LT1021 LINER [Linear Technology], LT1021 Datasheet - Page 13

• Manufacturer Part Number: LT1021
• Description: Precision Reference
• Manufacturer: LINER [Linear Technology]

15V
15V
*
TYPICAL APPLICATIONS
THIS RESISTOR PROVIDES POSITIVE FEEDBACK TO
THE BRIDGE TO ELIMINATE LOADING EFFECT OF
THE AMPLIFIER. EFFECTIVE Z
STAGE IS 1M . IF R2 TO R5 ARE CHANGED,
SET R6 = R3
IN
LT1021-10
*
GND
TRIMS 1mA REFERENCE CURRENT
TC BY 40ppm/ C. THIS TRIM SCHEME HAS
VERY LITTLE EFFECT ON ROOM TEMPERATURE
CURRENT TO MINIMIZE ITERATIVE TRIMMING
IN
LT1021-10
OUT
357
1/2W
GND
R1
Precision DAC Reference with System TC Trim
6
OUT
1
LM301A
100pF 8
IN
1.24k
1%
8.87k
1%
OF AMPLIFIER
Strain Gauge Conditioner for 350 Bridge
28mA
†
+
–
10k
1%
D1
1N457
TC TRIM*
3
2
50k
28.5mA
U
10k
1%
**
50k
D2
1N457
†
BRIDGE IS ULTRALINEAR WHEN ALL LEGS ARE
ACTIVE, TWO IN COMPRESSION AND TWO IN TENSION,
OR WHEN ONE SIDE IS ACTIVE WITH ONE COMPRESSED
AND ONE TENSIONED LEG
OFFSET AND DRIFT OF LM301A ARE VIRTUALLY
ELIMINATED BY DIFFERENTIAL CONNECTION OF LT1012C
–15V
5V
–5V
357
1/2W
50k
ROOM TEMP
TRIM
200k
1%
350 STRAIN
GAUGE BRIDGE**
20k
20k
R2
R4
10.36k
1%
1mA
DAC
R5
2M
2
3
–
+
2M
R6*
LT1012C
2M
R3
8.45k
1021 TA17
1021 TA09
6
V
OUT
100
*
SELECT R1 TO DELIVER TYPICAL LOAD CURRENT.
LT1021 WILL THEN SOURCE OR SINK AS NECESSARY
TO MAINTAIN PROPER OUTPUT. DO NOT REMOVE LOAD
AS OUTPUT WILL BE DRIVEN UNREGULATED HIGH. LINE
REGULATION IS DEGRADED IN THIS APPLICATION
Negative Shunt Reference Driven
Handling Higher Load Currents
LT1021-10
GND
15V
IN
by Current Source
OUT
30mA
LM334
–11V TO – 40V
LT1021-10
GND
OUT
2.5mA
R
R1*
169
L
1021 TA08
–10V (I
V
10V
TYPICAL LOAD
CURRENT = 30mA
OUT
LT1021
LOAD
27
13
1021 TA14
1mA)