LT1677CN8#TR [Linear]
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| 型号： | LT1677CN8#TR |
| 厂家： | 
Linear |
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Final Electrical Specifications
LT1677
Low Noise, Rail-to-Rail
Precision Op Amp
February 2000
U
FEATURES
DESCRIPTIO
The LT®1677 features the lowest noise performance avail-
able 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 com-
mon mode range exceeds the power supply by 100mV.
■
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 AVOL: 4V/µV Min, RL = 1k
The voltage gain of the LT1677 is extremely high, especially
with a single supply: 20 million driving a 1k load.
■
High CMRR: 109dB Min
High PSRR: 108dB Min
■
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.
■
Gain Bandwidth Product: 7.2MHz
Slew Rate: 2.5V/µs
Operating Temperature Range: –40°C to 85°C
■
■
U
APPLICATIO S
, LTC and LT are registered trademarks of Linear Technology Corporation.
■
Low Noise Signal Processing
■
Microvolt Accuracy Threshold Detection
■
Strain Gauge Amplifiers
Tape Head Preamplifiers
Direct Coupled Audio Gain Stages
Infrared Detectors
■
■
■
U
TYPICAL APPLICATIO
Precision High Side Current Sense
SOURCE
R
IN
1k
2
3
–
+
7
LT1677
4
R
LINE
0.1Ω
6
ZETEX
BC856B
V
OUT
R
OUT
V
R
OUT
LOAD
OUT
20k
= R
LINE
I
R
LOAD
IN
= 2V/AMP
1677 TA01
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.
1
LT1677
W W U W
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
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
U W
U
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
ORDER PART
TOP VIEW
TOP VIEW
NUMBER
V
V
OS
V
V
OS
OS
OS
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
TRIM
–IN
TRIM
TRIM
TRIM
–IN
+
+
–
+
V
–
+
V
LT1677CS8
LT1677IS8
LT1677CN8
LT1677IN8
+IN
OUT
NC
OUT
NC
+IN
–
–
V
V
S8 PART MARKING
S8 PACKAGE
N8 PACKAGE
8-LEAD PDIP
8-LEAD PLASTIC SO
1677
1677I
TJMAX = 150°C, θJA = 130°C/ W
TJMAX = 150°C, θJA = 190°C/ W
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
TA = 25°C, VS = ±15V, VCM = VO = 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS (Note 6)
MIN
TYP
MAX
UNITS
V
Input Offset Voltage
20
150
1.5
60
400
5
µV
µV
mV
OS
V
V
= 14V to 15.1V
= –13.3V to –15.1V
CM
CM
∆V
∆Time
Long Term Input Voltage Stability
Input Bias Current
0.3
µV/Mo
OS
I
±2
0.16
–0.4
±20
0.4
nA
µA
µA
B
V
V
= 14V to 15.1V
= –13.3V to –15.1V
CM
CM
–1.5
I
Input Offset Current
3
5
20
15
25
200
nA
nA
nA
OS
V
V
= 14V to 15.1V
= –13.3V to –15.1V
CM
CM
e
Input Noise Voltage
0.1Hz to 10Hz (Note 7)
70
33
100
nV
nV
nV
n
P-P
P-P
