LT1997IMS-3#PBF [Linear]
LT1997-3 - Precision, Wide Voltage Range Gain Selectable Amplifier; Package: MSOP; Pins: 16; Temperature Range: -40°C to 85°C;
| 型号： | LT1997IMS-3#PBF |
| 厂家： | 
Linear |
| 描述： | LT1997-3 - Precision, Wide Voltage Range Gain Selectable Amplifier; Package: MSOP; Pins: 16; Temperature Range: -40°C to 85°C |
| 文件： | 总36页 (文件大小：2416K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1997-3
Precision, Wide Voltage
Range Gain Selectable
Amplifier
FeaTures
DescripTion
TheLT®1997-3combinesaprecisionoperationalamplifier
with highly-matched resistors to form a one-chip solution
for accurately amplifying voltages. Gains from –13 to +14
with accuracy of 0.006% (60ppm) can be achieved using
noexternalcomponents. TheLT1997-3isparticularlywell
suited for use as a difference amplifier, where the excellent
resistor matching results in a common mode rejection
ratio of greater than 91dB.
n
Pin Configurable as a Difference Amplifier, Inverting
Amplifier or Noninverting Amplifier
n
91dB Minimum DC CMRR (Gain = 1)
n
65dB AC CMRR (at 100kHz, Gain = 1)
n
0.006% (60ppm) Maximum Gain Error (Gain = 1)
n
1ppm/°C Maximum Gain Error Drift
n
2ppm Maximum Gain Nonlinearity
n
160V Common Mode Voltage Range
n
Wide Supply Voltage Range: 3.3V to 50V
Theamplifierfeaturesa60μVmaximuminputoffsetvoltage
anda–3dBbandwidthof1.1MHz(Gain=1).TheLT1997-3
operates from any supply voltage from 3.3V to 50V and
draws only 350μA supply current. The output typically
swings to within 100mV of either supply rail.
n
Rail-to-Rail Output
350µA Supply Current
n
n
60µV Maximum Op Amp Offset Voltage
n
1.1MHz –3dB Bandwidth (Gain = 1)
n
Low-Power Shutdown: 20µA
n
The resistors maintain their excellent matching over
temperature; the matching temperature coefficient is
guaranteedlessthan1ppm/°C.Theresistorsareextremely
linear with voltage, resulting in a gain nonlinearity of less
than 2ppm.
Space-Saving MSOP and DFN Packages
applicaTions
n
High Side or Low Side Current Sensing
n
Bidirectional Wide Common Mode Range Current
The LT1997-3 is fully specified at 5V and 15V supplies
and from –40°C to 125°C. The device is available in space
saving 16-lead MSOP and 4mm × 4mm DFN14 packages.
L, LT, LTC, LTM, Linear Technology, Over-The-Top and the Linear logo are registered
trademarks of Analog Devices, Inc. All other trademarks are the property of their respective
owners.
Sensing
n
n
n
n
High Voltage to Low Voltage Level Translation
Industrial Data-Acquisition Front-Ends
Replacement for Isolation Circuits
Differential to Single-Ended Conversion
Typical applicaTion
Typical Distribution of CMRR (G = 1)
Gain = 1 Difference Amplifier
1200
V
= –28V TO 26.5V
15V
SOURCE
V
= ±±1V
S
V
CM
= –28V TO +26.1V
+
–INA –INB –INC
V
LT1997-3
1000
800
600
400
200
0
4621 UNITS
2.5k
7.5k
FROM 3 RUNS
22.5k
22.5k
22.5k
–
+
OUT
R
R
C
SENSE
V
OUT
= 1ꢀV/ꢀA
1Ω
1Ω
7.5k
2.5k
45k
45k
REF2
REF1
LOAD
–30
–20
–10
0
10
20
30
–
V
CMRR (µV/V = ppm)
+INA +INB +INC
SHDN
19973 TA01b
19973 TA01a
–15V
19973f
1
For more information www.linear.com/LT1997-3
LT1997-3
absoluTe MaxiMuM raTings
(Note 1)
+
–
Output Short-Circuit Duration
(Note 3) ..........................................Thermally Limited
Temperature Range (Notes 4, 5)
LT1997I-3 ................................................–40 to 85°C
LT1997H-3.............................................–40 to 125°C
Maximum Junction Temperature .......................... 150°C
Storage Temperature Range ......................–65 to 150°C
MSOP Lead Temperature (Soldering, 10 sec)........300°C
Supply Voltages (V to V )........................................60V
–
+INA, –INA (Note 2)......................................... V 160V
+INB, –INB, +INC, –INC
–
–
(Note 2) ..............................(V + 80V) to (V – 0.3V)
–
–
REF, REF1, REF2..................... (V + 60V) to (V – 0.3V)
+
–
SHDN..................................... (V + 0.3V) to (V – 0.3V)
Output Current (Continuous) (Note 6)....................50mA
pin conFiguraTion
TOP VIEW
TOP VIEW
+INA
1
14 –INA
1
3
+INA
+INB
16 –INA
14 –INB
+INB
NC
3
4
5
6
7
12 –INB
11 NC
15
5
6
7
8
+INC
REF1
REF2
12 –INC
+
–
V
11
V
+INC
SHDN
REF
10 –INC
+
10 SHDN
–
V
9
OUT
V
9
8
MS PACKAGE
OUT
VARIATION: MS16 (12)
16-LEAD PLASTIC MSOP
T
= 150°C, θ = 130°C/W
JA
JMAX
DF PACKAGE
14(12)-LEAD (4mm × 4mm) PLASTIC DFN
T
= 150°C, θ = 45°C/W , θ = 3°C/W
JA JC
JMAX
–
EXPOSED PAD (PIN 15) IS V , MUST BE SOLDERED TO PCB
orDer inForMaTion
http://www.linear.com/product/LT1997-3#orderinfo
SPECIFIED
TEMPERATURE RANGE
LEAD FREE FINISH
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
LT1997IDF-3#PBF
LT1997HDF-3#PBF
LT1997IMS-3#PBF
LT1997HMS-3#PBF
LT1997IDF-3#TRPBF
LT1997HDF-3#TRPBF
LT1997IMS-3#TRPBF
LT1997HMS-3#TRPBF
19973
19973
19973
19973
14-Lead (4mm × 4mm) Plastic DFN
14-Lead (4mm × 4mm) Plastic DFN
16-Lead Plastic MSOP
–40°C to 85°C
–40°C to 125°C
–40°C to 85°C
–40°C to 125°C
16-Lead Plastic MSOP
*The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for parts specified with wider operating temperature ranges.
Parts ending with PBF are RoHS and WEEE compliant.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/.
19973f
2
For more information www.linear.com/LT1997-3
LT1997-3
elecTrical characTerisTics The l denotes the specifications which apply over the full operating
temperature range, –40°C < TA < 85°C for I-grade parts, –40°C < TA < 125°C for H-grade parts, otherwise specifications are at
TA = 25°C. Difference Amplifier Configuration, V+ = 15V, V– = –15V, VCM = VOUT = VREF = VREF1 = VREF2 = 0V. VCMOP is the common
mode voltage of the internal op amp.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
0.001
0.001
0.002
MAX
UNITS
∆G
Gain Error
V
= 10V
OUT
G = 1
G = 3
G = 9
0.006
0.012
%
%
l
l
0.015
0.02
%
%
0.03
0.04
%
%
l
l
∆G/∆T
GNL
Gain Drift vs Temperature (Note 6)
Gain Nonlinearity
V
V
= 10V
= 10V
0.2
1
1
ppm/°C
OUT
2
3
ppm
ppm
OUT
l
–
+
V
OS
Op Amp Offset Voltage (Note 9)
V < V
< V – 1.75V
20
60
200
µV
µV
CMOP
l
l
–
+
∆V /∆T Op Amp Offset Voltage Drift (Note 6)
OS
V < V
< V – 1.75V
0.5
2
1.5
µV/°C
CMOP
–
+
I
Op Amp Input Bias Current
Op Amp Input Offset Current
Input Impedance (Note 8)
V + 0.25V < V
< V – 1.75V
–5
–15
5
15
nA
nA
B
CMOP
CMOP
l
l
–
+
I
V + 0.25V < V
< V – 1.75V
–3
–10
0.5
3
10
nA
nA
OS
R
Common Mode
G = 1
G = 3
G = 9
IN
l
l
l
19
12.6
10.5
22.5
15
12.5
26
17.4
14.5
kΩ
kΩ
kΩ
Differential
G = 1
l
l
l
38
12.6
4.2
45
15
5
52
17.4
5.8
kΩ
kΩ
kΩ
G = 3
G = 9
CMRR
CMRR
Common Mode Rejection Ratio,
MS16 Package
G = 1, V = –28V to +26.5V
91
87
106
dB
dB
CM
l
l
l
l
l
l
l
l
l
G = 3, V = –15V to +17.6V
90
86
99
dB
dB
CM
G = 9, V = –15V to +14.7V
96
94
112
101
94
dB
dB
CM
Common Mode Rejection Ratio,
DF14 Package
G = 1, V = –28V to +26.5V
91
87
dB
dB
CM
G = 1, V = –90V to +90V, +INB = –INB = 0V,
83
80
dB
dB
CM
V = 25V
S
G = 1, V = –120V to +120V, +INC = –INC = 0V,
81
77
91
dB
dB
CM
V = 25V, T = –40°C to 125°C
S
A
G = 1, V = –160V to +160V, +INC = –INC = 0V,
81
78
91
dB
dB
CM
V = 25V, T = –40°C to 85°C
S
A
G = 3, V = –15V to +17.6V
90
86
98
dB
dB
CM
G = 9, V = –15V to +14.7V
96
94
103
dB
dB
CM
l
l
l
l
V
Input Voltage Range (Note 7)
+INA/–INA
–30
–160
–15
26.5
160
17.6
14.7
V
V
V
V
CM
+INA/–INA, +INC/–INC Connected to Ground
+INB/–INB
+INC/–INC
–15
19973f
3
For more information www.linear.com/LT1997-3
LT1997-3
elecTrical characTerisTics The l denotes the specifications which apply over the full operating
temperature range, –40°C < TA < 85°C for I-grade parts, –40°C < TA < 125°C for H-grade parts, otherwise specifications are at
TA = 25°C. Difference Amplifier Configuration, V+ = 15V, V– = –15V, VCM = VOUT = VREF = VREF1 = VREF2 = 0V. VCMOP is the common
mode voltage of the internal op amp.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
∆R/R
Reference Divider Matching Error
∆R RREF1 –RREF2
Available in MS16 Package Only
