LTC2984 datasheet(53/78 Pages) AD

53 / 78 page

LTC2984

2984fb

For more information www.linear.com/LTC2984

APPLICATIONS INFORMATION

Figure 25. Single-Ended Thermistor Channel Assignment

Convention

2984 F25

CHTHERM

COM

EXCITATION

CURRENT

FLOW

= CHTHERM (1 ≤ THERM ≤ 20)

2ND TERMINAL TIES TO SENSE RESISTOR (CHRSENSE)

CHANNEL

ASSIGNMENT

Figure 26. Sense Resistor Channel Assignment Convention

2984 F26

CHRSENSE-1

CHRSENSE

RSENSE

EXCITATION

CURRENT

FLOW

= CHRSENSE (2 ≤ RSENSE ≤ 20)

CHANNEL

ASSIGNMENT

Figure 27. Single-Ended Thermistor Example

2984 F27

SENSE RESISTOR ASSIGNED TO CH4 (CHSENSE=4)

CH3

CHANNEL ASSIGNMENT

MEMORY LOCATIONS 0x20C TO 0x20F

CH4

CH5

COM

THERMISTOR ASSIGNED TO CH5 (CHTHERM=5)

CHANNEL ASSIGNMENT

MEMORY LOCATIONS 0x210 TO 0x213

RESULT MEMORY LOCATIONS 0x020 TO 0x023

RSENSE

10.1k

100pF

TYPE 44031

100pF

Example: Single-Ended Thermistor

The simplest thermistor configuration is the single-ended

configuration. Thermistors using this configuration share

a common ground (COM) between all sensors and are

each tied to a unique sense resistor (RSENSE sharing is

not allowed for single-ended thermistors). Single-ended

thermistors follow the convention shown in Figure 25.

Terminal 1 ties to ground (COM) and terminal 2 ties to

CHTHERM and the sense resistor. Channel assignment

data (see Table 54) is mapped to memory locations cor-

responding to CHTHERM.

Sense resistor channel assignments follow the general

convention shown in Figure 26. The sense resistor is tied

betweenCHRSENSEandCHRSENSE-1,whereCHRSENSEistied

Figure 27 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.ThethermistorisassignedchannelCH5(memory

locations 0x210 to 0x213) and the sense resistor to CH4

(memory locations 0x20C to 0x20F). Channel assignment

data are shown in Tables 60 and 61.

A conversion is initiated on CH5 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 CH5).

to the 2nd terminal of the thermistor. Channel assignment

data (see Table 37) is mapped into the memory location

corresponding to CHRSENSE.

LTC2984 Datasheet(PDF) 53 Page - Analog Devices

LTC2984 Datasheet(HTML) 53 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78

Datasheet Download

Link URL