LT1920
Single Resistor Gain
Programmable, Precision
Instrumentation Amplifier
FEATURES
s
s
s
s
s
s
s
s
s
s
s
s
s
s
DESCRIPTIO
Single Gain Set Resistor: G = 1 to 10,000
Gain Error: G = 10, 0.3% Max
Gain Nonlinearity: G = 10, 30ppm Max
Input Offset Voltage: G = 10, 225µV Max
Input Offset Voltage Drift: 1
µ
V/
°
C Max
Input Bias Current: 2nA Max
PSRR at G = 1: 80dB Min
CMRR at G = 1: 75dB Min
Supply Current: 1.3mA Max
Wide Supply Range:
±
2.3V to
±18V
1kHz Voltage Noise: 7.5nV/√Hz
0.1Hz to 10Hz Noise: 0.28µV
P-P
Available in 8-Pin PDIP and SO Packages
Meets IEC 1000-4-2 Level 4 ESD Tests with
Two External 5k Resistors
APPLICATIO S
s
s
s
s
s
Bridge Amplifiers
Strain Gauge Amplifiers
Thermocouple Amplifiers
Differential to Single-Ended Converters
Medical Instrumentation
The LT
®
1920 is a low power, precision instrumentation
amplifier that requires only one external resistor to set gains
of 1 to 10,000. The low voltage noise of 7.5nV/√Hz (at 1kHz)
is not compromised by low power dissipation (0.9mA typical
for
±2.3V
to
±15V
supplies).
The high accuracy of 30ppm maximum nonlinearity and
0.3% max gain error (G = 10) is not degraded even for load
resistors as low as 2k (previous monolithic instrumentation
amps used 10k for their nonlinearity specifications). The
LT1920 is laser trimmed for very low input offset voltage
(125µV max), drift (1µV/°C), high CMRR (75dB, G = 1) and
PSRR (80dB, G = 1). Low input bias currents of 2nA max are
achieved with the use of superbeta processing. The output
can handle capacitive loads up to 1000pF in any gain configu-
ration while the inputs are ESD protected up to 13kV (human
body). The LT1920 with two external 5k resistors passes the
IEC 1000-4-2 level 4 specification.
The LT1920, offered in 8-pin PDIP and SO packages, is a pin
for pin and spec for spec improved replacement for the
AD620. The LT1920 is the most cost effective solution for
precision instrumentation amplifier applications. For even
better guaranteed performance, see the LT1167.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
V
S
R5
392k
1
LT1634CCZ-1.25
2
2
Single Supply Barometer
Gain Nonlinearity
–
–
5k
R6
1k
5k
R1
825Ω
2
6
R4
50k
R3
50k
6
R8
100k
R
SET
5
5k
5k
R2
12Ω
8
3
LT1920
G = 60
5
4
TO
4-DIGIT
DVM
6
1
2
1
+
–
1/2
LT1490
4
1
4
7
+
1/2
LT1490
7
R7
50k
5
–
V
S
= 8V TO 30V
+
+
3
NONLINEARITY (100ppm/DIV)
OUTPUT VOLTAGE (2V/DIV)
G = 1000
R
L
= 1k
V
OUT
=
±10V
3
8
LUCAS NOVA SENOR
NPC-1220-015-A-3L
V
S
VOLTS
2.800
3.000
3.200
INCHES Hg
28.00
30.00
32.00
1920 TA01
U
1167 TA02
U
U
1
LT1920
ABSOLUTE
MAXIMUM
RATINGS
(Note 1)
PACKAGE/ORDER INFORMATION
TOP VIEW
R
G
1
–IN 2
+IN 3
–V
S
4
N8 PACKAGE
8-LEAD PDIP
S8 PACKAGE
8-LEAD PLASTIC SO
T
JMAX
= 150°C,
θ
JA
= 130°C/ W (N8)
T
JMAX
= 150°C,
θ
JA
= 190°C/ W (S8)
–
+
8
7
6
5
R
G
+V
S
OUTPUT
REF
Supply Voltage ......................................................
