LT1167 Linear Technology, LT1167 Datasheet - Page 15

• Manufacturer Part Number: LT1167
• Description: Single Resistor Gain Programmable/ Precision Instrumentation Amplifier
• Manufacturer: Linear Technology

APPLICATIONS
Table 1. “Roll Your Own” vs LT1167 Error Budget
ERROR SOURCE
Absolute Accuracy at T
Input Offset Voltage, V
Output Offset Voltage, V
Input Offset Current, nA
CMR, dB
Drift to 85 C
Gain Drift, ppm/ C
Input Offset Voltage Drift, V/ C
Output Offset Voltage Drift, V/ C
Resolution
Gain Nonlinearity, ppm of Full Scale
Typ 0.1Hz to 10Hz Voltage Noise, V
G = 100, V
All errors are min/max and referred to input.
Current Source
Figure 7 shows a simple, accurate, low power program-
mable current source. The differential voltage across Pins
2 and 3 is mirrored across R
amplified and applied across R
PRECISION BRIDGE TRANSDUCER
350
350
S
= 15V
10V
350
350
A
= 25 C
U
INFORMATION
U
P-P
G
. The voltage across R
499
X
R
, defining the output
W
G
LT1167C CIRCUIT CALCULATION
60 V/20mV
(300 V/100)/20mV
[(450pA)(350/2) ]/20mV
110dB [ 3.16ppm)(5V)]/20mV
(50ppm + 10ppm)(60 C)
[(0.4 V/ C)(60 C)]/20mV
[6 V/ C)(60 C)]/100/20mV
15ppm
0.28 V
LT1167 MONOLITHIC
INSTRUMENTATION AMPLIFIER
G = 100, R
SUPPLY CURRENT = 1.3mA MAX
P-P
+
–
Figure 6. “Roll Your Own” vs LT1167
/20mV
G
LT1167C
= 10ppm TC
U
REF
G
is
current. The 50 A bias current flowing from Pin 5 is
buffered by the LT1464 JFET operational amplifier. This
has the effect of improving the resolution of the current
source to 3pA, which is the maximum I
Replacing R
increases the range of available output currents.
“ROLL YOUR OWN”’ CIRCUIT
100 V/20mV
[(60 V)(2)/100]/20mV
[(450pA)(350 )/2]/20mV
[(0.02% Match)(5V)]/20mV
Total Absolute Error
(100ppm/ C Track)(60 C)
[(1.6 V/ C)(60 C)]/20mV
[(1.1 V/ C)(2)(60 C)]/100/20mV
Total Drift Error
10ppm
(0.3 V
Total Resolution Error
Grand Total Error
CALCULATION
P-P
100 **
)( 2)/20mV
G
+
–
–
+
LT1114A
LT1114A
with a programmable resistor greatly
1/4
1/4
** DISCRETE 1% RESISTOR, 100ppm/ C TC
* 0.02 RESISTOR MATCH, 3ppm/ C TRACKING
“ROLL YOUR OWN” INST AMP, G = 100
100ppm TRACKING
SUPPLY CURRENT = 1.35mA FOR 3 AMPLIFIERS
10k**
10k**
10k*
10k*
LT1167C “ROLL YOUR OWN”
ERROR, ppm OF FULL SCALE
3000
3944
3600
1200
4980
8953
150
790
180
15
14
29
4
–
+
LT1114A
B
1/4
of the LT1464A.
10k*
10k*
LT1167
10866
16461
5000
5564
6000
4800
500
60
66
10
21
31
4
15
1167 F06