1 ±5V 1400 ns

R

O

I

SHDN

I

S

Output Resistance AV = 1, f = 20kHz ±15V 1.5 Ω Shutdown Input Current SHDN = VEE + 0.1V ±15V – 10 µA

SHDN = V

CC

±15V 0.1 2 µA

Supply Current ±15V 250 330 µA

±5V 220 300 µA

SHDN = V

+ 0.1V ±5V 10 µA

EE

0°C ≤ TA ≤ 70°C, VCM = 0V unless otherwise noted.

SYMBOL PARAMETER CONDITIONS V

V

OS

I

OS

I

B

Input Offset Voltage ±15V 0.8 mV

Input VOS Drift (Note 5) ±2.5V to ±15V 3 8 µV/°C Input Offset Current ±2.5V to ±15V 20 nA Input Bias Current ±2.5V to ±15V 75 nA

SUPPLY

MIN TYP MAX UNITS

±5V 0.8 mV

±2.5V 1.0 mV

3

LT1351

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS V

0°C ≤ TA ≤ 70°C, VCM = 0V unless otherwise noted.

SUPPLY

MIN TYP MAX UNITS

CMRR Common Mode Rejection Ratio VCM = ±12V ±15V 78 dB

= ±2.5V ±5V 77 dB

V

CM

= ±0.5V ±2.5V 67 dB

V

CM

PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V 89 dB A

VOL

V

OUT

Large-Signal Voltage Gain V

= ±12V, RL = 5k ±15V 25 V/mV

OUT

= ±10V, RL = 2k ±15V 20 V/mV

V

OUT

= ±2.5V, RL = 5k ±5V 20 V/mV

V

OUT

V

= ±2.5V, RL = 2k ±5V 15 V/mV

OUT

= ±2.5V, RL = 1k ±5V 10 V/mV

V

OUT

= ±1V, RL = 5k ±2.5V 15 V/mV

V

OUT

Output Swing RL = 5k, VIN = ±10mV ±15V 13.4 ±V

= 2k, VIN = ±10mV ±15V 13.3 ±V

R

L

= 1k, VIN = ±10mV ±15V 12.0 ±V

R

L

= 1k, VIN = ±10mV ±5V 3.4 ±V

R

L

RL= 500Ω, VIN = ±10mV ±5V 3.3 ±V

= 5k, VIN = ±10mV ±2.5V 1.2 ±V

R

L

I

OUT

SC

Output Current V

Short-Circuit Current V

= ±12V ±15V 12.0 mA

OUT

= ±3.3V ±5V 6.6 mA

V

OUT

= 0V, VIN = ±3V ±15V 24 mA

OUT

SR Slew Rate AV = –1, RL = 5k (Note 3) ±15V 100 V/µs

±5V 21 V/µs

GBW Gain Bandwidth f = 200kHz, RL = 10k ±15V 1.8 MHz

±5V 1.6 MHz

I

SHDN

I

S

Shutdown Input Current SHDN = VEE + 0.1V ±15V – 20 µA

SHDN = V

CC

±15V 3 µA

Supply Current ±15V 380 µA

±5V 355 µA

SHDN = V

+ 0.1V ±5V 20 µA

EE

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

SYMBOL PARAMETER CONDITIONS V

V

OS

Input Offset Voltage ±15V 1.0 mV

SUPPLY

±5V 1.0 mV

±2.5V 1.2 mV

Input VOS Drift (Note 5) ±2.5V to ±15V 3 8 µV/°C

I

OS

I

B

Input Offset Current ±2.5V to ±15V 30 nA Input Bias Current ±2.5V to ±15V 100 nA

CMRR Common Mode Rejection Ratio VCM = ±12V ±15V 76 dB

= ±2.5V ±5V 76 dB

V

CM

= ±0.5V ±2.5V 66 dB

V

CM

PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V 87 dB A

VOL

Large-Signal Voltage Gain V

= ±12V, RL = 5k ±15V 20 V/mV

OUT

= ±10V, RL = 2k ±15V 15 V/mV

V

OUT

= ±2.5V, RL = 5k ±5V 15 V/mV

V

OUT

= ±2 .5V, RL = 2k ±5V 10 V/mV

