Datasheet

1-Wire Digital Thermometer with
Sequence Detect and PIO
DS28EA00
Maxim Integrated 7
MSB
8-BIT
CRC CODE
48-BIT SERIAL NUMBER
MSB MSBLSB
LSB
LSB
8-BIT FAMILY CODE
(42h)
MSBLSB
Figure 2. 64-Bit Registration Number
1ST
STAGE
2ND
STAGE
3RD
STAGE
4TH
STAGE
7TH
STAGE
8TH
STAGE
6TH
STAGE
5TH
STAGE
X
0
X
1
X
2
X
3
X
4
POLYNOMIAL = X
8
+ X
5
+ X
4
+ 1
INPUT DATA
X
5
X
6
X
7
X
8
Figure 3. 1-Wire CRC Generator
SCRATCHPAD (POWER-UP STATE)
BYTE
ADDRESS
TEMPERATURE LSB (50h)0
TEMPERATURE MSB (05h)1
TH REGISTER OR USER BYTE 1*2
TL REGISTER OR USER BYTE 2*
*POWER-UP STATE DEPENDS ON VALUE(S) STORED IN EEPROM.
3
CONFIGURATION REGISTER*4
RESERVED (FFh)5
RESERVED (0Ch)6
RESERVED (10h)
BACKUP EEPROM
N/A
N/A
TH REGISTER OR USER BYTE 1
TL REGISTER OR USER BYTE 2
CONFIGURATION REGISTER
N/A
N/A
N/A7
Figure 4. Memory Map
Memory Description
The memory map of the DS28EA00 is shown in Figure 4.
It consists of an 8-byte scratchpad and 3 bytes of back-
up EEPROM. The first 2 bytes form the Temperature
Readout register, which is updated after a temperature
conversion and is read only. The next 3 bytes are user-
writable; they contain the Temperature High (TH) and the
Temperature Low (TL) Alarm register and a Configuration
register. The remaining 3 bytes are “reserved.” They
power up with constant data and cannot be written by
the user. The TH, TL, and Configuration register data in
the scratchpad control the resolution of a temperature
conversion and decide whether a temperature is consid-
ered as “alarming.” TH, TL, and Configuration can be
copied to the EEPROM to become nonvolatile. The
scratchpad is automatically loaded with EEPROM data
when the DS28EA00 powers up.