LT1678IS8_技术文档

LT1678/LT1679

Dual/Quad Low Noise,

Rail-to-Rail, Precision Op Amps

U

FEATURES

DESCRIPTIO

The LT^®1678/LT1679 are dual/quad rail-to-rail op amps

offering both low noise and precision: 3.9nV/√Hz wideband

noise, 1/f corner frequency of 4Hz and 90nV peak-to-peak

0.1Hz to 10Hz noise are combined with outstanding

precision: 100µV maximum offset voltage, greater than

100dB common mode and power supply rejection and

20MHz gain bandwidth product. The LT1678/LT1679 bring

precisionaswellaslownoisetosinglesupplyapplicationsas

low as 3V. The input range exceeds the power supply by

100mV with no phase inversion while the output can swing

to within 170mV of either rail.

■

Rail-to-Rail Input and Output

100% Tested Low Voltage Noise:

■

3.9nV/√Hz Typ at 1kHz

5.5nV/√Hz Max at 1kHz

■

Single Supply Operation from 2.7V to 36V

■

Offset Voltage: 100µV Max

■

Low Input Bias Current: 20nA Max

■

High A_VOL: 3V/µV Min, R_L= 10k

■

High CMRR: 100dB Min

High PSRR: 106dB Min

■

Gain Bandwidth Product: 20MHz

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

Matching Specifications

No Phase Inversion

8-Lead SO and 14-Lead SO Packages

■

The LT1678/LT1679 are offered in the SO-8 and SO-14

packages. A full set of matching specifications are also

provided, facilitating their use in matching dependent appli-

cations such as a two op amp instrumentation amplifier

design. The LT1678/LT1679 are specified for supply volt-

ages of ±15V, single 5V as well as single 3V. For a single

amplifier with similiar performance, see the LT1677 data

sheet.

■

U

APPLICATIO S

■

Strain Gauge Amplifiers

■

Portable Microphones

■

Battery-Powered Rail-to-Rail Instrumentation

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

■

Low Noise Signal Processing

■

Microvolt Accuracy Threshold Detection

■

Infrared Detectors

U

TYPICAL APPLICATIO

Instrumentation Amplifier with Shield Driver

3

0.1Hz to 10Hz Voltage Noise

+

1k

30k

1

1/4

V

= ±2.5V

S

LT1679

–

2

R

F

15V

4

3.4k

5

6

GUARD

+

R

G

7

1/4

LT1679

100Ω

OUTPUT

30k

10

+

–

+

–

11

8

1/4

LT1679

R

G

INPUT

100Ω

9

–15V

–

GUARD

GAIN = 1000

0

2

4

6

8

10

R

F

13

12

–

TIME (sec)

3.4k

14

1/4

LT1679

16789 TA01

16789 TA01b

1k

+

sn16789 16789fs

1

LT1678/LT1679

W W

U W

ABSOLUTE AXI U RATI GS

(Note 1)

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

Operating Temperature Range

Supply Voltage ...................................................... ±18V

Input Voltages (Note 2) ............ 0.3V Beyond Either Rail

Differential Input Current (Note 2) ..................... ±25mA

Output Short-Circuit Duration (Note 3)............ Indefinite

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

(Note 4)............................................. –40°C to 85°C

Specified Temperature Range

(Note 5)............................................. –40°C to 85°C

U W

U

PACKAGE/ORDER I FOR ATIO

ORDER PART

NUMBER

ORDER PART

TOP VIEW

NUMBER

TOP VIEW

A

OUT A

–IN A

+IN A

1

2

3

4

5

6

7

14

13

12

11

10

9

OUT D

–IN D

+IN D

+

OUT A

1

2

3

4

8

7

6

5

V

A

B

D

C

LT1678CS8

LT1678IS8

LT1679CS

LT1679IS

OUT B

–IN B

+IN B

–IN A

+IN A

+

–

V

B

+IN B

–IN B

+IN C

–IN C

OUT C

–

V

S8 PART MARKING

S8 PACKAGE

8-LEAD PLASTIC SO

OUT B

8

1678

1678I

T_JMAX= 150°C, θ_JA= 190°C/ W

S PACKAGE

14-LEAD PLASTIC SO

T_JMAX= 150°C, θ_JA= 160°C/ W

Consult LTC Marketing for parts specified with wider operating temperature ranges.

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 3V, V_CM= V_O= 1.7V; V_S= 5V, V_CM= V_O= 2.5V unless

otherwise noted.

SYMBOL

PARAMETER

CONDITIONS (Note 6)

MIN

TYP

MAX

UNITS

V

Input Offset Voltage

(Note 11)

35

55

75

100

270

350

µV

OS

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

V =5V, V = V + 0.1V

150

180

200

550

750

1000

µV

S

CM

S

V =5V, V = V – 0.3V, 0°C ≤ T ≤ 70°C

●

S

CM

S

A

V =5V, V = V – 0.3V, –40°C ≤ T ≤ 85°C

S

CM

S

A

V =5V, V = –0.1V

1.5

1.8

2.0

30

45

50

mV

S

CM

V =5V, V = 0V, 0°C ≤ T ≤ 70°C

●

S

CM

A

V =5V, V = 0V, –40°C ≤ T ≤ 85°C

S

CM

A

∆V

∆Temp

Average Input Offset Drift (Note 10)

Input Bias Current

●

0.40

3

µV/°C

OS

I

(Note 11)

±2

±3

±7

±20

±35

±50

nA

B

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

V = 5V, V = V + 0.1V

0.19

0.25

0.40

0.60

0.75

µA

S

CM

S

V = 5V, V = V – 0.3V, 0°C ≤ T ≤ 70°C

●

S

CM

S

A

V = 5V, V = V – 0.3V, –40°C ≤ T ≤ 85°C

S

CM

S

A

V = 5V, V = –0.1V

–5

–8.4

–10

–0.41

–0.45

–0.47

µA

S

CM

V = 5V, V = 0V, 0°C ≤ T ≤ 70°C

●

S

CM

A

V = 5V, V = 0V, –40°C ≤ T ≤ 85°C

S

CM

A

sn16789 16789fs

2

LT1678/LT1679

ELECTRICAL CHARACTERISTICS

otherwise noted.

