LT1789-1/LT1789-10
1
1789fc
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.
The high accuracy of the LT1789-1 (40ppm maximum non-
linearity 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 instrumenta-
tion 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).
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
FEATURES
APPLICATIONS
DESCRIPTION
Micropower,
Single Supply Rail-to-Rail
Output Instrumentation Amplifiers
0.5A to 4A Voltage Controlled Current Source
n Micropower: 95μA Supply Current Max
n Low Input Offset Voltage: 100μV Max
n Low Input Offset Voltage Drift: 0.5μV/°C Max
n Single Gain Set Resistor:
G = 1 to 1000 (LT1789-1)
G = 10 to 1000 (LT1789-10)
n Inputs Common Mode to V–
n Wide Supply Range: 2.2V to 36V Total Supply
n CMRR at G = 10: 96dB Min
n Gain Error: G = 10, 0.25% Max
n Gain Nonlinearity: G = 10, 40ppm Max
n Input Bias Current: 40nA Max
n PSRR at G = 10: 100dB Min
n 1kHz Voltage Noise: 48nV/√Hz
n 0.1Hz to 10Hz Noise: 1.5μVP-P
n Portable Instrumentation
n Bridge Amplifiers
n Strain Gauge Amplifiers
n Thermocouple Amplifiers
n Differential to Single-Ended Converters
n Medical Instrumentation
5
7
VS
4
* ENSURE ADEQUATE POWER
DISSIPATION CAPABILITY AT
HIGHER VOLTAGES,
CURRENTS AND DUTY CYCLES
ILOAD
RLOAD*
1789 TA01
RSENSE*
0.1Ω
TIP127*
6
3
2
R4
10k
C2
3300pF
R3
100Ω
C3
0.1μF
2
1
3
8
C1
4700pF
VIN 7
R2
10k
6
VS
4
5
R1
90.9k
4
3
2
1
–
+
120Ω
8k
VS
VS = 3.3V TO 32V
= 1A PER VOLT AS SHOWN
ILOAD =
RISE TIME ≈ 250μs, 10% TO 90%,
1A TO 2A OUTPUT STEP INTO 0.25Ω LOAD
VIN
RSENSE • 10
LT1636
–
+
REF LT1789-1
LT1789-1/LT1789-10
2
1789fc
PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS
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
(Note 1)
1
2
3
4
8
7
6
5
TOP VIEW
RG
+VS
OUT
REF
RG
–IN
+IN
–VS
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
VS = 3V, 0V; VS = 5V, 0V; RL = 20k, VCM = VREF = half
supply, TA = 25°C, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
G Gain Range LT1789-1, G = 1 + (200k/RG)
LT1789-10, G = 10 • [1+ (200k/RG)] 1 1000 10 1000
Gain Error (Note 6) G = 1, VO = 0.1V to (+VS) – 1V 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)
0.06
0.06
0.13
0.25
0.27 0.01
0.09
0.16
0.25
0.30 %
%
%
Gain Nonlinearity (Note 6) G = 1, VO = 0.1V to (+VS) – 1V 35 100 ppm
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 15
20
100
100
100 ppm
ppm
ppm
LT1789-1/LT1789-10
3
1789fc
3V AND 5V ELECTRICAL CHARACTERISTICS
VS = 3V, 0V; VS = 5V, 0V; RL = 20k, VCM = VREF = half
supply, TA = 25°C, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
VOST Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI Input Offset Voltage G = 1000 15 100 20 160 μV
VOSO 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
IBInput Bias Current (Note 6) 19 40 19 40 nA
enInput Noise Voltage,
RTI (Referred to Input) G = 1, fO = 0.1Hz to 10Hz
G = 10
G = 100, 1000
5.0
1.5
1.0 4.6
1.1
μVP-P
μVP-P
μVP-P
Total RTI Noise = √eni2 + (eno/G)2
eni Input Noise Voltage Density, RTI fO = 1kHz (Note 7) 48 85 52 90 nV/√Hz
eno Output Noise Voltage Density, RTI fO = 1kHz (Note 3) 330 270 nV/√Hz
inInput Noise Current fO = 0.1Hz to 10Hz 16 16 pAP-P
Input Noise Current Density fO = 1kHz 62 62 fA/√Hz
