Datasheet LT1677 Datasheet (Linear Technology)

Final Electrical Specifications

FEATURES

■

Rail-to-Rail Input and Output

■

100% Tested Low Voltage Noise:

3.2nV/√Hz Typ at 1kHz

4.5nV/√Hz Max at 1kHz

■

Offset Voltage: 60µV Max

■

Low VOS Drift: 0.2µV/°C Typ

■

Low Input Bias Current: 20nA Max

■

Wide Supply Range: 3V to ±15V

■

High A

■

High CMRR: 109dB Min

■

High PSRR: 108dB Min

■

Gain Bandwidth Product: 7.2MHz

■

Slew Rate: 2.5V/µs

■

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

: 4V/µV Min, RL = 1k

VOL

U

APPLICATIO S

■

Low Noise Signal Processing

■

Microvolt Accuracy Threshold Detection

■

Strain Gauge Amplifiers

■

Tape Head Preamplifiers

■

Direct Coupled Audio Gain Stages

■

Infrared Detectors

LT1677

Low Noise, Rail-to-Rail

Precision Op Amp

February 2000

U

DESCRIPTIO

The LT®1677 features the lowest noise performance avail­able for a rail-to-rail operational amplifier: 3.2nV/√Hz
wideband noise, 1/f corner frequency of 13Hz and 70nV
peak-to-peak 0.1Hz to 10Hz noise. Low noise is combined
with outstanding precision: 20µV offset voltage and

0.2µV/°C drift, 130dB common mode and power supply
rejection and 7.2MHz gain bandwidth product. The com­mon mode range exceeds the power supply by 100mV.

The voltage gain of the LT1677 is extremely high, especially
with a single supply: 20 million driving a 1k load.

In the design, processing and testing of the device, particular
attention has been paid to the optimization of the entire
distribution of several key parameters. Consequently, the
specifications of even the lowest cost grade have been
spectacularly improved compared to competing rail-to-rail
amplifiers.

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

TYPICAL APPLICATIO

U

Precision High Side Current Sense

SOURCE

R

IN

1k

2

–

LT1677

+

7

6

ZETEX
BC856B

V

4

R

OUT

20k

1677 TA01

OUT

V

I

LOAD

OUT

= R

LINE

= 2V/AMP

R

OUT

R

IN

R

LINE

0.1Ω

3

LOAD

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.

1

LT1677

TOP VIEW

S8 PACKAGE

8-LEAD PLASTIC SO

1

2

3

4

8

7

6

5

V

OS

TRIM

V

OS

TRIM
V

+

OUT
NC

–IN
+IN

V

–

–
+

WWWU

ABSOLUTE AXI U RATI GS

(Note 1)

Supply Voltage ...................................................... ±22V

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

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

UU

W

PACKAGE/ORDER I FOR ATIO

TOP VIEW

V

OS

1

TRIM

–IN

2

+IN

3

–

V

4

T

= 150°C, θJA = 130°C/W

JMAX

–
+

N8 PACKAGE
8-LEAD PDIP

V

OS

8

TRIM

+

V

7

OUT

6

NC

5

Consult factory for Military grade parts.

ORDER PART

NUMBER

LT1677CN8
LT1677IN8

Operating Temperature Range

LT1677C (Note 4) ............................. –40°C to 85°C

LT1677I ............................................. – 40°C to 85°C

Specified Temperature Range

LT1677C (Note 5) ............................. –40°C to 85°C

LT1677I ............................................. – 40°C to 85°C

ORDER PART

NUMBER

LT1677CS8
LT1677IS8

S8 PART MARKING

1677

T

= 150°C, θJA = 190°C/W

JMAX

1677I

ELECTRICAL CHARACTERISTICS

TA = 25°C, VS = ±15V, VCM = VO = 0V unless otherwise noted.

SYMBOL PARAMETER CONDITIONS (Note 6) MIN TYP MAX UNITS

V

OS

∆V

OS

Input Offset Voltage 20 60 µV

= 14V to 15.1V 150 400 µV

V

CM

= –13.3V to –15.1V 1.5 5 mV

V

CM

Long Term Input Voltage Stability 0.3 µV/Mo

∆Time
I

B

I

OS

e

n

Input Bias Current ±2 ±20 nA

= 14V to 15.1V 0.16 0.4 µA

V

CM

= –13.3V to –15.1V –1.5 –0.4 µA

V

CM

Input Offset Current 315 nA

= 14V to 15.1V 5 25 nA

V

CM

V

= –13.3V to –15.1V 20 200 nA

CM

Input Noise Voltage 0.1Hz to 10Hz (Note 7) 70 nV

VCM = 15V 33 nV
VCM = –15V 100 nV

Input Noise Voltage Density VCM = 0V, fO = 10Hz 5.2 nV/√Hz

V

= 15V, fO = 10Hz 25 nV/√Hz

CM

= –15V, fO = 10Hz 7 nV/√Hz

V

CM

VCM = 0V, fO = 1kHz (Note 8) 3.2 4.5 nV/√Hz
V

= 15V, fO = 1kHz 17 nV/√Hz

CM

2

VCM = –15V, fO = 1kHz 5.3 nV/√Hz

P-P
P-P
P-P

LT1677

ELECTRICAL CHARACTERISTICS

TA = 25°C, VS = ±15V, VCM = VO = 0V unless otherwise noted.