V

OUT

V

= ±2.5V, RL = 1k ±5V 8 V/mV

OUT

= ±1V, RL = 5k ±2.5V 10 V/mV

V

OUT

MIN TYP MAX UNITS

4

LT1351

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS V

V

OUT

Output Swing RL = 5k, VIN = ±10mV ±15V 13.3 ±V

R

L

R

L

R

L

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

SUPPLY

= 2k, VIN = ±10mV ±15V 13.2 ±V = 1k, VIN = ±10mV ±15V 10.0 ±V = 1k, VIN = ±10mV ±5V 3.3 ±V

MIN TYP MAX UNITS

RL= 500Ω, VIN = ±10mV ±5V 3.2 ±V

= 5k, VIN = ±10mV ±2.5V 1.1 ±V

R

L

I

OUT

I

SC

Output Current V

Short-Circuit Current V

= ±10V ±15V 10.0 mA

OUT

= ±3.2V ±5V 6.4 mA

V

OUT

= 0V, VIN = ±3V ±15V 20 mA

OUT

SR Slew Rate AV = –1, RL = 5k (Note 3) ±15V 50 V/µs

±5V 15 V/µs

GBW Gain Bandwidth f = 200kHz, RL = 10k ±15V 1.6 MHz

±5V 1.4 MHz

I

SHDN

I

S

Shutdown Input Current SHDN = VEE + 0.1V ±15V – 30 µA

SHDN = V

CC

±15V 5 µA

Supply Current ±15V 390 µA

±5V 380 µA

SHDN = V

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

+ 0.1V ±5V 30 µA

EE

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.

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.

W

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TYPICAL PERFORMANCE CHARACTERISTICS

Supply Current vs Supply Voltage and Temperature

350

300

125°C

250

25°C

200

–55°C

SUPPLY CURRENT (µA)

150

100

0

5

10

SUPPLY VOLTAGE (±V)

15

20

1351 G01

Input Common Mode Range vs Supply Voltage

+

V

TA = 25°C

–0.5 –1.0 –1.5 –2.0

2.0

1.5

COMMON MODE RANGE (V)

1.0

0.5 V

= 1mV

∆V

OS

–

0

5

10

SUPPLY VOLTAGE (±V)

15

1351 G02

Input Bias Current vs Input Common Mode Voltage

30

TA = 25°C

= ±15V

V

S

+

–10

+ I

I

B

2

–



B

–5 0 5

10 15

1351 G03



20

IB =

10

0

INPUT BIAS CURRENT (nA)

–10

–20

20

–15

INPUT COMMON MODE VOLTAGE (V)

5

LT1351

LOAD RESISTANCE (Ω)

10

60

OPEN-LOOP GAIN (dB)

90

100

110

100 1k 10k

1351 G06

80

70

TA = 25°C

VS = ±5V

VS = ±15V

OUTPUT CURRENT (mA)

–20

V

–

OUTPUT VOLTAGE SWING (V)

0.5

1.5

2.0

V

+

25°C

–1.5



–10

0

5

1351 G09

1.0

–1.0

–0.5

–2.0

–15 –5

10

15

20

VS = ±5V V

IN

= 10mV

85°C

–40°C

85°C

25°C

SETTLING TIME (µs)

0.5

OUTPUT STEP (V)

2

6

10

1.3

1351 G12

–2

–6

0

4

8

–4

–8

–10

0.7

0.9

1.1

0.6 1.4

0.8

1.0

1.2

1.5

VS = ±15V A

V

= –1

R

G

= RF = 2k

C

F

= 5pF

R

L

= 2k

10mV 1mV

1mV10mV

W

U

TYPICAL PERFORMANCE CHARACTERISTICS

Input Bias Current vs Temperature Open-Loop Gain vs Resistive LoadInput Noise Spectral Density

