LINER LT1789CS8-1 Micropower, single supply rail-to-rail output instrumentation amplifier Datasheet

LT1789-1/LT1789-10
Micropower,
Single Supply Rail-to-Rail
Output Instrumentation Amplifiers
DESCRIPTION
FEATURES
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The LT®1789-1/LT1789-10 are micropower, precision
instrumentation amplifiers that are optimized for single
supply operation from 2.2V to 36V. The quiescent current
is 95μA max, the inputs common mode to ground and the
output swings within 110mV of ground. The gain is set
with a single external resistor for a gain range of 1 to 1000
for the LT1789-1 and 10 to 1000 for the LT1789-10.
Micropower: 95μA Supply Current Max
Low Input Offset Voltage: 100μV Max
Low Input Offset Voltage Drift: 0.5μV/°C Max
Single Gain Set Resistor:
G = 1 to 1000 (LT1789-1)
G = 10 to 1000 (LT1789-10)
Inputs Common Mode to V–
Wide Supply Range: 2.2V to 36V Total Supply
CMRR at G = 10: 96dB Min
Gain Error: G = 10, 0.25% Max
Gain Nonlinearity: G = 10, 40ppm Max
Input Bias Current: 40nA Max
PSRR at G = 10: 100dB Min
1kHz Voltage Noise: 48nV/√Hz
0.1Hz to 10Hz Noise: 1.5μVP-P
The high accuracy of the LT1789-1 (40ppm maximum nonlinearity and 0.25% max gain error) is unmatched by other
micropower instrumentation amplifiers. The LT1789-10
maximizes both the input common mode range and dynamic
output range when an amplification of 10 or greater is required,
allowing precise signal processing where other instrumentation amplifiers fail to operate. The LT1789-1/LT1789-10 are
laser trimmed for very low input offset voltage, low input
offset voltage drift, high CMRR and high PSRR. The output
can handle capacitive loads up to 400pF (LT1789-1), 1000pF
(LT1789-10) in any gain configuration while the inputs are
ESD protected up to 10kV (human body).
APPLICATIONS
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Portable Instrumentation
Bridge Amplifiers
Strain Gauge Amplifiers
Thermocouple Amplifiers
Differential to Single-Ended Converters
Medical Instrumentation
The LT1789-1/LT1789-10 are offered in the 8-pin SO
package, requiring significantly less PC board area than
discrete multi op amp and resistor designs.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
0.5A to 4A Voltage Controlled Current Source
C1
4700pF
R1
90.9k
VIN
R2
10k
VS
C3
0.1μF
VS
2
3
–
+
7
6
LT1636
RISE TIME ≈ 250μs, 10% TO 90%,
1A TO 2A OUTPUT STEP INTO 0.25Ω LOAD
TIP127*
7
R4
10k
C2
3300pF
120Ω
* ENSURE ADEQUATE POWER
DISSIPATION CAPABILITY AT
HIGHER VOLTAGES,
CURRENTS AND DUTY CYCLES
VS
5
4
VS = 3.3V TO 32V
VIN
ILOAD =
RSENSE • 10
= 1A PER VOLT AS SHOWN
8k
R3
100Ω
+
3
3
8
6
1
LT1789-1
REF
2
1
5
–
4
RSENSE*
0.1Ω ILOAD
4
2
RLOAD*
1789 TA01
1789fc
1
LT1789-1/LT1789-10
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
Supply Voltage (V+ to V–)..........................................36V
Input Differential Voltage ..........................................36V
Input Current (Note 3) ......................................... ±20mA
Output Short-Circuit Duration .......................... Indefinite
Operating Temperature Range .................–40°C to 85°C
Specified Temperature Range (Note 4)
LT1789C-1, LT1789C-10 .......................–40°C to 85°C
LT1789I-1, LT1789I-10 ........................–40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
TOP VIEW
RG 1
8 RG
–IN 2
7 +VS
+IN 3
6 OUT
–VS 4
5 REF
S8 PACKAGE
8-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 190°C/W
ORDER INFORMATION
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT1789CS8-1#PBF
LT1789CS8-1#TRPBF
17891
8-Lead Plastic SO
–40°C to 85°C
LT1789IS8-1#PBF
LT1789IS8-1#TRPBF
1789I1
8-Lead Plastic SO
–40°C to 85°C
LT1789CS8-10#PBF
LT1789CS8-10#TRPBF
178910
8-Lead Plastic SO
–40°C to 85°C
LT1789IS8-10#PBF
LT1789IS8-10#TRPBF
789I10
8-Lead Plastic SO
–40°C to 85°C
LEAD BASED FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LT1789CS8-1
LT1789CS8-1#TR
17891
8-Lead Plastic SO
–40°C to 85°C
LT1789IS8-1
LT1789IS8-1#TR
1789I1
8-Lead Plastic SO
–40°C to 85°C
LT1789CS8-10
LT1789CS8-10#TR
178910
8-Lead Plastic SO
–40°C to 85°C
LT1789IS8-10
LT1789IS8-10#TR
789I10
8-Lead Plastic SO
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
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/
3V AND 5V ELECTRICAL CHARACTERISTICS
supply, TA = 25°C, unless otherwise noted.
VS = 3V, 0V; VS = 5V, 0V; RL = 20k, VCM = VREF = half
LT1789-1
SYMBOL PARAMETER
CONDITIONS
G
Gain Error (Note 6)
LT1789-1, G = 1 + (200k/RG)
LT1789-10, G = 10 • [1+ (200k/RG)]
G = 1, VO = 0.1V to (+VS) – 1V
Gain Nonlinearity (Note 6)
Gain Range
MIN
TYP
1
LT1789-10
MAX
MIN
TYP
MAX
UNITS
1000
10
0.02
0.20
LT1789-1, VO = 0.1V to (+VS) – 0.3V
LT1789-10, VO = 0.2V to (+VS) – 0.3V
G = 10 (Note 2)
G = 100 (Note 2)
G = 1000 (Note 2)
G = 1, VO = 0.1V to (+VS) – 1V
0.06
0.06
0.13
35
0.25
0.27
LT1789-1, VO = 0.1V to (+VS) – 0.3V
LT1789-10, VO = 0.2V to 4.7V, VS = 5V
(Note 8)
G = 10
G = 100
G = 1000
12
18
90
40
75
1000
%
0.01
0.09
0.16
0.25
0.30
%
%
%
ppm
15
20
100
100
100
ppm
ppm
ppm
100
1789fc
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LT1789-1/LT1789-10
3V AND 5V ELECTRICAL CHARACTERISTICS
supply, TA = 25°C, unless otherwise noted.
