ANALOG DEVICES LT 1354 CS8 Datasheet

FEATURES

■

12MHz Gain-Bandwidth

■

400V/µs Slew Rate

■

1.25mA Maximum Supply Current

■

Unity Gain Stable

■

C-LoadTM Op Amp Drives All Capacitive Loads

■

10nV/√Hz Input Noise Voltage

■

800µV Maximum Input Offset Voltage

■

300nA Maximum Input Bias Current

■

70nA Maximum Input Offset Current

■

12V/mV Minimum DC Gain, RL=1k

■

230ns Settling Time to 0.1%, 10V Step

■

280ns Settling Time to 0.01%, 10V Step

■

±12V Minimum Output Swing into 500Ω

■

±2.5V Minimum Output Swing into 150Ω

■

Specified at ±2.5V, ±5V, and ±15V

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APPLICATIONS

■

Wideband Amplifiers

■

Buffers

■

Active Filters

■

Data Acquisition Systems

■

Photodiode Amplifiers

LT1354

12MHz, 400V/µs Op Amp

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DESCRIPTION

®

The LT operational amplifier with outstanding AC and DC performance. The LT1354 has much lower supply current, lower input offset voltage, lower input bias current, and higher DC gain than devices with comparable bandwidth. The circuit topology is a voltage feedback amplifier with the slewing characteristics of a current feedback amplifier. The amplifier is a single gain stage with outstanding settling characteristics which makes the circuit an ideal choice for data acquisition systems. The output drives a 500Ω load to ±12V with ±15V supplies and a 150Ω load to ±2.5V on ±5V supplies. The amplifier is also stable with any capacitive load which makes it useful in buffer or cable driver applications.

The LT1354 is a member of a family of fast, high performance amplifiers using this unique topology and employing Linear Technology Corporation’s advanced bipolar complementary processing. For dual and quad amplifier versions of the LT1354 see the LT1355/LT1356 data sheet. For higher bandwidth devices with higher supply current see the LT1357 through LT1365 data sheets. Singles, duals, and quads of each amplifier are available.

C-Load is a trademark of Linear Technology Corporation

1354 is a low power, high speed, high slew rate

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

TYPICAL APPLICATION

100kHz, 4th Order Butterworth Filter

6.81k

100pF

V

IN

11.3k6.81k

330pF

–

LT1354

+

5.23k

U

10.2k

1000pF

5.23k

–

LT1354

+

47pF

V

1354 TA01

AV = –1 Large-Signal Response

OUT

1354 TA02

1

LT1354

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

U

W

U

PACKAGE/ORDER INFORMATION

TOP VIEW

1NULL 2

–IN +IN

3

–

V

N8 PACKAGE, 8-LEAD PLASTIC DIP

= 150°C, θJA = 130°C/W

JMAX

Consult factory for Industrial and Military grade parts.

8

NULL

+

7

V

6

V

OUT

54

NC

ORDER PART

NUMBER

LT1354CN8

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

TOP VIEW

1NULL 2

–IN +IN

3

–

V

S8 PACKAGE, 8-LEAD PLASTIC SOIC

T

= 150°C, θJA = 190°C/WT

JMAX

8

NULL

7

V

6

V

54

NC

+

OUT

ORDER PART

NUMBER

LT1354CS8

S8 PART MARKING

1354

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 V

PSRR Power Supply Rejection Ratio VS = ±2.5V to ±15V 92 106 dB A

VOL

Input Offset Voltage ±15V 0.3 0.8 mV

Input Offset Current ±2.5V to ±15V 20 70 nA Input Bias Current ±2.5V to ±15V 80 300 nA Input Noise Voltage f = 10kHz ±2.5V to ±15V 10 nV/√Hz Input Noise Current f = 10kHz ±2.5V to ±15V 0.6 pA/√Hz Input Resistance V