40

VS = ±15V

36 32 28 24 20 16 12

INPUT BIAS CURRENT (nA)

8 4 0

–50

+

=

–25

+ I

I

B

2

–



B

0

TEMPERATURE (°C)



I

B

50

25

75

100

1351 G04

125

INPUT VOLTAGE NOISE (nV/√Hz)

100

TA = 25°C

= ±15V

V

S

= 101

A

V

= 100k

R

S

e

n

10

i

n

1

10

FREQUENCY (Hz)

100

1k 10k

 1351 G05

10

INPUT CURRENT NOISE (pA/√Hz)

1

0.1

Open-Loop Gain vs Temperature

100

VS = ±15V

= ±12V

V

O

99

= 5k

R

L

98

97

96

OPEN-LOOP GAIN (dB)

95

94

–50

–25 0

Output Short-Circuit Current vs Temperature

60

VS = ±15V

55

50

45



40

35

6

30

OUTPUT SHORT-CIRCUIT CURRENT (mA)

25

–50

–25 0

TEMPERATURE (°C)

SOURCE

TEMPERATURE (°C)

50 100 125

25 75

SINK

50 100 125

25 75

Output Voltage Swing vs Supply Voltage

+

V

15

RL = 2k

R

= 1k

L

RL = 1k

RL = 2k

1351 G08

1351 G07

–1

–2

–3



OUTPUT VOLTAGE SWING (V)

TA = 25°C V

3

2

1

–

V

0

= ±10mV

IN

510 20

SUPPLY VOLTAGE (V)

Settling Time vs Output Step (Noninverting)

10

8 6 4 2 0

–2

OUTPUT STEP (V)

–4 –6 –8

–10

0.7

1351 G10

10mV 1mV

0.8 1

0.9

SETTLING TIME (µs)

10mV

1.2 1.6

1.1

1.3

1mV

VS = ±15V

= 1

A

V

OUTPUT FILTER:

1.6MHz LPF

1.4

1.5

1351 G11

Output Voltage Swing vs Load Current

Settling Time vs Output Step (Inverting)

W

FREQUENCY (Hz)

100

0

COMMON MODE REJECTION RATIO (dB)

20

40

60

80

100

120

1k 10k 100k 1M

1351 G21

10M

TA = 25°C V

S

= ±15V

FREQUENCY (Hz)

10k

–2

GAIN (dB)

0

2

4

6

100k 1M 10M

1351 G15

–4

–6

–8

–10

8

10

TA = 25°C V

S

= ±15V

A

V

= –1

R

FB

= RG = 5k

C = 500pF

C = 100pF

C = 5000pF

C = 1000pF

C = 10pF

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TYPICAL PERFORMANCE CHARACTERISTICS

Gain and Phase vs Frequency

70

60

50

40

30

GAIN (dB)

20

10

0

–10

10k

1k 100k 1M 100M

PHASE

VS = ±15V

V

GAIN

FREQUENCY (Hz)

T

= 25°C

A

= –1

A

V

= RG = 5k

R

F

V

= ±15V

S

= ±5VVS = ±5V

S

10M

1351 G13

120

100

80

PHASE (DEG)

60

40

20

0

–20

–40

Output Impedance vs Frequency

1000

TA = 25°C

= ±15V

V

S

100

AV = 100

AV = 10

10

1

OUTPUT IMPEDANCE (Ω)

0.1

0.01 1k 100k 1M 10M

10k

AV = 1

FREQUENCY (Hz)

LT1351

Frequency Response vs Capacitive Load

1351 G14

Gain Bandwidth and Phase Margin vs Temperature

4.50

4.25

4.00

0

–25

TEMPERATURE (°C)