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 3V, V_CM= V_O= 1.7V; V_S= 5V, V_CM= V_O= 2.5V unless

SYMBOL

PARAMETER

CONDITIONS (Note 6)

MIN

TYP

MAX

UNITS

I

Input Offset Current

(Note 11)

4

5

8

25

35

55

nA

OS

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

V = 5V, V = V + 0.1V

6

10

15

30

40

65

nA

S

CM

S

V = 5V, V = V – 0.3V, 0°C ≤ T ≤ 70°C

●

S

CM

S

A

V = 5V, V = V – 0.3V, –40°C ≤ T ≤ 85°C

S

CM

S

A

V = 5V, V = –0.1V

0.1

0.15

1.6

2.0

2.4

µA

S

CM

V = 5V, V = 0V, 0°C ≤ T ≤ 70°C

●

S

CM

A

V = 5V, V = 0V, –40°C ≤ T ≤ 85°C

S

CM

A

e

Input Noise Voltage

0.1Hz to 10Hz (Note 7)

90

nV

P-P

nV

P-P

nV

P-P

n

V

= V

180

CM

S

= 0V

1600

Input Noise Voltage Density (Note 8)

f = 10Hz

4.4

6.6

19

nV/√Hz

O

V

= V , f = 10Hz

CM

S O

= 0V, f = 10Hz

O

f = 1kHz

3.9

5.3

9

5.5

nV/√Hz

O

V

= V , f = 1kHz

CM

S O

= 0V, f = 1kHz

O

i

Input Noise Current Density

Input Voltage Range

f = 10Hz

O

1.2

0.3

pA/√Hz

n

O

f = 1kHz

V

–0.1

0

V + 0.1V

S

V

CM

S

●

V – 0.3V

R

IN

Input Resistance

Common Mode

2

GΩ

C

Input Capacitance

4.2

pF

IN

CMRR

Common Mode Rejection Ratio

V = 5V, V = 1.9V to 3.9V

98

92

120

dB

S

CM

V = 5V, V = 1.9V to 3.9V

●

S

CM

PSRR

Power Supply Rejection Ratio

Large-Signal Voltage Gain

V = 2.7V to 36V, V = V = 1.7V

100

98

125

120

dB

S

CM

O

V = 3.1V to 36V, V = V = 1.7V

S

CM

O

A

V = 3V, R = 10k, V = 2.5V to 0.7V

0.6

0.3

3

2

V/µV

VOL

S

L

O

V = 3V, R = 2k, V = 2.2V to 0.7V

0.5

0.4

3

0.9

0.8

V/µV

S

L

O

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

V = 3V, R = 600Ω, V = 2.2V to 0.7V

0.20

0.15

0.10

0.43

0.40

0.35

V/µV

S

L

O

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

V = 5V, R = 10k, V = 4.5V to 0.7V

1

0.6

0.3

3.8

2

V/µV

S

L

O

O°C < T < 70°C

●

A

–40 < T < 85°C

A

V = 5V, R = 2k, V = 4.2V to 0.7V

0.7

0.6

0.5

3.5

3.2

3.0

V/µV

S

L

O

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

V = 5V, R = 600Ω, V = 4.2V to 0.7V

0.6

0.5

0.4

3.0

2.8

2.5

V/µV

S

L

O

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

V

Output Voltage Swing Low (Note 11)

Above GND

SINK

OL

I

= 0.1mA

80

125

130

170

200

250

mV

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

sn16789 16789fs

3

LT1678/LT1679

ELECTRICAL CHARACTERISTICS

otherwise noted.

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= 3V, V_CM= V_O= 1.7V; V_S= 5V, V_CM= V_O= 2.5V unless

SYMBOL

PARAMETER

CONDITIONS (Note 6)

MIN

TYP

MAX

UNITS

V

Output Voltage Swing Low (Note 11)

Above GND

OL

I

= 2.5mA

170

195

205

250

320

350

mV

SINK

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

Above GND

I

= 10mA

370

440

465

600

720

770

mV

SINK

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

V

Output Voltage Swing High (Note 11)

Below V

OH

S

I

= 0.1mA

A

75

85

93

150

200

250

mV

SOURCE

0°C ≤ T ≤ 70°C

–40°C ≤ T ≤ 85°C

●

A

Below V

S

I

= 2.5mA

A

110

195

205

250

350

375

mV

SOURCE

0°C ≤ T ≤ 70°C

–40°C ≤ T ≤ 85°C

●

A

Below V

S

I

= 10mA

A

170

200

230

400

500

550

mV

SOURCE

0°C ≤ T ≤ 70°C

●

–40°C ≤ T ≤ 85°C

A

I

Output Short-Circuit Current (Note 3)