0.001
0.006
0.012
%
%
l
l
=
⎛
⎜
⎝
⎞
⎟
⎠
R
REF1+RREF2
R
2
PSRR
Power Supply Rejection Ratio
V = 1.65V to 25V, V = V
= Mid-Supply
114
124
dB
S
CM
OUT
(Note 9)
e
ni
Input Referred Noise Voltage Density
f = 1kHz
G = 1
50
30
22
nV/√Hz
nV/√Hz
nV/√Hz
G = 3
G = 9
Input Referred Noise Voltage
f = 0.1Hz to 10Hz
G = 1
1.4
1
0.8
µV
µV
µV
P-P
P-P
P-P
G = 3
G = 9
l
l
V
V
Output Voltage Swing Low (Referred
No Load
100
280
150
500
mV
mV
OL
–
to V )
I
= 5mA
SINK
l
l
Output Voltage Swing High (Referred
No Load
SOURCE
100
530
180
900
mV
mV
OH
+
to V )
I
= 5mA
+
–
l
l
I
SC
Short-Circuit Output Current
50Ω to V
50Ω to V
10
10
28
30
mA
mA
l
SR
Slew Rate
∆V
= 5V
0.45
0.75
V/µs
OUT
BW
Small Signal –3dB Bandwidth
G = 1
G = 3
G = 9
1100
700
300
kHz
kHz
kHz
t
Settling Time
G = 1
S
0.1%, ∆V
= 10V
OUT
14.6
95
µs
µs
OUT
0.01%, ∆V
= 10V
G = 3
0.1%, ∆V
= 10V
OUT
13.6
29
µs
µs
OUT
0.01%, ∆V
= 10V
G = 9
0.1%, ∆V
= 10V
OUT
13.8
29
µs
µs
OUT
0.01%, ∆V
= 10V
V
Supply Voltage
Turn-On Time
3
50
50
V
V
S
l
3.3
t
16
µs
V
ON
+
l
l
l
V
V
SHDN Input Logic Low (Referred to V )
–2.5
IL
+
SHDN Input Logic High (Referred to V )
–1.2
V
IH
I
I
SHDN Pin Current
–10
350
–15
µA
SHDN
S
+
+
Supply Current
Active, V
Active, V
≥ V – 1.2V
400
600
25
µA
µA
µA
µA
SHDN
SHDN
Shutdown, V
Shutdown, V
l
l
≥ V – 1.2V
+
+
≤ V – 2.5V
≤ V – 2.5V
20
SHDN
SHDN
70
19973f
4
For more information www.linear.com/LT1997-3
LT1997-3
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, –40°C < TA < 85°C for I-grade parts, –40°C < TA < 125°C for H-grade parts, otherwise specifications are at
TA = 25°C. Difference Amplifier Configuration, V+ = 5V, V– = 0V, VCM = VOUT = VREF = VREF1 = VREF2 = Mid-Supply. VCMOP is the
common mode voltage of the internal op amp.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
0.001
0.001
0.002
MAX
UNITS
∆G
Gain Error
V
OUT
= 1V to 4V
G = 1
G = 3
G = 9
0.006
0.012
%
%
l
l
0.015
0.02
%
%
0.03
0.04
%
%
l
l
∆G/∆T
GNL
Gain Drift vs Temperature (Note 6)
Gain Nonlinearity
V
V
= 1V to 4V
= 1V to 4V
0.2
1
1
ppm/°C
ppm
OUT
OUT
–
+
V
Op Amp Offset Voltage (Note 9)
V < V
< V – 1.75V
20
60
200
µV
µV
OS
CMOP
l
l
–
+
∆V /∆T Op Amp Offset Voltage Drift (Note 6)
OS
V < V
< V – 1.75V
0.5
2
1.5
µV/°C
CMOP
–
+
I
Op Amp Input Bias Current
Op Amp Input Offset Current
Input Impedance (Note 8)
V + 0.25V < V
< V – 1.75V
–5
–15
5
15
nA
nA
B
CMOP
l
l
–
+
I
OS
V + 0.25V < V
< V – 1.75V
–3
–10
0.5
3
10
nA
nA
CMOP
R
Common Mode
G = 1
G = 3
G = 9
IN
l
l
l
19
12.6
10.5
22.5
15
12.5
26
17.4
14.5
kΩ
kΩ
kΩ
l
l
l
l
Differential
G = 1
38
12.6
4.2
45
15
5
52
17.4
5.8
kΩ
kΩ
kΩ
G = 3
G = 9
CMRR
CMRR
Common Mode Rejection Ratio,
MS16 Package
G = 1, V = –2.5V to +4.0V
90
88
100
103
108
96
dB
dB
CM
l
l
l
l
l
l
l
G = 3, V = 0V to +3.5V
90
87
dB
dB
CM
G = 9, V = 0V to +3.3V
96
94
dB
dB
CM
Common Mode Rejection Ratio,
DF14 Package
G = 1, V = –2.5V to +4.0V
90
88
dB
dB
CM
G = 3, V = 0V to +3.5V
90
87
101
107
0.001
dB
dB
CM
G = 9, V = 0V to +3.3V
96
94
dB
dB
CM
∆R/R
Reference Divider Matching Error
Available in MS16 Package Only
0.006
0.012
%
%
∆R RREF1 –RREF2
=
⎛
⎜
⎝
⎞
⎟
⎠
R
REF1+RREF2
R
2
l
PSRR
Power Supply Rejection Ratio
V = 1.65V to 25V, V = V
= Mid-Supply
114
124
dB
S
CM
OUT
(Note 9)
e
Input Referred Noise Voltage Density
f = 1kHz
G = 1
ni
50
30
22
nV/√Hz
nV/√Hz
nV/√Hz
G = 3
G = 9
19973f
5
For more information www.linear.com/LT1997-3
LT1997-3
elecTrical characTerisTics The l denotes the specifications which apply over the full operating
temperature range, –40°C < TA < 85°C for I-grade parts, –40°C < TA < 125°C for H-grade parts, otherwise specifications are at
TA = 25°C. Difference Amplifier Configuration, V+ = 5V, V– = 0V, VCM = VOUT = VREF = VREF1 = VREF2 = Mid-Supply. VCMOP is the
common mode voltage of the internal op amp.
SYMBOL PARAMETER
Input Referred Noise Voltage
CONDITIONS
MIN
TYP
MAX
UNITS
f = 0.1Hz to 10Hz
G = 1
G = 3
G = 9
1.4
1
0.8
µV
µV
µV
P-P
P-P
P-P
–
l
l
V
V
Output Voltage Swing Low (Referred to V ) No Load
= 5mA
15
280
50
500
mV
mV
OL
I
SINK
+
l
l
Output Voltage Swing High (Referred to V ) No Load
15
450
50
800
mV
mV
OH
I
= 5mA
SOURCE
+
l
l
I
SC
Short-Circuit Output Current
50Ω to V
50Ω to V
10
10
27
25
mA
mA
–
l
SR
Slew Rate
∆V
OUT
= 3V
0.45
0.75
V/µs
BW
Small signal –3dB Bandwidth
G = 1
G = 3
G = 9
1100
700
300
kHz
kHz
kHz
t
Settling Time
G = 1
S
0.1%, ∆V
= 2V
OUT
5.4
91
µs
µs
OUT
0.01%, ∆V
= 2V
G = 3
0.1%, ∆V
= 2V
OUT
6
21
µs
µs
OUT
0.01%, ∆V
= 2V
G = 9
0.1%, ∆V
= 2V
OUT
7
36
µs
µs
OUT
0.01%, ∆V
= 2V
V
Supply Voltage
Turn-On Time
3
50
50
V
V
S
l
3.3
t
22
µs
V
ON
+
l
l
l
V
V
SHDN Input Logic Low (Referred to V )
–2.5
IL
+
SHDN Input Logic High (Referred to V )
–1.2
V
IH
I
I
SHDN Pin Current
–10
330
–15
µA
SHDN
S
+
+
Supply Current
Active, V
≥ V – 1.2V
370
525
20
µA
µA
µA
µA
SHDN
SHDN
l
l
Active, V
≥ V –1.2V
+
+
Shutdown, V
Shutdown, V
≤ V – 2.5V
≤ V – 2.5V
15
SHDN
SHDN
40
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 5: The LT1997I-3 is guaranteed to meet specified performance
from –40°C to 85°C. The LT1997H-3 is guaranteed to meet specified
performance from –40°C to 125°C.
Note 6: This parameter is not 100% tested.
Note 2: See “Common Mode Voltage Range” and “High Common Mode
Voltage Difference Amplifiers” in the Applications Information section of
this data sheet for other considerations when taking +INA/–INA pins to
160V and +INB/–INB/+INC/–INC pins to +80V.
Note 3: A heat sink may be required to keep the junction temperature
below absolute maximum. This depends on the power supply, input
voltages and the output current.
Note 7: The Input Voltage Range numbers specified in the table guarantee
that the internal op amp operates in its normal operating region. The Input
voltage range can be significantly higher if the internal op amp operates in
its Over-The-Top® operating region. See “Common Mode Voltage Range”
in the Applications Information section to determine the valid input voltage
range under various operating conditions.
Note 8: Input impedance is tested by a combination of direct
Note 4: The LT1997I-3 is guaranteed functional over the operating
temperature range of –40°C to 85°C. The LT1997H-3 is guaranteed
functional over the operating temperature range of –40°C to 125°C.
measurements and correlation to the CMRR and gain error tests.
Note 9: Offset voltage, offset voltage drift and PSRR are defined as
referred to the internal op amp. You can calculate output offset as follows.
In the case of balanced source resistance, V
= (V • NOISEGAIN)
OS,OUT
OS
+ (I • 22.5k) + (I • 22.5k • (1– R /R )) where R and R are the total
OS
B
P
N
P
N
resistance at the op amp positive and negative terminal, respectively.
19973f
6
For more information www.linear.com/LT1997-3
LT1997-3
TA = 25°C, VS = ±15V, Difference Amplifier
Typical perForMance characTerisTics
configuration, unless otherwise noted.
Typical Distribution of CMRR
(G = 1)
Typical Distribution of CMRR
(G = 1)
Typical Distribution of CMRR
(G = 3)
1200
1000
800
600
400
200
0
500
450
400
350
300
250
200
150
100
50
1400
1200
1000
800
600
400
200
0
22.
k
22.
k
k
V
= ±1 V
V
= ±1 V
V = 25V
S
S
S
2.5k
7.
7.
k
k
22.
22.
k
k
–
+
–
+
V
CM
= –1 V TO +17.6V
V
CM
= –28V TO +26. V
V
CM
= –160V TO +160V
+INC = –INC = 0V
22.5k
22.5k
22.5k
–
+
44 0 UNITS
FROM 3 RUNS
462 UNITS
FROM 3 RUNS
2709 UNITS
FROM 2 RUNS
22.
k
22.
22.5k
2.5k
0
–30
–20
–10
0
10
20
30
–100 –75 –50 –25
0
25 50 75 100
–30
–20
–10
0
10
20
30
CMRR (µV/V = ppm)
CMRR (µV/V = ppm)
CMRR (µV/V = ppm)
19973 G01
19973 G02
19973 G03
Typical Distribution of CMRR
(G = 9)
Typical Distribution of Gain Error
(G = 1)
Typical Distribution of Gain Error
(G = 3)
1200
1000
800
600
400
200
0
800
700
600
500
400
300
200
100
0
800
700
600
500
400
300
200
100
0
22.
k
22.
k
V
= ±1 V
V
OUT
= ±1 V
= ±1 V
22.
k
V = ±1 V
S
OUT
S
S
2.
2.
k
k
22.
22.
k
k
V
CM
= –1 V TO +14.7V
V
V
= ±1 V
–
+
–
+
7.