VS = 3V, 0V; VS = 5V, 0V; RL = 20k, VCM = VREF = half
LT1789-1
SYMBOL PARAMETER
CONDITIONS
TYP
MAX
TYP
MAX
UNITS
G = 1000
15
100
20
160
μV
Output Offset Voltage
G = 1 (LT1789-1), G =10 (LT1789-10)
150
750
650
3000
μV
IOS
Input Offset Current
(Note 6)
0.2
4
0.2
4
nA
IB
Input Bias Current
en
Input Noise Voltage,
RTI (Referred to Input)
(Note 6)
19
40
19
40
G = 1, fO = 0.1Hz to 10Hz
G = 10
G = 100, 1000
5.0
1.5
1.0
VOST
Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI
Input Offset Voltage
VOSO
MIN
LT1789-10
MIN
nA
μVP-P
μVP-P
μVP-P
4.6
1.1
Total RTI Noise = √eni2 + (eno/G)2
eni
Input Noise Voltage Density, RTI
fO = 1kHz (Note 7)
48
eno
Output Noise Voltage Density, RTI fO = 1kHz (Note 3)
330
270
nV/√Hz
in
Input Noise Current
fO = 0.1Hz to 10Hz
16
16
pAP-P
Input Noise Current Density
fO = 1kHz
62
62
fA/√Hz
1.6
GΩ
1.6
1.6
pF
pF
V
RIN
Input Resistance
VIN = 0V to (+VS) – 1V (Note 6)
CIN
Input Capacitance
Differential
Common Mode
VCM
Input Voltage Range
CMRR
Common Mode Rejection Ratio
PSRR
Power Supply Rejection Ratio
0.75
85
1.6
52
0.75
1.6
1.6
0
+VS – 1
0
90
+VS – 1.2
nV/√Hz
1k Source Imbalance (Note 6)
LT1789-1,VCM = 0V to (+VS) – 1V
LT1789-10, VCM = 0V to (+VS) – 1.2V
G=1
G = 10
G = 100
G = 1000
79
96
100
100
88
106
114
114
88
98
98
105
113
113
dB
dB
dB
dB
VS = 2.5V to 12.5V, VCM = VREF = 1V
G=1
G = 10
G = 100
G = 1000
90
100
102
102
100
113
116
116
94
102
102
109
120
120
dB
dB
dB
dB
Minimum Supply Voltage
2.2
2.5
2.2
2.5
V
IS
Supply Current
(Note 7)
67
95
67
95
μA
VOL
Output Voltage Swing LOW
(Note 7)
54
100
62
110
mV
VOH
Output Voltage Swing HIGH
(Note 7)
ISC
Short-Circuit Current
Short to GND
Short to +VS
BW
Bandwidth
Slew Rate
G=1
G = 10
G = 100
G = 1000
G = 10, VOUT = 0.5V to 4.5V
Settling Time to 0.01%
4V Step
SR
RREFIN
Reference Input Resistance
IREFIN
Reference Input Current
AVREF
Reference Gain to Output
VREF = 0V
+VS – 0.3 +VS – 0.19
+VS – 0.3 +VS – 0.19
2.2
8.5
V
2.2
8.5
60
30
3
0.2
25
12
1.5
mA
mA
kHz
kHz
kHz
kHz
0.023
0.062
V/μs
240
190
μs
220
220
kΩ
2.7
2.7
μA
1 ±0.0001
1 ±0.0001
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LT1789-1/LT1789-10
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the temperature range of
0°C ≤ TA ≤ 70°C. VS = 3V, 0V; VS = 5V, 0V; RL = 20k, VREF = half supply, unless otherwise noted. (Note 4)
LT1789-1
SYMBOL PARAMETER
Gain Error (Note 6)
Gain Nonlinearity (Note 6)
CONDITIONS
MIN
TYP
LT1789-10
MAX
G = 1, VO = 0.3V to (+VS) – 1V
l
0.25
VO = 0.3V to (+VS) – 0.5V
G = 10 (Note 2)
G = 100 (Note 2)
l
l
0.53
0.55
G = 1, VO = 0.3V to (+VS) – 1V
l
185
LT1789-1, VO = 0.3V to (+VS) – 0.5V
LT1789-10, VO = 0.3V to 4.7V, VS = 5V
(Note 8)
l
G = 10
l
G = 100
90
120
G/T
Gain vs Temperature
G < 1000 (Notes 2, 3)
VOST
Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI
Input Offset Voltage
l
G = 1000
l
5
VOSIH
Input Offset Voltage Hysteresis
(Notes 3, 5)
Output Offset Voltage
G = 1 (LT1789-1), G = 10 (LT1789-10)
l
VOSOH
Output Offset Voltage Hysteresis
(Notes 3, 5)
l
50
100
VOSI/T
Input Offset Voltage Drift (RTI)
(Note 3)
l
0.2
(Note 3)
l
1.5
(Note 6)
l
3
MAX
0.30
0.53
UNITS
%
%
ppm
5
150
VOSO
Output Offset Voltage Drift
TYP
%
50
l
VOSO/T
MIN
10
3
130
130
ppm
ppm
50
ppm/°C
190
µV
10
µV
3700
µV
300
900
µV
0.5
0.3
0.7
µV/°C
4
7
20
µV/°C
950
IOS
Input Offset Current
IOS/T
Input Offset Current Drift
IB
Input Bias Current
IB/T
Input Bias Current Drift
l
VCM
Input Voltage Range
l
0.2
CMRR
Common Mode Rejection Ratio
1k Source Imbalance (Note 6)
LT1789-1, VCM = 0.2V to (+VS) – 1V
LT1789-10, VCM = 0.2V to (+VS) – 1.5V
l
G=1
l
G = 10
l
G = 100, 1000
77
94
98
85
96
dB
dB
dB
VS = 2.5V to 12.5V, VCM = VREF = 1V
G=1
G = 10
G = 100, 1000
88
98
100
92
100
dB
dB
dB
PSRR
Power Supply Rejection Ratio
(Note 6)
VOL
VOH
Supply Current
Output Voltage Swing LOW
Output Voltage Swing HIGH
l
l
l
l
4.5
3
3
45
45
50
50
(+VS) – 1
0.2
nA
pA/°C
nA
pA/°C
(+VS) – 1.5
V
l
2.5
2.5
V
(Note 7)
l
115
115
µA
(Note 7)
l
110
120
mV
(Note 7)
l +VS – 0.38
Minimum Supply Voltage
IS
4.5
l
