LTC2983
18
2983fc
For more information www.linear.com/LTC2983
APPLICATIONS INFORMATION
specific configurations. These include pointers to cold junction
or sense resistor channels, pointers to memory locations of
custom linearization data, sense resistor values and diode
ideality factors. Also included in this data are, if applicable, the
excitation current level, single-ended/differential input mode,
as well as sensor specific controls. Separate detailed operation
sections for thermocouples, RTDs, diodes, thermistors, and
sense resistors describe the assignment data associated with
each sensor type in more detail. The LTC2983 demonstration
Table 5. Sensor Type Selection
31 30 29 28 27 SENSOR TYPE
0 0 0 0 0 Unassigned
0 0 0 0 1 Type J Thermocouple
0 0 0 1 0 Type K Thermocouple
0 0 0 1 1 Type E Thermocouple
0 0 1 0 0 Type N Thermocouple
0 0 1 0 1 Type R Thermocouple
0 0 1 1 0 Type S Thermocouple
0 0 1 1 1 Type T Thermocouple
0 1 0 0 0 Type B Thermocouple
0 1 0 0 1 Custom Thermocouple
0 1 0 1 0 RTD PT-10
0 1 0 1 1 RTD PT-50
0 1 1 0 0 RTD PT-100
0 1 1 0 1 RTD PT-200
0 1 1 1 0 RTD PT-500
0 1 1 1 1 RTD PT-1000
1 0 0 0 0 RTD 1000 (0.00375)
1 0 0 0 1 RTD NI-120
1 0 0 1 0 RTD Custom
1 0 0 1 1 Thermistor 44004/44033 2.252kΩ at 25°C
1
0 1 0 0 Thermistor 44005/44030 3kΩ at 25°C
1 0 1 0 1 Thermistor 44007/44034 5kΩ at 25°C
1 0 1 1 0 Thermistor 44006/44031 10kΩ at 25°C
1 0 1 1 1 Thermistor 44008/44032 30kΩ at 25°C
1 1 0 0 0 Thermistor YSI 400 2.252kΩ at 25°C
1 1 0 0 1 Thermistor Spectrum 1003k 1kΩ
1 1 0 1 0 Thermistor Custom Steinhart-Hart
1 1 0 1 1 Thermistor Custom Table
1 1 1 0 0 Diode
1 1 1 0 1 Sense Resistor
1 1 1 1 0 Direct ADC
1 1 1 1 1 Reserved
Table 7. Input Channel Mapping
B7 B6 B5 B4 B3 B2 B1 B0 CHANNEL SELECTED
1 0 0 0 0 0 0 0 Multiple Channels
1 0 0 0 0 0 0 1 CH1
1 0 0 0 0 0 1 0 CH2
1 0 0 0 0 0 1 1 CH3
1 0 0 0 0 1 0 0 CH4
1 0 0 0 0 1 0 1 CH5
1 0 0 0 0 1 1 0 CH6
1 0 0 0 0 1 1 1 CH7
1 0 0 0 1 0 0 0 CH8
1 0 0 0 1 0 0 1 CH9
1 0 0 0 1 0 1 0 CH10
1 0 0 0 1 0 1 1 CH11
1 0 0 0 1
1 0 0 CH12
1 0 0 0 1 1 0 1 CH13
1 0 0 0 1 1 1 0 CH14
1 0 0 0 1 1 1 1 CH15
1 0 0 1 0 0 0 0 CH16
1 0 0 1 0 0 0 1 CH17
1 0 0 1 0 0 1 0 CH18
1 0 0 1 0 0 1 1 CH19
1 0 0 1 0 1 0 0 CH20
1 0 0 1 0 1 1 1 Sleep
All Other Combinations Reserved
Table 6. Command Status Register
B7 B6 B5 B4 B3 B2 B1 B0
Start = 1 Done = 0 0 Channel Selection 1 to 20 Start Conversion
1 0 0 1 0 1 1 1 Initiate Sleep
software includes a utility for checking configuration data and
generating annotated C-code for programming the channel
assignment data.
State 3: Initiate Conversion
Once the channel assignment is complete, the device is
ready to begin a conversion. A conversion is initiated by
writing Start (B7=1) and Done (B6=0) followed by the
desired input channel (B4 – B0) into RAM memory loca-
tion 0x000 (see Tables 6 and 7). It is possible to initiate
a measurement cycle on multiple channels by setting the
channel selection bits (B4 to B0) to 00000; see the Running
Conversions Consecutively on Multiple Channels section
of the data sheet.
To Next Page
Loading...