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