RIN Input Resistance VIN = 0V to (+VS) – 1V (Note 6) 0.75 1.6 0.75 1.6 GΩ
CIN Input Capacitance Differential
Common Mode 1.6
1.6 1.6
1.6 pF
pF
VCM Input Voltage Range 0 +VS – 1 0 +VS – 1.2 V
CMRR Common Mode Rejection Ratio 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
PSRR Power Supply Rejection Ratio 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
ISSupply 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) +VS – 0.3 +VS – 0.19 +VS – 0.3 +VS – 0.19 V
ISC Short-Circuit Current Short to GND
Short to +VS
2.2
8.5 2.2
8.5 mA
mA
BW Bandwidth G = 1
G = 10
G = 100
G = 1000
60
30
3
0.2
25
12
1.5
kHz
kHz
kHz
kHz
SR Slew Rate G = 10, VOUT = 0.5V to 4.5V 0.023 0.062 V/μs
Settling Time to 0.01% 4V Step 240 190 μs
RREFIN Reference Input Resistance 220 220 kΩ
IREFIN Reference Input Current VREF = 0V 2.7 2.7 μA
AVREF Reference Gain to Output 1 ±0.0001 1 ±0.0001
LT1789-1/LT1789-10
4
1789fc
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
Gain Error (Note 6) G = 1, VO = 0.3V to (+VS) – 1V l0.25 %
VO = 0.3V to (+VS) – 0.5V
G = 10 (Note 2)
G = 100 (Note 2)
l
l
0.53
0.55
0.30
0.53
%
%
Gain Nonlinearity (Note 6) G = 1, VO = 0.3V to (+VS) – 1V l185 ppm
LT1789-1, VO = 0.3V to (+VS) – 0.5V
LT1789-10, VO = 0.3V to 4.7V, VS = 5V
(Note 8)
G = 10
G = 100
l
l
90
120
130
130
ppm
ppm
G/T Gain vs Temperature G < 1000 (Notes 2, 3) l5 50 5 50 ppm/°C
VOST Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI Input Offset Voltage G = 1000 l150 190 µV
VOSIH Input Offset Voltage Hysteresis (Notes 3, 5) l3 10 3 10 µV
VOSO Output Offset Voltage G = 1 (LT1789-1), G = 10 (LT1789-10) l950 3700 µV
VOSOH Output Offset Voltage Hysteresis (Notes 3, 5) l50 100 300 900 µV
VOSI/T Input Offset Voltage Drift (RTI) (Note 3) l0.2 0.5 0.3 0.7 µV/°C
VOSO/T Output Offset Voltage Drift (Note 3) l1.5 4 7 20 µV/°C
IOS Input Offset Current (Note 6) l4.5 4.5 nA
IOS/T Input Offset Current Drift l3 3 pA/°C
IBInput Bias Current (Note 6) l45 45 nA
IB/T Input Bias Current Drift l50 50 pA/°C
VCM Input Voltage Range l0.2 (+VS) – 1 0.2 (+VS) – 1.5 V
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
G = 1
G = 10
G = 100, 1000
l
l
l
77
94
98
85
96
dB
dB
dB
PSRR Power Supply Rejection Ratio VS = 2.5V to 12.5V, VCM = VREF = 1V
G = 1
G = 10
G = 100, 1000
l
l
l
88
98
100
92
100
dB
dB
dB
Minimum Supply Voltage l2.5 2.5 V
ISSupply Current (Note 7) l115 115 µA
VOL Output Voltage Swing LOW (Note 7) l110 120 mV
VOH Output Voltage Swing HIGH (Note 7) l+VS – 0.38 +VS – 0.38 V
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/LT1789-10
5
1789fc
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)
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
Gain Error (Note 6) G = 1, VO = 0.3V to (+VS) – 1V l0.30 %
VO = 0.3V to (+VS) – 0.5V
G = 10 (Note 2)
G = 100 (Note 2)
l
l
0.57
0.59
0.35
0.62
%
%
Gain Nonlinearity (Note 6) G = 1, VO = 0.3V to (+VS) – 1V l250 ppm
LT1789-1, VO = 0.3V to (+VS) – 0.5V
LT1789-10, VO = 0.3V to 4.7V, VS = 5V
(Note 8)
G = 10
G = 100
l
l
105
160
150
170
ppm
ppm
G/T Gain vs Temperature G < 1000 (Notes 2, 3) l5 50 5 50 ppm/°C
VOST Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI Input Offset Voltage G = 1000 l175 205 µV