Input Capacitance ±15V 3 pF Input Voltage Range

Input Voltage Range

Large-Signal Voltage Gain V

+

–

CM

Differential ±15V 11 MΩ

CM

V

CM

V

CM

OUT

V

OUT

V

OUT

V

OUT

V

OUT

V

OUT

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

SUPPLY

±5V 0.3 0.8 mV ±2.5V 0.4 1.0 mV

= ±12V ±15V 70 160 MΩ

±15V 12.0 13.4 V ±5V 2.5 3.5 V ±2.5V 0.5 1.1 V

±15V –13.2 –12.0 V ±5V –3.4 –2.5 V ±2.5V – 0.9 – 0.5 V

= ±12V ±15V 80 97 dB = ±2.5V ±5V 78 84 dB = ±0.5V ±2.5V 68 75 dB

= ±12V, RL = 1k ±15V 12 36 V/mV = ±10V, RL = 500Ω±15V 5 15 V/mV = ±2.5V, RL = 1k ±5V 12 36 V/mV = ±2.5V, RL = 500Ω±5V 5 15 V/mV = ±2.5V, RL = 150Ω±5V 1 4 V/mV = ±1V, RL = 500Ω±2.5V 5 20 V/mV

MIN TYP MAX UNITS

2

LT1354

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS V

V

I

OUT

SC

Output Swing RL = 1k, V

R

= 500Ω, V

L

R

= 500Ω, V

L

R

= 150Ω, V

L

RL = 500Ω, V

Output Current V

Short-Circuit Current V

V

OUT OUT

OUT

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

SUPPLY

= ±40mV ±15V 13.3 13.8 ±V

IN

= ±40mV ±15V 12.0 12.5 ±V

IN

= ±40mV ±5V 3.5 4.0 ±V

IN

= ±40mV ±5V 2.5 3.1 ±V

IN

= ±40mV ±2.5V 1.3 1.7 ±V

IN

= ±12V ±15V 24.0 30 mA = ±2.5V ±5V 16.7 25 mA

= 0V, V

= ±3V ±15V 30 42 mA

IN

MIN TYP MAX UNITS

SR Slew Rate AV = –2, (Note 3) ±15V 200 400 V/µs

±5V 70 120 V/µs

Full Power Bandwidth 10V Peak, (Note 4) ±15V 6.4 MHz

3V Peak, (Note 4) ±5V 6.4 MHz

GBW Gain-Bandwidth f = 200kHz, RL = 2k ±15V 9.0 12.0 MHz

±5V 7.5 10.5 MHz ±2.5V 9.0 MHz

tr, t

f

Rise Time, Fall Time AV = 1, 10%-90%, 0.1V ±15V 14 ns

±5V 17 ns

Overshoot AV = 1, 0.1V ±15V 20 %

±5V 18 %

Propagation Delay 50% VIN to 50% V

, 0.1V ±15V 16 ns

OUT

±5V 19 ns

t

s

Settling Time 10V Step, 0.1%, AV = –1 ±15V 230 ns

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

= –1 ±15V 280 ns

V

= –1 ±5V 240 ns

V

= –1 ±5V 380 ns

V

Differential Gain f = 3.58MHz, AV = 2, RL = 1k ±15V 2.2 %

±5V 2.1 %

Differential Phase f = 3.58MHz, AV = 2, RL = 1k ±15V 3.1 Deg

±5V 3.1 Deg

R

O

I

S

Output Resistance AV = 1, f = 100kHz ±15V 0.7 Ω Supply Current ±15V 1.0 1.25 mA

±5V 0.9 1.20 mA

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

SYMBOL PARAMETER CONDITIONS V

V

OS

I

OS

I

B

CMRR Common Mode Rejection Ratio V

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

VOL

Input Offset Voltage ±15V

Input VOS Drift (Note 5) ±2.5V to ±15V Input Offset Current ±2.5V to ±15V Input Bias Current ±2.5V to ±15V

