Rainbow Electronics DS28EA00 - Manual

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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 nonvolatile (NV), user-programmable
upper and lower trigger points. Each DS28EA00 has
its unique 64-bit registration 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 for communication. The
improved 1-Wire front end with hysteresis and glitch
filter enables the DS28EA00 to perform reliably in
large 1-Wire networks. Unlike other 1-Wire thermo-
meters, 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 output. 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
TYPICAL OPERATING CIRCUIT
V
DD
1-Wire
Master
PX.Y
(Micro-
controller)
#1 #2 #3
V DD
IO
DS28EA00
PIOB PIOA
GND
V DD
IO
DS28EA00
PIOB PIOA
GND
V DD
IO
DS28EA00
PIOB PIOA
GND
Schematic shows PIOs wired for sequence detect function.
Commands, Registers, and Modes are capitalized for
clarity.
1-Wire is a registered trademark of Dallas Semiconductor.
SPECIAL FEATURES
ƒ Digital Thermometer Measures Temperatures
from -40°C to +85°C
ƒ Thermometer Resolution is User-Selectable
from 9 to 12 Bits
ƒ Unique 1-Wire Interface Requires Only One
Port Pin for Communication
ƒ Each Device has a Unique 64-Bit Factory-
Lasered Registration Number
ƒ ROM Multidrop Capability Simplifies
Distributed Temperature-Sensing
Applications
ƒ Improved 1-Wire Interface with Hysteresis
and Glitch Filter
ƒ User-Definable Nonvolatile (NV) Alarm
Threshold Settings/User Bytes
ƒ Alarm Search Command to Quickly Identify
Devices Whose Temperature is Outside of
Programmed Limits
ƒ Standard and Overdrive 1-Wire Speed
ƒ Two General-Purpose Programmable IO (PIO)
Pins
ƒ Chain Function Sharing the PIO Pins to
Detect Physical Sequence of Devices in
Network
ƒ Operating Range: 3.0V to 5.5V, -40°C to +85°C
ƒ Can be Powered from Data Line
ƒ 8-Pin µSOP Package
ORDERING INFORMATION
PART TEMP RANGE PACKAGE
DS28EA00U+ -40 to +85°C 8-pin µSOP
DS28EA00U+T -40 to +85°C Tape & Reel
+ Denotes lead-free package.
PIN CONFIGURATION
1
2
3
4
8
7
6
5
V
DD
PIOB
PIOA
NC
IO
NC
NC
GND
+
8 pin µSOP
Package Outline Drawing 21-0036
DS28EA00
1-Wire Digital Thermometer
with Sequence Detect and PIO
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