LT1236
TYPICAL APPLICATIONS
Strain Gauge Conditioner for 350Ω Bridge
R1
357Ω
1/2W
Negative Shunt Reference Driven
by Current Source
28mA
LT1236-10
28.5mA
15V
IN
OUT
GND
3
6
LM301A†
2
1
100pF 8
5V
350Ω STRAIN
R3
GAUGE BRIDGE**
2M
R2
20k
R4
20k
2–
LT1012C
3+
6
VOUT
X100
R5
2M
R6*
2M
–5V
357Ω
1/2W
LT1236-10
OUT
GND
–10V (ILOAD ≤ 1mA)
2.5mA
LM334
27Ω
–11V TO – 40V
LT1236 TA13
–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 ULTRA-LINEAR 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
LT1236 TA08
Precision DAC Reference with System TC Trim
2-Pole Lowpass Filtered Reference
LT1236-10
15V IN
OUT
GND
1µF
MYLAR
8.87k
1%
1.24k
1%
D1
1N457
10k
50k
1%
TC TRIM*
LT1236
VIN IN
OUT
50k
ROOM TEMP
GND
R1
R2
36k
36k
TRIM
10.36k
f = 10Hz
1%
10k
D2
200k
1%
1N457
1%
50k
1mA
8.45k
VIN
–
LT1001
+
0.5µF
MYLAR
VREF
TOTAL NOISE
≤ 2µVRMS
1Hz ≤ f ≤ 10kHz
–VREF
LT1236 TA12
*TRIMS 1mA REFERENCE CURRENT
TC BY ±40ppm/°C. THIS TRIM
SCHEME HAS VERY LITTLE EFFECT ON ROOM
TEMPERATURE CURRENT TO MINIMIZE ITERATIVE
TRIMMING
10
DAC
LT1236 TA16