= ±12V ±15V

CM

V

= ±2.5V ±5V

CM

V

= ±0.5V ±2.5V

CM

Large-Signal Voltage Gain V

= ±12V, RL = 1k ±15V

OUT

V

= ±10V, RL = 500Ω±15V

OUT

V

= ±2.5V, RL = 1k ±5V

OUT

V

= ±2.5V, RL = 500Ω±5V

OUT

V

= ±2.5V, RL = 150Ω±5V

OUT

V

= ±1V, RL = 500Ω±2.5V

OUT

SUPPLY

±5V ±2.5V

MIN TYP MAX UNITS

●

79 dB

●

77 dB

●

67 dB

●

90 dB

●

10.0 V/mV

●

3.3 V/mV

●

10.0 V/mV

●

3.3 V/mV

●

0.6 V/mV

●

3.3 V/mV

1.0 mV

1.2 mV

58 µV/°C

100 nA 450 nA

3

LT1354

ELECTRICAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS V

V

I

OUT

SC

Output Swing RL = 1k, V

R

= 500Ω, V

L

R

= 500Ω, V

L

R

= 150Ω, V

L

R

= 500Ω, V

L

Output Current V

Short-Circuit Current V

V

OUT OUT

OUT

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

SUPPLY

= ±40mV ±15V

IN

= ±40mV ±15V

IN

= ±40mV ±5V

IN

= ±40mV ±5V

IN

= ±40mV ±2.5V

IN

= ±11.5V ±15V = ±2.3V ±5V

= 0V, V

= ±3V ±15V

IN

SR Slew Rate AV = –2, (Note 3) ±15V

±5V

GBW Gain-Bandwidth f = 200kHz, RL = 2k ±15V

±5V

I

S

Supply Current ±15V

±5V

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

SYMBOL PARAMETER CONDITIONS V

V

OS

Input Offset Voltage ±15V

Input VOS Drift (Note 5) ±2.5V to ±15V

I

OS

I

B

CMRR Common Mode Rejection Ratio V

Input Offset Current ±2.5V to ±15V Input Bias Current ±2.5V to ±15V

= ±12V ±15V

CM

V

= ±2.5V ±5V

CM

V

= ±0.5V ±2.5V

CM

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

V

I

VOL

OUT

SC

Large-Signal Voltage Gain V

= ±12V, RL = 1k ±15V

OUT

V

= ±10V, RL = 500Ω±15V

OUT

V

= ±2.5V, RL = 1k ±5V

OUT

V

= ±2.5V, RL = 500Ω±5V

OUT

V

= ±2.5V, RL = 150Ω±5V

OUT

V

= ±1V, RL = 500Ω±2.5V

OUT

Output Swing RL = 1k, V

R

= 500Ω, V

L

R

= 500Ω, V

L

R

= 150Ω, V

L

R

= 500Ω, V

L

Output Current V

Short-Circuit Current V

= ±11V ±15V

OUT

V

= ±2.1V ±5V

OUT

= 0V, V

OUT

= ±40mV ±15V

IN

= ±40mV ±15V

IN

= ±40mV ±5V

IN

= ±40mV ±5V

IN

= ±40mV ±2.5V

IN

= ±3V ±15V

IN

SR Slew Rate AV = –2, (Note 3) ±15V

GBW Gain Bandwith f = 200kHz, R

I

S

Supply Current ±15V

= 2k ±15V

L

SUPPLY

±5V ±2.5V

±5V

MIN TYP MAX UNITS

●

13.2 ±V

●

11.5 ±V

●

3.4 ±V

●

2.3 ±V

●

1.2 ±V

●

23.0 mA

●

15.3 mA

●

24 mA

●

150 V/µs

●

60 V/µs

●

7.5 MHz

●

6.0 MHz

●

1.45 mA

1.40 mA

MIN TYP MAX UNITS

●

78 dB

●

76 dB

●

66 dB

●

90 dB

●

7.0 V/mV

●

1.7 V/mV

●

7.0 V/mV

●

1.7 V/mV

●

0.4 V/mV

●

1.7 V/mV

●

13.0 ±V

●

11.0 ±V

●

3.4 ±V

●

2.1 ±V

●

1.2 ±V

●

22 mA

●

14 mA

●

23 mA

●

120 V/µs

●

50 V/µs

●

7.0 MHz

●

5.5 MHz

●

1.5 mV

1.7 mV

58 µV/°C

200 nA 550 nA

1.50 mA

1.45 mA

4

ELECTRICAL CHARACTERISTICS

LOAD RESISTANCE (Ω)

10

50

OPEN-LOOP GAIN (dB)

60

100

100 10k

1354 G06

80

70

1k

90

VS = ±5V

VS = ±15V

T

A

= 25°C

The ● denotes specifications that apply over the full specified temperature range.

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 dutails.

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 ±10V on the output with ±6V input for ±15V supplies and ± 1V on the output with ±1.75V input for ±5V supplies.

Note 4: Full power bandwidth is calculated from the slew rate measurement: FPBW = SR/2πV

Note 5: This parameter is not 100% tested. Note 6: The LT1354 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.