Slew Rate (Note 13)

V = 3V

15

13

22

19

mA

SC

S

●

V = 5V

S

18

14

29

25

mA

SR

A = –1, R = 10k

4

3.5

3

6

5.8

5.5

V/µs

V

L

R = 10k, 0°C ≤ T ≤ 70°C

●

L

A

R = 10k, –40°C ≤ T ≤ 85°C

L

A

GBW

Gain Bandwidth Product (Note 11)

Settling Time

f = 100kHz

O

13

12.5

20

19

MHz

O

●

t

2V Step 0.1%, A = +1

2V Step 0.01%, A = +1

1.4

2.4

µs

S

V

R

Open-Loop Output Resistance

Closed-Loop Output Resistance

I

= 0

OUT

V

100

1

Ω

O

A = 100, f = 10kHz

I

Supply Current per Amplifier (Note 12)

2

2.5

3.4

3.8

mA

S

●

∆V

Offset Voltage Match

(Notes 11, 15)

35

55

75

150

400

525

µV

OS

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

∆IB+

Noninverting Bias Current Match

(Notes 11, 15)

±2

±3

±7

±30

±55

±75

nA

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

∆CMRR

∆PSRR

Common Mode Rejection Match

(Notes 11, 14, 15)

V = 5V, V = 1.9V to 3.9V

94

88

110

dB

S

CM

●

Power Supply Rejection Match

(Notes 11, 14, 15)

V = 2.7V to 36V, V = V = 1.7V

96

94

120

dB

S

CM

O

V = 3.1V to 36V, V = V = 1.7V

S

CM

O

sn16789 16789fs

4

LT1678/LT1679

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= ±15V, V_CM= V_O= 0V unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS (Note 6)

MIN

TYP

MAX

UNITS

V

Input Offset Voltage

20

30

45

150

350

420

µV

OS

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

∆V

∆Temp

Average Input Offset Drift (Note 10)

Input Bias Current

●

0.40

3

µV/°C

OS

I

±2

±3

±7

±20

±35

±50

nA

B

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

I

Input Offset Current

3

5

8

25

35

55

nA

OS

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

e

Input Noise Voltage

0.1Hz to 10Hz (Note 7)

90

180

1600

nV

P-P

nV

P-P

nV

P-P

n

V

= 15V

= –15V

CM

Input Noise Voltage Density

f = 10Hz

4.4

6.6

19

nV/√Hz

O

V

= 15V, f = 10Hz

= –15V, f = 10Hz

CM

O

V

O

f = 1kHz

3.9

5.3

9

5.5

14

nV/√Hz

O

V

= 15V, f = 1kHz

= –15V, f = 1kHz

CM

O

i

Input Noise Current Density

f = 10Hz

1.2

0.3

pA/√Hz

n

O

f = 1kHz

O

V

Input Voltage Range (Note 16)

Input Resistance

●

–13.3

V

GΩ

pF

CM

R

Common Mode

2

IN

C

Input Capacitance

4.2

IN

CMRR

Common Mode Rejection Ratio

V

= –13.3V to 14V

100

96

130

124

dB

CM

●

PSRR

Power Supply Rejection Ratio

Large-Signal Voltage Gain

V = ±1.7V to ±18V

106

100

130

125

dB

S

A

R = 10k, V = ±14V

0°C ≤ T ≤ 70°C

–40°C ≤ T ≤ 85°C

3

2

1

7

6

4

V/µV

VOL

L

O

●

A

R = 2k, V = ±13.5V

0.8

0.5

0.4

1.7

1.4

1.1

V/µV

L

O

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

sn16789 16789fs

5

LT1678/LT1679

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_S= ±15V, V_CM= V_O= 0V unless otherwise noted.

SYMBOL

V

PARAMETER

CONDITIONS (Note 6)

Above –V

MIN

TYP

MAX

UNITS

Output Voltage Swing Low

OL

S

I

= 0.1mA

110

125

130

200

230

260

mV

SINK

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

Above –V

S

I

= 2.5mA

170

195

205

280

350

380

mV

SINK

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

Above –V

S

I

= 10mA

370

440

450

600

700

750

mV

SINK

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

V

Output Voltage Swing High

Below +V

S

OH

I

= 0.1mA

80

90

100

150

200

250

mV

SOURCE

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

Below +V

S

I

= 2.5mA

A

110

120

200

300

350

mV

SOURCE

0°C ≤ T ≤ 70°C

–40°C ≤ T ≤ 85°C

●

A

Below +V

S

I

= 10mA

A

200

250

450

500

550

mV

SOURCE

0°C ≤ T ≤ 70°C

●

–40°C ≤ T ≤ 85°C

A

I

Output Short-Circuit Current (Note 3)

Slew Rate

20

15

35

28

mA

SC

●

SR

R = 10k (Note 9)

4

3.5

3

6

5.8

5.5

V/µs

L

R = 10k (Note 9) 0°C ≤ T ≤ 70°C

●

L

A

R = 10k (Note 9) –40°C ≤ T ≤ 85°C

L

A

GBW

THD

Gain Bandwidth Product

f = 100kHz

O

13

12.5

20

19

MHz

O

●

Total Harmonic Distortion

Settling Time

R = 2k, A = 1, f = 1kHz, V = 20V

P-P

0.00025

%

L

V

O

t

10V Step 0.1%, A = +1

10V Step 0.01%, A = +1

2.7

3.9

µs

S

V

R

O

Open-Loop Output Resistance

Closed-Loop Output Resistance

I

= 0

OUT

V

100

1

Ω

A = 100, f = 10kHz

I

Supply Current per Amplifier

2.5

3

3.5

4.5

mA

S

●

Channel Separation

f = 10Hz, V = ±10V, R = 10k

132

dB

O

L

∆V

OS

Offset Voltage Match

(Note 15)

