EVAL-ADT7X20EBZ AD [Analog Devices], EVAL-ADT7X20EBZ Datasheet

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EVAL-ADT7X20EBZ

Manufacturer Part Number
EVAL-ADT7X20EBZ
Description
Manufacturer
AD [Analog Devices]
Datasheet
Preliminary Technical Data
FEATURES
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
I
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
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.
2
C-compatible interface
A0
A1
3
4
CONFIGURATION
TEMPERATURE
SOFTWARE
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
REGISTER
STATUS
VALUE
RESET
T
T
T
T
CRIT
HYST
HIGH
LOW
ID
FUNCTIONAL BLOCK DIAGRAM
TEMPERATURE
REFERENCE
INTERNAL
SENSOR
REGISTER
POINTER
I
V
2
12
C INTERFACE
DD
Figure 1.
GND
11
MODULATOR
±0.25°C Accurate, 16-Bit Digital
OSCILLATOR
FILTER
LOGIC
INTERNAL
Σ-Δ
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
GENERAL DESCRIPTION
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 I
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.
I
2
T
T
T
C Temperature Sensor
CRIT
HIGH
LOW
ADT7420
©2010 Analog Devices, Inc. All rights reserved.
2
C addresses. The CT pin is an open-
10
9
1
2
CT
INT
SCL
SDA
ADT7420
www.analog.com

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EVAL-ADT7X20EBZ Summary of contents

Page 1

Preliminary Technical Data FEATURES 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 ...

Page 2

ADT7420 TABLE OF CONTENTS Features .............................................................................................. 1 Applications ....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Specifications ..................................................................................... Timing Specifications ............................................................ 4 Absolute Maximum Ratings ............................................................ 5 ESD Caution .................................................................................. 5 Pin Configuration ...

Page 3

Preliminary Technical Data SPECIFICATIONS T = −40°C to +125° 2 5.5 V, unless otherwise noted Table 1. Parameter Min TEMPERATURE SENSOR AND ADC 1 Accuracy ADC Resolution Temperature Resolution 13-Bit 16-Bit Temperature Conversion Time ...

Page 4

ADT7420 TIMING SPECIFICATIONS T = −40°C to +150° 2 5.5 V, unless otherwise noted. All input signals are specified with rise time ( (10 and timed ...

Page 5

Preliminary Technical Data ABSOLUTE MAXIMUM RATINGS Table 3. Parameter V to GND DD SDA Voltage to GND SCL Output Voltage to GND A0 Input Voltage to GND A1 Input Voltage to GND CT and INT Output Voltage to GND ESD ...

Page 6

ADT7420 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Table 4. Pin Function Descriptions Pin No. Mnemonic Description 2 1 SCL I C Serial Clock Input. The serial clock is used to clock in and clock out data to and from any register ...

Page 7

Preliminary Technical Data TYPICAL PERFORMANCE CHARACTERISTICS 1.0 0.5 0 0.5 1.0 –50 –30 – TEMPERATURE (°C) Figure 4. Temperature Accuracy 1.0 0.5 0 0.5 1.0 –50 –30 – TEMPERATURE (°C) Figure ...

Page 8

ADT7420 0.30 I CONTINUOUS CONVERSION DD 0.25 0.20 0.15 0.10 I 1SPS DD 0.05 0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) Figure 8. Average Operating Supply Current vs. Supply Voltage at 25° ...

Page 9

Preliminary Technical Data THEORY OF OPERATION CIRCUIT INFORMATION The ADT7420 is a 13-bit digital temperature sensor that is extend- able to 16 bits for greater resolution. An on-board temperature sensor generates a voltage proportional to absolute temperature, which is compared ...

Page 10

ADT7420 CT and INT Operation in One-Shot Mode See Figure 12 for more information on one-shot CT pin operation for T overtemperature events when one of the CRIT limits is exceeded. Note that in interrupt mode, a read from any ...

Page 11

Preliminary Technical Data SHUTDOWN The ADT7420 can be placed in shutdown mode by writing 1 to Bit 5 and 1 to Bit 6 of the configuration register (Register Address 0x03), in which case the entire IC is shut down and ...

Page 12

ADT7420 TEMPERATURE DATA FORMAT One LSB of the ADC corresponds to 0.0625°C in 13-bit mode or 0.0078°C in 16-bit mode. The ADC can theoretically measure a temperature range of 255°C, but the ADT7420 is guaranteed to measure a low value ...

Page 13

Preliminary Technical Data REGISTERS The ADT7420 contains 14 registers: • Nine temperature registers • A status register • register • A configuration register • An address pointer register • A software reset All registers are eight bits wide. ...

Page 14

ADT7420 STATUS REGISTER This 8-bit read-only register reflects the status of the overtempera- ture and undertemperature interrupts that can cause the CT and INT pins to go active. It also reflects the status of a temperature conversion operation. The interrupt ...

Page 15

Preliminary Technical Data T SETPOINT REGISTERS HIGH The T setpoint MSB and T setpoint LSB registers store HIGH HIGH the overtemperature limit value. An overtemperature event occurs when the temperature value stored in the temperature value register exceeds the value ...

Page 16

ADT7420 T SETPOINT REGISTER HYST This 8-bit read/write register stores the temperature hysteresis value for the and T temperature limits. The HIGH LOW CRIT temperature hysteresis value is stored in straight binary format using four LSBs. ...

Page 17

Preliminary Technical Data SERIAL INTERFACE TO INTERRUPT PIN ON MICROCONTROLLER Control of the ADT7420 is carried out via the I serial interface. The ADT7420 is connected to this bus as a slave and is under the control of a master ...

Page 18

ADT7420 WRITING DATA It is possible to write either a single byte of data or two bytes to the ADT7420, depending on which registers are to be written. Writing a single byte of data requires the serial bus address, the ...

Page 19

Preliminary Technical Data READING DATA Reading data from the ADT7420 is done in a single data byte operation for the configuration register, the status register, the T register, and the ID register. A two data byte read HYST operation is ...

Page 20

ADT7420 1 SCL SDA START ADT7410 DEVICE ADDRESS 1 SR SCL SDA REPEAT ADT7410 DEVICE ADDRESS START NOTES 1. A START CONDITION AT THE BEGINNING IS DEFINED AS A HIGH-TO-LOW TRANSITION ON SDA WHILE ...

Page 21

Preliminary Technical Data INT AND CT OUTPUTS The INT and CT pins are open-drain outputs, and both pins require a 10 kΩ pull-up resistor UNDERTEMPERATURE AND OVERTEMPERATURE DETECTION The INT and CT pins have two undertemperature/overtemperature ...

Page 22

ADT7420 (COMPARATOR MODE) POLARITY = ACTIVE LOW (INTERRUPT MODE) POLARITY = ACTIVE LOW (COMPARATOR MODE) POLARITY = ACTIVE HIGH (INTERRUPT MODE) POLARITY = ACTIVE HIGH Figure 19. INT Output Temperature Response Diagram for T TEMPERATURE –13°C –14°C –15°C –16°C –17°C ...

Page 23

Preliminary Technical Data APPLICATIONS INFORMATION THERMAL RESPONSE TIME The time required for a temperature sensor to settle to a specified accuracy is a function of the thermal mass of the sensor and the thermal conductivity between the sensor and the ...

Page 24

... Temperature Range ADT7420UCPZ −40°C to +150°C ADT7420UCPZ-R2 −40°C to +150°C ADT7420UCPZ-RL7 −40°C to +150°C EVAL-ADT7X20EBZ RoHS Compliant Part. 2 Maximum accuracy over the −20°C to +105°C temperature range refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors). ...

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