UW

TYPICAL PERFORMANCE CHARACTERISTICS

LT1354

.

P

Supply Current vs Supply Voltage and Temperature

1.4

1.2

1.0

0.8

SUPPLY CURRENT (mA)

0.6

0.4 10501520

SUPPLY VOLTAGE (±V)

125°C

25°C

–55°C

1354 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

SUPPLY VOLTAGE (±V)

10501520

1354 G02

Input Bias Current vs Temperature

200

175

150

125

100

75

50

INPUT BIAS CURRENT (nA)

25

0

–50 –25 25 100 12550 750

TEMPERATURE (°C)

VS = ±15V

+

I

B

I

=

————

B

 

+ I

–



B

2

1354 G04

Input Noise Spectral Density

100

e

n

i

n

10

INPUT VOLTAGE NOISE (nV/√Hz)

1

10

1k100 100k10k

FREQUENCY (Hz)

VS = ±15V

= 25°C

T

A

= 101

A

V

= 100k

R

S

10

INPUT CURRENT NOISE (pA/√Hz)

1

0.1

1354 G05

Input Bias Current vs Input Common-Mode Voltage

200

VS = ±15V

= 25°C

T

A

+

–

I

+ I

150

I

=

B

 

100

50

INPUT BIAS CURRENT (nA)

0

–50

–15 –10 0 10 155–5

INPUT COMMON-MODE VOLTAGE (V)

B

————

2



Open-Loop Gain vs Resistive Load

1354 G03

5

LT1354

SUPPLY VOLTAGE (±V)

8

GAIN-BANDWIDTH (MHz)

12

10

18

16

14

11

9

17

15

13

30

PHASE MARGIN (DEG)

38

34

50 48

44

40

36

32

46

42

10501520

1354 G15

TA = 25°C

PHASE MARGIN

GAIN-BANDWIDTH

SETTLING TIME (ns)

–10

OUTPUT SWING (V)

–6

–4

–8

10

8 6 4

–2

2 0

50 200 300 350250100 150

1355/1356 G12

VS = ±15V A

V

= –1

10mV

1mV

UW

TYPICAL PERFORMANCE CHARACTERISTICS

Open-Loop Gain vs Temperature

97

RL = 1k

96

= ±12V

V

O

= ±15V

V

S

95

94

93

92

91

OPEN-LOOP GAIN (dB)

90

89

88

–50 –25 25 100 12550 750

TEMPERATURE (°C)

Output Short-Circuit Current vs Temperature

65

60

55

50 45

40

35

30

25

OUTPUT SHORT-CIRCUIT CURRENT (mA)

20

–50 –25 25 100 12550 750

SOURCE

TEMPERATURE (°C)

SINK

VS = ±5V

1354 G07

1354 G10

Output Voltage Swing vs Supply Voltage

+

V

TA = 25°C

–1

–2

–3

3

2

OUTPUT VOLTAGE SWING (V)

1

–

V

R

= 500Ω

L

R

= 500Ω

L

10501520

SUPPLY VOLTAGE (±V)

Settling Time vs Output Step (Noninverting)

10

VS = ±15V

8

= 1

A

V

6

10mV

4 2 0

–2

OUTPUT SWING (V)

–4 –6 –8

–10

10mV

50 200 300 350250100 150

SETTLING TIME (ns)

1mV

RL = 1k

= 1k

R

L

1354 G08

1354 G11

Output Voltage Swing vs Load Current

+

V

–0.5

VS = ±5V

–1.0 –1.5 –2.0 –2.5

2.5

2.0

OUTPUT VOLTAGE SWING (V)

1.5

1.0

–

+0.5

V

= 100mV

V

IN

–40°C

–50 –40 –10 30 40 5001020–20–30

–40°C

85°C

25°C

OUTPUT CURRENT (mA)

Settling Time vs Output Step (Inverting)

85°C

25°C

1354 G09

Output Impedance vs Frequency

1k

100

10

1

OUTPUT IMPEDANCE (Ω)

0.1

0.01 10k

6

VS = ±15V

= 25°C

T

AV = 100

AV = 1

100k 100M

1M

FREQUENCY (Hz)

A

AV = 10

10M

1354 G13

70

60

50

40

30

GAIN (dB)