±20V
Differential Input Voltage (Within the
Supply Voltage) .....................................................
±40V
Input Voltage (Equal to Supply Voltage) ................
±20V
Input Current (Note 3) ........................................
±20mA
Output Short-Circuit Duration .......................... Indefinite
Operating Temperature Range ................ – 40°C to 85°C
Specified Temperature Range
LT1920C (Note 4) .................................... 0°C to 70°C
LT1920I .............................................. – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LT1920CN8
LT1920CS8
LT1920IN8
LT1920IS8
S8 PART MARKING
1920
1920I
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
SYMBOL
G
PARAMETER
Gain Range
Gain Error
V
S
=
±15V,
V
CM
= 0V, T
A
= 25°C, R
L
= 2k, unless otherwise noted.
MIN
1
0.008
0.010
0.025
0.040
q
CONDITIONS (Note 6)
G = 1 + (49.4k/R
G
)
G=1
G = 10 (Note 2)
G = 100 (Note 2)
G = 1000 (Note 2)
G < 1000 (Note 2)
V
O
=
±10V,
G = 1
V
O
=
±10V,
G = 10 and 100
V
O
=
±10V,
G = 100 and 1000
V
OST
= V
OSI
+ V
OSO
/G
G = 1000, V
S
=
±5V
to
±15V
G = 1000, V
S
=
±5V
to
±15V
(Note 3)
G = 1, V
S
=
±5V
to
±15V
G = 1, V
S
=
±5V
to
±15V
(Note 3)
TYP
MAX
10k
0.1
0.3
0.3
0.35
50
30
UNITS
%
%
%
%
ppm/°C
ppm
ppm
ppm
µV
µV
µV/°C
µV
µV
µV/°C
nA
nA
µV
P-P
µV
P-P
µV
P-P
nV/√Hz
nV/√Hz
pA
P-P
fA/√Hz
GΩ
pF
G/T
Gain vs Temperature
Gain Nonlinearity (Note 5)
20
10
10
20
30
V
OST
V
OSI
V
OSI
/T
V
OSO
V
OSO
/T
I
OS
I
B
e
n
Total Input Referred Offset Voltage
Input Offset Voltage
Input Offset Drift (RTI)
Output Offset Voltage
Output Offset Drift
Input Offset Current
Input Bias Current
Input Noise Voltage, RTI
q
q
125
185
1
1000
1500
15
1
2
400
q
q
5
0.3
0.5
0.1Hz to 10Hz, G = 1
0.1Hz to 10Hz, G = 10
0.1Hz to 10Hz, G = 100 and 1000
f
O
= 1kHz
f
O
= 1kHz
f
O
= 0.1Hz to 10Hz
f
O
= 10Hz
V
IN
=
±10V
f
O
= 100kHz
2.00
0.50
0.28
7.5
67
10
124
200
1.6
Total RTI Noise =
√
e
ni 2
+ (e
no
/G)
2
e
ni
e
no
i
n
R
IN
C
IN(DIFF)
Input Noise Voltage Density, RTI
Output Noise Voltage Density, RTI
Input Noise Current
Input Noise Current Density
Input Resistance
Differential Input Capacitance
2
U
W
U
U
W W
W
LT1920
ELECTRICAL CHARACTERISTICS
SYMBOL
C
IN(CM)
V
CM
PARAMETER
Common Mode Input Capacitance
Input Voltage Range
f
O
= 100kHz
G = 1, Other Input Grounded
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
1k Source Imbalance,
V
CM
= 0V to
±10V
G=1
G = 10
G = 100
G = 1000
V
S
=
±2.3
to
±18V
G=1
G = 10
G = 100
G = 1000
V
S
=
±2.3V
to
±18V
R
L
= 10k
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
V
S
=
±2.3V
to
±5V
V
S
=
±5V
to
±18V
G=1
G = 10
G = 100
G = 1000
G = 1, V
OUT
=
±10V
10V Step
G = 1 to 100
G = 1000
V
REF
= 0V
– V
S
+ 1.6
1
±
0.0001
Note 5:
This parameter is measured in a high speed automatic tester that
does not measure the thermal effects with longer time constants. The
magnitude of these thermal effects are dependent on the package used,
heat sinking and air flow conditions.