SYMBOL PARAMETER CONDITIONS (Note 6) MIN TYP MAX UNITS

i

n

Input Noise Current Density fO = 10Hz 1.2 pA/√Hz

fO = 1kHz 0.3 pA/√Hz

V

CM

R

IN

C

IN

Input Voltage Range ±15.1 ±15.2 V
Input Resistance Common Mode 2 GΩ
Input Capacitance 3.8 pF

VS = ±2.5V 4.2 pF

CMRR Common Mode Rejection Ratio VCM = –13.3V to 14.0V 109 130 dB

V

= ±15.1V 74 95 dB

CM

PSRR Power Supply Rejection Ratio VS = ±1.7V to ±18V 106 130 dB

V

= 2.7V to 40V, VCM = VO = 1.7V 108 125 dB

S

A

VOL

Large-Signal Voltage Gain RL ≥ 10k, VO = ±14V 7 25 V/µV

RL ≥ 1k, VO = ±13.5V 4 20 V/µV
R

≥ 600Ω, VO = ±10V 0.4 0.7 V/µV

L

VCC = 5V or 3V, VEE = 0V, VCM = 1.7V,
RL to GND, V
R

≥ 10k, VCC – 0.5V 2 10 V/µV

L

= 0.5V to:

OUT

RL ≥ 1k, VCC – 0.7V 1.5 4 V/µV

V

OL

V

OH

I

SC

Output Voltage Swing Low Above V

Output Voltage Swing High Below V

EE

I

= 0.1mA 80 170 mV

SINK

I

= 2.5mA 110 250 mV

SINK

I

= 10mA 300 500 mV

SINK

CC

I
I
I

= 0.1mA 110 170 mV

SOURCE

= 2.5mA 190 300 mV

SOURCE

= 10mA 500 700 mV

SOURCE

Output Short-Circuit Current (Note 3) 25 35 mA
SR Slew Rate RL ≥ 10k (Note 9) 1.7 2.5 V/µs
GBW Gain Bandwidth Product fO = 100kHz 4.5 7.2 MHz
THD Total Harmonic Distortion RL = 2k, AV = 1, fO = 1kHz, VO = 10V
t

S

Settling Time 10V Step 0.1%, AV = +1 5 µs

P-P

0.0006 %

10V Step 0.01%, AV = +1 6 µs

R

O

I

S

Open-Loop Output Resistance I

Closed-Loop Output Resistance A

= 0 80 Ω

OUT

= 100, f = 10kHz 1 Ω

V

Supply Current 2.75 3.5 mA

3

LT1677

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the temperature range of

0°C < TA < 70°C. VS = ±15V, VCM = VO = 0V unless otherwise noted.

SYMBOL PARAMETER CONDITIONS (Note 6) MIN TYP MAX UNITS

V

OS

∆V

OS

∆Temp
I

B

I

OS

V

CM

CMRR Common Mode Rejection Ratio VCM = –13.3V to 14.0V ● 106 126 dB

PSRR Power Supply Rejection Ratio VS = ±1.7V to ±18V ● 104 127 dB

A

VOL

V

OL

V

OH

I

SC

SR Slew Rate RL ≥ 10k (Note 9) ● 1.5 2.3 V/µs
GBW Gain Bandwidth Product fO = 100kHz ● 6.2 MHz
I

S

Input Offset Voltage ● 30 120 µV

V

= 14.0V to 14.8V ● 180 550 µV

CM

= –13.3V to –15V ● 1.8 6 mV

V

CM

Average Input Offset Drift SO-8 ● 0.40 2 µV/°C

N8 (Note 10)

● 0.20 0.5 µV/°C

Input Bias Current ● ±3 ±35 nA

= 14.0V to 14.8V ● 0.19 0.6 µA

V

CM

V

= –13.3V to –15V ● –2 – 0.43 µA

CM

Input Offset Current ● 220 nA

= 14.0V to 14.8V ● 90 220 nA

V

CM

= –13.3V to –15V ● 90 350 nA

V

CM

Input Voltage Range ● –15 14.8 V

= –15V to 14.8V ● 73 93 dB

V

CM

V

= 2.8V to 40V, VCM = VO = 1.7V ● 106 122 dB

S

Large-Signal Voltage Gain RL ≥ 10k, VO = ±14V ● 420 V/µV

≥ 1k, VO = ±13.5V ● 210 V/µV

R

L

≥ 600Ω, VO = ±10V ● 0.3 0.5 V/µV

R

L

VCC = 5V or 3V, VEE = 0V, VCM = 1.7V,
V

= 0.4V to:

OUT

≥ 10k, VCC – 0.5V ● 38 V/µV

R

L

≥ 1k, VCC – 0.7V ● 0.5 4 V/µV

R

L

Output Voltage Swing Low Above V

Output Voltage Swing High Below V

EE

I

= 0.1mA ● 85 200 mV

SINK

= 2.5mA ● 160 320 mV

I

SINK

= 10mA ● 400 600 mV

I

SINK

CC

I
I
I

= 0.1mA ● 140 200 mV

SOURCE

= 2.5mA ● 230 350 mV

SOURCE

= 10mA ● 580 800 mV

SOURCE

Output Short-Circiut Current (Note 3) ● 20 27 mA

Supply Current ● 3.0 3.9 mA

4

LT1677

ELECTRICAL CHARACTERISTICS

The ● denotes the specifications which apply over the temperature range of

–40°C < TA < 85°C. VS = ±15V, VCM = VO = 0V unless otherwise noted. (Note 5)

SYMBOL PARAMETER CONDITIONS (Note 6) MIN TYP MAX UNITS

V

OS

∆V

OS

∆Temp
I

B

I

OS

V

CM

CMRR Common Mode Rejection Ratio VCM = –13.3V to 14.0V ● 105 124 dB

PSRR Power Supply Rejection Ratio VS = ±1.7V to ±18V ● 103 125 dB

A

VOL

V

OL

V

OH

I

SC

SR Slew Rate RL ≥ 10k (Note 9) ● 1.2 2.0 V/µs
GBW Gain Bandwidth Product fO = 100kHz ● 5.8 MHz
I

S

Input Offset Voltage ● 45 180 µV

V

= 14.0V to 14.7V ● 200 650 µV

CM

= –13.3V to –15V ● 2 6.5 mV

V

CM

Average Input Offset Drift SO-8 ● 0.40 2.0 µV/°C

N8 (Note 10)

● 0.20 0.5 µV/°C

Input Bias Current ● ±7 ±50 nA

= 14.0V to 14.7V ● 0.25 0.75 µA

V

CM

V

= –13.3V to –15V ● –2.3 –0.45 µA

CM

Input Offset Current ● 640 nA

= 14.0V to 14.7V ● 100 250 nA

V

CM

= –13.3V to –15V ● 100 400 nA

V

CM

Input Voltage Range ● –15 14.7 V

V

= –15V to 14.7V ● 72 91 dB

CM

V

= 3.1V to 40V, VCM = VO = 1.7V ● 105 120 dB

S

Large-Signal Voltage Gain RL ≥ 10k, VO = ±14V ● 317 V/µV

≥ 1k, VO = ±13.5V ● 1.5 8 V/µV

R

L

≥ 600Ω, VO = ±10V ● 0.2 0.35 V/µV

R

L

VCC = 5V or 3V, VEE = 0V, VCM = 1.7V,
V

= 0.5V to:

OUT

≥ 10k, VCC – 0.5V ● 215 V/µV

R

L

≥ 1k, VCC – 0.7V ● 0.2 2 V/µV

R

L

Output Voltage Swing Low Above V

Output Voltage Swing High Below V

EE

I

= 0.1mA ● 90 230 mV

SINK

= 2.5mA ● 175 350 mV

I

SINK

= 10mA ● 450 650 mV

I

SINK

CC

I
I
I

= 0.1mA ● 150 250 mV

SOURCE

= 2.5mA ● 250 375 mV

SOURCE

= 10mA ● 600 850 mV

SOURCE

Output Short-Circuit Current (Note 3) ● 18 25 mA

Supply Current ● 3.1 4.0 mA

Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.

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 4: The LT1677C and LTC1677I are guaranteed functional over the
Operating Temperature Range of –40°C to 85°C.

Note 5: The LT1677C is guaranteed to meet specified performance from
0°C to 70°C. The LT1677C is 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 LT1677I is guaranteed to meet the
extended temperature limits.

Note 6: Typical parameters are defined as the 60% yield of parameter
distributions of individual amplifier; i.e., out of 100 LT1677s, typically 60
op amps will be better than the indicated specification.

Note 7: See the test circuit and frequency response curve for 0.1Hz to
10Hz tester in the Applications Information section of the LT1677 data
sheet.