20

10

0

–10

10k

Gain and Phase vs Frequency

PHASE

VS = ±15V

GAIN

VS = ±5V



= 25°C

T

A

= –1

A

V

= RG = 2k

R

F

100k 100M

VS = ±5V

1M

FREQUENCY (Hz)

10M

1354 G14

120

100

PHASE (DEG)

80

60

40

20

0

Gain-Bandwidth and Phase Margin vs Supply Voltage

UW

FREQUENCY (Hz)

100k

–5

GAIN (dB)

–3 –4

5

1M 100M

1354 G18

1

–1

10M

3

–2

2

0

4

±15V

±2.5V

T

A

= 25°C

A

V

= –1

R

F

= RG = 2k

±5V

FREQUENCY (Hz)

0

COMMON-MODE REJECTION RATIO (dB)

40

20

120

100

80

60

1k 100M10M1M100k10k

1354 G21

VS = ±15V T

A

= 25°C



INPUT LEVEL (V

P-P

)

0

SLEW RATE (V/µs)

100

500

400

200

300

0 8 16 2012421018146

1354 G24

VS = ±15V A

V

= –1

R

F

= RG = 2k SR = TA = 25°C



SR

+

+ SR–

—————

2

TYPICAL PERFORMANCE CHARACTERISTICS

LT1354

Gain-Bandwidth and Phase Margin vs Temperature

18 17 16 15 14

13 12 11

GAIN-BANDWIDTH (MHz)

10

GAIN-BANDWIDTH V

S

9 8

–50 –25 25 100 12550 750

= ±5V

PHASE MARGIN

= ±15V

V

S

TEMPERATURE (°C)

Frequency Response vs Capacitive Load

10

VS = ±15V

8

= 25°C

T

A

= –1

A

6

V

4 2

0

–2

–4

VOLTAGE MAGNITUDE (dB)

–6 –8

–10

100k

1M 100M10M

FREQUENCY (Hz)

PHASE MARGIN

= ±5V

V

S

GAIN-BANDWIDTH

= ±15V

V

S

C = 1000pF

C = 500pF

C = 100pF

C = 50pF

C = 0

1354 G16

1354 G19

Frequency Response vs Supply Voltage (A

52 50 48 46

44 42 40

38 36 34

32

5

T

= 25°C

A

4

= 1

A

V

= 2k

R

3

–4

–1 –2

–3

–5

L

2 1

0

100k

PHASE MARGIN (DEG)

GAIN (dB)

Power Supply Rejection Ratio vs Frequency

100

80

60

40

20

POWER SUPPLY REJECTION RATIO (dB)

+PSRR

0

= 1)

V

±15V

±5V

±2.5V

1M 100M

FREQUENCY (Hz)

10M

1354 G17

VS = ±15V

= 25°C

T

A

–PSRR

100k 1M1k 10k100 10M 100M

1354 G20

Frequency Response vs Supply Voltage (A

= –1)

V

Common-Mode Rejection Ratio vs Frequency

Slew Rate vs Supply Voltage

600

AV = –1

= RG = 2k

R

F

500

400

300

200

SLEW RATE (V/µs)

100

0

015105

+

SR

+ SR–

SR =

—————

TA = 25°C 

2

SUPPLY VOLTAGE (±V)

1354 G22

Slew Rate vs Temperature

350

AV = –2 

300

250

SR+ + SR–

SR = ————— 

200

150

SLEW RATE (V/µs)

100

50

–50 –25 25 100 12550 750

2

TEMPERATURE (°C)

= ±15V

V

S

V

S

Slew Rate vs Input Level

= ±5V

1354 G23

7

LT1354

FREQUENCY (Hz)

100k 1M

0

OUTPUT VOLTAGE (V

P-P

)

10

10M

1354 G27

6

2

4

8

AV = –1

AV = 1

VS = ±5V R

L

= 5k

A

V

= 1,

2% MAX DISTORTION A

V

= –1,

3% MAX DISTORTION

W

U

TYPICAL PERFORMANCE CHARACTERISTICS

Total Harmonic Distortion vs Frequency

0.1 TA = 25°C

= 3V

V R

0.01

0.001

TOTAL HARMONIC DISTORTION (%)

0.0001 10



O

RMS

= 2k

L

AV = –1

AV = 1

100 100k

1k

FREQUENCY (Hz)