VOSIH Input Offset Voltage Hysteresis (Notes 3, 5) l3 10 3 10 µV
VOSO Output Offset Voltage G = 1 (LT1789-1), G = 10 (LT1789-10) l1050 4000 µV
VOSOH Output Offset Voltage Hysteresis (Notes 3, 5) l50 100 300 900 µV
VOSI/T Input Offset Voltage Drift (RTI) (Note 3) l0.2 0.5 0.3 0.7 µV/°C
VOSO/T Output Offset Voltage Drift (Note 3) l1.5 4 7 20 µV/°C
IOS Input Offset Current (Note 6) l55nA
IOS/T Input Offset Current Drift l3 3 pA/°C
IBInput Bias Current (Note 6) l50 50 nA
IB/T Input Bias Current Drift l50 50 pA/°C
VCM Input Voltage Range l0.2 +VS – 1 0.2 +VS – 1.5 V
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
G = 1
G = 10
G = 100, 1000
l
l
l
75
92
96
84
94
dB
dB
dB
PSRR Power Supply Rejection Ratio VS = 2.5V to 12.5V, VCM = VREF = 1V
G = 1
G = 10
G = 100, 1000
l
l
l
86
96
98
90
98
dB
dB
dB
Minimum Supply Voltage l2.5 2.5 V
ISSupply Current (Note 7) l125 125 µA
VOL Output Voltage Swing LOW (Note 7) l120 130 mV
VOH Output Voltage Swing HIGH (Note 7) l+VS – 0.40 +VS – 0.40 V
LT1789-1/LT1789-10
6
1789fc
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
G Gain Range LT1789-1, G = 1 + (200k/RG)
LT1789-10, G = 10 • [1+ (200k/RG)]
1 1000
10 1000
Gain Error VO = ±10V
G = 1
G = 10 (Note 2)
G = 100 (Note 2)
G = 1000 (Note 2)
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
%
%
%
%
Gain Nonlinearity VO = ±10V
G = 1
G = 10
G = 100
G = 1000
8
1
6
20
20
10
20
100
5
5
25
40
40
160
ppm
ppm
ppm
ppm
VOST 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
IBInput Bias Current 17 40 17 40 nA
enInput Noise Voltage, RTI fO = 0.1Hz to 10Hz
G = 1
G = 10
G = 100, 1000
5.0
1.5
1.0
4.6
1.1
μVP-P
μVP-P
μVP-P
Total RTI Noise = √eni2 + (eno/G)2
eni Input Noise Voltage Density, RTI fO = 1kHz 49 90 53 95 nV/√Hz
eno Output Noise Voltage Density, RTI fO = 1kHz 330 270 nV/√Hz
inInput Noise Current fO = 0.1Hz to 10Hz 19 19 pAP-P
Input Noise Current Density fO = 1kHz 62 62 fA/√Hz
RIN Input Resistance 2 4.7 2 4.7 GΩ
CIN Input Capacitance Differential
Common Mode
20
17
20
17
pF
pF
VCM Input Voltage Range –15 –14 –15 –14 V
CMRR Common Mode Rejection Ratio 1k Source Imbalance, VCM = –15V to 14V
G = 1
G = 10
G = 100, 1000
80
98
102
89
108
117
93
102
108
123
dB
dB
dB
PSRR Power Supply Rejection Ratio LT1789-1 VS = ±1.25V to ±16V
LT1789-10 VS = ±1.50V to ±16V
G = 1
G = 10
G = 100, 1000
94
104
102
107
118
121
100
106
115
123
dB
dB
dB
Minimum Supply Voltage ±1.25 ±1.50 V
ISSupply Current 85 130 85 130 μA
VOOutput Voltage Swing ±14.5 ±14.7 ±14.5 ±14.7 V
ISC Short-Circuit Current Short to –VS
Short to +VS
2.2
8.5
2.2
8.5
mA
mA
ELECTRICAL CHARACTERISTICS
VS = ±15V, RL = 20k, VCM = VOUT = 0V, TA = 25°C, unless otherwise noted.
LT1789-1/LT1789-10
7
1789fc
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
BW Bandwidth G = 1
G = 10
G = 100
G = 1000
60
30
3
0.2
25
12
1.5
kHz
kHz
kHz
kHz
SR Slew Rate VOUT = ±10V 0.012 0.026 0.028 0.066 V/μs
Settling Time to 0.01% 10V Step 460 270 μs
RREFIN Reference Input Resistance 220 220 kΩ
IREFIN Reference Input Current VREF = 0V 2.7 2.7 μA
AVREF Reference Gain to Output 1 ±0.0001 1 ±0.0001
ELECTRICAL CHARACTERISTICS
VS = ±15V, RL = 20k, VCM = VOUT = 0V, TA = 25°C, unless otherwise noted.