Note 8: Noise is 100% tested.
Note 9: Slew rate is measured in A

= –1; input signal is ±7.5V, output

V

measured at ±2.5V.
Note 10: This parameter is not 100% tested.

5

LT1677

TEMPERATURE (°C)

–50

2

RMS VOLTAGE NOISE DENSITY (nV/√Hz)

4

7

0

50

75

1677 G05

3

1kHz

10Hz

6

5

–25

25

100

125

VS = ±15V
V

CM

= 0V

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Voltage Noise vs Frequency

100

10

V

CM

10 1 100 1000

FREQUENCY (Hz)

RMS VOLTAGE NOISE DENSITY (nV/√Hz)

1

0.1

–13.5V TO 14.5V

1/f CORNER 13Hz

= ±15V

V

S

= 25°C

T

A

Input Bias Current Over the
Common Mode Range

800

VS = ±15V

= 25°C

T

A

600

400

200

0

–200

–400

INPUT BIAS CURRENT (nA)

–600

–800

–16

VCM = –13.6V

INPUT BIAS CURRENT

VCM = –15.3V

–12

–8

COMMON MODE INPUT VOLTAGE (V)

0

–4

1/f CORNER 10Hz

VCM > 14.5V

1/f CORNER 8.5Hz

< –14.5V

V

CM

VCM = 15.15V

VCM = 14.3V

4

8

12

1677 G06

1677 G03

RMS CURRENT NOISE DENSITY (pA/√Hz)

2.5

2.0

1.5

1.0

0.5
0

–0.5
–1.0

OFFSET VOLTAGE (mV)

–1.5
–2.0
–2.5

16

–1.0

Current Noise vs Frequency

10

VS = ±15V
T

= 25°C

A

VCM < –13.5V

1/f CORNER 180Hz

1/f CORNER 90Hz

FREQUENCY (Hz)

0.1

1

10

1/f CORNER 60Hz

100 1000 10000

Offset Voltage Shift
vs Common Mode

VOS IS REFERRED

= 0V

TO V

CM

VS = ±1.5V TO ±15V

= 25°C

T

A

5 TYPICAL PARTS

2.0

–0.8

V

1.0

EE

VCM – VEE (V) VCM – VCC (V)

–0.4

V

CM

–13.5V TO 14.5V

VCM > 14.5V

1677 G04

0.4

V

CC

1677 G08

250
200
150
100
50
0
–50
–100
–150
–200
–250

Voltage Noise vs Temperature

VOS vs Temperature of
Representative Units

140

VS = ±15V

120
100

OFFSET VOLTAGE (µV)

–20

VOLTAGE OFFSET (µV)

–40
–60
–80

= 0V

V

CM

SO-8
N8

80
60
40
20

0

–55

–35 –15 5 25 45 65 85 105 125

TEMPERATURE (°C)

1677 G11

Common Mode Range
vs Temperature

2.5

2.0

1.5

1.0

0.5
0

–0.5
–1.0

OFFSET VOLTAGE (mV)

–1.5
–2.0
–2.5

–1.0

6

VS = ±2.5V TO ±15V

125°C

25°C

–55°C

VOS IS REFERRED

= 0V

TO V

CM

V

EE

V

CM

2.0

1.0

– VEE (V) VCM – VCC (V)

–0.8

125°C

–0.4

V

25°C

CC

–55°C

1677 G09

0.4

250
200
150
100
50
0
–50
–100
–150
–200
–250

Distribution of Input Offset
Voltage Drift (N8)

20
18
16

OFFSET VOLTAGE (µV)

14

12

10

8
6

PERCENT OF UNITS (%)

4
2
0

–0.25

VS = ±15V

= –40°C TO 85°C

T

A

120 PARTS
(2 LOTS)

–0.15 –0.05 0.05 0.15 0.25 0.35 0.45

INPUT OFFSET VOLTAGE DRIFT (µV/°C)

1677 G02

Long-Term Stability of Four
Representative Units

5
4
3
2
1

0
–1
–2
–3

OFFSET VOLTAGE CHANGE (µV)

–4
–5

100 300

200

0

400

TIME (HOURS)

700

600

800

1677 G13

500 900

UW

TYPICAL PERFOR A CE CHARACTERISTICS

LT1677

Common Mode Rejection Ratio

Supply Current vs Supply Voltage

4

3

2

SUPPLY CURRENT (mA)

1

0

TA = 125°C

= 25°C

T

A

TA = –55°C

±5 ±10 ±15 ±20

SUPPLY VOLTAGE (V)

1677 G28

vs Frequency

160

VS = ±15V

= 25°C

T

A

140

= 0V

V

EM

120

100

80

60

40

20

COMMON MODE REJECTION RATIO (dB)

0

1k 100k 1M 10M

10k

FREQUENCY (Hz)