PHASE MARGIN

GAIN BANDWIDTH

3.75

3.50

3.25

3.00

2.75

GAIN BANDWIDTH (MHz)

2.50

2.25

2.00 –50

Gain Bandwidth and Phase Margin vs Supply Voltage

4.50

TA = 25°C

4.25

4.00

3.75

3.50

3.25

3.00

2.75

GAIN BANDWIDTH (MHz)

2.50

2.25

2.00

0

5 SUPPLY VOLTAGE (±V)

VS = ±15V

V

= ±5V

S

V

= ±15V

S

= ±5V

V

S

50

25

PHASE MARGIN

GAIN BANDWIDTH

75

10

Frequency Response vs Supply Voltage (AV = 1)

100

1351 G16

50 48 46

PHASE MARGIN (DEG)

44 42 40 38 36 34 32 30

125

5 4 3 2 1

0

GAIN (dB)

–1 –2 –3 –4 –5

10k

TA = 25°C

= 1

A

V

= 5k

R

L



±15V

±5V

±2.5V

100k 1M 10M

FREQUENCY (Hz)

1351 G17

Power Supply Rejection Ratio vs Frequency

50 48 46 44 42 40 38 36 34 32 30

15

20

1351 G19

120

100

PHASE MARGIN (DEG)

80

60

40

20

POWER SUPPLY REJECTION RATIO (dB)

0

10

100

1k 10k 100k

FREQUENCY (Hz)

–PSRR = +PSRR

TA = 25°C

= ±15V

V

S

1M 10M

1351 G20

Frequency Response vs Supply Voltage (AV = –1)

5

TA = 25°C

4

= –1

A

V

= RG = 5k

R

L

3 2 1 0

GAIN (dB)

–1 –2 –3 –4 –5

10k

100k 1M 10M

FREQUENCY (Hz)

±2.5V

Common Mode Rejection Ratio vs Frequency



±15V

±5V

1351 G18

7

LT1351

CAPACITIVE LOAD (F)

10p

40

OVERSHOOT (%)

50

60

70

80

100p 1n 10n 0.1µ 1µ

1351 G30

30 20 10

0

90

100

TA = 25°C V

S

= ±15V

R

L

= 5k

AV = 1

A

V

= –1

W

U

TYPICAL PERFORMANCE CHARACTERISTICS

Slew Rate vs Supply Voltage

200

TA = 25°C

= –1

A

V

= RG = 5k

R

F

+

+ SR–)/2

SR = (SR

150

100

SLEW RATE (V/µs)

50

0

510

SUPPLY VOLTAGE (±V)

Total Harmonic Distortion vs Frequency

1

TA = 25°C

= ±15V

V

S

= 5k

R

L

= 2V

V

O

P-P

0.1

0.01 AV = –1

TOTAL HARMONIC DISTORTION (%)

0.001 10

AV = 1

100 1k 10k 100k

FREQUENCY (Hz)

1351 G22

1351 G25

Slew Rate vs Temperature Slew Rate vs Input Level

250

200

VS = ±15V

150

100

SLEW RATE (V/µs)

50

15

0

–50 –25

0

TEMPERATURE (°C)

VS = ±5V

25

AV = –1

= RG = RL = 5k

R

F

SR = (SR

50

75

+

+ SR–)/2

100

125

1351 G23

Undistorted Output Swing vs Frequency (±15V)

30

AV = –1

25

)

P-P

20

15

10

OUTPUT VOLTAGE (V

VS = ±15V

5

= 5k

R

L

THD = 1%

0

10k

AV = 1

100k 1M

FREQUENCY (Hz)

1351 G26

200

TA = 25°C

= ±15V

V

S

175

= –1

A

V

= RG = 5k

R

FB

150

125

100

75

SLEW RATE (V/µs)

50

25

0

+

+ SR–)/2

SR = (SR

48 16

INPUT LEVEL (V

Undistorted Output Swing vs Frequency (±5V)

