LTC2984_15 Datasheet, PDF (76/78 Pages) Linear Technology – Multi-Sensor High Accuracy Digital Temperature Measurement System with EEPROM

LTC2984
CUSTOM THERMISTORS
Universal Sensor Hardware
The LTC2984 can be configured as a universal temperature
measurement device. Up to four sets of universal inputs
can be applied to a single LTC2984. Each of these sets can
directly digitize a 3-wire RTD, 4-Wire RTD, Thermistor, or
thermocouple without changing any on board hardware
(see Figure 45). Each sensor can share the same four ADC
inputs and protection/filtering circuitry are configured using
software changes (new channel assignment data) only.
One sense resistor and cold junction sensor are shared
among all four banks of sensors.
The LTC2984 includes many flexible, software configurable
input modes. In order to share four common inputs among
all four sensor types each sensor requires specific con-
figuration bits (see Table 88). 3-Wire RTDs are configured
with shared R_SENSE, 4-Wire RTDs and thermistors are
configured as shared and/or rotated, thermocouples are
configured differential with internal ground, and diodes
are configured as single-ended.
Table 88. Sensor Configuration for Universal Hookup
CONFIGURATION CONFIGURATION
SENSOR TYPE
OPTIONS
BITS
SEE TABLE
3-Wire RTD
Share
B18 = 1, B19 = 0 Table 32
4-Wire RTD
Share
B18 = 1, B19 = 0 Table 32
4-Wire RTD
Rotate
B18 = 0, B19 = 1 Table 32
Thermistor
Share
B19 = 0, B20 = 1 Table 56
Thermistor
Rotate
B19 = 1, B20 = 0 Table 56
Thermocouple Single-Ended
B21 = 1
Table 18
Diode
Single-Ended
B26 = 1
Table 21
2984f
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