Voltage Gain vs Frequency Gain, Phase Shift vs Frequency

50

40

30

20

10

VOLTAGE GAIN (dB)

0

VOLTAGE GAIN (dB)

180

140

100

60

20

VS = ±15V

= 25°C

T

A

VCM = 0V

V

= V

CM

EE

VCM = V

CC

VS = ±15V

= 0V

V

CM

= 25°C

T

A

= 10pF

C

L

1677 G14

100

80

PHASE SHIFT (DEG)

60

40

20

0

Power Supply Rejection Ratio
vs Frequency

160

VS = ±15V

= 25°C

T

A

140

120

100

80

POSITIVE SUPPLY

60

40

20

POWER SUPPLY REJECTION RATIO (dB)

0

10 100 10k

1

NEGATIVE SUPPLY

1k

FREQUENCY (Hz)

Overshoot vs Load Capacitance

60

VS = ±15V

= 25°C

T

A

= 10k TO 2k

R

50

L

40

30

OVERSHOOT (%)

20

10

100k

RISING

EDGE

FALLING

EDGE

1M

1677 G15

–20

0.01

1

100

FREQUENCY (Hz)

10k

PM, GBWP, SR vs Temperature

70

60

50

3

2

SLEW RATE (V/µs) PHASE MARGIN (DEG)

1

–50

–25

PHASE

GBW

SLEW

50

25

0

TEMPERATURE (°C)

–10

1M

100M

1677 G16

V

= ±15V

S

= 15pF

C

L

100

125

1677 G29

75

0.1

GAIN BANDWIDTH PRODUCT, f

8
7
6
5

O

= 100kHz (MHz)

4

1 10 100

FREQUENCY (MHz)

Large-Signal Transient Response

10V

–10V

= –1

A

VCL

= ±15V

V

S

–20

1677 G17

0

10

100 1000

CAPACITANCE (pF)

Small-Signal Transient Response

50mV

0

–50mV

A

= 1

VCL

= ±15V

V

S

C

= 15pF

L

1677 G30

7

LT1677

FREQUENCY (Hz)

0.001

TOTAL HARMONIC DISTROTION + NOISE (%)

0.01

20 1k 10k 20k

1677 G24

0.0001
100

0.1

AV = 100

AV = 10

AV = 1

ZL = 2k/15pF
V

O

= 20V

P-P

AV = +1, +10, +100
MEASUREMENT BANDWIDTH
= 10Hz TO 80kHz

UW

TYPICAL PERFOR A CE CHARACTERISTICS

Settling Time vs Output Step
(Inverting)

12

0.01% OF

SETTLING TIME (µs)

10

8

6

4

2

0

FULL SCALE

0.1% OF

FULL SCALE

= ±15V

V

S

= –1

A

V

= 25°C

T

A

–6 –2 2 6

V

FULL SCALE

OUTPUT STEP (V)

Output Short-Circuit Current
vs Time

50

= ±15V

V

S

40
30
20
10

–30
–35
–40

SHORT-CIRCUIT CURRENT (mA)

SINKING SOURCING

–45
–50

0

1

TIME FROM OUTPUT SHORT TO GND (MIN)

5k

IN

0.01% OF

2

–55°C

125°C

125°C

–55°C

5k

–

+

0.1% OF

FULL SCALE

25°C

3

25°C

V

OUT

1677 G32

1677 G23

Settling Time vs Output Step
(Noninverting)

12

V

= ±15V

S

= 1

A

V

10

= 25°C

T

A

8

0.01% OF

FULL SCALE

6

4

SETTLING TIME (µs)

0.1% OF

FULL SCALE

2

10–8–10 –4 0 4 8

0

–6 –2 2 6

V

IN

OUTPUT STEP (V)

2k

–

2k

+

0.01% OF

FULL SCALE

FULL SCALE

RL = 1k

0.1% OF

V

OUT

1677 G33

10–8–10 –4 0 4 8

Output Voltage Swing
vs Load Current

+

0

V

VS = ±15V

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.5

125°C

0.4

25°C

0.3

OUTPUT VOLTAGE SWING (V)

0.2

–55°C

0.1

–

V

0

–8

–6

–10

–4

–2

I

SINK

OUTPUT CURRENT (mA)

–55°C

25°C

125°C

0

2

6

4

8

I

SOURCE

10

1677 G22

Total Harmonic Distortion and
Closed-Loop Output Impedance
vs Frequency

100

10

1

AV = +100

0.1

OUTPUT IMPEDANCE (Ω)

0.01

0.001

4

100

10

AV = +1

10k

1k

FREQUENCY (Hz)

