LTC2983
47
2983fc
For more information www.linear.com/LTC2983
APPLICATIONS INFORMATION
Figure 24 shows a typical temperature measurement
system using a single-ended thermistor. In this example
a 10kΩ (44031 type) thermistor is tied to a 10.1kΩ sense
resistor. The thermistor is assigned channel CH5 (memory
locations 0x210 to 0x213) and the sense resistor to CH4
(memory locations 0x20C to 0x20F). Channel assignment
data are shown in Tables 56 and 57.
A conversion is initiated on CH
5
by writing 10000101 into
memory location 0x000. Once the conversion is complete,
the INTERRUPT pin goes HIGH and memory location
0x000 becomes 01000101. The resulting temperature in
°C can be read from memory locations 0x020 to 0x023
(corresponding to CH
5
).
Table 56. Channel Assignment Data for Single-Ended Thermistor (44006/44031 10kΩ at 25°C Type Thermistor, Single-Ended
Configuration, R
SENSE
on CH
4
, 1µA Excitation Current)
CONFIGURATION
FIELD
DESCRIPTION # BITS BINARY DATA MEMORY
ADDRESS 0x210
MEMORY
ADDRESS 0x211
MEMORY
ADDRESS 0x212
MEMORY
ADDRESS 0x213
(1) Thermistor
Type
44006/44031
10kΩ at 25°C
5 10110 1 0 1 1 0
(2) Sense
Resistor Channel
Pointer
CH
4
5 00100 0 0 1 0 0
(3) Sensor
Configuration
Single-Ended 3 100 1 0 0
(4) Excitation
Current
1µA 4 0011 0 0 1 1
Not Used Set These Bits
to 0
3 000 0 0 0
(5) Custom RTD
Data Pointer
Not Custom 12 000000000000 0 0 0 0 0 0 0 0 0 0 0 0
Table 57. Channel Assignment Data for Sense Resistor (Value = 10.1kΩ)
CONFIGURATION
FIELD
DESCRIPTION # BITS BINARY DATA MEMORY
ADDRESS 0x20C
MEMORY
ADDRESS 0x20D
MEMORY
ADDRESS 0x20E
MEMORY
ADDRESS 0x20F
(1) Sensor Type Sense Resistor 5 11101 1 1 1 0 1
(2) Sense
Resistor Value
10.1kΩ 27 000100111011101000000000000 0 0 0 1 0 0 1 1 1 0 1 1 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0
Figure 24. Single-Ended Thermistor Example
2983 F24
SENSE RESISTOR ASSIGNED TO CH
4
(CH
SENSE=4
)
CH
3
CHANNEL ASSIGNMENT
MEMORY LOCATIONS 0x20C TO 0x20F
CH
4
CH
5
COM
THERMISTOR ASSIGNED TO CH
5
(CH
THERM=5
)
CHANNEL ASSIGNMENT
MEMORY LOCATIONS 0x210 TO 0x213
RESULT MEMORY LOCATIONS 0x020 TO 0x023
R
SENSE
10.1k
100pF
100pF
TYPE 44031
100pF
2
1
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