10

9 8

)

P-P

7 6 5 4

3

OUTPUT VOLTAGE (V

2

VS = ±5V

= 5k

R

L

1

THD = 1%

0

10k

FREQUENCY (Hz)

P-P

20

)

1351 G24

AV = 1

1351 G27

12

= –1

A

V

100k 1M

24

8

2nd and 3rd Harmonic Distortion vs Frequency

–30

= ±15V

V

S

= 1

A

V

–40

= 5k

R

L

= 2V

V

O

P-P

–50

3RD HARMONIC

–60

–70

HARMONIC DISTORTION (dB)

–80

–90

100k

2ND HARMONIC

FREQUENCY (Hz)

1351 G28

1M

Shutdown Supply Current vs Temperature

100

VS = ±15V

90 80 70 60 50 40 30

SUPPLY CURRENT (µA)

20 10

0

–50

–25

V

SHDN

0

= V

SHDN

= V

EE

V

SHDN

25

TEMPERATURE (°C)

EE

+ 0.1

= V

+ 0.2

EE

50

Capacitive Load Handling

100

125

1351 G29

75

W

U

TYPICAL PERFORMANCE CHARACTERISTICS

LT1351

Small-Signal Transient (AV = 1)

Large-Signal Transient (AV = 1)

Small-Signal Transient (AV = –1)

Large-Signal Transient (AV = –1)

Small-Signal Transient (AV = –1, CL = 1000pF)

1351 G331351 G321351 G31

Large-Signal Transient (AV = 1, CL = 10,000pF)

U

WUU

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 removed. The suggested nulling circuit for the LT1351 is shown in Figure 1.

+

V

3

+

LT1351

2

–

Figure 1. Offset Nulling

7

4

8

1

100k

–

V

0.1µF

6

0.1µF

1351 F01

1351 G361351 G351351 G34

Layout and Passive Components

The LT1351 amplifier is easy to apply and tolerant of less than ideal layouts. For maximum performance (for example fast settling time) use a ground plane, short lead lengths and RF-quality bypass capacitors (0.01µF to 0.1µF). For high drive current applications use low ESR bypass capacitors (1µ F to 10µ F tantalum). For details see Design Note 50.

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 peaking or even oscillations. For feedback resistors greater than 10k, a parallel capacitor of value, CF > (RG)(CIN/RF) should be used to cancel the input pole and optimize dynamic performance. For applications where the DC

9

LT1351

U

WUU

APPLICATIONS INFORMATION

noise gain is one and a large feedback resistor is used, C should be greater than or equal to CIN. An example would be an I-to-V converter as shown in the Typical Applications section.

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 Frequency Response vs Capacitive Load, Capacitive Load Handling and the transient response photos clearly show these effects.

Input Considerations

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 can withstand transient differential input voltages up to 10V without damage and need no clamping or source resistance for protection. Differential inputs, however, 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.

a comparator, peak detector or other open-loop application with large, sustained differential inputs

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 part should not be used as

. Under

F

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 10µ A. 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.

A level shift application is shown in the Typical Applications section so that a ground-referenced logic signal can control the Shutdown pin.

Circuit Operation

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.

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 CT. 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 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 output step in unity gain has a 10 times greater input step. The curve of Slew Rate vs Input Level illustrates this relationship.

Capacitive load compensation is provided by the RC, 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

C

10

LT1351

U

WUU

APPLICATIONS INFORMATION

resistive load) the network is incompletely bootstrapped and adds to the compensation at the high impedance node. The added capacitance slows down the amplifier and a zero is created by the RC combination, both of

WW

SI PLIFIED SCHE ATIC

+

V

Q10

Q3

Q7

R1

–IN

Q5

Q6

1k

Q4

Q8

Q1

Q2

+IN

which improve the phase margin. The design ensures that even for very large load capacitances the total phase lag can never exceed 180 degrees (zero phase margin) and the amplifier remains stable.