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)
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
Gain Error VO = ±10V
G = 1
G = 10 (Note 2)
G = 100 (Note 2)
G = 1000 (Note 2)
l
l
l
l
0.15
0.38
0.38
0.43
0.20
0.43
0.48
%
%
%
%
Gain Nonlinearity VO = ±10V
G = 1
G = 10
G = 100
G = 1000
l
l
l
l
25
15
25
120
45
45
180
ppm
ppm
ppm
ppm
G/T Gain vs Temperature G < 1000 (Notes 2, 3) l5 50 5 50 ppm/°C
VOST Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI Input Offset Voltage G = 1000 l285 325 µV
VOSIH Input Offset Voltage Hysteresis (Notes 3, 5) l8 30 8 30 µV
VOSO Output Offset Voltage G = 1 l1.2 4 mV
VOSOH Output Offset Voltage Hysteresis (Notes 3, 5) l50 120 400 1000 µV
VOSI/T Input Offset Voltage Drift (RTI) (Note 3) l0.2 0.7 0.3 0.8 µV/°C
VOSO/T Output Offset Voltage Drift (Note 3) l1.5 5 8 22 µV/°C
IOS Input Offset Current l4.5 4.5 nA
IOS/T Input Offset Current Drift l2 2 pA/°C
IBInput Bias Current l45 45 nA
IB/T Input Bias Current Drift l35 35 pA/°C
VCM Input Voltage Range G = 1, Other Input Grounded l–14.8 14 –14.8 14 V
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
91
100
dB
dB
dB
LT1789-1/LT1789-10
8
1789fc
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
PSRR Power Supply Rejection Ratio LT1789-1, VS = ±1.25V to ±16V
LT1789-10, VS = ±1.50V to ±16V
G = 1
G = 10
G = 100, 1000
l
l
l
92
102
104
98
104
dB
dB
dB
Minimum Supply Voltage l±1.25 ±1.50 V
ISSupply Current l150 150 µA
VOOutput Voltage Swing l±14.25 ±14.25 V
SR Slew Rate VOUT = ±10V l0.010 0.026 V/µs
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)
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)
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
Gain Error VO = ±10V
G = 1
G = 10 (Note 2)
G = 100 (Note 2)
G = 1000 (Note 2)
l
l
l
l
0.20
0.57
0.57
0.62
0.25
0.62
0.67
%
%
%
%
Gain Nonlinearity VO = ±10V
G = 1
G = 10
G = 100
G = 1000
l
l
l
l
30
20
30
130
50
50
200
ppm
ppm
ppm
ppm
G/T Gain vs Temperature G < 1000 (Notes 2, 3) l5 50 5 50 ppm/°C
VOST Total Input Referred Offset Voltage VOST = VOSI + VOSO/G
VOSI Input Offset Voltage G = 1000 l305 340 µV
VOSIH Input Offset Voltage Hysteresis (Notes 3, 5) l8 30 8 30 µV
VOSO Output Offset Voltage G = 1 l1.3 4.2 mV
VOSOH Output Offset Voltage Hysteresis (Notes 3, 5) l50 120 400 1000 µV
VOSI/T Input Offset Voltage Drift (RTI) (Note 3) l0.2 0.7 0.3 0.8 µV/°C
VOSO/T Output Offset Voltage Drift (Note 3) l1.5 5 8 22 µV/°C
IOS Input Offset Current l55nA
IOS/T Input Offset Current Drift l2 2 pA/°C
IBInput Bias Current l50 50 nA
IB/T Input Bias Current Drift l35 35 pA/°C
VCM Input Voltage Range G = 1, Other Input Grounded l–14.8 14 –14.8 14 V
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
89
98
dB
dB
dB
LT1789-1/LT1789-10
9
1789fc
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.
SYMBOL PARAMETER CONDITIONS
LT1789-1 LT1789-10
UNITSMIN TYP MAX MIN TYP MAX
PSRR Power Supply Rejection Ratio LT1789-1, VS = ±1.25V to ±16V
LT1789-10, VS = ±1.50V to ±16V
G = 1
G = 10
G = 100, 1000
l
l
l
90
100
102
96
102
dB
dB
dB
Minimum Supply Voltage l±1.25 ±1.50 V
ISSupply Current l160 160 µA
VOOutput Voltage Swing l±14.15 ±14.15 V
SR Slew Rate VOUT = ±10V l0.008 0.024 V/µs
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)
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.
TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Supply Voltage
Input Bias Current
vs Temperature
Input Bias Current
vs Common Mode Input Voltage
TOTAL SUPPLY VOLTAGE (V)
0
20
SUPPLY CURRENT (μA)