+VS – 0.38
V
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LT1789-1/LT1789-10
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the temperature range of
–40°C ≤ TA ≤ 85°C. VS = 3V, 0V; VS = 5V, 0V; RL = 20k, VREF = half supply, unless otherwise noted. (Note 4)
LT1789-1
SYMBOL PARAMETER
Gain Error (Note 6)
Gain Nonlinearity (Note 6)
CONDITIONS
MIN
TYP
LT1789-10
MAX
G = 1, VO = 0.3V to (+VS) – 1V
l
0.30
VO = 0.3V to (+VS) – 0.5V
G = 10 (Note 2)
G = 100 (Note 2)
l
l
0.57
0.59
G = 1, VO = 0.3V to (+VS) – 1V
l
250
LT1789-1, VO = 0.3V to (+VS) – 0.5V
LT1789-10, VO = 0.3V to 4.7V, VS = 5V
(Note 8)
l
G = 10
l
G = 100
105
160
G/T
Gain vs Temperature
G < 1000 (Notes 2, 3)
VOST
Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI
Input Offset Voltage
l
G = 1000
l
5
Input Offset Voltage Hysteresis
(Notes 3, 5)
VOSO
Output Offset Voltage
G = 1 (LT1789-1), G = 10 (LT1789-10)
l
VOSOH
Output Offset Voltage Hysteresis
(Notes 3, 5)
l
50
100
VOSI/T
Input Offset Voltage Drift (RTI)
(Note 3)
l
0.2
(Note 3)
l
1.5
(Note 6)
l
3
MAX
0.35
0.62
UNITS
%
%
ppm
5
175
VOSIH
Output Offset Voltage Drift
TYP
%
50
l
VOSO/T
MIN
10
3
150
170
ppm
ppm
50
ppm/°C
205
µV
10
µV
4000
µV
300
900
µV
0.5
0.3
0.7
µV/°C
4
7
20
µV/°C
1050
IOS
Input Offset Current
IOS/T
Input Offset Current Drift
IB
Input Bias Current
IB/T
Input Bias Current Drift
l
VCM
Input Voltage Range
l
0.2
CMRR
Common Mode Rejection Ratio
1k Source Imbalance (Note 6)
LT1789-1, VCM = 0.2V to (+VS) – 1V
LT1789-10, VCM = 0.2V to (+VS) – 1.5V
l
G=1
l
G = 10
l
G = 100, 1000
75
92
96
84
94
dB
dB
dB
VS = 2.5V to 12.5V, VCM = VREF = 1V
G=1
G = 10
G = 100, 1000
86
96
98
90
98
dB
dB
dB
PSRR
Power Supply Rejection Ratio
(Note 6)
VOL
VOH
Supply Current
Output Voltage Swing LOW
Output Voltage Swing HIGH
l
l
l
l
5
3
3
50
50
50
50
+VS – 1
0.2
nA
pA/°C
nA
pA/°C
+VS – 1.5
V
l
2.5
2.5
V
(Note 7)
l
125
125
µA
(Note 7)
l
120
130
mV
(Note 7)
l +VS – 0.40
Minimum Supply Voltage
IS
5
l
+VS – 0.40
V
1789fc
5
LT1789-1/LT1789-10
ELECTRICAL CHARACTERISTICS
VS = ±15V, RL = 20k, VCM = VOUT = 0V, TA = 25°C, unless otherwise noted.
LT1789-1
SYMBOL PARAMETER
G
CONDITIONS
Gain Range
MIN
TYP
LT1789-10
MAX
MIN
TYP
MAX
UNITS
VOST
LT1789-1, G = 1 + (200k/RG)
LT1789-10, G = 10 • [1+ (200k/RG)]
Gain Error
VO = ±10V
G=1
G = 10 (Note 2)
G = 100 (Note 2)
G = 1000 (Note 2)
Gain Nonlinearity
VO = ±10V
G=1
G = 10
G = 100
G = 1000
Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI
Input Offset Voltage
G = 1000
30
235
30
295
μV
VOSO
Output Offset Voltage
G = 1 (LT1789-1), G =10 (LT1789-10)
0.2
1
0.6
3.3
mV
IOS
Input Offset Current
0.2
4
0.2
4
nA
IB
Input Bias Current
17
40
17
40
nA
en
Input Noise Voltage, RTI
1
1000
10
1000
0.01
0.04
0.04
0.07
0.10
0.15
0.15
0.20
0.01
0.03
0.03
0.15
0.20
0.25
%
%
%
%
8
1
6
20
20
10
20
100
5
5
25
40
40
160
ppm
ppm
ppm
ppm
fO = 0.1Hz to 10Hz
G=1
G = 10
G = 100, 1000
5.0
1.5
1.0
μVP-P
μVP-P
μVP-P
4.6
1.1
Total RTI Noise = √eni2 + (eno/G)2
eni
Input Noise Voltage Density, RTI
fO = 1kHz
49
eno
Output Noise Voltage Density, RTI fO = 1kHz
330
in
Input Noise Current
fO = 0.1Hz to 10Hz
19
19
pAP-P
Input Noise Current Density
fO = 1kHz
62
62
fA/√Hz
4.7
GΩ
20
17
pF
pF
V
RIN
Input Resistance
CIN
Input Capacitance
VCM
Input Voltage Range
CMRR
Common Mode Rejection Ratio
PSRR
Power Supply Rejection Ratio
2
Differential
Common Mode
LT1789-1 VS = ±1.25V to ±16V
LT1789-10 VS = ±1.50V to ±16V
G=1
G = 10
G = 100, 1000
Supply Current
VO
Output Voltage Swing
ISC
Short-Circuit Current
2
20
17
–14
–15
nV/√Hz
nV/√Hz
–14
89
108
117
93
102
108
123
dB
dB
dB
94
104
102
107
118
121
100
106
115
123
dB
dB
dB
±1.25
85
±14.5
Short to –VS
Short to +VS
95
80
98
102
Minimum Supply Voltage
IS
53
270
4.7
–15
1k Source Imbalance, VCM = –15V to 14V
G=1
G = 10
G = 100, 1000
90
±14.7
2.2
8.5
130
85
±14.5
±14.7
2.2
8.5
±1.50
V
130
μA
V
mA
mA
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LT1789-1/LT1789-10
ELECTRICAL CHARACTERISTICS
VS = ±15V, RL = 20k, VCM = VOUT = 0V, TA = 25°C, unless otherwise noted.