7.
k
k
–
+
44 0 UNITS
FROM 3 RUNS
4864 UNITS
FROM 3 RUNS
22.
k
22.
k
22.
k
4864 UNITS
FROM 3 RUNS
–15
–10
–5
0
5
10
15
–50 –40 –30 –20 –10
0
10 20 30 40 50
–150 –100 –50
0
50
100
150
CMRR (µV/V=ppm)
GAIN ERROR (ppm)
GAIN ERROR (ppm)
19973 G04
19973 G05
19973 G06
Typical Distribution of Gain Error
(G = 9)
Typical Distribution of Gain
Nonlinearity
CMRR vs Frequency
140
120
100
80
800
700
600
500
400
300
200
100
0
1200
1000
800
600
400
200
0
22.
k
22.
k
V
OUT
= ±1 V
= ±1 V
V
= ±1 V
= ±1 V
G = 1
S
S
2.
2.
k
k
V
V
OUT
22.
22.
k
k
–
+
–
+
4864 UNITS
FROM 3 RUNS
22.
k
22.
k
60
40
G = 1
G = 3
G = 9
20
4864 UNITS
FROM 3 RUNS
0
10
100
1k
10k 100k
1M
10M
–300 –200 –100
0
100
200
300
0
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6 1.8 2.0
FREQUENCY (Hz)
GAIN ERROR (ppm)
GAIN NONLINEARITY (ppm)
19973 G09
19973 G07
19973 G08
19973f
7
For more information www.linear.com/LT1997-3
LT1997-3
T = 25°C, V = ±15V, Difference Amplifier
Typical perForMance characTerisTics
A
S
configuration, unless otherwise noted.
Typical Distribution of
Op Amp PSRR
Typical Gain Error for RL = 10kΩ
G = 1 (Curves Offset for Clarity)
Typical Distribution of Op Amp
Offset Voltage
1200
1000
800
600
400
200
0
800
700
600
500
400
300
200
100
0
4864 UNITS
V
= ±±1.65 ꢀt ±ꢁ65
S
6360 UNITS
FROM 3 RUNS
FROM 3 RUNS
V
V
V
V
= ±±18
= ±±15
= ±±12
= ±±10
S
S
S
S
–20 –16 –12 –8 –4
0
4
8
12 16 20
–1.5
–1
–0.5
0
0.5
1
1.5
–60
–40
–20
0
20
40
60
OUTPUT VOLTAGE (V)
PSRR (µV/V)
OFFSET VOLTAGE (µV)
19973 G12
19973 G11
19973 G10
Typical Gain Error for Low Supply
Voltages, G = 1
(Curves Offset for Clarity)
Typical Gain Error for RL = 5kΩ
G = 1 (Curves Offset for Clarity)
Typical Gain Error for RL = 2kΩ
G = 1 (Curves Offset for Clarity)
V
S
V
S
V
S
V
S
= ±±18
= ±±15
= ±±12
= ±±10
V
S
V
S
V
S
V
S
= ±±18
= ±±15
= ±±12
= ±±10
V
= ±±5, R =10kΩ
S
L
V
= ±±5, R =2kΩ
S
L
V
= ±±5, R =1kΩ
L
S
V
= ±±2.5, R =1kΩ
L
S
–6 –5 –4 –3 –2 –1
0
1
2
3
4
5
6
–20 –16 –12 –8 –4
0
4
8
12 16 20
–20 –16 –12 –8 –4
0
4
8
12 16 20
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
19973 G15
19973 G13
19973 G14
Typical Gain Error for RL = 10kΩ
G = 3 (Curves Offset for Clarity)
Typical Gain Error for RL = 5kΩ
G = 3 (Curves Offset for Clarity)
Typical Gain Error for RL = 2kΩ
G = 3 (Curves Offset for Clarity)
V
V
V
V
= ±±18
= ±±15
= ±±12
= ±±10
V
V
V
V
= ±±18
= ±±15
= ±±12
= ±±10
V
V
V
V
= ±±18
= ±±15
= ±±12
= ±±10
S
S
S
S
S
S
S
S
S
S
S
S
–20 –16 –12 –8 –4
0
4
8
12 16 20
–20 –16 –12 –8 –4
0
4
8
12 16 20
–20 –16 –12 –8 –4
0
4
8
12 16 20
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
19973 G16
19973 G17
19973 G18
19973f
8
For more information www.linear.com/LT1997-3
LT1997-3
T = 25°C, V = ±15V, Difference Amplifier
Typical perForMance characTerisTics
A
S
configuration, unless otherwise noted.
Typical Gain Error for RL = 10kΩ
G = 9 (Curves Offset for Clarity)
Typical Gain Error for RL = 5kΩ
G = 9 (Curves Offset for Clarity)
Typical Gain Error for RL = 2kΩ
G = 9 (Curves Offset for Clarity)
V
= ±±18
V
= ±±18
S
V
V
V
= ±±18
= ±±15
= ±±12
S
S
S
S
V
= ±±15
S
V
S
V
S
V
S
= ±±15
= ±±12
= ±±10
V
= ±±12
S
V
= ±±10
S
V
= ±±10
S
–20 –16 –12 –8 –4
0
4
8
12 16 20
–20 –16 –12 –8 –4
0
4
8
12 16 20
–20 –16 –12 –8 –4
0
4
8
12 16 20
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
19973 G20
19973 G21
19973 G19
Gain Error vs Temperature
CMRR vs Temperature
50
40
30
20
10
0
100
80
10
8
V
= ±±15
S
10 UNITS,
G=1
60
6
40
4
20
2
0
0
–10
–20
–30
–40
–50
–20
–40
–60
–80
–100
–2
–4
–6
–8
–10
V
= ±±15
OUT
= 10kΩ
S
V
= ±±10
R
L
10 UNITS
G=1
–75 –50 –25
0
25 50 75 100 125 150 175
–75 –50 –25
0
25 50 75 100 125 150 175
TEMPERATURE (°C)
TEMPERATURE (°C)
19973 G23
19973 G22
Maximum Power Dissipation vs
Temperature
Output Voltage vs Load Current
20
15
5
4
3
2
1
0
DF14(12) θ = 45°C/W
JA
10
5
130°C
85°C
25°C
–45°C
0
–5
–10
–15
–20
MS16(12) θ = 130°C/W
JA
0
5
10
15
20
25
30
–60 –40 –20
0
20 40 60 80 100 120 140 160
OUTPUT CURRENT (mA)
AMBIENT TEMPERATURE (°C)
19973 G24
19973 G25
19973f
9
For more information www.linear.com/LT1997-3
LT1997-3
T = 25°C, V = ±15V, Difference Amplifier
Typical perForMance characTerisTics
A
S
configuration, unless otherwise noted.
Frequency Response vs
Capacitive Load (G = 1)
Frequency Response vs
Capacitive Load (G = 3)
Gain vs Frequency
30
25
20
15
10
5
30
20
30
20
10
0
G = 9
10
G = 3
0
–10
–20
–30
–10
–20
–30
G = 1
0pF
0pF
0
220pF
220pF
560pF
680pF
560pF
–5
680pF
1000pF
–10
0.001
0.01
0.1
1
2
0.001
0.01
0.1
1
10
0.001
0.01
0.1
1
10
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (MHz)
19973 G26
19973 G27
19973 G28
Frequency Response vs
Capacitive Load (G = 9)
Op Amp Noise Density vs
Frequency
0.1Hz to 10Hz Noise
40
35
30
25
20
15
10
5
30
20
MEASURED IN G = 13
REFERRED TO OP AMP INPUTS
MEASURED IN G = 13
REFERRED TO OP AMP INPUTS
10
0
–10
–20
–30
0pF
220pF
560pF
680pF
1000pF
0
1
10
100
1k
10k
100k
0.001
0.01
0.1
1
10
FREQUENCY (Hz)
TIME (10s/DIV)
FREQUENCY (MHz)
19973 G30
19973 G31
19973 G29
Negative PSRR vs Frequency
Positive PSRR vs Frequency
140
120
100
80
160
140
120
100
80
60
60
40
40
G = 1
G = 3
G = 9
G = 1
G = 3
G = 9
20
20
0
0
10
100
1k
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
FREQUENCY (Hz)
19973 G33
19973 G32
19973f
10
For more information www.linear.com/LT1997-3
LT1997-3
T = 25°C, V = ±15V, Difference Amplifier
Typical perForMance characTerisTics
A
S
configuration, unless otherwise noted.
Slew Rate vs Temperature
Large-Signal Step Response
Small-Signal Step Response
140
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
G = 1
G = 1
R
L
= 10kΩ
120
100
80
R
L
= 10kΩ
= 560pF
R =10kΩ
L
L
C
C
= 680pF
L
RISING EDGE
60
40
20
0
–20
–40
–60
–80
–100
FALLING EDGE
C
= 560pF
L
C
= 0pF
L
0
5
10 15 20 25 30 35 40
–75 –50 –25
0
25 50 75 100 125 150 175
TIME (µs)
TIME (10µs/DIV)
TEMPERATURE (°C)
19973 G36
19973 G35
19973 G34
Small-Signal Step Response
Small-Signal Step Response
140
120
100
80
140
120
100
80
G = 3
G = 9
R =10kΩ
L
R =10kΩ
L
C
L
= 1000pF
C = 1000pF
L
C
= 680pF
C
= 680pF
L
L
60
60
40
40
20
20
0
0
–20
–40
–60
–80
–100
–20
–40
–60
–80
–100
C
= 560pF
C
= 560pF
L
L
C
L
= 0pF
C = 0pF
L
0
5
10 15 20 25 30 35 40
0
5
10 15 20 25 30 35 40
TIME (µs)
TIME (µs)
19973 G37
19973 G38
Settling Time
Settling Time
6
5
6
6
5
6
OUTPUT VOLTAGE
G = 1
G = 1
5
5
4
4
4
4
3
3
3
3
ERROR VOLTAGE
2
2
2
2
ERROR VOLTAGE
1
1
1
1
0
0
0
0
–1
–2
–3
–4
–5
–6
–1
–2
–3
–4
–5
–6
–1
–2
–3
–4
–5
–6
–1
–2
–3
–4
–5
–6
OUTPUT VOLTAGE
TIME (20µs/DIV)
TIME (20µs/DIV)
19973 G39
19973 G40
19973f
11
For more information www.linear.com/LT1997-3
LT1997-3
T = 25°C, V = ±15V, Difference Amplifier
Typical perForMance characTerisTics
A
S
configuration, unless otherwise noted.