5

30

45

225

525

630

µV

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

∆IB+

Noninverting Bias Current Match

(Note 15)

±2

±3

±7

±30

±55

±75

nA

0°C ≤ T ≤ 70°C

●

A

–40°C ≤ T ≤ 85°C

A

∆CMRR

∆PSRR

Common Mode Rejection Match

(Notes 14, 15)

V

= –13.3V to 14V

96

92

120

115

dB

CM

●

Power Supply Rejection Match

(Notes 14, 15)

V = ±1.7V to ±18V

100

96

123

120

dB

S

sn16789 16789fs

6

LT1678/LT1679

ELECTRICAL CHARACTERISTICS

Note 1: Absolute Maximum Ratings are those values beyond which the life

Note 8: Noise is 100% tested at ±15V supplies.

of the device may be impaired.

Note 9: Slew rate is measured in A = –1; input signal is ±10V, output

V

measured at ±5V.

Note 10: This parameter is not 100% tested.

Note 2: The inputs are protected by back-to-back diodes. Current limiting

resistors are not used in order to achieve low noise. If differential input

voltage exceeds ±1.4V, the input current should be limited to 25mA. If the

common mode range exceeds either rail, the input current should be

limited to 10mA.

Note 3: A heat sink may be required to keep the junction temperature

below absolute maximum.

Note 11: V = 5V limits are guaranteed by correlation to V = 3V and

S

V = ±15V tests.

S

Note 12: V = 3V limits are guaranteed by correlation to V = 5V and

S

V = ±15V tests.

S

Note 13: Guaranteed by correlation to slew rate at V = ±15V and GBW at

S

Note 4: The LT1678C/LT1679C and LT1678I/LT1679I are guaranteed

functional over the Operating Temperature Range of –40°C to 85°C.

V = 3V and V = ±15V tests.

S

Note 14: ∆CMRR and ∆PSRR are defined as follows:

1. CMRR and PSRR are measured in µV/V on the individual amplifiers.

2. The difference is calculated between the matching sides in µV/V.

3. The result is converted to dB.

Note 15: Matching parameters are the difference between amplifiers A and

B on the LT1678 and between amplifiers A and D and B and C in the

LT1679.

Note 5: The LT1678C/LT1679C are guaranteed to meet specified

performance from 0°C to 70°C. The LT1678C/LT1679C are designed,

characterized and expected to meet specified performance from –40°C to

85°C but is not tested or QA sampled at these temperatures. The LT1678I/

LT1679I are guaranteed to meet specified performance from –40°C to

85°C.

Note 6: Typical parameters are defined as the 60% yield of parameter

distributions of individual amplifier; i.e., out of 100 LT1678/LT1679s,

typically 60 op amps will be better than the indicated specification.

Note 16: Input range guaranteed by the common mode rejection ratio test.

Note 7: See the test circuit and frequency response curve for 0.1Hz to10Hz

tester in the Applications Information section.

U W

TYPICAL PERFOR A CE CHARACTERISTICS

0.01Hz to 1Hz Voltage Noise

0.1Hz to 10Hz Voltage Noise

Voltage Noise vs Frequency

100

10

1

V

= ±15V

= 25°C

V

= 5V, 0V

V

= 5V, 0V

S

A

S

T

V

= 14.5V

CM

V

= 0V

CM

0

2

4

6

8

10

0

20

40

60

80

100

0.1

1

10

FREQUENCY (Hz)

100

1000

TIME (sec)

16789 G01

16789 G02

16789 G03

sn16789 16789fs

7

LT1678/LT1679

U W

TYPICAL PERFOR A CE CHARACTERISTICS

Voltage Noise vs Temperature

Input Bias Current vs Temperature

Current Noise vs Frequency

6

5

4

3

2

1

10

16

14

12

10

8

V

= ±15V

CM

V

T

= ±15V

= 25°C

V

= ±15V

CM

S

A

S

= 0V

10Hz

V

= 0V

CM

6

1

1kHz

4

2

= 14.5V

CM

0

–2

–4

–6

0.1

50

TEMPERATURE (°C)

100 125

–50 –25

0

25

75

–50

0

25

50

75 100 125

–25

0.01

0.1

1

10

FREQUENCY (kHz)

TEMPERATURE (°C)

16789 G05

16789 G06

16789 G04

Input Bias Current Over the

Common Mode Range

Offset Voltage Shift vs

Common Mode

Input Bias Current vs Temperature

1400

1200

1000

800

600

400

200

0

900

700

5

4

500

400

300

200

100

0

V

= ±15V

S

V

= –14V

V

= ±15V

= 25°C

CM

S

A

CURRENT OUT OF DUT

T

3

V

IS REFERRED TO

CM

500

OS

V

= 0V

2

V

= 14.5V

300

CM

V

CM

= –13.5V

1

100

INPUT BIAS CURRENT

0

–100

–300

–500

–700

–900

–1

–2

–3

–4

–5

–100

–200

–300

–400

–500

V

= 14.1V

CM

V

CM

= 14.7V

V

T

= ±1.5V TO ±15V

= 25°C

S

A

CURRENT INTO DUT

V

= –15.2V

–4

5 TYPICAL PARTS

+

CM

–

–50 –25

0

25

50

75 100 125

0

1.0

–16

–12

4

8

16

–1.0

V

2.0 –0.8 –0.4

V

0.4

–8

12

–

+

TEMPERATURE (°C)