LT1789-1
SYMBOL PARAMETER
CONDITIONS
BW
Slew Rate
G=1
G = 10
G = 100
G = 1000
VOUT = ±10V
Settling Time to 0.01%
10V Step
SR
Bandwidth
RREFIN
Reference Input Resistance
IREFIN
Reference Input Current
AVREF
Reference Gain to Output
MIN
TYP
LT1789-10
MAX
MIN
60
30
3
0.2
0.012
VREF = 0V
0.026
0.028
TYP
MAX
UNITS
25
12
1.5
kHz
kHz
kHz
kHz
0.066
V/μs
460
270
μs
220
220
kΩ
2.7
2.7
μA
1 ±0.0001
1 ±0.0001
The l denotes the specifications which apply over the temperature range of 0°C ≤ TA ≤ 70°C. VS = ±15V, RL = 20k, VCM = VREF = 0V,
unless otherwise noted. (Note 4)
LT1789-1
SYMBOL PARAMETER
Gain Error
Gain Nonlinearity
CONDITIONS
MIN
VO = ±10V
G=1
G = 10 (Note 2)
G = 100 (Note 2)
G = 1000 (Note 2)
l
l
l
l
VO = ±10V
G=1
G = 10
G = 100
G = 1000
l
l
l
l
G < 1000 (Notes 2, 3)
l
TYP
LT1789-10
MAX
MIN
TYP
MAX
UNITS
0.15
0.38
0.38
0.43
0.20
0.43
0.48
%
%
%
%
25
15
25
120
45
45
180
ppm
ppm
ppm
ppm
50
ppm/°C
325
µV
30
µV
4
mV
µV
G/T
Gain vs Temperature
VOST
Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI
Input Offset Voltage
G = 1000
l
VOSIH
Input Offset Voltage Hysteresis
(Notes 3, 5)
l
VOSO
Output Offset Voltage
G=1
l
VOSOH
Output Offset Voltage Hysteresis
(Notes 3, 5)
l
50
120
400
1000
VOSI/T
Input Offset Voltage Drift (RTI)
(Note 3)
l
0.2
0.7
0.3
0.8
µV/°C
(Note 3)
l
1.5
5
8
22
µV/°C
4.5
nA
5
50
5
285
8
30
8
1.2
VOSO/T
Output Offset Voltage Drift
IOS
Input Offset Current
l
IOS/T
Input Offset Current Drift
l
IB
Input Bias Current
l
IB/T
Input Bias Current Drift
l
VCM
Input Voltage Range
G = 1, Other Input Grounded
l
–14.8
CMRR
Common Mode Rejection Ratio
1k Source Imbalance,
VCM = –14.8V to 14V
G=1
G = 10
G = 100, 1000
l
l
l
78
96
100
4.5
2
2
45
pA/°C
45
35
35
14
–14.8
91
100
nA
pA/°C
14
V
dB
dB
dB
1789fc
7
LT1789-1/LT1789-10
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the temperature range of
0°C ≤ TA ≤ 70°C. VS = ±15V, RL = 20k, VCM = VREF = 0V, unless otherwise noted. (Note 4)
LT1789-1
SYMBOL PARAMETER
CONDITIONS
PSRR
LT1789-1, VS = ±1.25V to ±16V
LT1789-10, VS = ±1.50V to ±16V
G=1
G = 10
G = 100, 1000
Power Supply Rejection Ratio
MIN
l
l
l
TYP
LT1789-10
MAX
92
102
104
MIN
TYP
MAX
UNITS
dB
dB
dB
98
104
Minimum Supply Voltage
l
±1.25
±1.50
V
IS
Supply Current
l
150
150
µA
VO
Output Voltage Swing
l
±14.25
±14.25
V
SR
Slew Rate
l
0.010
0.026
V/µs
VOUT = ±10V
The l denotes the specifications which apply over the temperature range of –40°C ≤ TA ≤ 85°C. VS = ±15V, RL = 20k, VCM = VREF = 0V,
unless otherwise noted. (Note 4)
LT1789-1
SYMBOL PARAMETER
Gain Error
Gain Nonlinearity
G/T
Gain vs Temperature
CONDITIONS
MIN
VO = ±10V
G=1
G = 10 (Note 2)
G = 100 (Note 2)
G = 1000 (Note 2)
l
l
l
l
VO = ±10V
G=1
G = 10
G = 100
G = 1000
l
l
l
l
G < 1000 (Notes 2, 3)
l
TYP
5
LT1789-10
MAX
MIN
MAX
UNITS
0.20
0.57
0.57
0.62
0.25
0.62
0.67
%
%
%
%
30
20
30
130
50
50
200
ppm
ppm
ppm
ppm
50
ppm/°C
340
µV
30
µV
4.2
mV
µV
50
TYP
5
VOST
Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI
Input Offset Voltage
G = 1000
l
VOSIH
Input Offset Voltage Hysteresis
(Notes 3, 5)
l
VOSO
Output Offset Voltage
G=1
l
(Notes 3, 5)
l
50
120
400
1000
0.2
0.7
0.3
0.8
µV/°C
1.5
5
8
22
µV/°C
5
nA
VOSOH
Output Offset Voltage Hysteresis
VOSI/T
Input Offset Voltage Drift (RTI)
(Note 3)
l
VOSO/T
Output Offset Voltage Drift
(Note 3)
l
IOS
Input Offset Current
l
IOS/T
Input Offset Current Drift
l
Input Bias Current
l
l
IB
305
8
30
8
1.3
5
2
2
50
IB/T
Input Bias Current Drift
VCM
Input Voltage Range
G = 1, Other Input Grounded
l
–14.8
CMRR
Common Mode Rejection Ratio
1k Source Imbalance,
VCM = –14.8V to 14V
G=1
G = 10
G = 100, 1000
l
l
l
76
94
98
pA/°C
50
35
35
14
–14.8
89
98
nA
pA/°C
14
V
dB
dB
dB
1789fc
8
LT1789-1/LT1789-10
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the temperature range of
–40°C ≤ TA ≤ 85°C. VS = ±15V, RL = 20k, VCM = VREF = 0V, unless otherwise noted. (Note 4)
LT1789-1
SYMBOL PARAMETER
CONDITIONS
PSRR
LT1789-1, VS = ±1.25V to ±16V
LT1789-10, VS = ±1.50V to ±16V
G=1
G = 10
G = 100, 1000
Power Supply Rejection Ratio
IS
VO
SR
MIN
l
l
l
UNITS
dB
dB
dB
96
102
±1.50
V
Supply Current
l
160
160
µA
Output Voltage Swing
l
±14.15
±14.15
V
Slew Rate
l
0.008
0.024
V/µs
VOUT = ±10V
Note 5: Hysteresis in offset voltage is created by package stress that
differs depending on whether the IC was previously at a higher or lower
temperature. Offset voltage hysteresis is always measured at 25°C, but
the IC is cycled to 85°C I-grade (or 70°C C-grade) or – 40°C I-grade
(0°C C-grade) before successive measurement. 60% of the parts will
pass the typical limit on the data sheet.
Note 6: VS = 5V limits are guaranteed by correlation to VS = 3V and
VS = ±15V tests.
Note 7: VS = 3V limits are guaranteed by correlation to VS = 5V and
VS = ±15V tests.
Note 8: This parameter is not tested at VS = 3V on the LT1789-10 due
to an increase in sensitivity to test system noise. Actual performance is
expected to be similar to performance at VS = 5V.
(LT1789-1, LT1789-10)
Input Bias Current
vs Temperature
0
125°C
90
80
25°C
–55°C
50
40
Input Bias Current
vs Common Mode Input Voltage
–10
VS = 5V, 0V
VCM = 2.5V
–12
–5
INPUT BIAS CURRENT (nA)
INPUT BIAS CURRENT (nA)
110
SUPPLY CURRENT (μA)
MAX
±1.25
120
–10
–15
–20
20
5
10 15 20 25 30 35
TOTAL SUPPLY VOLTAGE (V)
40
1789 G01
–25
–50
–25
50
25
0
75
TEMPERATURE (°C)
100
125
1789 G02
–55°C
–14
–16
125°C
–18
25°C
–20
85°C
–22
–24
–26
–28
30
0
TYP
l
Supply Current vs Supply Voltage
60
MIN
90
100
102
TYPICAL PERFORMANCE CHARACTERISTICS
70
MAX
Minimum Supply Voltage
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 2: Does not include the effect of the external gain resistor RG.
Note 3: This parameter is not 100% tested.
Note 4: The LT1789C-1/ LT1789C-10 is guaranteed to meet specified
performance from 0°C to 70°C and is designed, characterized and
expected to meet these extended temperature limits, but is not tested at
–40°C and 85°C. The LT1789I-1/ LT1789I-10 is guaranteed to meet the
extended temperature limits.