2nd and 3rd Harmonic Distortion vs Frequency

–20

VS = ±15V

= 2V

V

–30

R A

–40

–50

–60

HARMONIC DISTORTION (dB)

–70



O

P-P

= 2k

L

= 2

V

3RD HARMONIC

2ND HARMONIC

10k

1354 G25

Undistorted Output Swing vs Frequency (±15V)

30

25

)

P-P

20

15

VS = ±15V

10

= 5k

R

L

= 1,

A

OUTPUT VOLTAGE (V

V

1% MAX DISTORTION

5

= –1,

A

V

4% MAX DISTORTION

0 100k 1M

FREQUENCY (Hz)

Differential Gain and Phase vs Supply Voltage

DIFFERENTIAL GAIN

AV = 2

= 1k

R

3.4

3.3

3.2

DIFFERENTIAL PHASE (DEGREES)

L

= 25°C

T

A



DIFFERENTIAL PHASE

AV = 1

AV = –1

10M

1355/1356 G26

Undistorted Output Swing vs Frequency (±5V)

Capacitive Load Handling

2.5

2.0

1.5

100

DIFFERENTIAL PHASE (PERCENT)

TA = 25°C

= ±15V

V

S



50

OVERSHOOT (%)

AV = 1

AV = –1

–80

8

100k 200k 400k

1M 2M 4M

FREQUENCY (Hz)

Small-Signal Transient

= 1)

(A

V

1354 G28

1354 TA31

10M

3.1

±5 ±10 ±15

SUPPLY VOLTAGE (V)

Small-Signal Transient

= –1)

(A

V

1354 G29

1354 TA32

0

10p

1000p 0.01µ

100p 0.1µ

CAPACITIVE LOAD (F)

Small-Signal Transient

= –1, CL = 1000pF)

(A

V

1µ

1354 G30

1354 TA33

W

U

TYPICAL PERFORMANCE CHARACTERISTICS

LT1354

Large-Signal Transient

= 1)

(A

V

1354 TA34 1354 TA35 1354 TA36

U

WUU

Large-Signal Transient (A

= –1)

V

APPLICATIONS INFORMATION

The LT1354 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 LT1354 is shown below.

Offset Nulling

+

V

3

2

Layout and Passive Components

The LT1354 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 (1µF to 10µF tantalum). Sockets should be avoided when maximum frequency performance is required, although low profile sockets can provide reasonable performance up to 50MHz. For more details see Design Note 50.

+

–

1

LT1354

10k

7

6

4

8

–

V

1354 AI01

Large-Signal Transient

= 1, CL = 10,000pF)

(A

V

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 oscillations. For feedback resistors greater than 5kΩ, a parallel capacitor of value

> (RG • CIN)/R

C

F

should be used to cancel the input pole and optimize dynamic performance. For unity-gain applications where a large feedback resistor is used, C than or equal to C

IN

.

should be greater

F

Capacitive Loading

The LT1354 is stable with any capacitive load. This is accomplished by sensing the load induced output pole and adding compensation at the amplifier gain node. 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 as shown in the typical performance curves.The photo of the small-signal response with 1000pF load shows 43% peaking. The large signal response with a 10,000pF load shows the output slew rate being limited to 5V/µs by the short-circuit current. Coaxial cable can be driven directly, but for best pulse fidelity a resistor of value equal to the characteristic impedance of the cable (i.e., 75Ω) should be placed in series with the output. The other end of the cable should be terminated with the same value resistor to ground.

9

LT1354

U

WUU

APPLICATIONS INFORMATION

Input Considerations

Each of the LT1354 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.

Power Dissipation

The LT1354 combines high speed and large output drive in a small package. Because of the wide supply voltage range, it is possible to exceed the maximum junction temperature under certain conditions. Maximum junction temperature (T ture (T

) and power dissipation (PD) as follows:

A

) is calculated from the ambient tempera-

J

The part should not be used as

. Under

either supply voltage (or the maximum swing if less than 1/2 supply voltage). Therefore P

P

Example: LT1354CS8 at 70°C, VS = ±15V, RL = 100Ω (Note: the minimum short-circuit current at 70°C is 24mA, so the output swing is guaranteed only to 2.4V with 100Ω.)