P-P
V
V
= 15V
= –15V
CM
CM
Input Noise Voltage Density
V
V
V
= 0V, f = 10Hz
5.2
25
7
nV/√Hz
nV/√Hz
nV/√Hz
CM
CM
CM
O
= 15V, f = 10Hz
O
= –15V, f = 10Hz
O
V
V
V
= 0V, f = 1kHz (Note 8)
3.2
17
5.3
4.5
nV/√Hz
nV/√Hz
nV/√Hz
CM
CM
CM
O
= 15V, f = 1kHz
O
= –15V, f = 1kHz
O
2
LT1677
ELECTRICAL CHARACTERISTICS
TA = 25°C, VS = ±15V, VCM = VO = 0V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS (Note 6)
MIN
TYP
MAX
UNITS
i
Input Noise Current Density
f = 10Hz
O
1.2
0.3
pA/√Hz
pA/√Hz
n
O
f = 1kHz
V
Input Voltage Range
Input Resistance
Input Capacitance
±15.1
±15.2
V
CM
R
Common Mode
2
GΩ
IN
IN
C
3.8
4.2
pF
pF
V = ±2.5V
S
CMRR
PSRR
Common Mode Rejection Ratio
Power Supply Rejection Ratio
Large-Signal Voltage Gain
V
V
= –13.3V to 14.0V
109
74
130
95
dB
dB
CM
CM
= ±15.1V
V = ±1.7V to ±18V
V = 2.7V to 40V, V = V = 1.7V
106
108
130
125
dB
dB
S
S
CM
O
A
R ≥ 10k, V = ±14V
7
4
0.4
25
20
0.7
V/µV
V/µV
V/µV
VOL
L
L
L
O
R ≥ 1k, V = ±13.5V
O
R ≥ 600Ω, V = ±10V
O
V
= 5V or 3V, V = 0V, V = 1.7V,
CC
EE
CM
R to GND, V
L
= 0.5V to:
OUT
R ≥ 10k, V – 0.5V
2
1.5
10
4
V/µV
V/µV
L
CC
R ≥ 1k, V – 0.7V
L
CC
V
V
Output Voltage Swing Low
Output Voltage Swing High
Above V
OL
OH
EE
I
I
I
= 0.1mA
= 2.5mA
= 10mA
80
110
300
170
250
500
mV
mV
mV
SINK
SINK
SINK
Below V
CC
I
I
I
= 0.1mA
= 2.5mA
= 10mA
110
190
500
170
300
700
mV
mV
mV
SOURCE
SOURCE
SOURCE
I
Output Short-Circuit Current (Note 3)
Slew Rate
25
1.7
4.5
35
2.5
mA
V/µs
MHz
%
SC
SR
R ≥ 10k (Note 9)
L
GBW
THD
Gain Bandwidth Product
Total Harmonic Distortion
Settling Time
f = 100kHz
O
7.2
R = 2k, A = 1, f = 1kHz, V = 10V
P-P
0.0006
L
V
O
O
t
10V Step 0.1%, A = +1
5
6
µs
µs
S
V
10V Step 0.01%, A = +1
V
R
O
Open-Loop Output Resistance
Closed-Loop Output Resistance
I
= 0
OUT
V
80
1
Ω
Ω
A = 100, f = 10kHz
I
Supply Current
2.75
3.5
mA
S
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
Input Offset Voltage
●
●
●
30
180
1.8
120
550
6
µV
µV
mV
OS
V
V
= 14.0V to 14.8V
= –13.3V to –15V
CM
CM
∆V
∆Temp
Average Input Offset Drift
Input Bias Current
SO-8
N8 (Note 10)
●
●
0.40
0.20
2
0.5
µV/°C
µV/°C
OS
I
●
●
●
±3
0.19
–0.43
±35
0.6
nA
µA
µA
B
V
V
= 14.0V to 14.8V
= –13.3V to –15V
CM
CM
–2
I
Input Offset Current
●
●
●
2
90
90
20
220
350
nA
nA
nA
OS
V
V
= 14.0V to 14.8V
= –13.3V to –15V
CM
CM
V
Input Voltage Range
●
–15
14.8
V
CM
CMRR
Common Mode Rejection Ratio
V
V
= –13.3V to 14.0V
= –15V to 14.8V
●
●
106
73
126
93
dB
dB
CM
CM
PSRR
Power Supply Rejection Ratio
Large-Signal Voltage Gain
V = ±1.7V to ±18V
V = 2.8V to 40V, V = V = 1.7V
S
●
●
104
106
127