100
TYP
LT1789-10
VS = 5V, 0V
VREF = 2.5V
–30
–0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
COMMON MODE INPUT VOLTAGE (V)
1789 G03
1789fc
9
LT1789-1/LT1789-10
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage Swing
vs Load Current
Gain vs Frequency
4.4
1.4
4.2
1.2
VS = 5V, 0V
VREF = 2.5V
4.0
1.0
125°C
0.8
25°C
0.6
0.4
SINK
–55°C
0.2
60
50
40
G = 100
30
20
G = 10
10
0
1k
10k
FREQUENCY (Hz)
100k
1789 G04
COMMON MODE REJECTION RATIO (dB)
120
VS = 5V, 0V
VREF = 2.5V
110
G = 10
100
G = 100, 1000
90
G=1
80
70
60
50
40
10
1k
100
FREQUENCY (Hz)
10k 20k
Negative Power Supply Rejection
Ratio vs Frequency
140
120
G = 1000
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
G = 100
100
G = 10
80
G=1
60
40
20
0
10
100
1k
FREQUENCY (Hz)
10k 20k
1879 G07
80
Positive Power Supply Rejection
Ratio vs Frequency
140
G=1
80
60
40
20
0
100
1k
FREQUENCY (Hz)
10
AV = 1
2
0
–2
–4
–8
AV ≥ 100
10
100
CAPACITIVE LOAD (pF)
4
–6
AV = 10
1
10k 20k
VS = ±15V
RL = 20k
G=1
6
40
0
1789 G10
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
G = 10
100
8
50
10
100k
G = 100, 1000
120
10
60
30
125
Settling Time to 0.01% vs
Output Step
70
20
1k
10k
FREQUENCY (Hz)
100
1789 G09
OUTPUT STEP (V)
1k
10
75
50
25
TEMPERATURE (°C)
0
1789 G06
VS = 5V, 0V
VREF = 2.5V
VOUT = 100mVP-P
90
OVERSHOOT (%)
OUTPUT IMPEDANCE (Ω)
100
VS = 5V, 0V
VREF = 2.5V
1
100
0.010
–50 –25
Overshoot vs Capacitive Load
100
FALLING
1789 G08
Output Impedance vs Frequency
10k
0.025
1789 G05
NEGATIVE POWER SUPPLY REJECTION RATIO (dB)
Common Mode Rejection Ratio
vs Frequency
RISING
0.030
0.015
–20
100
10
0.035
0.020
G=1
–10
0
0.01
0.1
1
OUTPUT CURRENT (mA)
0.001
G = 1000
SLEW RATE (V/μs)
1.6
25°C
VS = 5V, 0V
0.045 VREF = 2.5V
G=1
0.040 RL = 20k
POSITIVE POWER SUPPLY REJECTION RATIO (dB)
125°C
0.050
VS = 5V, 0V
VREF = 2.5V
70
GAIN (dB)
–55°C
4.8
SOURCE
Slew Rate vs Temperature
80
OUTPUT VOLTAGE SWING—SINKING (V)
OUTPUT VOLTAGE SWING—SOURCING (V)
5.0
4.6
(LT1789-1)
–10
1000
1789 G11
0
100
300
400
200
SETTLING TIME (μs)
500
1789 G12
1789fc
10
LT1789-1/LT1789-10
TYPICAL PERFORMANCE CHARACTERISTICS
Voltage Noise Density vs
Frequency
Current Noise Density vs
Frequency
G=1
G = 10
100
G = 100, 1000
1000
CURRENT NOISE DENSITY (fA/√Hz)
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
10
VS = 5V, 0V
VREF = 2.5V
100
RS
LT1789-1
10
1
10
100
FREQUENCY (Hz)
1k
10
100
FREQUENCY (Hz)
1
1k
1789 G13
1789 G14
0.1Hz to 10Hz Noise Voltage,
G=1
0.1Hz to 10Hz Noise Voltage,
RTI, G = 1000
VS = 5V, 0V
VREF = 2.5V
NOISE VOLTAGE (2μV/DIV)
NOISE VOLTAGE (0.5μV/DIV)
VS = 5V, 0V
VREF = 2.5V
0
1
2
3
4 5 6
TIME (SEC)
7
8
0
9 10
1
3
2
4 5 6
TIME (SEC)
7
8
9 10
1789 G16
1789 G15
0.1Hz to 10Hz Noise Current
Turn-On Characteristics
1.5
CHANGE IN OUTPUT VOLTAGE (V)
VS = 5V, 0V
VREF = 2.5V
NOISE CURRENT (5pA/DIV)
VOLTAGE NOISE DENSITY (nV/√Hz)
1000
(LT1789-1)
VS = 5V, 0V
VREF = 2.5V
VCM = 2.5V
G = 1000
TA = 25°C
0.5
–0.5
–1.5
0
1
2
3
4 5 6
TIME (SEC)
7
8
9 10
0
10
20
30
40
TIME (ms)
1789 G17
1789 G18
1789fc
11
LT1789-1/LT1789-10
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage Swing
vs Load Current
Gain vs Frequency
SOURCE
25°C
1.4
4.2
4.0
1.2
VS = 5V, 0V
VREF = 2.5V
1.0
125°C
0.8
25°C
0.6
0.4
SINK
–55°C
0.2
60
0.01
0.1
1
OUTPUT CURRENT (mA)
40
G = 100
30
20
G = 10
10
110
VS = 5V, 0V
VREF = 2.5V
G = 10
100
90
80
70
60
50
40
10
100
1k
FREQUENCY (Hz)
10k 20k
–20
100
1k
10k
FREQUENCY (Hz)
Negative Power Supply Rejection
Ratio vs Frequency
140
G = 1000
120
100
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
G = 100
80
G = 10
60
40
20
0
10
90
80
100
1k
FREQUENCY (Hz)
10k 20k
Positive Power Supply Rejection
Ratio vs Frequency
140
G = 100, 1000
120
G = 10
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
100
80
60
40
20
0
100
1k
FREQUENCY (Hz)
10
10
6
50
40
0
10
G = 1000
4
2
0
–2
–4
–6
G = 100
–8
G = 10
100
CAPACITIVE LOAD (pF)
10k 20k
VS = ±15V
RL = 20k
G = 10
8
30
125
100
1789 G26
VS = 5V, 0V
VREF = 2.5V
VOUT = 100mVP-P
60
10
1789 G27
75
Settling Time to 0.01% vs
Output Step
70
20
100k
50
1789 G23
OUTPUT STEP (V)
1k
OVERSHOOT (%)
OUTPUT IMPEDANCE (Ω)
100
1k
10k
FREQUENCY (Hz)
25
1789 G25
VS = 5V, 0V
VREF = 2.5V
1
100
0
TEMPERATURE (°C)
Overshoot vs Capacitive Load
10
–25
1789 G22
Output Impedance vs Frequency
100
FALLING
0.07
0.04
–50
100k
1789 G24
10k
0.08
0.05
–10
NEGATIVE POWER SUPPLY REJECTION RATIO (dB)
COMMON MODE REJECTION RATIO (dB)
G = 100, 1000
0.09
0.06
1789 G21
120
RISING
0
10
Common Mode Rejection Ratio
vs Frequency
0.11
0.10
50
0
0.001
G = 1000
SLEW RATE (V/μs)
1.6
POSITIVE POWER SUPPLY REJECTION RATIO (dB)
125°C
0.12
VS = 5V, 0V
VREF = 2.5V
70
GAIN (dB)
–55°C
4.8
4.4
Slew Rate vs Temperature
80
OUTPUT VOLTAGE SWING—SINKING (V)
OUTPUT VOLTAGE SWING—SOURCING (V)
5.0
4.6
(LT1789-10)
1000
1789 G28
–10
0
100
300
400
200
SETTLING TIME (μs)
500
1789 G29
1789fc
12
LT1789-1/LT1789-10
TYPICAL PERFORMANCE CHARACTERISTICS
Voltage Noise Density vs
Frequency
Current Noise Density vs
Frequency
G = 10
100
G = 100
G = 1000
1000
CURRENT NOISE DENSITY (fA/√Hz)
