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