122
dB
dB
S
CM
O
A
R ≥ 10k, V = ±14V
●
●
●
4
2
0.3
20
10
0.5
V/µV
V/µV
V/µV
VOL
L
O
R ≥ 1k, V = ±13.5V
L
O
R ≥ 600Ω, V = ±10V
L
O
V
V
= 5V or 3V, V = 0V, V = 1.7V,
EE CM
CC
= 0.4V to:
OUT
R ≥ 10k, V – 0.5V
●
●
3
0.5
8
4
V/µV
V/µV
L
CC
R ≥ 1k, V – 0.7V
L
CC
V
V
Output Voltage Swing Low
Output Voltage Swing High
Above V
EE
OL
OH
I
I
I
= 0.1mA
= 2.5mA
= 10mA
●
●
●
85
160
400
200
320
600
mV
mV
mV
SINK
SINK
SINK
Below V
CC
= 0.1mA
= 2.5mA
= 10mA
I
I
I
●
●
●
140
230
580
200
350
800
mV
mV
mV
SOURCE
SOURCE
SOURCE
I
Output Short-Circiut Current (Note 3)
Slew Rate
●
●
●
●
20
27
2.3
6.2
3.0
mA
V/µs
MHz
mA
SC
SR
R ≥ 10k (Note 9)
1.5
L
GBW
Gain Bandwidth Product
Supply Current
f = 100kHz
O
I
3.9
S
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
Input Offset Voltage
●
●
●
45
200
2
180
650
6.5
µV
µV
mV
OS
V
V
= 14.0V to 14.7V
= –13.3V to –15V
CM
CM
∆V
∆Temp
Average Input Offset Drift
Input Bias Current
SO-8
N8 (Note 10)
●
●
0.40
0.20
2.0
0.5
µV/°C
µV/°C
OS
I
●
●
●
±7
0.25
–0.45
±50
0.75
nA
µA
µA
B
V
V
= 14.0V to 14.7V
= –13.3V to –15V
CM
CM
–2.3
–15
I
Input Offset Current
●
●
●
6
100
100
40
250
400
nA
nA
nA
OS
V
V
= 14.0V to 14.7V
= –13.3V to –15V
CM
CM
V
Input Voltage Range
●
14.7
V
CM
CMRR
Common Mode Rejection Ratio
V
V
= –13.3V to 14.0V
= –15V to 14.7V
●
●
105
72
124
91
dB
dB
CM
CM
PSRR
Power Supply Rejection Ratio
Large-Signal Voltage Gain
V = ±1.7V to ±18V
V = 3.1V to 40V, V = V = 1.7V
S
●
●
103
105
125
120
dB
dB
S
CM
O
A
R ≥ 10k, V = ±14V
●
●
●
3
1.5
0.2
17
8
0.35
V/µV
V/µV
V/µV
VOL
L
O
R ≥ 1k, V = ±13.5V
L
O
R ≥ 600Ω, V = ±10V
L
O
V
V
= 5V or 3V, V = 0V, V = 1.7V,
EE CM
CC
= 0.5V to:
OUT
R ≥ 10k, V – 0.5V
●
●
2
0.2
15
2
V/µV
V/µV
L
CC
R ≥ 1k, V – 0.7V
L
CC
V
V
Output Voltage Swing Low
Output Voltage Swing High
Above V
EE
OL
OH
I
I
I
= 0.1mA
= 2.5mA
= 10mA
●
●
●
90
175
450
230
350
650
mV
mV
mV
SINK
SINK
SINK
Below V
CC
= 0.1mA
= 2.5mA
= 10mA
I
I
I
●
●
●
150
250
600
250
375
850
mV
mV
mV
SOURCE
SOURCE
SOURCE
I
Output Short-Circuit Current (Note 3)
Slew Rate
●
●
●
●
18
25
2.0
5.8
3.1
mA
V/µs
MHz
mA
SC
SR
R ≥ 10k (Note 9)
1.2
L
GBW
Gain Bandwidth Product
Supply Current
f = 100kHz
O
I
4.0
S
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 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 8: Noise is 100% tested.
Note 9: Slew rate is measured in A = –1; input signal is ±7.5V, output
Note 4: The LT1677C and LTC1677I are guaranteed functional over the
Operating Temperature Range of –40°C to 85°C.
V
measured at ±2.5V.
Note 10: This parameter is not 100% tested.
