DS28EA00 Datasheet, PDF (1/29 Pages) Dallas Semiconductor – 1-Wire Digital Thermometer with Sequence Detect and PIO

Rev 2; 4/09
1-Wire Digital Thermometer with
Sequence Detect and PIO
General Description
The DS28EA00 is a digital thermometer with 9-bit (0.5°C)
to 12-bit (1/16°C) resolution and alarm function with non-
volatile (NV), user-programmable upper and lower trigger
points. Each DS28EA00 has its own unique 64-bit regis-
tration number that is factory programmed into the chip.
Data is transferred serially through the 1-Wire^® protocol,
which requires only one data line and a ground reference
for communication. The improved 1-Wire front-end with
hysteresis and glitch filter enables the DS28EA00 to per-
form reliably in large 1-Wire networks. Unlike other 1-Wire
thermometers, the DS28EA00 has two additional pins to
implement a sequence-detect function. This feature
allows the user to discover the registration numbers
according to the physical device location in a chain, e.g.,
to measure the temperature in a storage tower at different
height. If the sequence-detect function is not needed,
these pins can be used as general-purpose input or out-
put. The DS28EA00 can derive the power for its operation
directly from the data line (“parasite power”), eliminating
the need for an external power supply.
Applications
Data Communication Equipment
Process Temperature Monitoring
HVAC Systems
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
DS28EA00U+
-40°C to +85°C
8 μSOP
DS28EA00U+T&R
-40°C to +85°C
8 μSOP
+Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
V_DD
1-Wire
MASTER
PX. Y
MICROCONTROLLER
#1
V_DD
IO
DS28EA00
PIOB
PIOA
GND
Features
♦ Digital Thermometer Measures Temperatures
from -40°C to +85°C
♦ Thermometer Resolution is User Selectable from
9 to 12 Bits
♦ Unique 1-Wire Interface Requires Only One Port
Pin for Communication
♦ Each Device Has a Unique 64-Bit, Factory-
Lasered Registration Number
♦ Multidrop Capability Simplifies Distributed
Temperature-Sensing Applications
♦ Improved 1-Wire Interface with Hysteresis and
Glitch Filter
♦ User-Definable NV Alarm Threshold Settings/User
Bytes
♦ Alarm Search Command to Quickly Identify
Devices Whose Temperature is Outside of
Programmed Limits
♦ Standard and Overdrive 1-Wire Speed
♦ Two General-Purpose Programmable IO (PIO) Pins
♦ Chain Function Sharing the PIO Pins to Detect
Physical Sequence of Devices in Network
♦ Operating Range: +3.0V to +5.5V, -40°C to +85°C
♦ Can Be Powered from Data Line
♦ 8-Pin µSOP Package
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
#2
V_DD
IO
DS28EA00
PIOB
PIOA
GND
#3
V_DD
IO
DS28EA00
PIOB
PIOA
GND
NOTE: SCHEMATIC SHOWS PIO PINS WIRED FOR SEQUENCE-DETECT FUNCTION.
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.