100k

1M

1677 G31

Noise vs Frequency for

Noninverting Gain

Total Harmonic Distortion and
Noise vs Frequency for Inverting
Gain

0.1
ZL = 2k/15pF

= 20V

V

O

P-P

AV = –1, –10, – 100
MEASUREMENT BANDWIDTH
= 10Hz TO 80kHz

0.01

0.001

TOTAL HARMONIC DISTROTION + NOISE (%)

0.0001

8

AV = –100

AV = –10

AV = –1

100

20 1k 10k 20k

FREQUENCY (Hz)

1677 G25

Total Harmonic Distortion and
Noise vs Output Amplitude for
Noninverting Gain

1

0.1

0.01

0.001

TOTAL HARMONIC DISTORTION + NOISE (%)

0.0001

0.3

ZL = 2k/15pF

= 1kHz

f

O

= +1, +10, +100

A

V

MEASUREMENT BANDWIDTH
= 10Hz TO 22kHz

AV = 100

AV = 10

AV = 1

11030
OUTPUT SWING (V

P-P

Total Harmonic Distortion and
Noise vs Output Amplitude for
Inverting Gain

1

0.1

0.01

0.001

TOTAL HARMONIC DISTORTION + NOISE (%)

0.0001

)

1677 G26

0.3

ZL = 2k/15pF

= 1kHz

f

O

= –1, –10, –100

A

V

MEASUREMENT BANDWIDTH
= 10Hz TO 22kHz

AV = –100

AV = –10

AV = –1

11030
OUTPUT SWING (V

P-P

)

1677 G27

WUUU

1677 F03

1k

4.7k

OUTPUT

8

7

6

4

1

2

3

15V

–15V

–

+

LT1677

4.7k

APPLICATIO S I FOR ATIO

General

The LT1677 series devices may be inserted directly into
OP-07, OP-27, OP-37 and sockets with or without removal
of external compensation or nulling components. In addi­tion, the LT1677 may be fitted to 741 sockets with the
removal or modification of external nulling components.

INPUT

LT1677

10k

1

–

2

3

8

LT1677

+

4

15V

7

6

OUTPUT

Rail-to-Rail Operation

To take full advantage of an input range that can exceed
the supply, the LT1677 is designed to eliminate phase
reversal. Referring to the photographs shown in Figure 1,
the LT1677 is operating in the follower mode (AV = +1) at
a single 3V supply. The output of the LT1677 clips cleanly
and recovers with no phase reversal. This has the benefit
of preventing lock-up in servo systems and minimizing
distortion components.

Offset Voltage Adjustment

The input offset voltage of the LT1677 and its drift with
temperature are permanently trimmed at wafer
testing to a low level. However, if further adjustment of
VOS is necessary, the use of a 10kΩ nulling potentiometer
will not degrade drift with temperature. Trimming to a
value other than zero creates a drift of (VOS/300)µV/°C,
e.g., if VOS is adjusted to 300µV, the change in drift will be
1µV/°C (Figure 2).

–15V

1677 F02

Figure 2. Standard Adjustment

The adjustment range with a 10kΩ pot is approximately
±2.5mV. If less adjustment range is needed, the sensitiv-

ity and resolution of the nulling can be improved by using
a smaller pot in conjunction with fixed resistors. The
example has an approximate null range of ±200µV
(Figure 3).

Figure 3. Improved Sensitivity Adjustment

Input = –0.5V to 3.5V LT1677 Output

–0.5V

3V

2V

1V

0V

1577 F01a

3V

2V

1V

0V

–0.5V

1577 F01b

Figure 1. Voltage Follower with Input Exceeding the Supply Voltage (VS = 3V)

9

LT1677

WUUU

APPLICATIO S I FOR ATIO

Offset Voltage and Drift

Thermocouple effects, caused by temperature gradients
across dissimilar metals at the contacts to the input
terminals, can exceed the inherent drift of the amplifier
unless proper care is exercised. Air currents should be
minimized, package leads should be short, the two input
leads should be close together and maintained at the same
temperature.

The circuit shown to measure offset voltage is also used
as the burn-in configuration for the LT1677, with the
supply voltages increased to ±20V (Figure 4).

50k*

15V

–

2

100Ω*

3

50k*

Figure 4. Test Circuit for Offset Voltage and
Offset Voltage Drift with Temperature

LT1677

+

7

6

V

1000V

OUT =

4

*RESISTORS MUST HAVE LOW
THERMOELECTRIC POTENTIAL

–15V

V

OUT

OS

1677 F04

Unity-Gain Buffer Application

When RF ≤ 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 5).

During the fast feedthrough-like portion of the output, the
input protection diodes effectively short the output to the
input and a current, limited only by the output short-circuit
protection, will be drawn by the signal generator. With
RF ≥ 500Ω, the output is capable of handling the current
requirements (IL ≤ 20mA at 10V) and the amplifier stays
in its active mode and a smooth transition will occur.

creating additional phase shift and reducing the phase
margin. A small capacitor (20pF to 50pF) in parallel with R

F

will eliminate this problem.