Note 5: The LT1677C is guaranteed to meet specified performance from
0°C to 70°C. The LT1677C is designed, characterized and expected to
5
LT1677
TYPICAL PERFOR A CE CHARACTERISTICS
U W
Voltage Noise vs Frequency
Current Noise vs Frequency
Voltage Noise vs Temperature
10
7
6
5
4
3
2
100
10
1
V
T
= ±15V
= 25°C
V
V
= ±15V
CM
S
A
S
= 0V
1/f CORNER 10Hz
10Hz
1kHz
V
< –13.5V
CM
V
> 14.5V
CM
1/f CORNER 8.5Hz
1/f CORNER 180Hz
1
V
CM
V
< –14.5V
V
CM
CM
–13.5V TO 14.5V
–13.5V TO 14.5V
1/f CORNER 90Hz
1/f CORNER 13Hz
V
= ±15V
= 25°C
S
A
1/f CORNER 60Hz
100
V
> 14.5V
CM
T
0.1
10
1000
10000
–50
0
25
50
75
125
–25
100
0.1
1
10
FREQUENCY (Hz)
100
1000
FREQUENCY (Hz)
TEMPERATURE (°C)
1677 G04
1677 G03
1677 G05
Offset Voltage Shift
vs Common Mode
VOS vs Temperature of
Representative Units
Input Bias Current Over the
Common Mode Range
140
120
100
80
2.5
2.0
250
800
600
V
V
= ±15V
S
V
= ±15V
= 25°C
S
A
= 0V
200
150
100
50
CM
T
SO-8
N8
1.5
V
IS REFERRED
CM
OS
400
TO V = 0V
1.0
V
CM
= –13.6V
V
CM
= 15.15V
60
200
0.5
40
INPUT BIAS CURRENT
= 14.3V
0
0
0
20
V
CM
–0.5
–1.0
–1.5
–2.0
–2.5
–50
–100
–150
–200
–250
0
–200
–400
–600
–800
V
CM
= –15.3V
–20
–40
–60
–80
V
T
= ±1.5V TO ±15V
= 25°C
S
A
5 TYPICAL PARTS
–55
–35 –15
5
25 45 65 85 105 125
–1.0
V
1.0 2.0 –0.8 –0.4
V
0.4
0
4
–16 –12 –8 –4
8
12 16
EE
CC
TEMPERATURE (°C)
COMMON MODE INPUT VOLTAGE (V)
V
– V (V) – V (V)
V
CM
CM
EE
CC
1677 G11
1677 G08
1677 G06
Distribution of Input Offset
Voltage Drift (N8)
Long-Term Stability of Four
Representative Units
Common Mode Range
vs Temperature
5
4
20
18
16
14
12
10
8
2.5
2.0
250
200
150
100
50
V
= ±15V
V
= ±2.5V TO ±15V
S
A
S
T
= –40°C TO 85°C
120 PARTS
(2 LOTS)
3
1.5
125°C
2
1.0
25°C
–55°C
1
0.5
–55°C
0
0
0
–1
–2
–3
–4
–5
–0.5
–1.0
–1.5
–2.0
–2.5
–50
–100
–150
–200
–250
V
IS REFERRED 125°C
OS
6
TO V = 0V
CM
25°C
4
2
0
0
100 200 300 400 500 600
TIME (HOURS)
700 800
900
–0.25 –0.15 –0.05 0.05 0.15 0.25 0.35 0.45
INPUT OFFSET VOLTAGE DRIFT (µV/°C)
1677 G02
–1.0
V
1.0 2.0 –0.8 –0.4
V
0.4
EE
CC
V
– V (V)
EE
V
– V (V)
CM CC
CM
1677 G13
1677 G09
6
LT1677
U W
TYPICAL PERFOR A CE CHARACTERISTICS
Power Supply Rejection Ratio
vs Frequency
Common Mode Rejection Ratio
vs Frequency
Supply Current vs Supply Voltage
4
3
2
1
160
140
120
100
80
160
140
120
100
V
T
= ±15V
= 25°C
V
T
= ±15V
= 25°C
EM
S
A
S
A
V
= 0V
T
= 125°C
= 25°C
A
T
A
NEGATIVE SUPPLY
80
60
POSITIVE SUPPLY
T
= –55°C
60
A
40
40
20
0
20
0
0
±5
±10
±15
±20
10
100
FREQUENCY (Hz)
10k 100k 1M
1k
10k
100k
FREQUENCY (Hz)
1M
10M
1
1k
SUPPLY VOLTAGE (V)
1677 G14
1677 G28
1677 G15
Overshoot vs Load Capacitance
Voltage Gain vs Frequency
Gain, Phase Shift vs Frequency
60
50
40
30
20
10
0
50
40
30
20
10
0
100
80
60
40
20
0
180
140
100
60
V
T
= ±15V
V
V
T
= ±15V
S
V
= ±15V
= 25°C
S
S
A
= 25°C
= 0V
A
T
CM
R
= 10k TO 2k
= 25°C
L
A
C
= 10pF
L
V
= 0V
CM
RISING
EDGE
V
= V
CC
V
CM
= V
EE
CM
FALLING