Note 6:
Typical parameters are defined as the 60% of the yield parameter
distribution.
–V
S
+ 1.1
–V
S
+ 1.2
–V
S
+ 1.4
–V
S
+ 1.6
20
27
1000
800
120
12
1.2
14
130
20
50
+V
S
– 1.6
–V
S
+ 1.9
–V
S
+ 1.9
–V
S
+ 2.1
–V
S
+ 2.1
V
S
=
±15V,
V
CM
= 0V, T
A
= 25°C, R
L
= 2k, unless otherwise noted.
MIN
TYP
1.6
+V
S
– 1.2
+V
S
– 1.4
+V
S
– 1.3
+V
S
– 1.4
MAX
UNITS
pF
V
V
V
V
CONDITIONS (Note 6)
q
q
CMRR
Common Mode Rejection Ratio
75
95
110
110
80
100
120
120
95
115
125
140
120
135
140
150
0.9
1.3
+V
S
– 1.2
+V
S
– 1.3
+V
S
– 1.3
+V
S
– 1.5
dB
dB
dB
dB
dB
dB
dB
dB
mA
V
V
V
V
mA
kHz
kHz
kHz
kHz
V/µs
µs
µs
kΩ
µA
V
PSRR
Power Supply Rejection Ratio
I
S
V
OUT
Supply Current
Output Voltage Swing
q
q
I
OUT
BW
Output Current
Bandwidth
SR
Slew Rate
Settling Time to 0.01%
R
REFIN
I
REFIN
V
REF
A
VREF
Reference Input Resistance
Reference Input Current
Reference Voltage Range
Reference Gain to Output
The
q
denotes specifications that apply over the full specified
temperature range.
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Does not include the effect of the external gain resistor R
G
.
Note 3:
This parameter is not 100% tested.
Note 4:
The LT1920C is designed, characterized and expected to meet the
industrial temperature limits, but is not tested at – 40°C and 85°C. I-grade
parts are guaranteed.
3
LT1920
TYPICAL PERFOR A CE CHARACTERISTICS
Gain Nonlinearity, G = 1
NONLINEARITY (10ppm/DIV)
NONLINEARITY (1ppm/DIV)
NONLINEARITY (10ppm/DIV)
G=1
OUTPUT VOLTAGE (2V/DIV)
R
L
= 2k
V
OUT
=
±10V
Gain Nonlinearity, G = 1000
0.20
NONLINEARITY (100ppm/DIV)
0.15
0.10
GAIN ERROR (%)
0.05
CHANGE IN OFFSET VOLTAGE (µV)
G = 1000 OUTPUT VOLTAGE (2V/DIV)
R
L
= 2k
V
OUT
=
±10V
Input Bias Current
vs Common Mode Input Voltage
500
400
INPUT BIAS CURRENT (pA)
300
200
100
0
–100
– 200
– 300
– 400
– 500
–15 –12 – 9 – 6 – 3 0 3 6 9 12 15
COMMON MODE INPUT VOLTAGE (V)
1920 G13
160
COMMON MODE REJECTION RATIO (dB)
140
120
100
80
60
40
20
0
0.1
1
10
1k
100
FREQUENCY (Hz)
G = 1000
G = 100
G = 10
G=1
NEGATIVE POWER SUPPLY REJECTION RATIO (dB)
85°C
0°C
– 40°C
70°C
25°C
4
U W
1167 G01
1167 G04
Gain Nonlinearity, G = 10
Gain Nonlinearity, G = 100
OUTPUT VOLTAGE (2V/DIV)
G = 10
R
L
= 2k
V
OUT
=
±
10V
1167 G02
G = 100 OUTPUT VOLTAGE (2V/DIV)
R
L
= 2k
V
OUT
=
±10V
