LTC2484CDD#PBF Linear Technology, LTC2484CDD#PBF Datasheet - Page 38

• Manufacturer Part Number: LTC2484CDD#PBF
• Description: IC ADC 24BIT 10-DFN
• Manufacturer: Linear Technology

Specifications of LTC2484CDD#PBF

• Number Of Bits: 24
• Sampling Rate (per Second): 6.8
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 1
• Power Dissipation (max): 480µW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 10-WFDFN Exposed Pad
• Number Of Elements: 1
• Resolution: 24Bit
• Architecture: Delta-Sigma
• Sample Rate: 0.0075KSPS
• Input Polarity: Bipolar
• Input Type: Voltage
• Rated Input Volt: ±2.75V
• Differential Input: Yes
• Power Supply Requirement: Single
• Single Supply Voltage (typ): 3.3/5V
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (typ): Not RequiredV
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Integral Nonlinearity Error: 10ppm of Vref
• Operating Temp Range: 0C to 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 10
• Package Type: DFN EP
• Input Signal Type: Differential
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LTC2484
APPLICATIONS INFORMATION
Complete Thermocouple Measurement System with
Cold Junction Compensation
The LTC2484 is ideal for direct digitization of thermocouples
and other low voltage output sensors. The input has a
typical offset error of 500nV (2.5μV max) offset drift of
10nV/°C and a noise level of 600nV
Figure 44 (last page of this data sheet) is a complete type
K thermocouple meter. The only signal conditioning is a
simple surge protection network. In any thermocouple
meter, the cold junction temperature sensor must be
at the same temperature as the junction between the
thermocouple materials and the copper printed circuit
board traces. The tiny LTC2484 can be tucked neatly
underneath an Omega MPJ-K-F thermocouple socket
ensuring close thermal coupling.
The LTC2484’s 1.4mV/°C PTAT circuit measures the
cold junction temperature. Once the thermocouple volt-
age and cold junction temperature are known, there
are many ways of calculating the thermocouple temp-
38
NC1M4V0
G1
+
2
IN OUT
LT1236
GND
TRIM
4
RMS
6
5
.
(OMEGA MPJ-K-F)
R7
8k
R8
1k
THERMOCOUPLE
TYPE K
JACK
Figure 43. Calibration Setup
ISOTHERMAL
R2
2k
26.3C
erature including a straight-line approximation, lookup
tables or a polynomial curve fi t. Calibration is per-
formed by applying an accurate 500mV to the ADC input
derived from an LT
local temperature with an accurate thermometer as
shown in Figure 43. In calibration mode, the up and
down buttons are used to adjust the local tempera-
ture reading until it matches an accurate thermometer.
Both the voltage and temperature calibration are easily
automated.
The complete microcontroller code for this application is
available on the LTC2484 product Web page at:
It can be used as a template for may different instruments
and it illustrates how to generate calibration coeffi cients
for the onboard temperature sensor. Extensive comments
detail the operation of the program. The read_LTC2484()
function controls the operation of the LTC2484 and is
listed below for reference.
http://www.linear.com
4
5
IN
IN
+
–
GND
REF
LTC2484
3
8
GND
V
5V
CC
2
11
SDO
SCK
SDI
CS
f
®
O
1236 reference and measuring the
C8
1μF
6
9
7
1
10
2484 F43
C7
0.1μF
2484fc