COMMON MODE INPUT VOLTAGE (V)

V

– V (V)

V

– V (V)

CM

16789 G09

16789 G07

16789 G08

V

_OSvs Temperature of

Distribution of Input Offset

Voltage Drift (SO-8)

Representive Units

Warm-Up Drift vs Time

200

100

0

30

25

20

15

10

5

10

8

V

= 5V, 0V

S

A

V

= 5V, 0V

CM

S

V

= ±15V

= 25°C

S

A

T

= –40°C TO 85°C

= 0V

T

111 PARTS (2 LOTS)

SO PACKAGE

6

–100

–200

–300

4

2

0

–1.0

1.0

–3.0 –2.0

0

2.0

3.0

1

2

3

–55 –35 –15

5

25

45

65

85 105 125

0

4

INPUT OFFSET VOLTAGE DRIFT (µV/°C)

TEMPERATURE (°C)

TIME (min)

16789 G11

16789 G10

16789 G12

sn16789 16789fs

8

LT1678/LT1679

U W

TYPICAL PERFOR A CE CHARACTERISTICS

Common Mode Rejection Ratio

vs Frequency

Common Mode Range vs

Temperature

Supply Current vs Supply Voltage

5

4

500

400

300

200

100

0

4.0

3.5

3.0

2.5

2.0

1.5

1.0

160

140

120

100

80

V

= ±2.5V TO ±15V

S

V

T

= ±15V

= 25°C

CM

S

A

V

= 0V

3

2

25°C

–55°C

1

T

= 125°C

A

–55°C

25°C

125°C

0

–1

–2

–3

–4

–5

–100

–200

–300

–400

–500

T

= 25°C

A

60

V

IS REFERRED TO

CM

OS

V

= 0V

40

T

= –55°C

A

125°C

20

0

–

1.0

–1.0

V

2.0 –0.8 –0.4

V

0.4

0

±5

±10

±15

±20

10k

100k

1M

10M

–

+

FREQUENCY (Hz)

SUPPLY VOLTAGE (V)

V

– V (V)

V

– V (V)

CM S

CM

S

16789 G14

16789 G15

16789 G09

Power Supply Rejection Ratio

vs Frequency

Voltage Gain vs Supply Voltage

% Overshoot vs Capacitive Load

10

60

50

40

30

20

10

0

160

140

120

100

80

V

= ±15V

= 2k TO 10k

= 1

V

T

= ±15V

= 25°C

S

L

S

A

R

A

R

= 10k

L

V

A

T

= 25°C

R

= 2k

L

NEGATIVE SUPPLY

1

RISING EDGE

60

POSITIVE SUPPLY

40

FALLING EDGE

T

= 25°C

A

L

20

R

TO GND

V

= V = V /2

CM

O S

0.1

0

100

0

0.001 0.01

0.1

1

10

1000

10

SUPPLY VOLTAGE (V)

30

20

10

100

CAPACITIVE LOAD (pF)

1000

FREQUENCY (kHz)

16789 G18

16789 G16

16789 G17

Phase Margin, Gain Bandwidth

Product and Slew Rate vs

Temperature

Small Signal

Large Signal

Transient Response

90

80

70

60

50

V

C

A

= ±15V

= 15pF

= –1

S

L

V

50mV

PHASE MARGIN

10V

R

= R = 1k

G

F

30

25

20

15

10

0V

GAIN BANDWIDTH PRODUCT

40

8

–10V

–50mV

+SR

–SR

6

A

V

= –1

A

V

C

= 1

VCL

5µs/DIV

0.5µs/DIV

VCL

S

= ±15V

S

L

= 15pF

4

16789 G20

16789 G21

–55 –35 –15

5

25 45 65 85 105 125

TEMPERATURE (°C)

16789 G19

sn16789 16789fs

9

LT1678/LT1679

U W

TYPICAL PERFOR A CE CHARACTERISTICS

Settling Time vs Output

Step (Inverting)

Settling Time vs Output

Step (Noninverting)

Gain, Phase Shift vs Frequency

6

5

4

3

2

1

0

6

5

4

3

2

1

0

50

40

30

20

10

0

100

2k

5k

V

C

= ±15V

V

A

T

= ±15V

= –1

= 25°C

V

A

T

= ±15V

= 1

= 25°C

S

V

A

S

V

A

= 0V

5k

CM

PHASE

V

–

+

IN

–

+

= 10pF 80

L

V

2k

OUT

T

= –55°C

A

V

IN

T

= 25°C

A

R

= 1k

L

60

40

20

0

T

= 125°C

A

0.01% OF

FULL SCALE

0.01% OF

FULL SCALE

0.01% OF

FULL SCALE

0.01% OF

FULL SCALE

T

= 125°C

A

0.1% OF

FULL SCALE

GAIN

0.1% OF

FULL SCALE

T

= 25°C

A

0.1% OF

FULL SCALE

0.1% OF

FULL SCALE

T

= –55°C

A

–10

–20

–10 –8 –6 –4 –2

0

2

4

6

8

10

–10 –8 –6 –4 –2

0

2

4

6

8

10

0.1

1

10

100

OUTPUT STEP (V)

FREQUENCY (MHz)

