Specifications

Sensors
Temperature sensing
www.digikey.com/maxim-industrial 73
DS600, MAX1416, MAX6133,
MAX6675
The thermocouple circuit shown in
Figure A uses the MAX1416 ADC
that allows direct interfacing with
thermocouples, thereby eliminating
external components and reducing
the overall footprint. The internal
programmable gain amplifier (PGA)
eliminates the need for an external
precision amplifier; self-calibration
avoids expensive calibration proce-
dures during manufacture. The
MAX1416 accommodates negative
temperatures because its input
common-mode range extends
30mV below ground.
Cold-junction temperature is
measured using a DS600 analog
temperature sensor located at the
thermocouple connector. With
±0.5°C accuracy, the DS600 provides
the most accurate cold-junction
compensation of any analog
temperature-sensor IC on the
market. Adding the cold-junction
temperature to the temperature
measured by the ADC corrects for the
parasitic thermocouples created when
the thermocouple connector is linked
to the system.
Figure B shows a fully integrated
thermocouple circuit using the
MAX6675 thermocouple-to-digital
converter, a complete thermocouple
interface IC. With the ADC, reference,
gain, and cold-junction compensation
all integrated, the MAX6675 measures
positive temperature values from a
K-type thermocouple and requires no
external components. Using the
MAX6675 thus reduces parts count,
design time, and system complexity.
The maximum measured temperature
is +1024.75°C. The 12-bit resolution
results in an LSB value of 0.25°C
(continued on next page)
Complete thermocouple interface designs eliminate external components,
use less space
5V
CLKIN
RESET
CS
DIN
SCLK
DOUT
DRDY
GND
GNDCTG
GND
IN
OUT
V
DD
V
DD
V
OUT
CLKOUT
AIN1+
AIN1-
AIN2+
AIN2-
REF+
REF-
5V
5V
20pF
20pF
0.1μF
0.1μF
10μF
ECS-49-20-1
PCC-SMP-K-R
THERMO-
COUPLE
CONNECTOR
CLOSE
PROXIMITY
MAX1416
DS600
MAX6133
Figure A. A thermocouple measurement circuit in which the MAX1416 measures the thermocouple output and the DS600
measures the cold-junction temperature.