EDGE
20
–10
–20
–20
10
100
CAPACITANCE (pF)
1000
0.1
1
10
100
0.01
1
100
10k
1M
100M
FREQUENCY (MHz)
FREQUENCY (Hz)
1677 G30
1677 G17
1677 G16
PM, GBWP, SR vs Temperature
Large-Signal Transient Response
Small-Signal Transient Response
70
60
50
3
V
S
C
L
= ±15V
= 15pF
PHASE
10V
50mV
0
8
7
6
5
4
GBW
–10V
–50mV
SLEW
2
AVCL = –1
VS = ±15V
A
VCL = 1
VS = ±15V
L = 15pF
C
1
–50
0
25
50
75 100 125
–25
TEMPERATURE (°C)
1677 G29
7
LT1677
TYPICAL PERFOR A CE CHARACTERISTICS
U W
Settling Time vs Output Step
(Inverting)
Settling Time vs Output Step
(Noninverting)
Output Voltage Swing
vs Load Current
+
12
10
12
10
V
0
0.01% OF
FULL SCALE
V
A
T
= ±15V
= 1
= 25°C
V = ±15V
S
S
V
A
2k
5k
–
+
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.5
0.4
0.3
0.2
0.1
0
5k
–
–55°C
V
IN
V
L
OUT
V
2k
OUT
+
V
IN
R
= 1k
8
6
8
6
25°C
0.01% OF
FULL SCALE
125°C
0.01% OF
FULL SCALE
0.01% OF
FULL SCALE
0.1% OF
FULL SCALE
125°C
25°C
0.1% OF
FULL SCALE
4
2
0
4
2
0
0.1% OF
FULL SCALE
0.1% OF
FULL SCALE
V
A
= ±15V
= –1
= 25°C
S
V
A
–55°C
T
–
V
–10 –8 –6 –4 –2
0
2
4
6
8
10
–10 –8 –6 –4 –2
0
2
4
6
8
10
–10 –8 –6 –4 –2
0
2
4
6
8
10
I
I
OUTPUT STEP (V)
SINK
SOURCE
OUTPUT STEP (V)
OUTPUT CURRENT (mA)
1677 G33
1677 G32
1677 G22
Total Harmonic Distortion and
Noise vs Frequency for
Noninverting Gain
Output Short-Circuit Current
vs Time
Closed-Loop Output Impedance
vs Frequency
0.1
50
40
30
20
10
100
10
V
S
= ±15V
Z
V
A
= 2k/15pF
L
O
V
–55°C
= 20V
P-P
= +1, +10, +100
MEASUREMENT BANDWIDTH
= 10Hz TO 80kHz
25°C
0.01
0.001
125°C
1
A
V
= 100
A
= +100
V
–30
–35
–40
–45
–50
0.1
25°C
A
V
= 10
125°C
–55°C
A
= +1
V
0.01
0.001
A
V
= 1
0.0001
10
100
1k
10k
100k
1M
0
2
3
1
4
100
20
1k
10k 20k
TIME FROM OUTPUT SHORT TO GND (MIN)
FREQUENCY (Hz)
FREQUENCY (Hz)
1677 G31
1677 G24
1677 G23
Total Harmonic Distortion and
Noise vs Output Amplitude for
Noninverting Gain
Total Harmonic Distortion and
Noise vs Output Amplitude for
Inverting Gain
Total Harmonic Distortion and
Noise vs Frequency for Inverting
Gain
1
0.1
0.01
1
Z
f
= 2k/15pF
= 1kHz
= +1, +10, +100
Z
V
A
= 2k/15pF
Z
f
= 2k/15pF
= 1kHz
= –1, –10, –100
L
L
O
V
L
= 20V
O
P-P
O
A
= –1, –10, – 100
A
V
V
MEASUREMENT BANDWIDTH
= 10Hz TO 22kHz
MEASUREMENT BANDWIDTH
= 10Hz TO 80kHz
MEASUREMENT BANDWIDTH
= 10Hz TO 22kHz
0.1
0.01
0.1
A
= 100
V
A
= –100
V
A
= –100
= –10
0.01
V
A
= 10
A
= –10
V
V
0.001
0.0001
A
V
A
= 1
0.001
A = –1
V
0.001
V
A
V
= –1
100
0.0001
0.0001
0.3
1
10
)
30
0.3
1
10
)
30
20
1k
10k 20k
OUTPUT SWING (V
OUTPUT SWING (V
P-P
P-P
FREQUENCY (Hz)
1677 G26
1677 G25
1677 G27
8
LT1677
W U U
APPLICATIO S I FOR ATIO
U
General
10k
8
15V
The LT1677 series devices may be inserted directly into
OP-07,OP-27,OP-37andsocketswithorwithoutremoval
of external compensation or nulling components. In addi-
tion, the LT1677 may be fitted to 741 sockets with the
removal or modification of external nulling components.
