Datasheet

13
LT1078/LT1079
10789fe
TYPICAL APPLICATIONS
U
Micropower, 10ppm/°C, ±5V Reference Gain of 10 Difference Amplifier
–
+
+
–
2M
220k
120k
3
2
1
8
4
1/2 LT1078
9V
5.000V
OUT
1M
6
5
7
LT1034BC-1.2
510k
1M
–5.000V
OUT
–9V
510k
1%
20k
160k
1%
1/2 LT1078
SUPPLY CURRENT = 9V BATTERY = 115µA
–9V BATTERY = 85µA
OUTPUT NOISE = 36µV
P-P
, 0.1Hz TO 10Hz
THE LT1078 CONTRIBUTES LESS THAN 3% OF THE TOTAL OUTPUT NOISE AND
DRIFT WITH TIME AND TEMPERATURE. THE ACCURACY OF THE –5V OUTPUT
DEPENDS ON THE MATCHING OF THE TWO 1M RESISTORS
LT1078/79 • TA03
+
–
1M
1M
10M
OUTPUT
0.0035V TO 2.4V
1/2 LT1078
BANDWIDTH= 20kHz
OUTPUT OFFSET= 0.7mV
OUTPUT NOISE= 80µV
P-P
(0.1Hz TO 10Hz)
260µV
RMS
OVER FULL
BANDWIDTH
THE USEFULNESS OF DIFFERENCE AMPLIFIERS IS LIMITED BY
THE FACT THAT THE INPUT RESISTANCE IS EQUAL TO THE SOURCE
RESISTANCE. THE PICOAMPERE OFFSET CURRENT AND LOW
CURRENT NOISE OF THE LT1078 ALLOWS THE USE OF 1M SOURCE
RESISTORS WITHOUT DEGRADATION IN PERFORMANCE. IN ADDITION,
WITH MEGOHM RESISTORS MICROPOWER OPERATION CAN BE MAINTAINED
LT1078/79 • TA04
–IN
+IN
10M
3V
Picoampere Input Current, Triple Op Amp Instrumentation Amplifier with Bias Current Cancellation
+
–
9
10
8
1/4 LT1079
–
+
+
–
–
+
R2
1M
R2
1M
1/4 LT1079
1/4 LT1079
1/4 LT1079
3
2
1
R1
1M
R1
1M
R
G
200k
6
5
7
12
13
14
R3
9.1M
R3
9.1M
9V
4
11
2R
20M
OUTPUT
4mV TO 8.2V
R
10M
2R
20M
–IN
+IN
GAIN = 1 +
()
2R1
R
G
R3
R2
= 100 FOR VALUES SHOWN
LT`1078/79 • TA05
INPUT BIAS CURRENT TYPICALLY < 150pA
INPUT RESISTANCE = 3R = 30M FOR VALUES SHOWN
NEGATIVE COMMON MODE LIMIT = (I
B
)(2R) + 20mV ≈ 140mV
GAIN BANDWIDTH PRODUCT = 1.8MHz