16789 G22

16789 G23

16789 G24

Output Voltage Swing vs

Load Current

Gain, Phase Shift vs Frequency

100

80

60

40

20

0

+V

100

80

60

40

20

0

50

40

30

20

10

0

50

40

30

20

10

0

S

0

V

= ±15V

V

C

= ±15V

CM

= 10pF

V

C

= ±15V

CM

= 10pF

S

T

= –55°C

A

–0.1

–0.2

–0.3

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

= 14.7V

= –14V

T

= 125°C

L

A

T

= 25°C

T

= –55°C

A

PHASE

A

T

= 25°C

A

PHASE

T

= 125°C

A

T

= 125°C

T

= –55°C

A

T

= 125°C

A

T

= –55°C

A

T

= 25°C

A

T

= 125°C

= 25°C

A

GAIN

T

= 25°C

T

= 25°C

A

GAIN

T

A

T

= –55°C

A

T

= –55°C

A

–20

100

–20

–10

–V

S

0.1

1

10

100

0.1

1

10

–10 –8 –6 –4 –2

0

2

4

6

8

10

FREQUENCY (MHz)

OUTPUT CURRENT (mA)

16789 G25

16789 G26

16789 G27

Total Harmonic Distortion and

Noise vs Frequency for

Noninverting Gain

Total Harmonic Distortion and

Noise vs Frequency for

Noninverting Gain

Closed-Loop Output

Impedance vs Frequency

0.1

100

10

Z

= 2k/15pF

Z

= 2k/15pF

L

V

= ±15V

S

V

A

= ±15V

V

A

= ±15V

S

O

V

S

O

V

= 20V

P-P

= 1, 10, 100

= –1, –10, –100

MEASUREMENT BANDWIDTH

= 10Hz TO 80kHz

MEASUREMENT BANDWIDTH

= 10Hz TO 80kHz

0.01

0.001

0.01

1

A

= –100

V

A

= 100

A

= 100

V

0.1

A

= 1

V

0.001

A

= –10

= –1

V

A

= 10

= 1

V

0.01

0.001

A

0.0001

20

10

100

1k

10k

100k

1M

20

100

1k

10k

50k

100

1k

10k

50k

FREQUENCY (Hz)

16789 G29

16789 G30

16789 G28

sn16789 16789fs

10

LT1678/LT1679

W U U

APPLICATIO S I FOR ATIO

U

Rail-to-Rail Operation

inputandacurrent, limitedonlybytheoutputshort-circuit

protection, will be drawn by the signal generator. With

R_F≥ 500Ω, the output is capable of handling the current

requirements (I_L≤ 20mA at 10V) and the amplifier stays

in its active mode and a smooth transition will occur.

To take full advantage of an input range that can exceed

thesupply, theLT1678/LT1679aredesignedtoeliminate

phase reversal. Referring to the photographs shown in

Figure 1, the LT1678/LT1679 are operating in the fol-

lower mode (A_V= +1) at a single 3V supply. The output

of the LT1678/LT1679 clips cleanly and recovers with no

phasereversal. Thishasthebenefitofpreventinglock-up

inservosystemsandminimizingdistortioncomponents.

As with all operational amplifiers when R_F> 2k, a pole will

be created with R_Fand the amplifier’s input capacitance,

creating additional phase shift and reducing the phase

margin.Asmallcapacitor(20pFto50pF)inparallelwithR_F

will eliminate this problem.

R

F

Input = –0.5V to 3.5V

–

+

6V/µs

3

2

1

OUTPUT

LT1678

16789 F02

Figure 2. Pulsed Operation

Noise Testing

0

The 0.1Hz to 10Hz peak-to-peak noise of the LT1678/

LT1679 are measured in the test circuit shown (Figure 3).

The frequency response of this noise tester (Figure 4)

indicates that the 0.1Hz corner is defined by only one zero.

The test time to measure 0.1Hz to 10Hz noise should not

exceed ten seconds, as this time limit acts as an additional

zero to eliminate noise contributions from the frequency

band below 0.1Hz.

–0.5

16789 F01a

50µs/DIV

LT1678 Output

3

2

1

Measuring the typical 90nV peak-to-peak noise perfor-

mance of the LT1678/LT1679 requires special test pre-

cautions:

0

1. The device should be warmed up for at least five

minutes. As the op amp warms up, its offset voltage

changes typically 3µV due to its chip temperature

increasing 10°C to 20°C from the moment the power

suppliesareturnedon. Intheten-secondmeasurement

interval these temperature-induced effects can easily

exceed tens of nanovolts.

–0.5

16789 F01b

50µs/DIV

Figure 1. Voltage Follower with Input Exceeding the Supply

Voltage (V_S= 3V)

Unity-Gain Buffer Application

When R_F≤ 100Ω and the input is driven with a fast, large-

signal pulse (>1V), the output waveform will look as

shown in the pulsed operation diagram (Figure 2).

2. For similar reasons, the device must be well shielded

from air currents to eliminate the possibility of

thermoelectric effects in excess of a few nanovolts,

which would invalidate the measurements.