R3

Q21

OUTPUT

Q11

Q9

Q13

R2

Q12

R6

Q17

C

T

Q18

R

C

R7

Q20

C1

Q19

C

Q22

C2

–

V

U

TYPICAL APPLICATIONS

4.64k

V

IN

13.3k

2200pF

Q14

Q15

20kHz, 4th Order Butterworth Filter

4.64k

470pF

–

LT1351

+

5.49k

11.3k

4700pF

5.49k

–

+

Q16

220pF

LT1351

Q23

V

1351 TA03

OUT

Q24

R4

R5

1351 SS

11

LT1351

TYPICAL APPLICATIONS

SHDN

U

1N4148

Shutdown Circuit

1M

S

G

SST177 D

1M

3

+

LT1351

2

–

G

5

S SST177 D

–

V

6

1351 TA04

DAC I-to-V Converter

12

DAC

INPUTS

565A TYPE

V



VOS + IOS (5kΩ) + < 0.5LSB

OUT

A

VOL

10pF

5k

–

LT1351

V

OUT

+

5k

1351 TA05

12

PACKAGE DESCRIPTION

U

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

LT1351

0.192 ± 0.004

(4.88 ± 0.10)

12

3

0.040 ± 0.006

SEATING

PLANE

(1.02 ± 0.15)

0.012

(0.30)

0.0256

REF

(0.65)



TYP

0.007

(0.18)

0.021 ± 0.006

(0.53 ± 0.015)

 * 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

0° – 6° TYP

0.118 ± 0.004** (3.00 ± 0.102)

4

0.034 ± 0.004 (0.86 ± 0.102)

0.006 ± 0.004 (0.15 ± 0.102)

MSOP (MS8) 1197

13

LT1351

PACKAGE DESCRIPTION

U

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

876

5

0.255 ± 0.015* (6.477 ± 0.381)

0.300 – 0.325

(7.620 – 8.255)

0.065

(1.651)

0.009 – 0.015

(0.229 – 0.381)

+0.035

0.325

–0.015 +0.889

8.255

()

–0.381

*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)

TYP

(2.540 ± 0.254)



12

0.045 – 0.065

(1.143 – 1.651)

0.100 ± 0.010

3

4

0.130 ± 0.005

(3.302 ± 0.127)

0.125

(3.175)

MIN

0.018 ± 0.003

(0.457 ± 0.076)

0.020

(0.508)



MIN

N8 1197

14

PACKAGE DESCRIPTION

U

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

8

5

6

LT1351

0.010 – 0.020

(0.254 – 0.508)

0.008 – 0.010

(0.203 – 0.254)

*

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  

× 45°

0°– 8° TYP

0.016 – 0.050

0.406 – 1.270

0.228 – 0.244

(5.791 – 6.197)

0.053 – 0.069

(1.346 – 1.752)

0.014 – 0.019

(0.355 – 0.483)

0.150 – 0.157** (3.810 – 3.988)

1

3

2

4

0.004 – 0.010

(0.101 – 0.254)

0.050

(1.270)

TYP

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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

15

LT1351

TYPICAL APPLICATION

V

IN

U

Low Power Sample-and-Hold

–

LT1351

+

DROOP: 20nA/2000pF = 10mV/ms ACQUISITION TIME: 10V, 0.1% = 2µs CHARGE INJECTION ERROR: 8pC/2000pF = 4mV

LTC201

2000pF

–

LT1351

+

V

OUT

1351 TA06

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LT1352/LT1353 Dual/Quad 250µA, 3MHz, 200V/µs Op Amp Good DC Precision, Stable with All Capacitive Loads LT1354 1mA, 12MHz, 400V/µs Op Amp Good DC Precision, Stable with All Capacitive Loads

16

Linear T echnolog y Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507

●

www.linear-tech.com

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

 LINEAR TECHNOLOGY CORPORATION 1996