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
10
VS = 5V, 0V
VREF = 2.5V
100
RS
LT1789-10
10
1
10
100
FREQUENCY (Hz)
1k
10
100
FREQUENCY (Hz)
1
1k
1789 G30
1789 G31
0.1Hz to 10Hz Noise Voltage,
RTI, G = 10
0.1Hz to 10Hz Noise Voltage,
RTI, G = 1000
VS = 5V, 0V
VREF = 2.5V
NOISE VOLTAGE (2μV/DIV)
NOISE VOLTAGE (0.5μV/DIV)
VS = 5V, 0V
VREF = 2.5V
0
1
2
3
4 5 6
TIME (SEC)
7
8
0
9 10
1
3
2
4 5 6
TIME (SEC)
7
8
1789 G32
9 10
1789 G33
0.1Hz to 10Hz Noise Current
Turn-On Characteristics
1.5
CHANGE IN OUTPUT VOLTAGE (V)
VS = 5V, 0V
VREF = 2.5V
NOISE CURRENT (5pA/DIV)
VOLTAGE NOISE DENSITY (nV/√Hz)
1000
(LT1789-10)
VS = 5V, 0V
VREF = 2.5V
VCM = 2.5V
G = 1000
TA = 25°C
0.5
–0.5
–1.5
0
1
2
3
4 5 6
TIME (SEC)
7
8
9 10
0
10
20
30
40
TIME (ms)
1789 G34
1789 G59
1789fc
13
LT1789-1/LT1789-10
TYPICAL PERFORMANCE CHARACTERISTICS
Large-Signal Transient Response
G = 1, 10, 100
(LT1789-1)
Large-Signal Transient Response
G = 1000
5V/DIV
5V/DIV
VS = ±15V
RL = 20k
CL = 50pF
500μs/DIV
1789 G38
VS = ±15V
RL = 20k
CL = 50pF
Small-Signal Transient Response
G=1
2ms/DIV
1789 G39
Small-Signal Transient Response
G = 10
20mV/DIV
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
100μs/DIV
1789 G40
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
Small-Signal Transient Response
G = 100
100μs/DIV
1789 G41
Small-Signal Transient Response
G = 1000
20mV/DIV
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
200μs/DIV
1789 G42
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
2ms/DIV
1789 G43
1789fc
14
LT1789-1/LT1789-10
TYPICAL PERFORMANCE CHARACTERISTICS
Large-Signal Transient Response
G = 10, 100
5V/DIV
(LT1789-10)
Large-Signal Transient Response
G = 1000
20mV/DIV
5V/DIV
VS = ±15V
RL = 20k
CL = 50pF
500μs/DIV
1789 G44
Small-Signal Transient Response
G = 10
VS = ±15V
RL = 20k
CL = 50pF
500μs/DIV
Small-Signal Transient Response
G = 100
20mV/DIV
1789 G45
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
100μs/DIV
1789 G46
Small-Signal Transient Response
G = 1000
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
200μs/DIV
1789 G47
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
2ms/DIV
1789 G48
1789fc
15
LT1789-1/LT1789-10
TYPICAL PERFORMANCE CHARACTERISTICS
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±15V
3.0
TA = 25°C
G=1
2.5
10
VALID OUTPUT VOLTAGE (V)
VALID OUTPUT VOLTAGE (V)
G≥2
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±2.5V
5
0
–5
–10
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±1.5V
1.5
TA = 25°C
AV = 10
2.0
AV = 1
1.5
VALID OUTPUT VOLTAGE (V)
15
(LT1789-1)
AV = 2
1.0
0.5
0
–0.5
–1.0
–1.5
TA = 25°C
AV = 1
1.0
AV = 2
AV = 10
0.5
0
–0.5
–1.0
–2.0
–15
–15
10
–5
0
5
–10
INPUT COMMON MODE VOLTAGE (V)
–2.5
–2.5
15
–1.5
1.5
–0.5
0.5
INPUT COMMON MODE VOLTAGE (V)
15V
+
VOUT
VCM
REF
–
20K
V–
–15V
VCM
VOUT
REF
–
VALID OUTPUT VOLTAGE (V)
VALID OUTPUT VOLTAGE (V)
3
G=1
2
G=2
G = 10
0
1
3
4
2
INPUT COMMON MODE VOLTAGE (V)
VCM
5
G=1
1
G=2
G = 10
0
0
2.0
0.5
1.5
2.5
1.0
INPUT COMMON MODE VOLTAGE (V)
V–
3.0
3V
V+
VD/2
VOUT
REF
–
1789 G51
TA = 25°C
+
LT1789-1
VD/2
20K
2
V+
VD/2
V–
–1.5V
5V
+
–
3
4
0
REF
Valid Output Voltage vs Input
Common Mode Voltage
VS = 3V
TA = 25°C
1
VCM
VD/2
1789 G50
Valid Output Voltage vs Input
Common Mode Voltage
VS = 5V
5
VOUT
LT1789-1
20K
V–
–2.5V
1789 G49
V+
VD/2
LT1789-1
VD/2
1.5
1.5V
+
V+
VD/2
LT1789-1
VD/2
0
0.5
1.0
–1.0 –0.5
INPUT COMMON MODE VOLTAGE (V)
2.5V
+
V+
VD/2
–1.5
–1.5
2.5
20K
1789 G52
VOUT
LT1789-1
VCM
VD/2
REF
–
V–
20K
1789 G53
1789fc
16
LT1789-1/LT1789-10
TYPICAL PERFORMANCE CHARACTERISTICS
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±15V
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±2.5V
15
2.5
5
0
–5
–10
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±1.5V
AV = 100
1.5
1.5
TA = 25°C
AV = 10
VALID OUTPUT VOLTAGE (V)
G = 100
2.0
VALID OUTPUT VOLTAGE (V)
10
TA = 25°C
1.0
0.5
0
–0.5
–1.0
–1.5
TA = 25°C
AV = 10
1.0
AV = 100
0.5
0
–0.5
–1.0
–2.0
–15
–15
10
–5
0
5
–10
INPUT COMMON MODE VOLTAGE (V)
–2.5
–2.5
15
–1.5
1.5
–0.5 0 0.5
INPUT COMMON MODE VOLTAGE (V)
15V
+
VOUT
REF
–
0
0.5
1.0
–1.0 –0.5
INPUT COMMON MODE VOLTAGE (V)
V–
20K
VCM
–15V
VOUT
V–
20K
VCM
REF
–
1789 G56
3
TA = 25°C
TA = 25°C
G = 10
4
G = 100
3
2
1
0
1
3
4
2
INPUT COMMON MODE VOLTAGE (V)
5
G = 100
2
1
0
0
2.0
0.5
1.5
2.5
1.0
INPUT COMMON MODE VOLTAGE (V)
+
V+
VD/2
VCM
VOUT
REF
–
V–
V+
VD/2
LT1789-10
VD/2
3.0
3V
5V
+
20K
Valid Output Voltage vs Input
Common Mode Voltage
VS = 3V
Valid Output Voltage vs Input
Common Mode Voltage
VS = 5V
0
V–
–1.5V
1789 G55
G = 10
VOUT
LT1789-10
VD/2
–2.5V
1789 G54
5
V+
VD/2
REF
–
1.5
1.5V
+
LT1789-10
VD/2
VALID OUTPUT VOLTAGE (V)
VCM
–1.5
–1.5
V+
VD/2
LT1789-10
VD/2
2.5
2.5V
+
V+
VD/2
VALID OUTPUT VOLTAGE (V)
VALID OUTPUT VOLTAGE (V)
G = 10
(LT1789-10)
20K
1789 G57
VOUT
LT1789-10
VCM
VD/2
REF
–
V–
20K
1789 G58
1789fc
17
LT1789-1/LT1789-10
BLOCK DIAGRAM
V+
V+
100k
V+
5.7k
+IN 3
–
RG 1
V–
V–
V+
V+
+
R1
R2
110k/10k* 110k/100k*
A1
5 REF
VB
V–
+
RG 8
A3
100k
–
5.7k
V+
–IN 2
–
V–
+