30
50
60
70
120
90
10 20 25
1789 G01
40
100
110
80
515 30 35 40
125°C
25°C
–55°C
TEMPERATURE (°C)
–50 –25
–25
INPUT BIAS CURRENT (nA)
–15
0
050 75
1789 G02
–20
–5
–10
25 100 125
VS = 5V, 0V
VCM = 2.5V
COMMON MODE INPUT VOLTAGE (V)
0
INPUT BIAS CURRENT (nA)
–18
–14
–10
4.5
1789 G03
–22
–26
–20
–16
–12
–24
–28
–30 1.5 2.5 3.5
10.5–0.5 5
234
VS = 5V, 0V
VREF = 2.5V
–55°C
125°C
25°C
85°C
(LT1789-1, LT1789-10)
LT1789-1/LT1789-10
10
1789fc
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage Swing
vs Load Current Gain vs Frequency Slew Rate vs Temperature
Common Mode Rejection Ratio
vs Frequency
Negative Power Supply Rejection
Ratio vs Frequency
Positive Power Supply Rejection
Ratio vs Frequency
Output Impedance vs Frequency Overshoot vs Capacitive Load
Settling Time to 0.01% vs
Output Step
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE SWING—SOURCING (V)
OUTPUT VOLTAGE SWING—SINKING (V)
4.8
5.0
4.6
4.0
4.4
4.2
0.8
1.0
1.6
1.4
1.2
0.6
0
0.4
0.2
0.001 0.1 1 10
1789 G04
0.01
–55°C
–55°C
25°C
25°C
125°C
125°C
SOURCE
SINK
VS = 5V, 0V
VREF = 2.5V
FREQUENCY (Hz)
100
GAIN (dB)
1k 10k 100k
1789 G05
G = 1000
G = 100
G = 10
80
70
60
50
40
30
20
10
–10
–20
0G = 1
VS = 5V, 0V
VREF = 2.5V
TEMPERATURE (°C)
–50
SLEW RATE (V/μs)
0.045
25
1789 G06
0.030
0.020
–25 0 50
0.015
0.010
0.050
0.040
0.035
0.025
75 100 125
VS = 5V, 0V
VREF = 2.5V
G = 1
RL = 20k
RISING
FALLING
FREQUENCY (Hz)
10010
40
COMMON MODE REJECTION RATIO (dB)
60
80
100
120
50
70
90
110
1k 20k10k
1879 G07
VS = 5V, 0V
VREF = 2.5V
G = 100, 1000
G = 10
G = 1
FREQUENCY (Hz)
10
NEGATIVE POWER SUPPLY REJECTION RATIO (dB)
140
120
100
80
60
40
20
0100 1k 20k10k
1789 G08
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
G = 1000
G = 100
G = 10
G = 1
FREQUENCY (Hz)
10
POSITIVE POWER SUPPLY REJECTION RATIO (dB)
140
120
100
80
60
40
20
0100 1k 20k10k
1789 G09
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
G = 100, 1000
G = 10
G = 1
FREQUENCY (Hz)
10
OUTPUT IMPEDANCE (Ω)
100
1k
10k
1k 10k 100k
1789 G10
1100
VS = 5V, 0V
VREF = 2.5V
CAPACITIVE LOAD (pF)
1
40
OVERSHOOT (%)
50
60
70
80
10 100 1000
1789 G11
30
20
10
0
90
100 VS = 5V, 0V
VREF = 2.5V
VOUT = 100mVP-P
AV = 1
AV = 10
AV ≥ 100
SETTLING TIME (μs)
0
OUTPUT STEP (V)
10
8
6
4
2
0
–2
–4
–6
–8
–10 400
1789 G12
100 200 300 500
VS = ±15V
RL = 20k
G = 1
(LT1789-1)
LT1789-1/LT1789-10
11
1789fc
TYPICAL PERFORMANCE CHARACTERISTICS
Voltage Noise Density vs
Frequency
Current Noise Density vs
Frequency
0.1Hz to 10Hz Noise Voltage,
G = 1
0.1Hz to 10Hz Noise Voltage,
RTI, G = 1000
0.1Hz to 10Hz Noise Current Turn-On Characteristics
FREQUENCY (Hz)
1
10
VOLTAGE NOISE DENSITY (nV/
√Hz
)
100
1000
10 100 1k
1789 G13
G = 100, 1000
G = 10
G = 1
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
FREQUENCY (Hz)
1
10
CURRENT NOISE DENSITY (fA/√Hz)
100
1000
10 100 1k
1789 G14
VS = 5V, 0V
VREF = 2.5V
LT1789-1
RS
TIME (SEC)
0
NOISE VOLTAGE (2μV/DIV)
4
1789 G15
1231098765
VS = 5V, 0V
VREF = 2.5V
TIME (SEC)
0
NOISE VOLTAGE (0.5μV/DIV)
4
1789 G16
1231098765
VS = 5V, 0V
VREF = 2.5V
TIME (SEC)
0
NOISE CURRENT (5pA/DIV)
4
1789 G17
1231098765
VS = 5V, 0V
VREF = 2.5V
TIME (ms)
0
CHANGE IN OUTPUT VOLTAGE (V)
40
1789 G18
10 20 30
1.5
0.5
–0.5
–1.5
VS = 5V, 0V
VREF = 2.5V
VCM = 2.5V
G = 1000
TA = 25°C
(LT1789-1)
LT1789-1/LT1789-10
12
1789fc
TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage Swing
vs Load Current Gain vs Frequency Slew Rate vs Temperature
Common Mode Rejection Ratio
vs Frequency
Negative Power Supply Rejection