Op Amp Offset Voltage vs
Quiescent Current vs Temperature
Thermal Shutdown vs Hysteresis
Temperature
550
500
450
400
350
300
250
200
600
200
150
100
50
10 UNITS
20 UNITS
500
400
300
200
100
0
0
–50
–100
–150
–200
–75 –50 –25
0
25 50 75 100 125 150 175
145
150
155
160
165
170
–60 –40 –20
0
20 40 60 80 100 120 140
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
19973 G42
19973 G43
19973 G41
Quiescent Current vs Supply
Voltage
Shutdown Quiescent Current vs
Supply Voltage
600
500
400
300
200
100
0
50
40
30
20
10
0
PARAMETRIC SWEEP IN ~25°C
INCREMENTS
150°C
125°C
85°C
25°C
–40°C
–55°C
T
= 150°C
A
V
= 0V
SHDN
T
= –55°C
A
0
10
20
30
40
50
0
10
20
30
40
50
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
19973 G44
19973 G45
Quiescent Current vs SHDN
Voltage
Minimum Supply Voltage
550
500
450
400
350
300
250
200
150
100
50
20
15
10
5
V
= ±±15
S
150°C
125°C
85°C
25°C
–40°C
–55°C
T
= 125°C
A
0
–5
T
= 25°C
A
–10
–15
–20
T
= –45°C
A
0
0
5
10
15
0
1
2
3
4
5
SHDN VOLTAGE (V)
TOTAL SUPPLY VOLTAGE (V)
19973 G46
19973 G47
19973f
12
For more information www.linear.com/LT1997-3
LT1997-3
pin FuncTions (DFN/MSOP)
V (Pin 9/Pin 11): Positive Supply Pin.
+
–INC (Pin 10/Pin 12): Inverting Gain-of-9 input Pin.
Connects a 2.5k internal resistor to the internal op amp’s
inverting input.
–
V (EXPOSED PAD Pin 15/Pin 8): Negative Supply Pin.
OUT (Pin 8/Pin 9): Output Pin.
REF (Pin 7/NA): Reference Input Pin. Sets the output level
when the difference between the inputs is zero.
+INA (Pin 1/Pin 1): Noninverting Gain-of-1 Input Pin.
Connects a 22.5k internal resistor to the internal op amp’s
noninverting input.
REF1 (NA/Pin 6): Reference 1 Input Pin. With REF2, sets
the output level when the difference between the inputs
is zero.
+INB (Pin 3/Pin 3): Noninverting Gain-of-3 Input Pin.
Connects a 7.5k internal resistor to the internal op amp’s
noninverting input.
REF2 (NA/Pin 7): Reference 2 Input. Pin. With REF1, sets
the output level when the difference between the inputs
is zero.
+INC (Pin 5/Pin 5): Noninverting Gain-of-9 Input Pin.
Connects a 2.5k internal resistor to the internal op amp’s
noninverting input.
SHDN (Pin 6/Pin 10): Shutdown Pin. Amplifier is active
+
when this pin is tied to V or left floating. Pulling the pin
+
–INA (Pin 14/Pin 16): Inverting Gain-of-1 input Pin. Con-
nects a 22.5k internal resistor to the internal op amp’s
inverting input.
>2.5V below V causes the amplifier to enter a low power
state.
–INB (Pin 12/Pin 14): Inverting Gain-of-3 input Pin.
Connects a 7.5k internal resistor to the internal op amp’s
inverting input.
block DiagraM
MSOP
DFN
+
+
–INA –INB –INC
V
–INA –INB –INC
V
2.5k
2.5k
22.5k
22.5k
7.5k
7.5k
22.5k
22.5k
OUT
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
45k
REF1
22.5k
REF
45k
+
+
REF2
V
V
10µA
10µA
–
–
+INA +INB +INC
SHDN
V
+INA +INB +INC
SHDN
V
19973 BD01
19973 BD02
19973f
13
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
–
+
V
V +
S
–IN
op amp (V
is between V and V – 1.75V, the op
CMOP)
amp operates in its normal region; b) If V
is between
+
CMOP
–INA –INB –INC
2.5k
V
LT1997-3
+
–
V – 1.75V and V + 76V, the op amp continues to oper-
ate, but in its Over-The-Top (OTT) region with degraded
performance (see Over-The-Top Operation section of this
data sheet for more detail).
7.5k
22.5k
22.5k
22.5k
–
+
OUT
REF
V
V
The LT1997-3 will not operate correctly if the common-
OUT
REF
mode voltage at the inputs of the internal op amp (V
CMOP)
–
7.5k
22.5k
is below V , but the part will not be damaged as long as
–
2.5k
V
CMOP
is greater than V – 25V and the junction tempera-
ture of the LT1997-3 does not exceed 150ºC.
–
+INA +INB +INC SHDN
V
TheallowedvoltagerangeonLT1997-3’sinputpinsareas
follows: The voltages at +INA and –INA input pins should
never be higher than V + 160V or lower than V – 160V
under any circumstances; The voltages at +INB, –INB,
+INC and –INC input pins should not go below V – 0.3V
19973 F01
V
+
V –
S
IN
–
–
Figure 1. Difference Amplifier with Dual-Supply
Operation (Gain = 1)
–
–
or above V + 80V.
Introduction
The common-mode voltage at the inputs of the internal op
TheLT1997-3isaprecision, highvoltage generalpurpose
opampcombinedwithahighly-matchedresistornetwork.
Itcaneasilybeconfiguredintomanydifferentclassicalgain
circuits without adding external components. The several
pages of simple circuits in this data sheet demonstrate
how easy the LT1997-3 is to use. It can be configured into
a difference amplifier (Figure 1), as well as into inverting
(Figure 7) and noninverting (Figure 3) single ended ampli-
fiers. The LT1997-3 provides the resistors and op amp
togetherinasmallpackageinordertosaveboardspaceand
reduce complexity. Highly accurate measurement circuits
can be easily constructed with the LT1997-3. The circuits
can be tailored to specific measurement applications.
amp (V
is determined by the voltages on pins +INA,
CMOP)
+INB, +INC and REF (see the “Calculating Input Voltage
Range” section). This condition is true provided that the
internal op amp’s output is not clipped and feedback
maintainstheinternalopamp’sinputsatthesamevoltage.
In addition to the limits mentioned above, the common
mode input voltage of the amplifier should be chosen so
that the input resistors do not dissipate too much power.
The power dissipated in a 22.5k resistor must be less than
1.5W. It must be less than 0.5W for the 7.5k resistor and
less than 0.165W for the 2.5k resistor. For most applica-
tions, the pin voltage limitations will be reached before
the resistor power limitation is reached.
Common Mode Voltage Range
Calculating Input Voltage Range
The common mode voltage range of the LT1997-3 is set
by the voltage range allowed on the LT1997-3’s input pins
and by the input voltage range of the internal op amp.
Figure 2 shows the LT1997-3 in the generalized case of a
differenceamplifier,withtheinputsshortedforthecommon
mode calculation. The values of R and R are dictated
by how the positive inputs and REF pin are connected.
F
G
The internal op amp of LT1997-3 has 2 operating regions:
a)ifthecommon-modevoltageattheinputsoftheinternal
19973f
14
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
By superposition we can write:
They are limited by the output swing of the amplifier (and
obviously by the allowed voltage range for the input pins).
RF
RF +RG
RG
RF +RG
VCMOP = V
•
+ VREF •
EXT
Over-The-Top Operation
When the input common mode voltage of the internal op
Or, solving for V
:
EXT
amp (V
) in the LT1997-3 is biased near or above the
CMOP
⎛
⎞
+
RG
RF
RG
RF
V supply, the op amp is operating in the Over-The-Top
(OTT) region. The op amp continues to operate with an
input common mode voltage of up to 76V above V (re-
gardless of the positive power supply voltage V ), but its
V
= V
• 1+
– V
•
REF
⎜
⎟
EXT
CMOP
⎝
⎠
–
+
But valid V
voltages are limited to V + – 1.75V
S
CMOP
(V – + 76V OTT) on the high side and V – on the low
performanceisdegraded.Theopamp’sinputbiascurrents
change from under 2nA to 14µA. The op amp’s input
offset current rises to 50nA, which adds 1.1mV to the
output offset voltage.
S
S
side, so:
⎛
⎞
⎟
⎠
RG
RF
RG
RF
MAX V = V + –1.75 • 1+
– V
•
(
)
⎜
EXT
REF
S
⎝
In addition, when operating in the Over-The-Top region,
the differential input impedance decreases from 1MΩ in
normaloperationtoapproximately3.7kΩinOver-The-Top
operation. This resistance appears across the summing
nodes of the internal op amp and boosts noise and offset
while decreasing speed. Noise and offset will increase by
between75%and450%dependingonthegainsetting.The
bandwidth will be reduced by 2X to 5.5X. For more detail
onOver-The-Topoperation,consulttheLT6015datasheet.
and:
⎛
⎞
RG
RF
RG
RF
MIN V = V – • 1+
– V
•
REF
(
)
⎜
⎟
EXT
S
⎝
⎠
R
F
V +
S
R
R
G
G
–
+
V
V
OUT
EXT
V
CMOP
The Classical Noninverting Amplifier: High Input Z
V –
S
R
F
AcommonopampconfigurationenabledbytheLT1997-3
is the noninverting amplifier. Figure 3 shows the textbook
representation of the circuit on the top. The LT1997-3 is
shown onthe bottomconfigured in aprecisiongainof 5.5.
One of the benefits of the noninverting op amp configu-
ration is that the input impedance is extremely high. The
LT1997-3 maintains this benefit. A large number of gains
can be achieved with the LT1997-3 in the noninverting
configuration. The complete list of such Hi-Z input non-
inverting gain configuration is shown in Table 1. Many of
these are also represented in Figure 4 in schematic form.
Note that the positive inputs are connected such that the
source impedance seen by the positive and negative in-
puts of the internal op amp are equal. This minimizes the
offset voltage due to the input bias current of the op amp.
The noise gain and amplifier’s gain in the noninverting
configuration are identical.
V
REF
19973 F02
Figure 2. Calculating the Common Mode Input Voltage Range
Exceeding the MAX V
limit will cause the amplifier to
EXT
transition into the Over-The-Top region. The maximum
input voltage for the Over-The-Top region is:
⎛
⎞
⎟
⎠
RG
RF
RG
RF
MAX V
= V – +76 • 1+
– V
•
(
)
⎜
REF
EXTOTT
S
⎝
Keep in mind that the above MAX and MIN values for input
voltagerangeshouldnotexceedtheallowedvoltagerange
specified earlier for LT1997-3’s input pins.
The negative inputs are not limited by the internal op amp
commonmoderange(V
becausetheydonotaffectit.
CMOP)
19973f
15
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
Table 1. Configuring the Negative Pins for Noninverting Gains.
