LT1021-7 데이터 시트보기 (PDF) - Linear Technology

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LT1021-7

Precision Reference

Linear Technology 

LT1021

TYPICAL APPLICATIONS

Strain Gauge Conditioner for 350Ω Bridge

Negative Shunt Reference Driven

by Current Source

R1

357Ω

1/2W

LT1021-10

28mA

28.5mA

15V

IN

OUT

GND

5V

350Ω STRAIN

R3

GAUGE BRIDGE**

2M

3

6

LM301A†

2

1

100pF 8

R2

20k

2–

R4

20k

LT1012C

3+

6

VOUT

× 100

R5

2M

R6*

2M

–5V

1021 TA09

357Ω

1/2W

–15V

*THIS RESISTOR PROVIDES POSITIVE FEEDBACK TO

THE BRIDGE TO ELIMINATE LOADING EFFECT OF

THE AMPLIFIER. EFFECTIVE ZIN OF AMPLIFIER

STAGE IS ≥1MΩ. IF R2 TO R5 ARE CHANGED,

SET R6 = R3

**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

LT1021-10

OUT

GND

–10V (ILOAD ≤ 1mA)

2.5mA

LM334

27Ω

–11V TO – 40V

1021 TA14

Precision DAC Reference with System TC Trim

LT1021-10

15V IN

OUT

GND

8.87k

1%

1.24k

1%

D1

1N457

10k

50k

1%

TC TRIM*

50k

ROOM TEMP

TRIM

10k

D2

200k

1%

1N457

1%

10.36k

1%

50k

1mA

8.45k

*TRIMS 1mA REFERENCE CURRENT

TC BY ± 40ppm/°C. THIS TRIM SCHEME HAS

VERY LITTLE EFFECT ON ROOM TEMPERATURE

CURRENT TO MINIMIZE ITERATIVE TRIMMING

DAC

1021 TA17

Handling Higher Load Currents

15V 30mA

IN

LT1021-10

OUT

GND

R1*

169Ω

VOUT

10V

RL

TYPICAL LOAD

CURRENT = 30mA

1021 TA08

*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

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