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PDF LTC2984 Data sheet ( Hoja de datos )
| Número de pieza | LTC2984 | |
| Descripción | Multi-Sensor High Accuracy Digital Temperature Measurement System | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC2984
FEATURES
Multi-Sensor High
Accuracy Digital Temperature
Measurement System with EEPROM
DESCRIPTION
nn Directly Digitizes 2-, 3-, or 4-Wire RTDs,
Thermocouples, Thermistors, and Diodes
nn On-Chip EEPROM Stores Channel Configuration Data
and Custom Coefficients
nn Single 2.85V to 5.25V Supply
nn 20 Flexible Inputs Allow Interchanging Sensors
nn Automatic Thermocouple Cold Junction Compensation
nn Built-In Standard and User-Programmable Coefficients
for Thermocouples, RTDs and Thermistors
nn Measures Negative Thermocouple Voltages
nn Automatic Burn Out, Short-Circuit and Fault Detection
nn Buffered Inputs Allow External Protection
nn Simultaneous 50Hz/60Hz Rejection
nn Includes 15ppm/°C (Max) Reference (I-Grade)
APPLICATIONS
nn Direct Thermocouple Measurements
nn Direct RTD Measurements
nn Direct Thermistor Measurements
nn Custom Sensor Applications
The LTC®2984 measures a wide variety of temperature
sensors and digitally outputs the result, in °C or °F, with
0.1°C accuracy and 0.001°C resolution. The LTC2984 can
measure the temperature of virtually all standard (type B,
E, J, K, N, S, R, T) or custom thermocouples, automatically
compensate for cold junction temperatures and linearize
the results. The device can also measure temperature with
standard 2-, 3-, or 4-wire RTDs, thermistors, and diodes.
It has 20 reconfigurable analog inputs enabling many sen-
sor connections and configuration options. The LTC2984
includes excitation current sources and fault detection
circuitry appropriate for each type of temperature sensor
as well as an EEPROM for storing custom coefficients and
channel configuration data.
The LTC2984 allows direct interfacing to ground referenced
sensors without the need for level shifters, negative supply
voltages, or external amplifiers. All signals are buffered and
simultaneously digitized with three high accuracy, 24-bit ∆∑
ADC's, driven by an internal 10ppm/°C (maximum) reference.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Patents Pending
TYPICAL APPLICATION
Thermocouple Measurement with Automatic Cold Junction Compensation
2.85V TO 5.25V
1k
0.1µF
1k
24-BIT
∆∑ ADC
LTC2984
RSENSE
2k
43
PT-100
RTD
2
1
24-BIT
∆∑ ADC
LINEARIZATION/
FAULT DETECTION
SPI
INTERFACE
°C/°F
24-BIT
∆∑ ADC
VREF (10ppm/°C)
EEPROM
2984 TA01a
For more information www.linear.com/LTC2984
Typical Temperature Error
Contribution
0.5
0.4
0.3 THERMISTOR
0.2 THERMOCOUPLE
0.1
0
–0.1
–0.2 3904 DIODE
–0.3 RTD
–0.4
–0.5
–200 0
200 400 600 800 1000 1200 1400
TEMPERATURE (°C)
2984 TA01b
2984f
1
1 page  
LTC2984
R EFERENCE ELECTRICAL CHARACTERISTICS
the full operating temperature range, otherwise specifications are at TA = 25°C.
PARAMETER
Output Voltage
Output Voltage Temperature Coefficient
Output Voltage Temperature Coefficient
Line Regulation
Load Regulation
Output Voltage Noise
Output Short-Circuit Current
Turn-On Time
Long Term Drift of Output Voltage (Note 13)
Hysteresis (Note 14)
CONDITIONS
VREFOUT (Note 10)
I-Grade
C-Grade
IOUT(SOURCE) = 100µA
IOUT(SINK) = 100µA
0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
Short VREFOUT to GND
Short VREFOUT to VDD
0.1% Setting, CLOAD = 1µF
∆T = 0°C to 70°C
∆T = –40°C to 85°C
The l denotes the specifications which apply over
MIN
2.49
l
l
l
l
l
TYP
3
3
4
4.5
40
30
115
60
30
70
MAX
2.51
15
20
10
5
5
UNITS
V
ppm/°C
ppm/°C
ppm/V
mV/mA
mV/mA
µVP-P
µVP-P
mA
mA
µs
ppm/√khr
ppm
ppm
DIGITAL INPUTS AND DIGITAL OUTPUTS The l denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at TA = 25°C.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX
UNITS
External SCK Frequency Range
l0
2 MHz
External SCK LOW Period
l 250
ns
External SCK HIGH Period
l 250
ns
t1 CS↓ to SDO Valid
t2 CS↑ to SDO Hi-Z
t3 CS↓ to SCK↑
t4 SCK↓ to SDO Valid
t5 SDO Hold After SCK↓
t6 SDI Setup Before SCK↑
t7 SDI HOLD After SCK↑
High Level Input Voltage
Low Level Input Voltage
CS, SDI, SCK, RESET
CS, SDI, SCK, RESET
l0
l0
l 100
l
l 10
l 100
l 100
l VDD – 0.5
l
200 ns
200 ns
ns
225 ns
ns
ns
ns
V
0.5 V
Digital Input Current
CS, SDI, SCK, RESET
l –10
10 µA
Digital Input Capacitance
CS, SDI, SCK, RESET
10 pF
LOW Level Output Voltage (SDO, INTERRUPT)
High Level Output Voltage (SDO, INTERRUPT)
Hi-Z Output Leakage (SDO)
IO = –800µA
IO = 1.6mA
l
l VDD – 0.5
l –10
0.4 V
V
10 µA
For more information www.linear.com/LTC2984
2984f
5
5 Page 
BLOCK DIAGRAM
VREFP
1µF
VREFOUT
VREF_BYP
0.1µF
10ppm/°C REFERENCE
CH1 TO CH20
COM
21:6 MUX
ADC1
ADC2
ADC3
EXCITATION
CURRENT SOURCES
LTC2984
VDD
CHARGE
PUMP
LDO
ROM
EEPROM
Q1
Q2 10µF
Q3
10µF
LDO
10µF
RAM
PROCESSOR
INTERRUPT
SDO
SCK
SDI
CS
RESET
GND
2984 BD
For more information www.linear.com/LTC2984
2984f
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11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LTC2984.PDF ] | |
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