The Positive Inputs Are Driven as Shown in the Examples in
Figure 4
R
F
R
G
–
+
R //R
G
F
V
OUT
Negative Input Connections
V
IN
V
= GAIN • V
OUT
IN
G
Gain
1
-INA
-INB
-INC
GAIN = 1 + R /R
F
V
V
V
NONINVERTING OP AMP CONFIGURATION
OUT
OUT
OUT
1.077
1.1
1.25
1.273
1.3
1.4
2
GND
GND
GND
V
V
V
OUT
OUT
OPEN
V +
S
OUT
V
OPEN
+
OUT
–INA –INB –INC
V
LT1997-3
V
OUT
GND
GND
GND
OPEN
GND
V
V
V
OUT
OUT
OUT
2.5k
OPEN
GND
GND
7.5k
22.5k
22.5k
OPEN
OPEN
GND
GND
GND
OPEN
OPEN
GND
GND
GND
GND
GND
GND
–
OUT
REF
V
22.5k
OUT
2.5
2.8
3.25
3.5
4
V
OUT
V
OUT
+
7.5k
2.5k
22.5k
–
V
V
V
OUT
OUT
OUT
OPEN
GND
+INA +INB +INC SHDN
V
OPEN
GND
GND
GND
V –
S
5
19973 F03
V
IN
5.5
7
V
OUT
V
OUT
OPEN
GND
NONINVERTING OP AMP CONFIGURATION
IMPLEMENTED WITH THE LT1997-3, R = 11.25k, R = 2.5k, GAIN = 5.5
F
G
GAIN IS ACHIEVED BY GROUNDING, FLOATING OR FEEDING BACK
THE AVAILABLE RESISTORS TO ARRIVE AT THE DESIRED R AND R
10
OPEN
GND
OPEN
OPEN
GND
F
G
11
Figure 3. The LT1997-3 Configured as a Noninverting Op Amp
13
OPEN
GND
14
GND
19973f
16
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
V +
S
V +
S
V +
S
+
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V –
V –
V –
S
S
S
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
GAIN = 1
GAIN = 2
GAIN = 3.25
V +
V +
S
V +
S
S
+
+
+
V
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V –
V –
V –
S
S
S
V
IN
GAIN = 4
GAIN = 5
GAIN = 5.5
V +
S
V +
S
V +
S
+
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V –
V –
V –
S
S
S
V
IN
GAIN = 7
GAIN = 10
GAIN = 11
V +
S
V +
S
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
22.5k
–
+
–
+
V
OUT
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V –
S
V –
S
19973 F04
V
IN
V
IN
GAIN = 13
GAIN = 14
Figure 4. Some Implementations of Classical Noninverting Gains Using the LT1997-3. High Input Z is Maintained
19973f
17
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
Attenuation
Table 2. Configuring the Positive Pins for Various Attenuations
Positive Input Connections
The positive input resistors can be configured to attenuate
the input signal (Figure 5). This allows a trade-off to be
made between input range and precision. Attenuating the
inputcanpreventtheopampfromenteringthelessprecise
Over-the-Top operating region at the cost of decreasing
Gain
0.0714
0.0769
0.0909
0.1
+INA
+INB
GND
+INC
GND
GND
GND
GND
GND
GND
OPEN
GND
GND
OPEN
GND
GND
GND
OPEN
OPEN
OPEN
REF
GND
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
GND
OPEN
GND
OPEN
OPEN
GND
OPEN
theoutputsignal.Thefourpositiveresistors(R
+INC REF
attenuators. These are shown in Table 2.
,R
,
+INA +INB
0.143
0.182
0.2
V
IN
V
IN
R
, R ) can be arranged to make many precise input
OPEN
GND
GND
GND
LT1997-3
0.214
0.231
0.25
GND
V
IN
V
IN
–
+
V
IN
22.5k
OPEN
GND
R
A
R
G
7.5k
22.5k
REF
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
GND
OPEN
GND
V
CMOP
2.5k
+INA +INB +INC
0.286
0.308
0.357
0.4
V
IN
V
IN
V
IN
V
= A • V
IN
CMOP
A = R /(R + R )
G
A
G
OPEN
19973 F05
V
IN
V
IN
V
IN
UP TO +160V
GND
ATTENUATOR
ATTENUATING THE POSITIVE INPUT
BY GROUNDING AN UNUSED INPUT
0.5
OPEN
GND
GND
GND
GND
GND
GND
OPEN
R
= 22.5k, R = 2.5k, A = 0.1
A
G
0.6
GND
GND
V
IN
0.643
0.692
0.714
0.75
GND
GND
GND
V
IN
V
IN
V
IN
Figure 5. The Input of the LT1997-3 Can Be Attenuated to Increase
the Usable Input Range. The +INA Input Can Be Taken to ±160V.
OPEN
V
IN
The attenuations and noninverting gains are set indepen-
dently and can be combined to produce even more gain
options.346uniquegainsbetween0.0714and14(Figure6)
can be realized. When using the positive side resistors as
an attenuator, the benefit of canceling input bias current
effects on offset voltage reduces. The impedance seen by
the two op amp input nodes will not be identical.
OPEN
V
IN
OPEN
0.769
0.786
0.8
V
IN
V
IN
V
IN
GND
GND
V
IN
V
IN
V
IN
V
IN
OPEN
GND
GND
GND
GND
GND
GND
GND
0.818
0.857
0.9
GND
GND
OPEN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
OPEN
OPEN
OPEN
100
0.909
0.923
0.929
1
V
IN
OPEN
V
IN
V
IN
V
IN
10
V
IN
V
IN
V
IN
1
0.1
0.01
50
100
200
150
COUNT
300
0
250
350
19973 F06
Figure 6. Many Unique Gains Can Be Achieved by
Combining Attenuation with Noninverting Gain
19973f
18
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
The Inverting Configuration
Table 3. Configuring the Negative Pins for Inverting Gains
Negative Input Connections
-INB -INC
The inverting amplifier, shown in Figure 7, is another clas-
sical op amp configuration. The circuit is actually identical
to the noninverting amplifier of Figure 3, except that V
and GND have been swapped. The list of available gains
is shown in Table 3, and some of the circuits are shown
in Figure 8. Noise gain is 1+|Gain|, as is the usual case for
inverting amplifiers. For the best DC precision, match the
source impedances seen by the op amp inputs.
Gain
–0.077
–0.1
–0.25
–0.273
–0.3
–0.4
–1
-INA
V
IN
V
IN
V
IN
V
V
OUT
V
OUT
OUT
IN
OPEN
V
OPEN
OUT
V
OUT
V
V
OUT
V
OUT
V
OUT
IN
IN
IN
OPEN
V
V
IN
V
IN
V
OPEN
OPEN
OPEN
R
F
–1.5
–1.8
–2.25
–2.5
–3
V
OUT
V
OUT
V
IN
R
G
–
+
V
OUT
V
OUT
V
OUT
V
IN
V
IN
V
IN
V
IN
R //R
G
F
V
OUT
OPEN
V
= GAIN • V
IN
OUT
V
IN
GAIN = –R /R
F
G
INVERTING OP AMP CONFIGURATION
OPEN
V
OPEN
OPEN
IN
IN
–4
V
IN
V
V
IN
V +
S
–4.5
–6
V
OUT
V
OUT
OPEN
V
IN
V
V
+
IN
IN
–INA –INB –INC
V
LT1997-3
–9
OPEN
OPEN
OPEN
V
IN
V
IN
V
IN
V
IN
2.5k
–10
V
IN
7.5k
22.5k
22.5k
–12
OPEN
V
V
IN
IN
–13
V
IN
–
+
OUT
REF
V
22.5k
OUT
7.5k
2.5k
22.5k
–
+INA +INB +INC SHDN
V
V –
S
19973 F07
INVERTING OP AMP CONFIGURATION
IMPLEMENTED WITH THE LT1997-3, R = 11.25k, R = 2.5k, GAIN = –4.5
F
G
GAIN IS ACHIEVED BY GROUNDING, FLOATING OR FEEDING BACK
THE AVAILABLE RESISTORS TO ARRIVE AT THE DESIRED R AND R
F
G
Figure 7. The LT1997-3 Configured as an Inverting Op Amp
19973f
19
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
V
V +
V
IN
V
IN
V
IN
V +
S
V
IN
V
IN
V
IN
V +
S
IN
S
+
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V –
S
V –
S
V –
S
GAIN = –0.25
V +
GAIN = –1
GAIN = –2.25
V +
V
IN
V +
S
S
S
+
+
+
V
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V –
S
V –
S
V –
S
GAIN = –3
GAIN = –4
GAIN = –4.5
V +
V
IN
V +
S
V +
S
S
+
+
+
V
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V –
S
V –
S
V –
S
GAIN = –6
GAIN = –9
GAIN = –10
V
IN
V +
S
V
IN
V +
S
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
22.5k
–
+
–
+
V
OUT
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V –
S
V –
S
19973 F08
GAIN = –12
GAIN = –13
Figure 8. Inverting Gains with Input Impedance that Varies from 1.73kΩ (Gain = –13) to 22.5kΩ (Gain = –1)
19973f
20
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
Difference Amplifiers
The Common Mode Voltage at the inputs of the internal
CMOP
+INC and REF.
op amp (V
) is set by the voltages at pins +INA, +INB,
The LT1997-3 is ideally suited to be used as a difference
amplifier. Figure 9 shows the basic 4-resistor difference
amplifierandtheLT1997-3.Adifferencegainof3isshown,
but can be altered by additional dashed connections. By
connecting the 22.5k resistors in parallel, the gain is re-
duced by a factor of 2. Of course there are many possible
gains. Table 4 shows the difference gains and how they
are achieved. Note that, as for inverting amplifiers, the
noise gain is equal to the signal gain plus 1.
Table 4. Difference Amplifier Gains
Gain
0.077
0.1
0.25
0.273
0.3
0.4
1
V
V
OUT
–INB, –INC
–INC
GND (REF)
+INB, +INC
+INC
+IN
–IN
+INA
+INA
–INA
–INA
+INA
–INA
–INB
+INB
+INB
–INB
–INA, –INC
–INC
+INA, +INC
+INC
+INB
–INB
R
F
+INA, +INB
+INA
–INA, –INB
–INA
–INC
+INC
R
R
G
G
–
+
V
V
–
+
IN
IN
V
OUT
1.5
1.8
2.25
2.5
3
+INB
–INB
–INA
–INA, –INB
–INB
+INA
+INA, +INB
+INB
V
= GAIN • (V – V
GAIN = R /R
)
–IN
+
OUT
IN
R
F
+INC
–INC
F
G
+INC
–INC
DIFFERENCE AMPLIFIER CONFIGURATION
+INA, +INC
+INB
–INA, –INC
–INB
–INB
+INB
V +
S
V
4
+INA, +INB
+INC
–INA, –INB
–INC
–IN
4.5
6
–INA
–INA
+INA
+INA
+
–INA –INB –INC
V
LT1997-3
+INB, +INC
+INC
–INB, –INC
–INC
2.5k
9
7.5k
22.5k
22.5k
22.5k
10
+INA, +INC
+INB, +INC
–INA, –INC
–INB, –INC
12
–
+
OUT
REF
V
22.5k
OUT
13
+INA, +INB,
+INC
–INA, –INB,
–INC
7.5k
2.5k
–
+INA +INB +INC SHDN
V
V
+
IN
V –
S
19973 F09
DIFFERENCE AMPLIFIER CONFIGURATION
IMPLEMENTED WITH THE LT1997-3, R = 22.5k, R = 7.5k, GAIN = 3
F
G
ADDING THE DASHED CONNECTIONS CONNECT THE
TWO 22.5k RESISTORS IN PARALLEL, SO R IS REDUCED TO 11.25k.