During the fast feedthrough-like portion of the output, the

input protection diodes effectively short the output to the

sn16789 16789fs

11

LT1678/LT1679

W U U

U

APPLICATIO S I FOR ATIO

100

90

80

70

60

50

40

30

0.1µF

100k

10Ω

–

2k

*

+

22µF

LT1678

SCOPE

× 1

IN

4.3k

+

LT1001

4.7µF

R

= 1M

–

110k

2.2µF

VOLTAGE GAIN

100k

= 50,000

0.1µF

0.01

0.1

1

10

100

*DEVICE UNDER TEST

NOTE: ALL CAPACITOR VALUES ARE FOR

NONPOLARIZED CAPACITORS ONLY

24.3k

FREQUENCY (Hz)

16789 F03

16789 F04

Figure 4. 0.1Hz to 10Hz Peak-to-Peak

Noise Tester Frequency Response

Figure 3. 0.1Hz to 10Hz Noise Test Circuit

3. Sudden motion in the vicinity of the device can also

“feedthrough” to increase the observed noise.

Total Noise = [(op amp voltage noise)²+ (resistor noise)²

+ (current noise R_S)²]^1/2

Current noise is measured in the circuit shown in Figure 5

and calculated by the following formula:

Three regions can be identified as a function of source

resistance:

1/2

(i) R ≤ 400Ω. Voltage noise dominates

S

⎡

⎢

2⎤

)

2

)

− 130nV

e

•101

⎥

⎦

(

no

Resistor Noise

400Ω ≤ R ≤ 8k at 10Hz Dominates

(ii) 400Ω ≤ R ≤ 50k at 1kHz

S

⎣

i =

n

S

1MΩ 101

(

)(

)

(iii) R > 50k at 1kHz Current Noise

S

100k

R > 8k at 10Hz

Dominates

100Ω

500k

Clearly the LT1678/LT1679 should not be used in region

(iii), where total system noise is at least six times higher

than the voltage noise of the op amp, i.e., the low voltage

noisespecificationiscompletelywasted. Inthisregionthe

LT1113 or LT1169 are better choices.

–

LT1678

e

no

+

16789 F05

Figure 5.

1000

R

V

= ±15V

= 25°C

S

A

T

The LT1678/LT1679 achieve their low noise, in part, by

operatingtheinputstageat100µAversusthetypical10µA

of most other op amps. Voltage noise is inversely propor-

tional while current noise is directly proportional to the

square root of the input stage current. Therefore, the

LT1678/LT1679’s current noise will be relatively high. At

low frequencies, the low 1/f current noise corner fre-

quency(≈200Hz)minimizescurrentnoisetosomeextent.

R

SOURCE RESISTANCE = 2R

100

10

1

AT 1kHz

AT 10Hz

RESISTOR

NOISE ONLY

0.1

1

10

100

In most practical applications, however, current noise will

not limit system performance. This is illustrated in the

Total Noise vs Source Resistance plot (Figure 6) where:

SOURCE RESISTANCE (kΩ)

16789 F06

Figure 6. Total Noise vs Source Resistance

sn16789 16789fs

12

LT1678/LT1679

W U U

APPLICATIO S I FOR ATIO

U

Rail-to-Rail Input

Rail-to-Rail Output

The input common mode range for the LT1678/LT1679

can exceed the supplies by at least 100mV. As the

common mode voltage approaches the positive rail (+V_S

– 0.7V), the tail current for the input pair (Q1, Q2) is

reduced, which prevents the input pair from saturating

(refer to the Simplified Schematic). The voltage drop

across the load resistors R_C1, R_C2is reduced to less than

200mV, degrading the slew rate, bandwidth, voltage

noise, offset voltage and input bias current (the cancella-

tion is shut off).

The rail-to-rail output swing is achieved by using transis-

tor collectors (Q28, Q29 referring to the Simplified Sche-

matic)insteadofcustomaryclassA-Bemitterfollowersfor

theoutputstage.TheoutputNPNtransistor(Q29)sinksthe

currentnecessarytomovetheoutputinthenegativedirec-

tion. The change in Q29’s base emitter voltage is reflected

directly to the gain node (collectors of Q20 and Q16). For

large sinking currents, the delta V_BEof Q29 can dominate

the gain. Figure 7 shows the change in input voltage for a

change in output voltage for different load resistors con-

nected between the supplies. The gain is much higher for

outputvoltagesaboveground(Q28sourcescurrent)since

the change in base emitter voltage of Q28 is attenuated by

the gain in the PNP portion of the output stage. Therefore,

for positive output swings (output sourcing current) there

ishardlyanychangeininputvoltageforanyloadresistance.

Highestgainandbestlinearityareachievedwhentheoutput

is sourcing current, which is the case in single supply op-

erationwhentheloadisgroundreferenced.Figure8shows

gains for both sinking and sourcing load currents for a

worst-case load of 600Ω.

When the input common mode range goes below 1.5V

above the negative rail, the NPN input pair (Q1, Q2) shuts

off and the PNP input pair (Q8, Q9) turns on. The offset

voltage, input bias current, voltage noise and bandwidth

are also degraded. The graph of Offset Voltage Shift vs

Common Mode shows where the knees occur by display-

ing the change in offset voltage. The change-over points

aretemperaturedependent;seethegraphCommonMode

Range vs Temperature.