V–
R3
R4
110k/10k* 110k/100k*
A2
6 OUT
7 V+
VB
*LT1789-1/LT1789-10
V–
4 V–
1789 F01
Figure 1. Block Diagram
APPLICATIONS INFORMATION
Setting the Gain
Input and Output Offset Voltage
The gain of the LT1789-1 and LT1789-10 is set by the
value of resistor RG, applied across pins 1 and 8. For the
LT1789-1, the gain G will be:
The offset voltage of the LT1789-1/LT1789-10 has two
components: the output offset and the input offset. The
total offset voltage referred to the input (RTI) is found by
dividing the output offset by the programmed gain (G) and
adding it to the input offset. At high gains the input offset
voltage dominates, whereas at low gains the output offset
voltage dominates. The total offset voltage is:
G = 1+ 200k/RG
and RG can be calculated from the desired gain by
RG = 200k/(G – 1)
For the LT1789-10, the gain G will be
G =10 • (1 + 200k/RG)
and RG can be calculated from the desired gain by
To t a l i n p u t o f f s e t v o l t a g e
= input offset + (output offset/G)
(RTI)
To t a l o u t p u t o f f s e t v o l t a g e
= (input offset • G) + output offset
(RTO)
RG = 200k/(0.1 • G – 1)
For the lowest achievable gain, RG may be set to infinity
by leaving Pins 1 and 8 open.
1789fc
18
LT1789-1/LT1789-10
APPLICATIONS INFORMATION
Reference Terminal
Input Bias Current Return Path
The output voltage of the LT1789-1/LT1789-10 (Pin 6)
is referenced to the voltage on the reference terminal
(Pin 5). Resistance in series with the REF pin must be
minimized for best common mode rejection. For example,
a 22Ω resistance from the REF pin to ground will not
only increase the gain error by 0.02% but will lower the
CMRR to 80dB.
The low input bias current of the LT1789-1/LT1789-10
(19nA) and the high input impedance (1.6GΩ) allow the
use of high impedance sources without introducing significant offset voltage errors, even when the full common
mode range is required. However, a path must be provided
for the input bias currents of both inputs when a purely
differential signal is being amplified. Without this path the
inputs will float high and exceed the input common mode
range of the LT1789-1/LT1789-10, resulting in a saturated
input stage. Figure 3 shows three examples of an input bias
current path. The first example is of a purely differential
signal source with a 10kΩ input current path to ground.
Since the impedance of the signal source is low, only one
resistor is needed. Two matching resistors are needed for
higher impedance signal sources as shown in the second
example. Balancing the input impedance improves both
common mode rejection and DC offset. The need for input
resistors is eliminated if a center tap is present as shown
in the third example.
Output Offset Trimming
The LT1789-1/LT1789-10 is laser trimmed for low offset
voltage so that no external offset trimming is required for
most applications. In the event that the offset needs to be
adjusted, the circuit in Figure 2 is an example of an optional
offset adjust circuit. The op amp buffer provides a low
impedance to the REF pin where resistance must be kept
to a minimum for best CMRR and lowest gain error.
–
1
LT1789-1/-10
8
REF
3 +
+IN
5
RG
V+
OUTPUT
6
1
2
+
2
–
–IN
3
100Ω
LT1880
±10mV
ADJUSTMENT RANGE
10mV
10k
100Ω
–10mV
V–
1789 F02
Figure 2. Optional Trimming of Output Offset Voltage
–
THERMOCOUPLE
–
LT1789-1/
LT1789-10
RG
MICROPHONE,
HYDROPHONE,
ETC
10k
LT1789-1/
LT1789-10
RG
+
–
+
200k
LT1789-1/
LT1789-10
RG
+
200k
CENTER-TAP PROVIDES
BIAS CURRENT RETURN
1789 F03
Figure 3. Providing an Input Common Mode Current Path
1789fc
19
LT1789-1/LT1789-10
APPLICATIONS INFORMATION
Output Voltage vs Input Common Mode Voltage
All instrumentation amplifiers have limiting factors that
can cause an output to be invalid (the output is not equal
to the input differential voltage multiplied by the gain)
even though the output appears to be operating in a linear
region. Limiting factors such as input voltage range and
output swing can be easily measured, however, there are
also internal nodes that can limit. These internal nodes
cannot be measured externally and can lead to erroneous
output readings.
To ensure a valid output for a given input common mode
voltage and input differential voltage, the following four
limiting factors must be taken into consideration (refer to
the block diagram):
1) The input voltage ranges of the input amplifiers A1 and
A2.
2) The output swings of the input amplifiers A1 and A2
(internal nodes).
3) The input voltage range of the output amplifier A3
(internal node).
4) The output swing of the output amplifier A3.
These limits can be determined using the relationships
below.
1) The input voltage range limits can be found in the
electrical tables.
2) The output voltages of the input amplifiers A1 and A2
can be found by the following formulas:
VOUT A1 = (VD/2)(G)(R1/R2) + VCM + 0.6V
VOUT A2 = (–VD/2)(G)(R1/R2) + VCM + 0.6V
Where VD is the input differential voltage and VCM is the
input common mode voltage.