F
THE GAIN BECOMES 11.25k/7.5k = 1.5
Figure 9. The LT1997-3 Configured as a Difference
Amplifier. Gain Is Set by Connecting the Correct
Resistors or Combinations of Resistors. Gain of 3 Is
Shown, with Dashed Lines Modifying It to a Gain of 1.5
19973f
21
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
V
V +
S
V
V +
S
V
V +
S
–IN
–IN
–IN
+
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V
V
V –
V
V
V –
V
V
V –
S
+IN
–IN
S
+IN
–IN
S
+IN
–IN
GAIN = 0.25
V +
GAIN = 1
GAIN = 2.25
V +
S
V +
S
S
+
+
+
V
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V
V
V –
V
V
V –
V
V
V –
S
+IN
–IN
S
+IN
–IN
S
+IN
–IN
GAIN = 3
GAIN = 4
GAIN = 4.5
V +
S
V +
S
V +
S
+
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V
V –
S
V
V –
S
V
V –
S
+IN
+IN
+IN
GAIN = 6
GAIN = 9
GAIN = 10
V
V +
S
V
V +
S
–IN
–IN
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
22.5k
–
+
–
+
V
OUT
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
REF
22.5k
REF
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V
V –
S
V
V –
S
+IN
+IN
19973 F10
GAIN = 12
GAIN = 13
Figure 10. Many Difference Amplifier Gains Can Be Achieved by Strapping Pins
19973f
22
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
Difference Amplifier: Additional Integer Gains Using
Cross-Coupling
R
R
F
R
R
G
G
–
+
V
V
–
+
IN
IN
V
OUT
Figure 11 shows the basic difference amplifier as well as
the LT1997-3 with cross-coupled inputs. The additional
dashed connections reduce the differential gain from
3 to 2. Using this method, additional integer gains are
achievable, as shown in Table 5, so that all integer gains
from 1 to 13 are achieved with the LT1997-3. Note that
V
= GAIN • (V – V
GAIN = R /R
)
–IN
+
F
OUT
IN
F
G
DIFFERENCE AMPLIFIER CONFIGURATION
V
–IN
V +
S
the equations can be written by inspection from the V
+
+IN
–INA –INB –INC
V
LT1997-3
connections, and that the V connections are simply the
–IN
2.5k
opposite(swap+for–and–for+). Noisegain, bandwidth,
and input impedance specifications for the various cases
are also shown. Schematics of the difference amplifiers
using cross-coupling are shown in Figure 12. Additional
non-integergainsproducedwithcross-couplingarelisted
in Table 6.
7.5k
22.5k
22.5k
22.5k
–
+
OUT
REF
V
22.5k
OUT
7.5k
2.5k
–
+INA +INB +INC SHDN
V
19973 F12
V –
S
V
+
IN
DIFFERENCE AMPLIFIER CONFIGURATION
IMPLEMENTED WITH THE LT1997-3, R = 22.5k, R = 7.5k, GAIN = 3
F
G
GAIN CAN BE ADJUSTED BY CROSS-COUPLING THE INPUTS.
MAKING THE DASHED CONNECTIONS REDUCES THE GAIN FROM 3 TO 2
Figure 11. Cross-Coupling the Inputs of the LT1997-3 Allows
Additional Integer Gains to Be Constructed. The LT1997-3
Provides All Integer Gains from 1 to 13
Table 5. Connections Using Cross-Coupling. Note that Equations Can Be Written by Inspection of the V+IN Column
Differential
Input Impedance
(kΩ)
Common Mode
–3dB BW
(kHz)
Input Impedance
(kΩ)
Gain
2
V
V
Equation
3 – 1
Noise Gain
+IN
–IN
+INB, –INA
–INB, +INA
5
540
222
222
277
222
11.25
3.5
14.1
12.1
12.1
12.4
12.1
5
+INC, –INB, –INA –INC, +INB, +INA
+INC, +INA, –INB –INC, –INA, +INB
9 – 3 – 1
9 + 1 – 3
9 – 1
14
14
11
14
7
3.5
8
+INC, –INA
–INC, +INA
4.5
11
+INC, +INB, –INA –INC, –INB, +INA
9 + 3 – 1
3.5
Table 6. Additional Non-Integer Gains that Can Be Achieved Using Cross-Coupling
Gain
0.143
0.2
V
V
OUT
GND (REF)
–INB, +INC
+INC
+IN
–IN
+INA
–INA, +INB
+INB
–INA
+INA, –INB
–INB
+INB, –INC
–INC
0.333
+INA, –INC
–INA, +INC
19973f
23
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
V
V
V
–IN
V +
S
V +
S
–IN
–IN
V +
S
+
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
V
V
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
OUT
22.5k
REF
22.5k
–
22.5k
REF
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V –
S
V –
S
V –
S
V
V
V
+IN
+IN
+IN
GAIN = 2
GAIN = 5
GAIN = 7
V
V
V +
S
V +
S
–IN
–IN
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
2.5k
7.5k
7.5k
7.5k
22.5k
OUT
22.5k
22.5k
22.5k
22.5k
–
+
–
+
OUT
REF
V
V
OUT
22.5k
7.5k
2.5k
OUT
22.5k
REF
22.5k
–
2.5k
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
19973 F13
V –
S
V –
S
V
V
+IN
+IN
GAIN = 8
GAIN = 11
Figure 12. Integer Gain Difference Amplifiers Using Cross-Coupling
High Common Mode Voltage Difference Amplifiers
factor and is set by the voltage at the op amp’s positive
input (V ). By superposition we can write:
CMOP
The input range of a difference amplifier can be extended
by configuring the amplifier to divide the input common
modevoltage.Figure13showsthebasiccircuitonthetop.
The effective input voltage range of the circuit is extended
RF RT
RG +RF RT
RG RT
RF +RG RT
VCMOP = V
•
+ VREF •
EXT
RF RG
RT +RF RG
by the fact that resistors R attenuate the common mode
+VTERM
•
T
(CM) voltage seen by the internal op amp inputs (V
).
CMOP
For the LT1997-3, the most useful resistors for R are the
G
Solving for V
:
EXT
+INAand–INA22.5kΩresistors,becausetheydonothave
diode clamps to the V – supply and therefore can be taken
⎛
⎞
⎟
⎟
⎟
RG RT
RF +RG RT
S
V
CMOP – VREF
•
⎜
⎜
⎜
beyond both rails. +INB, –INB, +INC and –INC pins can be
⎛
⎞
⎟
⎠
RG
RF RT
taken 80V above V –, but not below V –. As before, the
V
= 1+
•
⎜
S
S
EXT
RF RG
RT +RF RG
⎝
input common mode of the internal op amp is the limiting
–V
•
⎜
⎟
TERM
⎝
⎠
19973f
24
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
R
Given the values of the resistors in the LT1997-3, this
equation has been simplified and evaluated, and the
resulting equations are provided in Table 7. Substituting
F
V +
S
R
R
G
G
–
+
V
V
–
IN
V + – 1.75V and V – for V will give the valid upper
S
S
LIM
V
OUT
V
CMOP
+
IN
)
and lower common mode extremes respectively for the
V
= GAIN • (V – V
)
–IN
(= V
+
OUT
IN
EXT
normal operating region of the op amp. Substituting
GAIN = R /R
F
G
R
R
T
T
V –
S
R
F
V – + 76V and V – for V will give the valid upper
LIM
S
S
V
V
REF
TERM
and lower common mode extremes respectively for the
Over-The-Top region of the op amp (see Over-The-Top
Operation section of this data sheet for more detail).
Following are sample calculations for the case shown
in Figure 13. Note that +INC and –INC are terminated so
row 3 of Table 7 provides the equation:
HIGH COMMON MODE VOLTAGE DIFFERENCE AMPLIFIER
INPUT COMMON MODE VOLTAGE TO OP AMP IS
ATTENUATED BY RESISTORS R CONNECTED TO V
T
TERM
V
–IN
V + = 12V
S
+
–INA –INB –INC
V
LT1997-3
2.5k
MAX V = 11• V + –1.75 – V – 9 • VTERM
(
)
EXT
REF
S
7.5k
22.5k
22.5k
= 11•(10.25V)– 2.5 – 9 •12
–
+
OUT
REF
= 2.25V
V
= 12V
V
V
22.5k
TERM
OUT
REF
7.5k
2.5k
22.5k
–
and:
MIN V = 11• V – – V – 9 • VTERM
= 2.5V
(
)
EXT
REF
S
+INA +INB +INC SHDN
V
19973 F14
= 11•(0)– 2.5 – 9 •12
V
+
= –110.5V
IN
HIGH NEGATIVE COMMON MODE VOLTAGE DIFFERENCE AMPLIFIER
IMPLEMENTED WITH THE LT1997-3, R = 22.5k, R = 22.5k, R = 2.5k, GAIN = 1
If the calculated V voltage exceeds the 160V absolute
F
G
T
EXT
V
= V + = 12V, V
S
= 2.5V, V – = 0V
REF S
TERM
maximum rating of the +INA, –INA pins, 160V or –160V
would become the de facto common mode limit. Several
moreexamplesofhighCMcircuitsareshowninFigure14,
Figure 15 and Figure 16 for various supplies.
Figure 13. Extending Common Mode Input Range
Table 7. Input Common Mode Voltage Ranges for the LT1997-3 when Configured as a High Common Mode Voltage Difference Amplifier
Max, Min V (Substitute V + – 1.75 (Normal Region)
EXT
S
Gain
V
+IN
V
R
T
Noise Gain
or V – + 76 (OTT), and V – for V
)
–IN
S
S
LIM
1
1
1
1
+INA
+INA
+INA
+INA
–INA
–INA
–INA
–INA
2
5
2 • V – V
LIM REF
R
R
, R
5 • V – V – 3 • V
LIM REF TERM
+INB –INB
, R
+INC –INC
11
14
11 • V – V – 9 • V
LIM REF TERM
R
||R
, R
||R
14 • V – V – 12 • V
LIM REF TERM
+INB +INC –INB –INC
19973f
25
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
5V
5V
5V
V
–IN
V
V
–IN
–IN
+
+
+
V
–INA –INB –INC
V
–INA –INB –INC
V
–INA –INB –INC
LT1997-3
LT1997-3
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
V
V
V
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
OUT
OUT
22.5k
REF
2.5V
5V
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V
V
V
V
V
V
+IN
+IN
+IN
V
= 4V TO –2.5V
V
= 6.5V TO 0V
V
= 1.5V TO –5V
CM
CM
CM
2.5V
5V
5V
5V
5V
+
–IN
–IN
–IN
+
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
OUT
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
V
V
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
OUT
22.5k
REF
22.5k
REF
2.5V
2.5V
2.5V
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V
V
V
V
V
V
+IN
+IN
+IN
2.5V
5V
V
= 6.25V TO –10V
V
= 13.75V TO –2.5V
V
= –1.25V TO –17.5V
CM
CM
CM
2.5V
5V
5V
5V
5V
–IN
–IN
–IN
+
+
+
V
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
22.5k
22.5k
22.5k
22.5k
OUT
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
V
V
V
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
OUT
OUT
22.5k
REF
2.5V
2.5V
2.5V
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V
V
V
V
V
V
+IN
+IN
+IN
2.5V
5V
V
= 10.75V TO –25V
V
= 33.25V TO –2.5V
V
= –11.75V TO –47.5V
CM
CM
CM
2.5V
5V
5V
5V
5V
–IN
–IN
–IN
+
+
+
V
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
OUT
REF
V
V
V
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
OUT
OUT
2.5V
2.5V
2.5V
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
19973 F15
V
+IN
V
+IN
V
+IN
2.5V
5V
V
= 13V TO –32.5V
V
= 43V TO –2.5V
V
= –17V TO –62.5V
CM
CM
CM
Figure 14. Common Mode Ranges for Various LT1997-3 Configurations on VS = 5V, 0V, with Gain = 1.