VOLTAGE GAIN SINGLE SUPPLY

V

= 5V

= 600Ω

S

L

R

= 600Ω

L

MEASURED ON TEKTRONIX 577

CURVE TRACER

R

= 1k

L

R

TO 0V

L

R

= 10k

L

INPUT VOLTAGE

(50µV/DIV)

INPUT VOLTAGE

(10µV/DIV)

R

TO 5V

L

T

= 25°C

= ±15V

CONNECTED TO 0V

A

S

V

R

L

MEASURED ON

TEKTRONIX 577

CURVE TRACER

–15 –10 –5

0

5

10 15

0

1

2

3

4

5

OUTPUT VOLTAGE (V)

16789 F07

16789 F08

Figure 7. Voltage Gain Split Supply

Figure 8. Voltage Gain Single Supply

sn16789 16789fs

13

LT1678/LT1679

W

SI PLIFIED SCHE ATIC

+

sn16789 16789fs

14

LT1678/LT1679

U

PACKAGE DESCRIPTIO

S8 Package

8-Lead Plastic Small Outline (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1610)

.189 – .197

(4.801 – 5.004)

.045 ±.005

NOTE 3

.050 BSC

7

5

8

6

.245

MIN

.160 ±.005

.150 – .157

(3.810 – 3.988)

NOTE 3

.228 – .244

(5.791 – 6.197)

.030 ±.005

TYP

1

3

4

2

RECOMMENDED SOLDER PAD LAYOUT

.010 – .020

(0.254 – 0.508)

× 45°

.053 – .069

(1.346 – 1.752)

.004 – .010

(0.101 – 0.254)

.008 – .010

(0.203 – 0.254)

0°– 8° TYP

.016 – .050

(0.406 – 1.270)

.050

(1.270)

BSC

.014 – .019

(0.355 – 0.483)

TYP

NOTE:

INCHES

1. DIMENSIONS IN

(MILLIMETERS)

2. DRAWING NOT TO SCALE

3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.

MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)

SO8 0303

S Package

14-Lead Plastic Small Outline (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1610)

.337 – .344

.045 ±.005

(8.560 – 8.738)

.050 BSC

NOTE 3

14

N

13

12

11

10

9

8

N

1

.245

MIN

.160 ±.005

.150 – .157

(3.810 – 3.988)

NOTE 3

.228 – .244

(5.791 – 6.197)

2

3

N/2

.030 ±.005

TYP

RECOMMENDED SOLDER PAD LAYOUT

7

1

2

3

4

5

6

.010 – .020

(0.254 – 0.508)

× 45°

.053 – .069

(1.346 – 1.752)

.004 – .010

(0.101 – 0.254)

.008 – .010

(0.203 – 0.254)

0° – 8° TYP

.050

(1.270)

BSC

.014 – .019

(0.355 – 0.483)

TYP

.016 – .050

(0.406 – 1.270)

S14 0502

NOTE:

INCHES

(MILLIMETERS)

2. DRAWING NOT TO SCALE

1. DIMENSIONS IN

3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.

MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)

sn16789 16789fs

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

LT1678/LT1679

U

TYPICAL APPLICATIO

Bridge Reversal Eliminates 1/f Noise and Offset Drift of a Low Noise, Non-autozeroed, Bipolar Amplifier.

Circuit Gives 14nV Noise Level or 19 Effective Bits Over a 10mV Span

V

REF

3

V

7V

REF

4

φ1

5,6,7,8

LT1461-5

2

10µF

0.1µF

5V

+

100k

10Ω

1

1/2 LT1678

–

+

REF

0.047µF

350Ω

1k

0.1%

100Ω

+

IN

1µF

350Ω

100Ω

0.1%

LTC2440

1k

100Ω

0.1%

–

IN

–

0.047µF

–

REF

V

REF

3

10Ω

100k

1/2 LT1678

+

4

2

φ1

φ2

2X

SILICONIX

Si9801

φ2

5,6,7,8

1

≈2s

16789 TA02

RELATED PARTS

PART NUMBER

LT1028/LT1128

LT1115

DESCRIPTION

COMMENTS

Lowest Noise 0.85nV/√Hz

Ultralow Noise Precision Op Amps

Ultralow Noise, Low distortion Audio Op Amp

0.002% THD, Max Noise 1.2nV/√Hz

Similar to LT1007

LT1124/LT1125

LT1126/LT1127

LT1226

Dual/Quad Low Noise, High Speed Precision Op Amps

Dual/Quad Decompensated Low Noise, High Speed Precision Op Amps

Low Noise, Very High Speed Op Amp

Similar to LT1037

1GHz, 2.6nV/√Hz, Gain of 25 Stable

Precision C-Load^TMStable

Rail-to-Rail 3.2nV/√Hz

LT1498/LT1499

LT1677

10MHz, 5V/µs, Dual/Quad Rail-to-Rail Input and Output Op Amps

Single Version of LT1678/LT1679

LT1792

Low Noise, Precision JFET Input Op Amp

4.2nV/√Hz, 10fA/√Hz

LT1793

Low Noise, Picoampere Bias Current Op Amp

6nV/√Hz, 1fA/√Hz, I = 10pA Max

B

LT1806

Low Noise, 325MHz Rail-to-Rail Input and Output Op Amp

Dual/Quad Rail-to-Rail Output Picoamp Input Precision Op Amps

3.5nV/√Hz

LT1881/LT1882

LT1884/LT1885

C

to 1000pF, I = 200pA Max

LOAD B

2.2MHz Bandwidth, 1.2V/µs SR

C-Load is a trademark of Linear Technology Corporation.

sn16789 16789fs

LT/TP 0104 1K • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

16

●

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


型号：	LT1678IS8
厂家：	Linear
描述：	Dual/Quad Low Noise, Rail-to-Rail, Precision Op Amps 双/四通道，低噪声，轨到轨，精密运算放大器运算放大器
文件：	总16页 (文件大小：297K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LT1678IS8 [Linear]

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