R

F

–

+

LT1677

Figure 5. Pulsed Operation

OUTPUT

2.5V/µs

1677 F05

Noise Testing

The 0.1Hz to 10Hz peak-to-peak noise of the LT1677 is
measured in the test circuit shown (Figure 6a). The fre­quency response of this noise tester (Figure 6b) 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.

Measuring the typical 70nV peak-to-peak noise perfor­mance of the LT1677 requires special test precautions:

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
supplies are turned on. In the ten-second measurement
interval these temperature-induced effects can easily
exceed tens of nanovolts.

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.

As with all operational amplifiers when RF > 2k, a pole will
be created with RF and the amplifier’s input capacitance,

10

3. Sudden motion in the vicinity of the device can also
“feedthrough” to increase the observed noise.

FREQUENCY (Hz)

100

90

80

70

60

50

40

30

0.01 1 10 100

1677 F06b

0.1

GAIN (dB)

WUUU

APPLICATIO S I FOR ATIO

0.1µF

100k

LT1677

10Ω

*DEVICE UNDER TEST
NOTE: ALL CAPACITOR VALUES ARE FOR
NONPOLARIZED CAPACITORS ONLY

–

*

LT1677

+

VOLTAGE GAIN
= 50,000

2k

4.7µF

24.3k

+

LT1001

–

100k

0.1µF

4.3k

22µF

2.2µF

Figure 6a. 0.1Hz to 10Hz Noise Test Circuit

Current noise is measured in the circuit shown in Figure 7
and calculated by the following formula:

12

/



e



()

no



i

=

n

2

nV

−

130

()

Ω

M

1 101

()()

•

101

2





110k

SCOPE
× 1
R

= 1M

IN

1677 F06a

100Ω

Figure 6b. 0.1Hz to 10Hz Peak-to-Peak
Noise Tester Frequency Response

100k

500k

–

500k

LT1677

+

e

1677 F07

no

Figure 7

The LT1677 achieves its low noise, in part, by operating
the input stage at 120µA versus the typical 10µA of most
other op amps. Voltage noise is inversely proportional
while current noise is directly proportional to the square
root of the input stage current. Therefore, the LT1677’s
current noise will be relatively high. At low frequencies, the
low 1/f current noise corner frequency (≈90Hz) mini-
mizes current noise to some extent.

In most practical applications, however, current noise will
not limit system performance. This is illustrated in the
Total Noise vs Source Resistance plot (Figure 8) where:

Total Noise = [(voltage noise)2 + (current noise • RS)2 +
(resistor noise)2]

1/2

Three regions can be identified as a function of source
resistance:

(i) RS ≤ 400Ω. Voltage noise dominates
(ii) 400Ω ≤ RS ≤ 50k at 1kHz

400Ω ≤ RS ≤ 8k at 10Hz

Resistor noise
dominates

}

1000

100

TOTAL NOISE DENSITY (nV/√Hz)

R

R

SOURCE RESISTANCE = 2R

10

1

0.1

VS = ±15V
T

A

AT 1kHz

AT 10Hz

RESISTOR
NOISE ONLY

1 10 100

SOURCE RESISTANCE (kΩ)

= 25°C

1677 F08

Figure 8. Total Noise vs Source Resistance

(iii) RS > 50k at 1kHz

RS > 8k at 10Hz

Current noise
dominates

}

Clearly the LT1677 should not be used in region (iii), where
total system noise is at least six times higher than the

11

LT1677

WUUU

APPLICATIO S I FOR ATIO

voltage noise of the op amp, i.e., the low voltage noise
specification is completely wasted. In this region the
LT1792 or LT1793 is the best choice.

Rail-to-Rail Input

The LT1677 has the lowest voltage noise, offset voltage
and highest gain when compared to any rail-to-rail op
amp. The input common mode range for the LT1677 can
exceed the supplies by at least 100mV. As the common
mode voltage approaches the positive rail (VCC – 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

U

TYPICAL APPLICATIO

resistors RC1, RC2 is reduced to less than 200mV, degrad­ing the slew rate, bandwidth voltage noise, offset voltage
and input bias current (the cancellation is shut off).

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 vs Com­mon Mode Range shows where the knees occur by
displaying the change in offset voltage. The change-over
points are temperature dependent, see Common Mode
Range vs Temperature.