Ratio vs Frequency
Positive Power Supply Rejection
Ratio vs Frequency
Output Impedance vs Frequency Overshoot vs Capacitive Load
Settling Time to 0.01% vs
Output Step
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE SWING—SOURCING (V)
OUTPUT VOLTAGE SWING—SINKING (V)
4.8
5.0
4.6
4.0
4.4
4.2
0.8
1.0
1.6
1.4
1.2
0.6
0
0.4
0.2
0.001 0.1 1 10
1789 G21
0.01
–55°C
–55°C
25°C
25°C
125°C
125°C
SOURCE
SINK
VS = 5V, 0V
VREF = 2.5V
FREQUENCY (Hz)
100
GAIN (dB)
80
70
60
50
40
30
20
10
0
–10
–20 1k 10k 100k
1789 G22
G = 100
G = 10
G = 1000
VS = 5V, 0V
VREF = 2.5V
TEMPERATURE (°C)
–50
SLEW RATE (V/μs)
100
1789 G23
050
0.12
0.11
0.10
0.09
0.08
0.07
0.06
0.05
0.04 –25 25 75 125
RISING
FALLING
FREQUENCY (Hz)
10
COMMON MODE REJECTION RATIO (dB)
120
110
100
90
80
70
60
50
40 100 1k 10k 20k
1789 G24
G = 10
G = 100, 1000 VS = 5V, 0V
VREF = 2.5V
FREQUENCY (Hz)
10
NEGATIVE POWER SUPPLY REJECTION RATIO (dB)
140
120
100
80
60
40
20
0100 1k 10k 20
k
1789 G25
G = 100
G = 10
G = 1000
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
FREQUENCY (Hz)
10
POSITIVE POWER SUPPLY REJECTION RATIO (dB)
140
120
100
80
60
40
20
0100 1k 10k 20k
1789 G26
G = 10
G = 100, 1000
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
FREQUENCY (Hz)
10
OUTPUT IMPEDANCE (Ω)
100
1k
10k
1k 10k 100k
1789 G27
1100
VS = 5V, 0V
VREF = 2.5V
CAPACITIVE LOAD (pF)
40
30
50
60
70
80
10 100 1000
1789 G28
20
10
0
90
100
OVERSHOOT (%)
VS = 5V, 0V
VREF = 2.5V
VOUT = 100mVP-P
G = 10
G = 100
G = 1000
(LT1789-10)
SETTLING TIME (μs)
0
OUTPUT STEP (V)
10
8
6
4
2
0
–2
–4
–6
–8
–10 400
1789 G29
100 200 300 500
VS = ±15V
RL = 20k
G = 10
LT1789-1/LT1789-10
13
1789fc
TYPICAL PERFORMANCE CHARACTERISTICS
Voltage Noise Density vs
Frequency
Current Noise Density vs
Frequency
0.1Hz to 10Hz Noise Voltage,
RTI, G = 10
0.1Hz to 10Hz Noise Voltage,
RTI, G = 1000
0.1Hz to 10Hz Noise Current Turn-On Characteristics
FREQUENCY (Hz)
1
10
VOLTAGE NOISE DENSITY (nV/
√Hz
)
100
1000
10 100 1k
1789 G30
G = 1000
G = 10
G = 100
VS = 5V, 0V
VREF = 2.5V
INPUT REFERRED
FREQUENCY (Hz)
1
10
CURRENT NOISE DENSITY (fA/√Hz)
100
1000
10 100 1k
1789 G31
VS = 5V, 0V
VREF = 2.5V
LT1789-10
RS
TIME (SEC)
0
NOISE VOLTAGE (2μV/DIV)
4
1789 G32
1231098765
VS = 5V, 0V
VREF = 2.5V
TIME (SEC)
0
NOISE VOLTAGE (0.5μV/DIV)
4
1789 G33
1231098765
VS = 5V, 0V
VREF = 2.5V
TIME (SEC)
0
NOISE CURRENT (5pA/DIV)
4
1789 G34
1231098765
VS = 5V, 0V
VREF = 2.5V
TIME (ms)
0
CHANGE IN OUTPUT VOLTAGE (V)
40
1789 G59
10 20 30
1.5
0.5
–0.5
–1.5
VS = 5V, 0V
VREF = 2.5V
VCM = 2.5V
G = 1000
TA = 25°C
(LT1789-10)
LT1789-1/LT1789-10
14
1789fc
(LT1789-1)
TYPICAL PERFORMANCE CHARACTERISTICS
Large-Signal Transient Response
G = 1, 10, 100
Large-Signal Transient Response
G = 1000
Small-Signal Transient Response
G = 1
Small-Signal Transient Response
G = 10
Small-Signal Transient Response
G = 100
Small-Signal Transient Response
G = 1000
1789 G38
500μs/DIV
5V/DIV
VS = ±15V
RL = 20k
CL = 50pF
1789 G39
2ms/DIV
5V/DIV
VS = ±15V
RL = 20k
CL = 50pF
1789 G40
100μs/DIV
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
1789 G41
100μs/DIV
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
1789 G42
200μs/DIV
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
1789 G43
2ms/DIV
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
LT1789-1/LT1789-10
15
1789fc
TYPICAL PERFORMANCE CHARACTERISTICS
Small-Signal Transient Response
G = 100
Small-Signal Transient Response
G = 1000
(LT1789-10)
Large-Signal Transient Response
G = 10, 100