These Ranges Guarantee that the Internal Op Amp Operates in Its Normal Operating Region
19973f
26
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
15V
15V
+
15V
+
V
–IN
V
–IN
V
–IN
+
–INA –INB –INC
V
–INA –INB –INC
V
–INA –INB –INC
V
LT1997-3
LT1997-3
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
OUT
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
V
V
V
V
V
V
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
OUT
OUT
OUT
OUT
OUT
22.5k
REF
–15V
15V
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V
V
V
V
V
V
+IN
+IN
+IN
–IN
–15V
= 41.5V TO –15V
–15V
= 26.5V TO –30V
–15V
= 11.5V TO –45V
V
V
CM
V
CM
CM
15V
+
–15V
15V
+
15V
15V
+
–IN
–IN
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
OUT
REF
V
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
–15V
V
+INA +INB +INC SHDN
V
V
V
V
V
V
V
+IN
+IN
+IN
–IN
–15V
= 66.25V TO –75V
–15V
= 111.25V TO –30V
15V
–15V
= 21.25V TO –120V
V
V
V
CM
CM
CM
15V
15V
+
–15V
15V
+
15V
+
–IN
–IN
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
OUT
REF
V
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
–15V
= 160V TO –30V
V
+INA +INB +INC SHDN
15V
= 10.75V TO –160V
V
V
V
V
V
V
V
+IN
+IN
+IN
–IN
–15V
= 145.75V TO –160V
–15V
–15V
V
V
V
CM
CM
CM
–15V
15V
15V
+
15V
15V
+
–IN
–IN
+
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
22.5k
22.5k
OUT
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
V
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
22.5k
REF
–
–
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
19973 F16
V
+IN
V
+IN
V
+IN
–15V
= 160V TO –160V
–15V
= 160V TO –30V
–15V
= 5.5V TO –160V
–15V
15V
V
V
V
CM
CM
CM
Figure 15. Common Mode Ranges for Various LT1997-3 Configurations on VS = ±15V, with Gain = 1.
These Ranges Guarantee that the Internal Op Amp Operates in Its Normal Operating Region
19973f
27
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
25V
25V
+
25V
+
V
–IN
V
–IN
V
–IN
+
–INA –INB –INC
V
–INA –INB –INC
V
–INA –INB –INC
V
LT1997-3
LT1997-3
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
OUT
REF
V
V
V
V
V
V
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
OUT
OUT
OUT
OUT
OUT
22.5k
–
22.5k
–
22.5k
–
–25V
25V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN V
V
V
V
V
V
V
+IN
+IN
+IN
–25V
= 71.5V TO –25V
–25V
= 46.5V TO –50V
–25V
V
V
V = 21.5V TO –75V
CM
CM
CM
25V
+
–25V
25V
+
25V
25V
+
–IN
–IN
–IN
–INA –INB –INC
V
–INA –INB –INC
V
–INA –INB –INC
V
LT1997-3
LT1997-3
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
OUT
REF
V
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
22.5k
–
22.5k
–
22.5k
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN V
V
V
V
V
V
V
+IN
+IN
+IN
–25V
–25V
–25V
25V
–25V
V
= 116.25V TO –125V
V
= 160V TO –50V
V
= 41.25V TO –160V
CM
CM
CM
25V
+
–25V
25V
+
25V
25V
+
–IN
–IN
–IN
–INA –INB –INC
V
–INA –INB –INC
V
–INA –INB –INC
V
LT1997-3
LT1997-3
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
OUT
REF
V
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
22.5k
–
22.5k
–
22.5k
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
V
V
V
V
V
V
+IN
+IN
+IN
–25V
–25V –25V
25V –25V
V
= 160V TO –160V
V
= 160V TO –50V
V
= 30.75V TO –160V
CM
CM
CM
–25V
25V
25V
+
25V
+
25V
+
–IN
–IN
–IN
–INA –INB –INC
V
–INA –INB –INC
V
–INA –INB –INC
V
LT1997-3
LT1997-3
LT1997-3
2.5k
7.5k
2.5k
7.5k
2.5k
7.5k
22.5k
22.5k
22.5k
22.5k
22.5k
22.5k
–
+
–
+
–
+
OUT
REF
OUT
REF
OUT
REF
V
V
OUT
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
22.5k
7.5k
2.5k
OUT
22.5k
–
22.5k
–
22.5k
–
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN
V
+INA +INB +INC SHDN V
19973 F17
V
+IN
V
+IN
V
+IN
–25V
–25V
–25V
–25V
25V
V
= 160V TO –160V
V
= 160V TO –50V
V = 25.5V TO –160V
CM
CM
CM
Figure 16. Common Mode Ranges for Various LT1997-3 Configurations on VS = ±±2V, with Gain = 1.
These Ranges Guarantee that the Internal Op Amp Operates in Its Normal Operating Region
19973f
28
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
Reference Resistors
V +
S
V
–IN
In the preceding discussions, the Reference resistor is
shown as a single 22.5k resistor. This is true in the DFN
package. In the MSOP package the reference resistor is
split into two 45k resistors (Figure 17). Tying the REF1
and REF2 pins to the same voltage produces the same
+
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
7.5k
22.5k
22.5k
22.5k
–
+
OUT
reference voltage as tying the V pin in the DFN package
V
OUT
REF
to that voltage. Connecting REF1 and REF2 to different
45k
45k
REF1
REF2
V
V
REF1
REF2
voltages produces an effective reference voltage that is
2.5k
the average of V
and V . This is especially useful
REF2
REF1
–
when the desired reference voltage is half way between
thesupplies. TyingREF1toV +andREF2toV –produces
+INA +INB +INC SHDN
V
S
S
V
V
V –
S
thedesiredmid-supplyvoltagewithoutthehelpofanother
+
IN
LT1997-3 MSOP
external reference voltage (Figure 17). The ratio of R
REF1
V +
S
to R
is very precise:
–IN
REF2
+
–INA –INB –INC
V
LT1997-3
∆R
R
RREF1 –RREF2
=
< 60ppm
2.5k
⎛
⎜
⎝
⎞
⎟
⎠
RREF1+RREF2
7.5k
7.5k
22.5k
2
22.5k
22.5k
–
+
OUT
REF
V
OUT
22.5k
–
V
REF
2.5k
+INA +INB +INC SHDN
V
V
V –
S
+
IN
19973 F11
LT1997-3 DFN
Figure 17. The LT1997-3 Reference Resistors: Split Resistors in
the MSOP Package Above, Single Resistor in the DFN Package
Below
19973f
29
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
Shutdown
Power Dissipation Considerations
The LT1997-3 has a shutdown pin (SHDN). Under normal
Because ofthe ability ofthe LT1997-3 to operate onpower
supplies up to 25V, to withstand very high input volt-
ages and to drive heavy loads, there is a need to ensure
the die junction temperature does not exceed 150°C. The
+
operation this pin should be tied to V or allowed to float.
+
Tying this pin 2.5V or more below V will cause the part
to enter a low power state. The supply current is reduced
to less than 25µA and the op amp output becomes high
impedance. The voltages at the input pins can be still be
present even in shutdown mode.
LT1997-3 is housed in DF14 (θ = 45°C/W, θ = 3°C/W)
JA
JC
and MS16 (θ = 130°C/W) packages.
JA
In general, the die junction temperature (T ) can be es-
J
timated from the ambient temperature (T ), the device’s
A
Supply Voltage
power dissipation (P ) and the thermal resistance of the
D
ThepositivesupplypinoftheLT1997-3shouldbebypassed
withasmallcapacitor(typically0.1µF)asclosetothesupply
pins as possible. When driving heavy loads, an additional
4.7µF electrolytic capacitor should be added. When using
device and board (θ ).
JA
T = T + P • θ
JA
J
A
D
The thermal resistance from the junction to the ambient
–
split supplies, the same is true for the V supply pin.
environment (θ ) is the sum of the thermal resistance
JA
fromthejunctiontotheexposedpad(θ )andthethermal
JC
Output
resistance from the exposed pad to the ambient environ-
ment (θ ). The θ value depends on how much PCB
CA
CA
The output of the LT1997-3 can typically swing to within
100mVofeitherrailwithnoloadandiscapableofsourcing
andsinkingapproximately25mAat25°C.TheLT1997-3is
internallycompensatedtodriveatleast1nFofcapacitance
under any output loading conditions. For larger capacitive
loads, a 0.22µF capacitor in series with a 150Ω resistor
between the output and ground will compensate the
amplifier to drive capacitive loads greater than 1nF. Ad-
ditionally, the LT1997-3 has more gain and phase margin
as its gain is increased.
metal is connected to the exposed pad in the board. The
more PCB metal that is used, the lower θ and θ will be.
CA
JA
Powerisdissipatedbytheamplifier’squiescentcurrent,by
the output current driving a resistive load, and by the input
current driving the LT1997-3’s internal resistor network.
P = V + – V – •I +P +P
RESD
(
)
D
S
S
S
OD
For a given supply voltage, the worst-case output power
dissipationP
occurswiththeoutputvoltageathalf
OD(MAX)
of either supply voltage. P
is given by:
OD(MAX)
Distortion
2
The LT1997-3 features excellent distortion performance
when the internal op amp is operating in the normal op-
erating region. Operating the LT1997-3 with the internal
op amp in the over the top region will increase distortion
due to the lower loop gain of the op amp. Operating the
LT1997-3 with input common mode voltages that go from
the normal to Over-The-Top operation will significantly
degrade the LT1997-3’s linearity as the op amp must
transition between two different input stages. Driving
resistiveloadssignificantlysmallerthanthe22.5kinternal
feedback resistor will also degrade the amplifier’s linearity
performance.
V 2
(
)
S
POD(MAX)
=
RLOAD
The power dissipated in the internal resistors (P
)
RESD
depends on the manner the input resistors have been
configured as well as the input voltage, the output voltage
and the voltage on the REF pin. The following equations
and Figure 18 show the different components of P
RESD
corresponding to the different groups of the LT1997-3’s
internalresistors,assumingthattheLT1997-3isusedwith
a dual supply configuration with +INC, –INC, and REF pins
19973f
30
For more information www.linear.com/LT1997-3
LT1997-3
applicaTions inForMaTion
at ground (refer to Figure 13 for resistor terminologies
used in equations below).
Example: For an LT1997-3 in a DFN package mounted on
a PC board with a thermal resistance of 45°C/W, operating
on 25V supplies and driving a 2.5kΩ load to 12.5V with
2
V
(
)
+IN
V
= 160V and +INC = –INC = REF = 0V, the total power
+IN
P
=
=
=
=
RESDA
RG +RF RT
dissipation is given by:
12.52 1602
2.5k 24.75k
2
⎛
⎜
⎝
⎞
R R
P = 50 • 0.6mA +
+
(
)
(
)
F
T
D
V–IN – V+IN •
⎟
R +RF RT
⎠
G
P
RESDB
2
2
2
⎛
⎞
⎟
⎠
⎛
⎜
⎝
⎞
⎛
⎜
⎝
⎞
RG
160
11
22.5k
160
11
160
11
147.5 –
– 12.5
⎟
⎜
⎟
⎝
⎠
⎠
+
+
+
2
⎛
⎜
⎝
⎞
R R
(
)
2.5k
22.5k
F
T
V
•
•
⎟
⎠
+IN
R +RF RT
G
= 2W
P
RESDC
RT
Assuming a thermal resistance of 45°C/W, the die tem-
perature will experience an 90°C rise above ambient.