1
–
+
2
3
7
6
OUTPUT
LT1677
INPUT
4
–15V
1677 F02
Rail-to-Rail Operation
Figure 2. Standard Adjustment
To take full advantage of an input range that can exceed
the supply, the LT1677 is designed to eliminate phase
reversal. ReferringtothephotographsshowninFigure1,
the LT1677 is operating in the follower mode (AV = +1) at
asingle3Vsupply. TheoutputoftheLT1677clipscleanly
and recovers with no phase reversal. This has the benefit
of preventing lock-up in servo systems and minimizing
distortion components.
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).
Offset Voltage Adjustment
1k
15V
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).
4.7k
4.7k
1
–
2
3
8
LT1677
4
7
6
OUTPUT
+
–15V
1677 F03
Figure 3. Improved Sensitivity Adjustment
LT1677 Output
Input = –0.5V to 3.5V
3V
2V
1V
0V
3V
2V
1V
0V
–0.5V
–0.5V
1577 F01a
1577 F01b
Figure 1. Voltage Follower with Input Exceeding the Supply Voltage (VS = 3V)
9
LT1677
W U U
U
APPLICATIO S I FOR ATIO
creating additional phase shift and reducing the phase
margin.Asmallcapacitor(20pFto50pF)inparallelwithRF
will eliminate this problem.
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
leadsshouldbeclosetogetherandmaintainedatthesame
temperature.
R
F
–
+
2.5V/µs
OUTPUT
LT1677
1677 F05
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).
Figure 5. Pulsed Operation
50k*
15V
Noise Testing
The 0.1Hz to 10Hz peak-to-peak noise of the LT1677 is
measured in the test circuit shown (Figure 6a). The fre-
quency 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.
–
2
7
6
100Ω* LT1677
V
OUT
+
3
V
= 1000V
OS
OUT
4
*RESISTORS MUST HAVE LOW
THERMOELECTRIC POTENTIAL
50k*
–15V
1677 F04
Figure 4. Test Circuit for Offset Voltage and
Offset Voltage Drift with Temperature
Measuring the typical 70nV peak-to-peak noise perfor-
mance of the LT1677 requires special test precautions:
Unity-Gain Buffer Application
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.
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
inputandacurrent, limitedonlybytheoutputshort-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.
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,
3. Sudden motion in the vicinity of the device can also
“feedthrough” to increase the observed noise.
10
LT1677
W U U
U
APPLICATIO S I FOR ATIO
0.1µF
100
90
80
70
60
50
40
30
100k
10Ω
–
+
2k
*
+
–
22µF
LT1677
SCOPE
× 1
IN
4.3k
LT1001
4.7µF
R
= 1M
110k
2.2µF
VOLTAGE GAIN
= 50,000
100k
0.1µF
*DEVICE UNDER TEST
NOTE: ALL CAPACITOR VALUES ARE FOR
NONPOLARIZED CAPACITORS ONLY
24.3k
0.01
0.1
1
10
100
1677 F06a
FREQUENCY (Hz)
1677 F06b
Figure 6b. 0.1Hz to 10Hz Peak-to-Peak
Noise Tester Frequency Response
Figure 6a. 0.1Hz to 10Hz Noise Test Circuit
100k
Current noise is measured in the circuit shown in Figure 7
and calculated by the following formula:
100Ω
500k
–
LT1677
e
no
1/2
500k
+
2
)
2
)
− 130nV
(
e
• 101
1677 F07
(
no
i =
n
1MΩ 101
(
)(
)
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
currentnoisewillberelativelyhigh.Atlowfrequencies,the
low 1/f current noise corner frequency (≈90Hz) mini-
mizes current noise to some extent.
