Datasheet

LTC1052/LTC7652
17
1052fa
TYPICAL APPLICATIO S
U
Direct Thermocouple-to-Frequency Converter
Direct 10-Bit Strain Gauge Digitizer
LT1004–1.2V
0.01% FILM-TRW MAR-6
TRW/MTR/5/ + 120
R
T
= YELLOW SPRINGS INST. #44007
100pF = POLYSTYRENE
FOR GENERAL PURPOSE (1mV FULL-SCALE)
10-BIT A-TO-D, REMOVE THERMOCOUPLE—
COLD JUNCTION NETWORK, GROUND POINT A,
AND DRIVE LTC1052 POSITIVE INPUT
*
**
†
5V
LTC1052/7652 • TA16
0.1µF
OUTPUT
0Hz TO 600Hz
0°C TO 60°C
3k
F
5V
74C04
1µF
+
2
6
16
–5V
5V
74C903
–
1N4148
R
T
5V
820pF
E
D
C10k B
A
74C04
0.68µF
3300pF
–5V
470Ω
6
8
4
1
7
3
0.1µF
33k
1.8k*
2
1k*
100pF
LTC1043
A
†
4.75k*
0.1µF
33k**
COLD JUNCTION TEMPERATURE TRACKING
150k**
STABILIZING AMP
TYPE K
THERMOCOUPLE 41.4µV/°C
100k
1N914
1µF
50k
60°C TRIM
OPTIONAL INPUT
FILTER-AND-OVERLOAD
CLAMP
+
–
LTC1052
5
187Ω*
487Ω*
301k*
COLD JUNCTION BIAS
–5V
LTC1052/7652 • TA17
SW2
1/2 LTC1043
11
CONNECT TO BRIDGE
END OF 470k RESISTOR
33µF
22.3k*
3.3M
BRIDGE DRIVE
1k*
1N4148
SW1
–5V
12
1N4148
8
13
7
14
5
10k
2
7
3
4
6
–5V
*0.1% METAL FILM TRW MAR-5
FREQUENCY
OUT A
FREQUENCY
OUT B
CONNECT DIRECTLY
ACROSS BRIDGE
DRIVE POINTS
(OPTIONAL)
TRANSDUCER ZERO NETWORK
10k
100k
SW1 = MAIN CURRENT SWITCH
SW2 = CURRENT LOADING COMPENSATION SWITCH
–5V
+
–
LM301A
20Ω
5V
1k
6
8
4
7
2
3
1
14k
5V
CLOCK
20Ω
74C00
28k
STRAIN GAUGE
TRANSDUCER
Z
IN
= 350Ω
Z
OUT
= 350Ω
1000pF
–5V
5V
3
1000pF
470k*
0.003µF
2
+
–
LTC1052
–5V
8
1
3.3MΩ*
6
0.01µF
7
OUTPUT
GATING
5V
5V
5V
5V
0.01µF
4114
1/2 74C903
1/2 74C74
INTEGRATOR
DATA OUTPUT =
OUT A
OUT B
= 1000 COUNTS FULL-SCALE
2N2905
16
+