Microvolt Comparator with Hysteresis

1%

15k
1%

15V

OUTPUT

1677 TA02

10M5%365Ω

7

3

INPUT

POSITIVE FEEDBACK TO ONE OF THE NULLING TERMINALS
CREATES APPROXIMATELY 5µV OF HYSTERESIS. OUTPUT
CAN SINK 16mA

INPUT OFFSET VOLTAGE IS TYPICALLY CHANGED LESS THAN
5µV DUE TO THE FEEDBACK

+

2

–

LT1677

–15V

8

6

4

12

WW

SI PLIFIED SCHE ATIC

+

V

R34

R32

2k

1.5k

Q28

Q34

Q32

Q35

C1

+

40pF

R1

500Ω

C2

R2

50Ω

+

200µA

Q18

80pF

OUT

R20

R19

LT1677

R29

10Ω

R25

R16

R14

R15

–

V

1677 SS

1k

1k

1k

1k

Q29

C4

20pF

+

C3

+

40pF

Q27

R3

100Ω

Q23

2k

Q20

2k

160µA

Q19

Q31

R54

100Ω

Q26

Q30

100µA

Q22

50µA

R23A

10k

Q14 Q16

Q38

R26

R30

Q25

Q15

100Ω

2k

R23B

10k

Q17

R24

R21

R13

100Ω

100Ω

100Ω

CC

CC

< 0.7V BELOW V

> 0.7V BELOW V

CM

CM

0µA V

ID = 100µA V

CC

CC

< 0.7V BELOW V

> 0.7V BELOW V

CM

CM

50µA V

IC = 200µA V

EE

EE

> 1.5V ABOVE V

< 1.5V ABOVE V

CM

CM

0µA V

IA, IB = 200µA V

Q11

Q4 Q7

8

PAD

C2B

C2A

R

1k

R

4.5k

C10

81pF

+

100µA

C1B

C1A

1k

R

PAD

4.5k

1

R

Q12

Q6

Q10

Q2B

Q3

Q1B Q2A

Q1A

D1

D2

Q5

D4

D3

–IN

+IN

50µA

ID

IC

R9

200Ω

R8

200Ω

Q21

Q13

Q8 Q9

Q24

×2

IB

IA

13

LT1677

PACKAGE DESCRIPTIO

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

0.255 ± 0.015*
(6.477 ± 0.381)

5

12

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

0.045 – 0.065

(1.143 – 1.651)

0.100
(2.54)

BSC

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 1098

14

PACKAGE DESCRIPTIO

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

LT1677

0.228 – 0.244

(5.791 – 6.197)

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)

0.053 – 0.069

0.014 – 0.019

(0.355 – 0.483)

TYP

0.150 – 0.157**
(3.810 – 3.988)

1

3

2

4

0.004 – 0.010

(0.101 – 0.254)

0.050

(1.270)

BSC

SO8 1298

15

LT1677

TYPICAL APPLICATIO

U

This 2-wire remote Geophone preamp operates on a
current-loop principle and so has good noise immunity.
Quiescent current is ≈10mA for a V

of 2.5V. Excitation

OUT

will cause AC currents about this point of ~±4mA for a
V

of ~±1V max. The op amp is configured for a voltage

OUT

2-Wire Remote Geophone Preamp

+

6mA

V

R

R8

–

V

11Ω

3V

C

A

AV =

R

R2 + R3

R6

4.99k

R7

24.9k

R1 + R

+

C3
220µF

GEOSOURCE

MD-105
= 847Ω

R

L

GEOPHONE

||

R4

≅ 107

L

R4
14k

R1

150Ω

2

–

–

LT1677

3

+

R3

16.2k

+

LINEAR

TECHNOLOGY

LM334Z

LT1431CZ

gain of ~107. Components R5 and Q1 convert the voltage
into a current for transmission back to R10, which con­verts it into a voltage again. The LM334 and 2N3904 are
not temperature compensated so the DC output contains
temperature information.

R9

20Ω

Q1

R2

100k

7

4

C2

0.1µF

6

2N3904

R5
243Ω

C4

1000pF

1677 TA03

12V

R10
250Ω

V

OUT

2.5V ±1V

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LT1028 Ultralow Noise Precision Op Amp Lowest Noise 0.85nV/√Hz
LT1115 Ultralow Noise, Low distortion Audio Op Amp 0.002% THD, Max Noise 1.2nV/√Hz
LT1124/LT1125 Dual/Quad Low Noise, High Speed Precision Op Amps Similar to LT1007
LT1126/LT1127 Dual/Quad Decompensated Low Noise, High Speed Precision Op Amps Similar to LT1037
LT1498/LT1499 10MHz, 5V/µs, Dual/Quad Rail-to-Rail Input and Output Op Amps Precision C-LoadTM Stable
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
LT1884 Dual Rail-to-Rail Output Picoamp Input Precision Op Amp 2.2MHz Bandwidth, 1.2V/µs SR
C-Load is a trademark of Linear Technology Corporation.

1677i LT/TP 0200 4K • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 2000

16

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

●

www.linear-tech.com