LTC2983
26
2983fc
For more information www.linear.com/LTC2983
Example: Single-Ended Type K and Differential Type T
Thermocouples with Shared Diode Cold Junction
Compensation
Figure 6 shows a typical temperature measurement
system where two thermocouples share a single cold
junction diode. In this example, a Type K thermocouple
is tied to CH1 and a Type T thermocouple is tied to CH3
and CH4. They both share a single cold junction diode
with ideality factor of
h=1.003 tied to CH2. Channel as-
signment data for both thermocouples and the diode are
APPLICATIONS INFORMATION
shown in Tables 22 to 24. Thermocouple #1 (Type K)
sensor type and configuration data are assigned to CH1.
32-bits of binary configuration data are mapped directly
into memory locations 0x200 to 0x203 (see Table 22).
The cold junction diode sensor type and configuration
data are assigned to CH2. 32-bits of binary configuration
data are mapped directly into memory locations 0x204
to 0x207 (see Table 23). Thermocouple #2 (Type T) sen-
sor type and configuration data are assigned to CH4.
32-bits of binary configuration data are mapped directly
Figure 6. Dual Thermocouple with Diode Cold Junction Example
TYPE K
0.1µF
TYPE T
η = 1.003
2983 F06
TYPE K THERMOCOUPLE ASSIGNED TO CH
1
(CH
TC=1
)
DIODE COLD JUNCTION ASSIGNED TO CH
2
(CH
D=2
)
TYPE T THERMOCOUPLE JUNCTION ASSIGNED TO CH
4
(CH
TC=4
)
CH4
CH3
CH2
CH1
0.1µF
COM
CHANNEL ASSIGNMENT
MEMORY LOCATIONS 0x200 TO 0x203
RESULT MEMORY LOCATIONS 0x010 TO 0x013
CHANNEL ASSIGNMENT
MEMORY LOCATIONS 0x204 TO 0x207
RESULT MEMORY LOCATIONS 0x014 TO 0x017
CHANNEL ASSIGNMENT
MEMORY LOCATIONS 0x20C TO 0x20F
RESULT MEMORY LOCATIONS 0x01C TO 0x01F
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