This implies that the maximum ambient temperature the
LT1997-3 should operate under the above conditions is:
2
⎛
⎜
⎝
⎞
R R
(
)
F
T
V
– VOUT
⎟
+IN
RG +RF RT
⎠
P
RESDD
RF
T = 150°C – 90°C = 60°C
A
It is recommended that the exposed pad of the DFN pack-
agehaveasmuchPCBmetalconnectedtoitasreasonably
available. The more PCB metal connected to the exposed
pad, the lower the thermal resistance. Connecting a large
amount of PCB metal to the exposed pad can reduce the
P
= P
+ P
+ P
+ P
RESDC RESDD
RESD
RESDA
RESDB
In general, P
lower output and REF pin voltages.
increases with higher input voltage and
RESD
V +
S
= 25V
V
= 160V – V
= 147.5V
–IN
OUT
θ
to even less than 45°C/W. Use multiple vias from the
+
JA
–INA –INB –INC
V
LT1997-3
–
–
exposedpadtotheV plane.Theexposedpadiselectrically
P
P
RESDD
RESDC
connected to the V pin. In addition, a heat sink may be
2.5k
22.5k
necessaryifoperatingnearmaximumjunctiontemperature.
7.5k
P
The MSOP package has no exposed pad and a higher
22.5k
22.5k
RESDB
–
+
thermal resistance (θ = 130°C/W). It should not be used
JA
P
OUT
V
=
RESDA
OUT
12.5V
in applications which have a high ambient temperature,
require driving a heavy load, or require an extreme input
voltage.
7.5k
2.5k
22.5k
REF
Thermal Shutdown
–
+INA +INB +INC SHDN
V
For safety, the LT1997-3 will enter shutdown mode when
the die temperature rises to approximately 163°C. This
thermal shutdown has approximately 9°C of hysteresis
requiring the die temperature to cool 9°C before enabling
the amplifier again.
V
+
IN
19973 F18
= 160V
V –
S
= –25V
Figure 18. Power Dissipation Example
19973f
31
For more information www.linear.com/LT1997-3
LT1997-3
ESD Protection
LT1997-3
+
–INA –INB –INC
V
The LT1997-3 is protected by a number of ESD structures.
The structures are shown in Figure 19.
–
–
–
2.5k
V
V
V
The ESD structures serve to protect the internal circuitry
but also limit signal swing on certain nodes. The structures
on the +INB, –INB, +INC, –INC pins and on the internal op
amp inputs limit the voltage on these nodes to 0.3V below
7.5k
22.5k
22.5k
–
+
OUT
–
22.5k
V
–
–
V and 80V above V . The voltage on the REF (DFN), REF1
(MSOP) and REF2 (MSOP) pins are limited to 0.3V below
–
V
7.5k
–
45k
45k
REF1
–
+
–
–
V
V
V and 60V above V . The voltage on the SHDN pin is
2.5k
REF2
–
+
limited to 0.3V below V and 0.3V above V .
10µA
–
V
V
–
V
–
+INA +INB +INC
SHDN
V
19973 F19
Figure 19. ESD Protection
Typical applicaTions
Differential Input/Output Gain of 10 Amplifier
V +
S
V
–
IN
+
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
22.5k
22.5k
22.5k
–
+
V
V
+
OUT
OUT
OCM
10k
10k
–
+
LT6015
7.5k
2.5k
22.5k
REF
V
–
OUT
–
+INA +INB +INC SHDN
V
19973 TA02
V
+
IN
V –
S
USE V
TO SET THE DESIRED
OCM
OUTPUT COMMON MODE LEVEL
19973f
32
For more information www.linear.com/LT1997-3
LT1997-3
Typical applicaTions
Bidirectional Current Sense Amplifier
V +
S
V
= –0.3V TO 50V
SOURCE
+
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
22.5k
22.5k
22.5k
–
+
OUT
V
V
= V
REF
+ 26 • I
• R
I
R
OUT
LOAD SENSE
LOAD
SENSE
R
C
7.5k
2.5k
45k
45k
REF2
REF1
REF
LOAD
–
+INA +INB +INC SHDN
V
19973 TA03
Precision RRIO Single-Supply Difference Amplifier
V
BATTERY
+
–INA –INB –INC
V
LT1997-3
2.5k
7.5k
22.5k
22.5k
22.5k
–
+
V
–IN
+IN
OUT
V
BATTERY
V
VOUT
=
+9 • V+IN – V–IN
( )
CM
2
V
7.5k
2.5k
45k
45k
REF2
REF1
V
= –0.3V TO V
BATTERY
CM
–
+INA +INB +INC SHDN
V
19973 TA04
19973f
33
For more information www.linear.com/LT1997-3
LT1997-3
package DescripTion
Please refer to http://www.linear.com/product/LT1997-3#packaging for the most recent package drawings.
DF Package
14(12)-Lead Plastic DFN (4mm × 4mm)
(Reference LTC DWG # 05-08-1963 Rev Ø)
3.00 REF
ꢀ.00
BSC
0.70 0.05
4.50 0.05
ꢀ.70 0.05
3.ꢀ0 0.05
3.38 0.05
PACKAGE OUTLINE
0.25 0.05
0.50 BSC
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED
3.00 REF
4.00 0.ꢀ0
(4 SIDES)
ꢀ.00
BSC
8
ꢀ4
0.40 0.ꢀ0
3.38 0.ꢀ0
ꢀ.70 0.ꢀ0
PIN ꢀ NOTCH
0.35 × 45°
CHAMFER
PIN ꢀ
TOP MARK
(NOTE 6)
(DFꢀ4)(ꢀ2) DFN ꢀꢀꢀ3 REV 0
7
R = 0.ꢀꢀ5
TYP
ꢀ
0.25 0.05
0.50 BSC
0.200 REF
0.75 0.05
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
NOTE:
ꢀ. PACKAGE OUTLINE DOES NOT CONFORM TO JEDEC MO-229
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.ꢀ5mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN ꢀ LOCATION
ON THE TOP AND BOTTOM OF PACKAGE
19973f
34
For more information www.linear.com/LT1997-3
LT1997-3
package DescripTion
Please refer to http://www.linear.com/product/LT1997-3#packaging for the most recent package drawings.
MS Package
16 (12)-Lead Plastic MSOP with 4 Pins Removed
(Reference LTC DWG # 05-08-1847 Rev B)
1.0
0.889 ±0.127
(.035 ±.005)
(.0394)
BSC
5.10
3.20 – 3.45
(.201)
4.039 ±0.102
(.159 ±.004)
(NOTE 3)
(.126 – .136)
MIN
0.280 ±0.076
(.011 ±.003)
REF
16 14 121110
9
0.50
(.0197)
BSC
0.305 ±0.038
(.0120 ±.0015)
TYP
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
RECOMMENDED SOLDER PAD LAYOUT
DETAIL “A”
0.254
(.010)
0° – 6° TYP
1
3 5 6 7 8
GAUGE PLANE
1.0
(.0394)
BSC
0.53 ±0.152
(.021 ±.006)
0.86
(.034)
REF
1.10
(.043)
MAX
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.17 – 0.27
(.007 – .011)
TYP
0.1016 ±0.0508
(.004 ±.002)
MSOP (MS12) 0213 REV B
0.50
(.0197)
BSC
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
19973f
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 representa-
35
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LT1997-3
Typical applicaTion
Low Noise, High CMRR Instrumentation Amplifier
+15V
Gain vs Frequency
+15V
+
70
60
50
40
30
20
10
0
–INA –INB –INC
V
LT1997-3
V
+
–
–IN
2.5k
7.5k
LT6018
22.5k
1.91k
49.9Ω
1.91k
22.5k
22.5k
–15V
–
+
OUT
REF
V
V
OUT
REF
+15V
7.5k
2.5k
22.5k
–
+
LT6018
V
+IN
1
10
100
1000
–
+INA +INB +INC SHDN
V
FREQUENCY (kHz)
–15V
19973 TA05b
19973 TA05a
–15V
INPUT REFERRED NOISE = 2.1nV/√Hz
CMRR = 140dB
relaTeD parTs
PART NUMBER
LT6375
DESCRIPTION
COMMENTS
270V Common Mode Voltage Difference Amplifier
250V Input Range Difference Amplifier
3.3V to 50V Operation, CMRR > 97dB, Input Voltage = 270V
2.7V to 36V Operation, CMRR > 70dB, Input Voltage = 250V
LT1990
LT1991
Precision, 100µA Gain Selectable Amplifier
Precision, 100µA Gain Selectable Amplifier
High Voltage, Bidirectional Current Sense Amplifier
Single, Dual, and Quad Over-The-Top Precision Op Amp
2.7V to 36V Operation, 50μV Offset, CMRR > 75dB, Input Voltage = 60V
Micropower, Pin Selectable Up to Gain = 118
LT1996
LT1999
-5V to 80V, 750µV, CMRR 80dB at 100kHz, Gain: 10V/V, 20V/V, 50V/V
LT6015/LT6016/
LT6017
3.2MHz, 0.8V/µs, 50µV V , 3V to 50V V , 0.335mA I , RRIO
OS S S
LT6018
LTC6090
LT6108
33V, Ultralow Noise, Precision Op Amp
140V Operational Amplifier
V : 50µV, GBW: 15MHz, SR: 30V/µs, en: 1.2nV/√Hz, I : 7.2mA
OS S
50pA I , 1.6mV V , 9.5V to 140V V , 4.5mA I , RR Output
B
OS
S
S
High Side Current Sense Amplifier with Reference and
Comparator with Shutdown
2.7V to 60V, 125µV, Resistor Set Gain, 1.25ꢀ Threshold Error
LT1787/LT1787HV Precision, Bidirectional High Side Current Sense Amplifier 2.7V to 60V Operation, 75μV Offset, 60μA Current Draw
LT6100
Gain-Selectable High Side Current Sense Amplifier
High Voltage High Side Current Sense Amplifier
Zero Drift High Side Current Sense Amplifier
Bidirectional, High Side Current Sense
4.1V to 48V Operation,
Pin-Selectable Gain: 10V/V, 12.5V/V, 20V/V, 25V/V, 40V/V, 50V/V
LTC6101/
LTC6101HV
4V to 60V/5V to 100V Operation, External Resistor Set Gain, SOT23
LTC6102/
LTC6102HV
4V to 60V/5V to 100V Operation, 10μV Offset, 1μs Step Response,
MSOP8/DFN Packages
LTC6104
4V to 60V, Gain Configurable, 8-Pin MSOP Package
19973f
LT 0317 • PRINTED IN USA
www.linear.com/LT1997-3
36
LINEAR TECHNOLOGY CORPORATION 2017
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LT1999 - High Voltage, Bidirectional Current Sense Amplifier; Package: MSOP; Pins: 8; Temperature Range: 0°C to 70°C
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