LTC2984 datasheet(52/78 Pages) AD

52 / 78 page

LTC2984

2984fb

For more information www.linear.com/LTC2984

Fault Reporting – Thermistor

Each sensor type has unique fault reporting mechanism

indicated in the upper byte of the data output word.

Table 58 shows faults reported during the measurement

of thermistors.

BitD31indicatesthethermistororRSENSEisopen,shorted,

or not plugged in. This is a hard fault and –999°C is re-

ported. Bit D30 indicates a bad ADC reading. This could be

a result of either a broken (open) sensor or an excessive

noise event (ESD or static discharge into the sensor path).

Table 58. Thermistor Fault Reporting

BIT

FAULT

ERROR TYPE

DESCRIPTION

OUTPUT RESULT

D31

Sensor Hard Fault

Hard

Open or Short Thermistor or RSENSE

–999°C

D30

Hard ADC-Out-of-Range

Hard

Bad ADC Reading (Could Be Large External Noise Event)

–999°C

D29

Not Used for Thermistors

N/A

Always 0

Valid Reading

D28

Not Used for Thermistors

N/A

Always 0

Valid Reading

D27

Sensor Over Range*

Soft

T > High Temp Limit

Suspect Reading

D26

Sensor Under Range*

Soft

T < Low Temp Limit

Suspect Reading

D25

ADC Out-of-Range

Soft

ADC Absolute Input Voltage Is Beyond ±1.125 • VREF/2

Suspect Reading

D24

Valid

N/A

Result Valid (Should Be 1) Discard Results if 0

Valid Reading

*Do not apply to custom Steinhart-Hart sensor type. Custom table thermistor over/under range is determined by the resistor table values, see custom

thermistor table example for details.

APPLICATIONS INFORMATION

This is a hard error and –999°C is output. In the case of

an excessive noise event, the device should recover and

the following conversions will be valid if the noise event

was a random infrequent event. Bits D29 and D28 are not

used for thermistors. Bits D27 and D26 indicate the read-

ing is over or under temperature limits (see Table 59). The

calculated temperature is reported, but the accuracy may

be compromised. Bit D25 indicates the absolute voltage

measuredbytheADCisbeyonditsnormaloperatingrange.

If a thermistor is used as the cold junction element, any

hard or soft error is flagged in the thermocouple result.

Table 59. Thermistor Temperature/Resistance Range

THERMISTOR TYPE

MIN (Ω)

MAX (Ω)

LOW Temp Limit (°C)

HIGH Temp Limit (°C)

Thermistor 44004/44033 2.252kΩ at 25°C

41.9

75.79k

–40

150

Thermistor 44005/44030 3kΩ at 25°C

55.6

101.0k

–40

150

Thermistor 44007/44034 5kΩ at 25°C

92.7

168.3k

–40

150

Thermistor 44006/44031 10kΩ at 25°C

237.0

239.8k

–40

150

Thermistor 44008/44032 30kΩ at 25°C

550.2

884.6k

–40

150

Thermistor YSI 400 2.252kΩ at 25°C

6.4

1.66M

–80

250

Spectrum 1003K 1kΩ at 25°C

51.1

39.51k

–50

125

Thermistor Custom Steinhart-Hart

N/A

Thermistor Custom Table

Second Table Entry

Last Table Entry

LTC2984 Datasheet(PDF) 52 Page - Analog Devices

LTC2984 Datasheet(HTML) 52 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