Large-Signal Transient Response
G = 1000
Small-Signal Transient Response
G = 10
1789 G44
500μs/DIV
5V/DIV
VS = ±15V
RL = 20k
CL = 50pF
1789 G45
500μs/DIV
5V/DIV
VS = ±15V
RL = 20k
CL = 50pF
1789 G46
100μs/DIV
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
1789 G47
200μs/DIV
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
1789 G48
2ms/DIV
20mV/DIV
VS = 5V, 0V
VREF = 2.5V
RL = 20k
CL = 50pF
LT1789-1/LT1789-10
16
1789fc
G = 1
INPUT COMMON MODE VOLTAGE (V)
–15
VALID OUTPUT VOLTAGE (V)
15
10
5
0
–5
–10
–15 –10 –5 0 5 10 15
G = 1
G ≥ 2
G = 1
TA = 25°C
INPUT COMMON MODE VOLTAGE (V)
–2.5 2.5
VALID OUTPUT VOLTAGE (V)
INPUT COMMON MODE VOLTAGE (V)
VALID OUTPUT VOLTAGE (V)
INPUT COMMON MODE VOLTAGE (V)
VALID OUTPUT VOLTAGE (V)
3.0
2.5
2.0
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5 –1.5 1.5
–0.5 0.5
AV = 1
TA = 25°C
AV = 2
AV = 10 AV = 1
INPUT COMMON MODE VOLTAGE (V)
–1.5
VALID OUTPUT VOLTAGE (V)
1.5
1.0
0.5
0
–0.5
–1.0
–1.5 –1.0 –0.5 0 0.5 1.0 1.5
TA = 25°C
AV = 2
AV = 10
–
+
LT1789-1
VD/2
VD/2
VCM
15V
–15V
20K
VOUT
REF –
+
LT1789-1
VD/2
VD/2
VCM
2.5V
–2.5V
20K
VOUT
REF –
+
LT1789-1
VD/2
VD/2
VCM
1.5V
–1.5V
20K
VOUT
REF
0
5
4
3
2
1
04
12350 0.5 1.5 2.5
3
2
1
01.0 2.0 3.0
G = 2
G = 10
G = 2
G = 10
1789 G49 1789 G50 1789 G51
–
+
LT1789-1
VD/2
VD/2
VCM
3V
20K
VOUT
REF
–
+
LT1789-1
VD/2
VD/2
VCM
5V
20K
VOUT
REF
1789 G52 1789 G53
V+
V–
V+
V–
V+
V–
V+
V–
V+
V–
TA = 25°C
TA = 25°C
(LT1789-1)
TYPICAL PERFORMANCE CHARACTERISTICS
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±15V
Valid Output Voltage vs Input
Common Mode Voltage
VS = 5V
Valid Output Voltage vs Input
Common Mode Voltage
VS = 3V
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±2.5V
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±1.5V
LT1789-1/LT1789-10
17
1789fc
TYPICAL PERFORMANCE CHARACTERISTICS
(LT1789-10)
INPUT COMMON MODE VOLTAGE (V)
–15
VALID OUTPUT VOLTAGE (V)
15
10
5
0
–5
–10
–15 –10 –5 0 05 10 15
TA = 25°C
INPUT COMMON MODE VOLTAGE (V)
–2.5 2.5
VALID OUTPUT VOLTAGE (V)
INPUT COMMON MODE VOLTAGE (V)
VALID OUTPUT VOLTAGE (V)
INPUT COMMON MODE VOLTAGE (V)
VALID OUTPUT VOLTAGE (V)
2.5
2.0
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
–2.5 –1.5 1.5
–0.5 0.5
INPUT COMMON MODE VOLTAGE (V)
–1.5
VALID OUTPUT VOLTAGE (V)
1.5
1.0
0.5
0
–0.5
–1.0
–1.5 –1.0 –0.5 0 0.5 1.0 1.5
0
5
4
3
2
1
04
12350 0.5 1.5 2.5
3
2
1
01.0 2.0 3.0
G = 10
1789 G54 1789 G55 1789 G56
1789 G57 1789 G58
AV = 10
AV = 100
AV = 10
G = 10
G = 100
G = 10
G = 100 G = 100
TA = 25°C TA = 25°C
TA = 25°C
TA = 25°C
AV = 100
–
+
LT1789-10
VD/2
VD/2
VCM
15V
–15V
20K
VOUT
REF
–
+
LT1789-10
VD/2
VD/2
VCM
2.5V
–2.5V
20K
VOUT
REF
–
+
LT1789-10
VD/2
VD/2
VCM
1.5V
–1.5V
20K
VOUT
REF
–
+
LT1789-10
VD/2
VD/2
VCM
3V
20K
VOUT
REF
–
+
LT1789-10
VD/2
VD/2
VCM
5V
20K
VOUT
REF
V+
V–
V+
V–
V+
V–
V+
V–
V+
V–
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±15V
Valid Output Voltage vs Input
Common Mode Voltage
VS = 5V
Valid Output Voltage vs Input
Common Mode Voltage
VS = 3V
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±2.5V
Valid Output Voltage vs Input
Common Mode Voltage
VS = ±1.5V
LT1789-1/LT1789-10
18
1789fc
BLOCK DIAGRAM
Figure 1. Block Diagram
Setting the Gain
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:
G = 1+ 200k/RG
and RG can be calculated from the desired gain by
R
G = 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
R
G = 200k/(0.1 • G – 1)
For the lowest achievable gain, RG may be set to infinity
by leaving Pins 1 and 8 open.