1167 G03
Gain Error vs Temperature
14
12
10
8
Warm-Up Drift
V
S
=
±
15V
T
A
= 25°C
G=1
S8
G=1
0
– 0.05
– 0.10
– 0.15
V
S
=
±15V
G = 10*
V
OUT
=
±10V
R
L
= 2k
G = 100*
*DOES NOT INCLUDE
G = 1000*
TEMPERATURE EFFECTS
OF R
G
– 25
0
25
50
TEMPERATURE (°C)
75
100
1920
G06
N8
6
4
2
0
0
3
4
TIME AFTER POWER ON (MINUTES)
1
2
5
– 0.20
– 50
1920
G09
Common Mode Rejection Ratio
vs Frequency
V
S
=
±15V
T
A
= 25°C
1k SOURCE
IMBALANCE
160
140
120
100
80
60
40
20
Negative Power Supply Rejection
Ratio vs Frequency
G = 100
G = 10
G=1
G = 1000
V
+
= 15V
T
A
= 25°C
10k
100k
1920 G14
0
0.1
1
10
1k
100
FREQUENCY (Hz)
10k
100k
1920 G15
LT1920
TYPICAL PERFOR A CE CHARACTERISTICS
Positive Power Supply Rejection
Ratio vs Frequency
POSITIVE POWER SUPPLY REJECTION RATIO (dB)
160
140
120
100
80
60
40
20
0
0.1
1
10
1k
100
FREQUENCY (Hz)
10k
100k
1920 G16
V
–
= – 15V
T
A
= 25°C
G = 10
G = 100
G=1
GAIN (dB)
G = 1000
SUPPLY CURRENT (mA)
Voltage Noise Density
vs Frequency
1000
VOLTAGE NOISE DENSITY (nV√Hz)
V
S
=
±15V
T
A
= 25°C
1/f
CORNER
= 10Hz
GAIN = 1
1/f
CORNER
= 9Hz
GAIN = 10
10
1/f
CORNER
= 7Hz
GAIN = 100, 1000
NOISE VOLTAGE (2µV/DIV)
100
BW LIMIT
GAIN = 1000
0
1
10
100
1k
FREQUENCY (Hz)
10k
100k
1920
G19
NOISE VOLTAGE (0.2µV/DIV)
Current Noise Density
vs Frequency
1000
CURRENT NOISE DENSITY (fA/√Hz)
V
S
=
±15V
T
A
= 25°C
CURRENT NOISE (5pA/DIV)
OUTPUT CURRENT (mA)
(SINK)
(SOURCE)
100
R
S
10
1
10
100
FREQUENCY (Hz)
1000
1920
G22
U W
Gain vs Frequency
60
50
40
30
20
10
0
–10
G=1
V
S
=
±
15V
T
A
= 25°C
0.1
1
10
FREQUENCY (kHz)
100
1000
1920 G17
Supply Current vs Supply Voltage
1.50
G = 1000
G = 100
1.25
85°C
1.00
25°C
– 40°C
0.75
G = 10
– 20
0.01
0.50
0
10
15
5
SUPPLY VOLTAGE (± V)
20
1920 G18
0.1Hz to 10Hz Noise Voltage,
G=1
V
S
=
±15V
T
A
= 25°C
0.1Hz to 10Hz Noise Voltage, RTI
G = 1000
V
S
=
±15V
T
A
= 25°C
0
1
2
3
4 5 6
TIME (SEC)
7
8
9
10
0
1
2
3
4 5 6
TIME (SEC)
7
8
9
10
1920 G20
1920 G21
0.1Hz to 10Hz Current Noise
V
S
=
±15V
T
A
= 25°C
50
40
30
20
10
0
– 10
– 20
– 30
– 40
– 50
0
1
2
3
4 5 6
TIME (SEC)
7
8
9
10
Short-Circuit Current vs Time
V
S
=
±15V
T
A
= – 40°C
T
A
= 25°C
T
A
= 85°C
T
A
= 85°C
T
A
= – 40°C
T
A
= 25°C
2
1
0
3
TIME FROM OUTPUT SHORT TO GROUND (MINUTES)
1920 G24
1920 G23
5
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