P

T

Circuit Operation

The LT1354 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 an 800Ω resistor. The input voltage appears across the resistor generating currents which are mirrored into the high impedance node. Complementary followers form an output stage which buffers the gain node from the load. 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 gain node 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. The LT1354 is tested for slew rate in a gain of –2 so higher slew rates can be expected in gains of 1 and –1, and lower slew rates in higher gain configurations.

= (V+ – V–)(I

DMAX

= (30V • 1.45mA) + (15V–2.4V)(24mA) = 346mW

DMAX

= 70°C + (346mW • 190°C/W) = 136°C

JMAX

) + (V+/2)2/R

SMAX

DMAX

is:

L

LT1354CN8: T LT1354CS8: T

Worst case power dissipation occurs at the maximum supply current and when the output voltage is at 1/2 of

= TA + (PD • 130°C/W)

J

= TA + (PD • 190°C/W)

J

10

The RC network across the output stage is bootstrapped when the amplifier is driving a light or moderate load and has no effect under normal operation. When driving a capacitive load (or a low value resistive load) the network is incompletely bootstrapped and adds to the compensation at the high impedance node. The added capacitance

LT1354

U

WUU

APPLICATIONS INFORMATION

slows down the amplifier which improves the phase margin by moving the unity gain frequency away from the pole formed by the output impedance and the capacitive load. The zero created by the RC combination adds phase

E

W

A

TI

C

R1

800Ω

W

SPL

I

IIFED S

–IN

CH

+

V

to ensure that even for very large load capacitances, the total phase lag can never exceed 180 degrees (zero phase margin) and the amplifier remains stable.

+IN

C

R

C

OUT

–

V

U

PACKAGE DESCRIPTION

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)

0.045 – 0.065

(1.143 – 1.651)

0.100 ± 0.010

Dimensions in inches (millimeters) unless otherwise noted.

N8 Package

8-Lead PDIP (Narrow 0.300)

(LTC DWG # 05-08-1510)

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

0.255 ± 0.015* (6.477 ± 0.381)



876



12

0.400* (10.160)

MAX

1354 SS01

3

5

4

N8 1197

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.

11

LT1354

PACKAGE DESCRIPTION

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°

(1.346 – 1.752)

0°– 8° TYP

0.016 – 0.050

0.406 – 1.270

U

TYPICAL APPLICATIONS

Instrumentation Amplifier

U

Dimensions in inches (millimeters) unless otherwise noted.

S8 Package

8-Lead Plastic Small Outline (Narrow 0.150)

(LTC DWG # 05-08-1610)

0.053 – 0.069

0.004 – 0.010

(0.101 – 0.254)

0.228 – 0.244

0.014 – 0.019

(0.355 – 0.483)

0.050

(1.270)

TYP

(5.791 – 6.197)

100kHz, 4th Order Butterworth Filter

(Sallen-Key)

0.189 – 0.197* (4.801 – 5.004)

7

8

1

2

5

6

0.150 – 0.157** (3.810 – 3.988)

3

4

SO8 0996

R5

432Ω

R1

20k

–

V

IN

–

LT1354

+

R2

2k

R3 2k

–

LT1354

+

R4

20k

C4

R3

2.43k

1000pF

R4

15.4k

–

LT1354

+

C3 68pF

C2

330pF

–

LT1354

V

IN

R1

V

OUT

2.87k

R2

26.7k

+

C1 100pF

+





R

4

1



A

=+ +

1

V

R

3

2





TRIM R5 FOR GAIN TRIM R1 FOR COMMON MODE REJECTION BW = 120kHz



RRRRRR

2

3





1

4





+

23

+

R

5

 

=

104





1354 TA03

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LT1355/LT1356 Dual/Quad 1mA, 12MHz, 400V/µs Op Amp Good DC Precision, Stable with All Capacitive Loads LT1357 2mA, 25MHz, 600V/µs Op Amp Good DC Precision, Stable with All Capacitive Loads LT1358/LT1359 Dual/Quad 2mA, 25MHz, 600V/µs Op Amp Good DC Precision, Stable with All Capacitive Loads

V

OUT

1354 TA04

12

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507

●

www.linear-tech.com

1354fa LT/TP 0598 REV A 2K • PRINTED IN USA

 LINEAR TECHNOLOGY CORP ORA TION 1994