ADT7420 Datasheet, PDF (1/24 Pages) Analog Devices – ±0.25°C Accurate, 16-Bit Digital I2C Temperature Sensor

Preliminary Technical Data
±0.25°C Accurate, 16-Bit Digital
I²C Temperature Sensor
ADT7420
FEATURES
GENERAL DESCRIPTION
Temperature accuracy: ±0.25°C from −20°C to +105°C
13- or 16-bit user selectable temperature-to-digital converter
Low drift silicon temperature sensor
No temperature calibration/correction required by user
Power saving 1 sample per second (SPS) mode
Fast first conversion on power-up of 6 ms
I²C-compatible interface
Operating temperature: −40°C to +150°C
Operating voltage: 2.7 V to 5.5 V
Critical overtemperature indicator
Programmable overtemperature/undertemperature interrupt
Low power consumption: 700 µW typical at 3.3 V
Shutdown mode for lower power: 7 µW typical at 3.3 V
16-lead RoHS-compliant LFCSP package
APPLICATIONS
RTD and thermistor replacement
Medical equipment
Cold junction compensation
Industrial control and test
Food transportation and storage
Environmental monitoring and HVAC
The ADT7420 is a high accuracy digital temperature sensor
offering breakthrough performance over a wide industrial
range, housed in an LFCSP package. It contains a band gap
temperature reference and a 13-bit ADC to monitor and digitize
the temperature to a 0.0625°C resolution. The ADC resolution,
by default, is set to 13 bits (0.0625°C). This can be changed to
16 bits (0.0078°C) by setting Bit 7 in the configuration register
to 1 (Register Address 0x03).
The ADT7420 is guaranteed to operate over supply voltages from
2.7 V to 5.5 V. Operating at 3.3 V, the average supply current is typi-
cally 210 μA. The ADT7420 has a shutdown mode that powers
down the device and offers a shutdown current of typically 2 μA.
The ADT7420 is rated for operation over the −40°C to +150°C
temperature range.
Pin A0 and Pin A1 are available for address selection, giving the
ADT7420 four possible I²C addresses. The CT pin is an open-
drain output that becomes active when the temperature exceeds
a programmable critical temperature limit. The default critical
temperature limit is 147°C. The INT pin is also an open-drain
output that becomes active when the temperature exceeds a
programmable limit. The INT and CT pins can operate in either
comparator or interrupt mode.
FUNCTIONAL BLOCK DIAGRAM
V_DD
12
TEMPERATURE
VALUE
REGISTER
ADT7420
CONFIGURATION
REGISTER
T_CRIT
REGISTER
INTERNAL
OSCILLATOR
T_CRIT
10 CT
T_HIGH
REGISTER
T_LOW
REGISTER
T_HYST
REGISTER
STATUS
REGISTER
INTERNAL
REFERENCE
TEMPERATURE
SENSOR
Σ-Δ
MODULATOR
T_HIGH
9 INT
ID
REGISTER
SOFTWARE
RESET
REGISTER
POINTER
REGISTER
FILTER
LOGIC
T_LOW
A0 3
A1 4
I²C INTERFACE
11
GND
Figure 1.
1 SCL
2 SDA
Rev. PrA
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
www.analog.com
Fax: [phone]
©2010 Analog Devices, Inc. All rights reserved.