1000
R
R
V
= ±15V
S
A
T
= 25°C
SOURCE RESISTANCE = 2R
100
10
1
AT 1kHz
AT 10Hz
RESISTOR
NOISE ONLY
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:
0.1
1
10
100
SOURCE RESISTANCE (kΩ)
1677 F08
Total Noise = [(voltage noise)2 + (current noise • RS)2 +
(resistor noise)2]1/2
Figure 8. Total Noise vs Source Resistance
Three regions can be identified as a function of source
resistance:
(iii) RS > 50k at 1kHz
RS > 8k at 10Hz
Current noise
dominates
(i) RS ≤ 400Ω. Voltage noise dominates
}
(ii) 400Ω ≤ RS ≤ 50k at 1kHz
400Ω ≤ RS ≤ 8k at 10Hz
Resistor noise
dominates
ClearlytheLT1677shouldnotbeusedinregion(iii),where
total system noise is at least six times higher than the
}
11
LT1677
W U U
U
APPLICATIO S I FOR ATIO
resistorsRC1, RC2 isreducedtolessthan200mV, degrad-
ing the slew rate, bandwidth voltage noise, offset voltage
and input bias current (the cancellation is shut off).
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.
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 Com-
mon 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.
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
Microvolt Comparator with Hysteresis
15V
10M
5%
365Ω
1%
7
3
+
15k
1%
INPUT
8
6
OUTPUT
LT1677
2
–
4
–15V
1677 TA02
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
12
LT1677
W
W
SI PLIFIED SCHE ATIC
+
+
13
LT1677
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
N8 Package
8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.400*
(10.160)
MAX
8
7
6
5
4
0.255 ± 0.015*
(6.477 ± 0.381)
1
2
3
0.130 ± 0.005
0.300 – 0.325
0.045 – 0.065
(3.302 ± 0.127)
(1.143 – 1.651)
(7.620 – 8.255)
0.065
(1.651)
TYP
0.009 – 0.015
(0.229 – 0.381)
0.125
0.020
(0.508)
MIN
(3.175)
MIN
+0.035
0.325
–0.015
0.018 ± 0.003
(0.457 ± 0.076)
0.100
(2.54)
BSC
+0.889
8.255
(
)
N8 1098
–0.381
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
14
LT1677
U
PACKAGE DESCRIPTIO
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
7
5
8
6
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
3
4
2
0.010 – 0.020
(0.254 – 0.508)
× 45°
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.008 – 0.010
(0.203 – 0.254)
0°– 8° TYP
0.016 – 0.050
(0.406 – 1.270)
0.050
(1.270)
BSC
0.014 – 0.019
(0.355 – 0.483)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
SO8 1298
15
LT1677
U
TYPICAL APPLICATIO
This 2-wire remote Geophone preamp operates on a
current-loop principle and so has good noise immunity.
Quiescent current is ≈10mA for a VOUT of 2.5V. Excitation
will cause AC currents about this point of ~±4mA for a
gain of ~107. Components R5 and Q1 convert the voltage
into a current for transmission back to R10, which con-
verts it into a voltage again. The LM334 and 2N3904 are
not temperature compensated so the DC output contains
temperature information.
V
OUT of ~±1V max. The op amp is configured for a voltage
2-Wire Remote Geophone Preamp
R9
20Ω
+
V
V
LINEAR
TECHNOLOGY
LM334Z
R
–
R8
11Ω
6mA
Q1
12V
3V
2N3904
R2
R6
C
100k
R4
4.99k
+
R
C3
14k
LT1431CZ
220µF
R7
24.9k
A
R5
243Ω
V
R1
150Ω
OUT
2.5V ±1V
2 –
C2
0.1µF
R10
250Ω
7
LT1677
4
GEOSOURCE
–
+
6
MD-105
R
= 847Ω
L
3
+
GEOPHONE
C4
1000pF
R3
16.2k
1677 TA03
||
R2 + R3 R4
107
A
=
V
R1 + R
L
RELATED PARTS
PART NUMBER
DESCRIPTION
Ultralow Noise Precision Op Amp
Ultralow Noise, Low distortion Audio Op Amp
Dual/Quad Low Noise, High Speed Precision Op Amps
COMMENTS
LT1028
Lowest Noise 0.85nV/√Hz
LT1115
0.002% THD, Max Noise 1.2nV/√Hz
Similar to LT1007
LT1124/LT1125
LT1126/LT1127
LT1498/LT1499
LT1792
Dual/Quad Decompensated Low Noise, High Speed Precision Op Amps
10MHz, 5V/µs, Dual/Quad Rail-to-Rail Input and Output Op Amps
Low Noise, Precision JFET Input Op Amp
Similar to LT1037
Precision C-LoadTM Stable
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
16 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
(408)432-1900 FAX:(408)434-0507 www.linear-tech.com
LINEAR TECHNOLOGY CORPORATION 2000
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