Input and Output Offset Voltage
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:
Total input offset voltage (RTI)
= input offset + (output offset/G)
Total output offset voltage (RTO)
= (input offset • G) + output offset
–
+
3
1
A1
V–
V–
+IN
RG
V+
V+
V–
V+
V+
5.7k
100k
R1
110k/10k*
VB
–
+
2
8
A2
V–
V–
V–
1789 F01
–IN
RG
V+
V+
5.7k
100k
R3
110k/10k*
R2
110k/100k*
R4
110k/100k*
VB
6OUT
7V+
4V–
5REF
–
+
A3
*LT1789-1/LT1789-10
APPLICATIONS INFORMATION
LT1789-1/LT1789-10
19
1789fc
APPLICATIONS INFORMATION
Figure 2. Optional Trimming of Output Offset Voltage
–
+
10k
100Ω
100Ω
–10mV
1789 F02
V–
V+
10mV
5
6
OUTPUT
2
3
1LT1880
±10mV
ADJUSTMENT RANGE
–
+
2
–IN
+IN
1
8
3
RG
REF
LT1789-1/-10
Reference Terminal
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.
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.
Input Bias Current Return Path
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 sig-
nificant 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.
Figure 3. Providing an Input Common Mode Current Path
10k
RGRGRG
1789 F03
THERMOCOUPLE
200k
MICROPHONE,
HYDROPHONE,
ETC
200k
CENTER-TAP PROVIDES
BIAS CURRENT RETURN
–
+
LT1789-1/
LT1789-10
–
+
LT1789-1/
LT1789-10
–
+
LT1789-1/
LT1789-10
LT1789-1/LT1789-10
20
1789fc
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:
V
OUT A1 = (VD/2)(G)(R1/R2) + VCM + 0.6V
V
OUT 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.
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.
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:
V
IN 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.
LT1789-1/LT1789-10
21
1789fc
TYPICAL APPLICATIONS
Avalanche Photo Diode Module Bias Current Monitor
OUTPUT
0V TO 1V =
0mA TO 1mA
5V
+
–
5V
A1
LT1789-1
–3.5V
0.2μF
S1
0.2μF
VOUT = 20V TO 90V
TO APD
FOR OPTIONAL “ZERO CURRENT” FEEDBACK TO
APD BIAS REGULATOR, SEE APPENDIX A, APPLICATION NOTE 92
APD
HIGH VOLTAGE
BIAS INPUT
1789 TA05
1k*
1%
100k*
–
+
5V
A2
LT1006
–3.5V
100k*
Q1
1M*
1M*
Q2
MPSA42
5V
S3
S2
20k
15
16 17 4
3
18
5
2
6
12
13 14
22μF
22μF
–3.5V TO
AMPLIFIERS
0.056μF
5V
20k*
20k
200k*
1μF
1μF
1μF
100V
1μF
100V
30k
10k
1N4690
5.6V
#
= 1N4148
= 0.1% METAL FILM RESISTOR
= TECATE CMC100105MX1825
= LTC1043 PIN NUMBER
= TP0610L
*
1μF 100V
CIRCLED NUMBERS
+
+
† FOR MORE INFORMATION REFER TO APPLICATION NOTE 92
Single Supply Positive Integrator
+
3
VIN
VOUT
8
1
2
3
2
4
5
6
R1
10k
C1
100μF
R2
10Ω
RESET
1789 TA02
VS = 2.7V TO 32V
TIME CONSTANT = (R1)(C1) = 1 SECOND AS SHOWN
7
VS
–
+1
4
VS
LT1636
–
+
LT1789-1
REF
LT1789-1/LT1789-10
22
1789fc
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)× 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 0303
.053 – .069
(1.346 – 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160 ±.005
RECOMMENDED SOLDER PAD LAYOUT
.045 ±.005
.050 BSC
.030 ±.005
TYP
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
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)
LT1789-1/LT1789-10
23
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
REVISION HISTORY
REV DATE DESCRIPTION PAGE NUMBER
C 5/10 Updated Input Noise Current Density Spec 6
(Revision history begins at Rev C)
LT1789-1/LT1789-10
24
1789fc
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2002
LT 0510 REV C • PRINTED IN USA
RELATED PARTS
TYPICAL APPLICATION
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
Voltage Controlled Current Source
10°C to 40°C Thermometer
IL
R1
1k
LOAD
1789 TA03
6
3V TO 32V
RG
IL = AV • VIN/R1
AV = 1 + 200k
RG
3
VIN 8
1
24
5
7
–
+
LT1789-1 REF
3
8
1
1
2
2
4
46
5
6
7
VS+
VS+
–
+
LT1789-10
36.5k
0.5%
866k
1%
56.2k
1%
100k
@ 25°C
THERMISTOR
THERMOMETRICS
DC95G104V
LT1790
–1.25
1789 TA04
29.4k
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
