LTC2983
51
2983fc
For more information www.linear.com/LTC2983
Table 60. Channel Assignment Data Differential Thermistor (44008/44032 30kΩ at 25°C Type Thermistor, Differential Configuration with
Sharing and Rotation, R
SENSE
on CH
16
, 250nA Excitation Current)
CONFIGURATION
FIELD
DESCRIPTION # BITS BINARY DATA MEMORY
ADDRESS 0x244
MEMORY
ADDRESS 0x245
MEMORY
ADDRESS 0x246
MEMORY
ADDRESS 0x247
(1) Thermistor
Type
44008/44032
30kΩ at 25°C
5 10111 1 0 1 1 1
(2) Sense
Resistor Channel
Pointer
CH
16
5 10000 1 0 0 0 0
(3) Sensor
Configuration
Differential,
Rotate and
Shared
3 001 0 0 1
(4) Excitation
Current
250nA
Excitation
Current
4 0001 0 0 0 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
APPLICATIONS INFORMATION
a 30kΩ (44032 Type) thermistor is tied to a 10.0kΩ sense
resistor and configured as rotated/shared. The second
thermistor a 2.25kΩ (44004 Type) is configured as a
non-rotated/shared. Channel assignment data are shown
in Tables 60 to 62.
A conversion is initiated on CH
18
by writing 10010010 into
memory location 0x000. Once the conversion is complete,
the INTERRUPT pin goes HIGH and memory location
0x000 becomes 01010010. The resulting temperature in
°C can be read from memory locations 0x054 to 0x057
(corresponding to CH
16
). A conversion can be initiated
and read from CH20 in a similar fashion.
Figure 30. Rotated and Shared Thermistor Example
2983 F30
THERMISTOR #1 ASSIGNED TO CH
18
(CH
THERM=18
)
CHANNEL ASSIGNMENT
MEMORY LOCATIONS 0x244 TO 0x247
RESULT MEMORY LOCATIONS 0x054 TO 0x057
100pF
CH
17
CH
16
CH
15
CH
18
CH
19
CH
20
THERMISTOR #2 ASSIGNED TO CH
20
(CH
THERM=20
)
CHANNEL ASSIGNMENT
MEMORY LOCATIONS 0x24C TO 0x24F
RESULT MEMORY LOCATIONS 0x05C TO 0x05F
SENSE RESISTOR ASSIGNED TO CH
16
(CH
SENSE=16
)
CHANNEL ASSIGNMENT
MEMORY LOCATIONS 0x23C TO 0x23F
TYPE 44032
R
SENSE
10k
100pF
2
1
100pF
TYPE 44033
100pF
2
1
100pF
100pF
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