The typical output swing limits for A1 and A2 can be found
in the Output Swing vs Load Current typical performance
curve, using R1 + R2 as the load resistance.
The LT1789-10 is less susceptible to this limiting factor
because the gain is taken in the output stage.
3) The voltage on the inputs to the output amplifier A3
can be determined by the following formula:
VIN A3 = (VOUT A1 – VREF)(R2/(R1 + R2))
The input voltage range of A3 has the same input limits as
the LT1789-1. This limiting factor is more prevalent with
single supplies, where both the reference voltage and input
common mode voltage are near V+. This is also more of
a concern with the LT1789-10 because the ratio of R1:R2
is 1:10 instead of 1:1.
4) The output voltage swing limits are also found in the
electrical tables.
The Output Voltage vs Input Common Mode Voltage typical
performance curves show the regions of operation for the
three supply voltages specified.
Single Supply Operation
There are usually two types of input signals that need
to be processed; differential signals, like the output of a
bridge or single ended signals, such as the output from
a thermistor. Both signals require special consideration
when operating with a single supply.
When processing differential signals , REF (Pin 5) must
be brought above the negative supply (Pin 4) to allow the
output to process both the positive and negative going input
signal. The maximum output operating range is obtained
by setting the voltage on the REF pin to half supply. This
must be done with a low impedance source to minimize
CMRR and gain errors.
For single ended input signals, the REF pin can be at the
same potential as the negative supply provided the output
of the instrumentation amplifier remains inside the specified
operating range. This maximizes the output range, however
the smallest input signal that can be processed is limited
by the output swing to the negative supply.
This limitation usually becomes dominant when gain is
taken in the input stage and the common mode input
voltage is close to either supply rail.
1789fc
20
LT1789-1/LT1789-10
TYPICAL APPLICATIONS
Single Supply Positive Integrator
3
VIN
VS
+
7
LT1789-1
REF
1
2
–
VS
R1
6 10k
8
5
3
+
C1
100μF
4
R2
10Ω
+
1
LT1636
2
–
VOUT
4
RESET
1789 TA02
VS = 2.7V TO 32V
TIME CONSTANT = (R1)(C1) = 1 SECOND AS SHOWN
Avalanche Photo Diode Module Bias Current Monitor
APD
HIGH VOLTAGE
BIAS INPUT
FOR OPTIONAL “ZERO CURRENT” FEEDBACK TO
APD BIAS REGULATOR, SEE APPENDIX A, APPLICATION NOTE 92
1k*
1%
1μF
100V
1μF
100V
100k*
100k*
VOUT = 20V TO 90V
TO APD
Q1
1N4690
5.6V
1M*
0.2μF
5V
–
10k
A1
LT1789-1
30k
+
Q2
MPSA42
0.2μF
5V
1μF
6
20k
+
2
S2
5
–
20k*
1M* –3.5V
–3.5V
20k
200k*
12
13
OUTPUT
0V TO 1V =
0mA TO 1mA
A2
LT1006
1μF
14
S1
18
5V
5V
3
15
+
* = 0.1% METAL FILM RESISTOR
1μF 100V = TECATE CMC100105MX1825
# CIRCLED NUMBERS = LTC1043 PIN NUMBER
+
S3
–3.5V TO
AMPLIFIERS
22μF
22μF
= 1N4148
= TP0610L
16
17
4
0.056μF
† FOR MORE INFORMATION REFER TO APPLICATION NOTE 92
5V
1789 TA05
1789fc
21
LT1789-1/LT1789-10
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.050 BSC
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
8
.245
MIN
.160 ±.005
.010 – .020
× 45°
(0.254 – 0.508)
NOTE:
1. DIMENSIONS IN
5
.150 – .157
(3.810 – 3.988)
NOTE 3
1
RECOMMENDED SOLDER PAD LAYOUT
.053 – .069
(1.346 – 1.752)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
6
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
.008 – .010
(0.203 – 0.254)
7
.014 – .019
(0.355 – 0.483)
TYP
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
2
3
4
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
SO8 0303
1789fc
22
LT1789-1/LT1789-10
REVISION HISTORY
(Revision history begins at Rev C)
REV
DATE
DESCRIPTION
PAGE NUMBER
C
5/10
Updated Input Noise Current Density Spec
6
1789fc
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
23
LT1789-1/LT1789-10
TYPICAL APPLICATION
Voltage Controlled Current Source
3V TO 32V
3
VIN
+
7
8
RG
1
2
6
LT1789-1 REF
5
–
R1
1k
4
IL
LOAD
IL = AV • VIN/R1
1789 TA03
AV = 1 + 200k
RG
10°C to 40°C Thermometer
VS+ 4 LT1790 6
–1.25
1 2
29.4k
1%
3
6
LT1789-10
1
2
100k
@ 25°C
7
8
36.5k
0.5%
THERMISTOR
THERMOMETRICS
DC95G104V
VS+
+
5
–
4
866k
1%
56.2k
1%
VOUT = 2.5V AT 25°C + 50mV/°C
OVER 10°C TO 40°C
LINEARITY = 0.3°C
ACCURACY = 1°C WORST CASE
TOLERANCE STACK-UP
VS+ = 4V TO 18V
1789 TA04
RELATED PARTS
PART NUMBER DESCRIPTION
COMMENTS
LTC1100
Precision Chopper-Stabilized Instrumentation Amplifier
Best DC Accuracy
LT1101
Precision, Micropower, Single Supply Instrumentation Amplifier
Fixed Gain of 10 or 100, IS <105μA
LT1102
High Speed, JFET Instrumentation Amplifier
Fixed Gain of 10 or 100, 30V/μs Slew Rate
LT1167
Single Resistor Gain Programmable, Precision Instrumentation Amplifier Gain Error: 0.08% Max, Gain Nonlinearity: 10ppm Max,
60μV Max Input Offset Voltage, 90dB Min CMRR
LT1168
Low Power, Single Resistor Programmable Instrumentation Amplifier
ISUPPLY = 530μA Max
LTC®1418
14-Bit, Low Power, 200ksps ADC with Serial and Parallel I/O
Single Supply 5V or ± 5V Operation, ± 1.5LSB INL and
± 1LSB DNL Max
LT1460
Precision Series Reference
Micropower; 2.5V, 5V, 10V Versions; High Precision
LT1468
16-Bit Accurate Op Amp, Low Noise Fast Settling
16-Bit Accuracy at Low and High Frequencies, 90MHz GBW,
22V/μs, 900ns Settling
LTC1562
Active RC Filter
Lowpass, Bandpass, Highpass Responses; Low Noise,
Low Distortion, Four 2nd Order Filter Sections
LTC1605
16-Bit, 100ksps, Sampling ADC
Single 5V Supply, Bipolar Input Range: ±10V,
Power Dissipation: 55mW Typ
1789fc
24 Linear Technology Corporation
LT 0510 REV C • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
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© LINEAR TECHNOLOGY CORPORATION 2002