DS2431Q+T&R Maxim Integrated Products, DS2431Q+T&R Datasheet - Page 8

• Manufacturer Part Number: DS2431Q+T&R
• Description: IC EEPROM 1KBIT 6TDFN
• Manufacturer: Maxim Integrated Products

Specifications of DS2431Q+T&R

• Format - Memory: EEPROMs - Serial
• Memory Type: EEPROM
• Memory Size: 1K (256 x 4)
• Interface: 1-Wire Serial
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 6-TDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -
• Speed: -

1024-Bit, 1-Wire EEPROM
Contact the factory to set up and register a custom
manufacturer ID. The last row is reserved for future use.
It is undefined in terms of R/W functionality and should
not be used.
In addition to the main EEPROM array, an 8-byte
volatile scratchpad is included. Writes to the EEPROM
array are a two-step process. First, data is written to the
scratchpad and then copied into the main array. This
allows the user to first verify the data written to the
scratchpad prior to copying into the main array. The
device only supports full row (8-byte) copy operations.
For data in the scratchpad to be valid for a copy opera-
tion, the address supplied with a Write Scratchpad
command must start on a row boundary, and 8 full
bytes must be written into the scratchpad.
The protection control registers determine how incom-
ing data on a Write Scratchpad command is loaded
into the scratchpad. A protection setting of 55h (write
protect) causes the incoming data to be ignored and
the target address main memory data to be loaded into
the scratchpad. A protection setting of AAh (EPROM
mode) causes the logical AND of incoming data and
target address main memory data to be loaded into the
scratchpad. Any other protection control register set-
ting leaves the associated memory page open for unre-
stricted write access. Protection-control byte settings of
55h or AAh also write protect the protection-control
byte. The protection-control byte setting of 55h does
not block the copy. This allows write-protected data to
be refreshed (i.e., reprogrammed with the current data)
in the device.
The copy-protection byte is used for a higher level of
security and should only be used after all other protec-
tion control bytes, user bytes, and write-protected
pages are set to their final value. If the copy-protection
Figure 6. Address Registers
8
_______________________________________________________________________________________
TARGET ADDRESS (TA1)
TARGET ADDRESS (TA2)
ENDING ADDRESS WITH
DATA STATUS (E/S)
(READ ONLY)
BIT #
T15
AA
T7
7
T14
T6
6
0
T13
T5
PF
5
byte is set to 55h or AAh, all copy attempts to the regis-
ter row and user-byte row are blocked. In addition, all
copy attempts to write-protected main memory pages
(i.e., refresh) are blocked.
The DS2431 employs three address registers: TA1, TA2,
and E/S (Figure 6). These registers are common to
many other 1-Wire devices but operate slightly different-
ly with the DS2431. Registers TA1 and TA2 must be
loaded with the target address to which the data is writ-
ten or from which data is read. Register E/S is a read-
only transfer-status register used to verify data integrity
with write commands. E/S bits E[2:0] are loaded with the
incoming T[2:0] on a Write Scratchpad command and
increment on each subsequent data byte. This is, in
effect, a byte-ending offset counter within the 8-byte
scratchpad. Bit 5 of the E/S register, called PF, is a logic
1 if the data in the scratchpad is not valid due to a loss
of power or if the master sends fewer bytes than needed
to reach the end of the scratchpad. For a valid write to
the scratchpad, T[2:0] must be 0 and the master must
have sent 8 data bytes. Bits 3, 4, and 6 have no func-
tion; they always read 0. The highest valued bit of the
E/S register, called authorization accepted (AA), acts as
a flag to indicate that the data stored in the scratchpad
has already been copied to the target memory address.
Writing data to the scratchpad clears this flag.
To write data to the DS2431, the scratchpad must be
used as intermediate storage. First, the master issues
the Write Scratchpad command to specify the desired
target address, followed by the data to be written to the
scratchpad. Note that Copy Scratchpad commands
must be performed on 8-byte boundaries, i.e., the three
T12
T4
4
0
Address Registers and Transfer Status
T11
T3
3
0
T10
T2
E2
2
Writing with Verification
T1
T9
E1
1
T0
T8
E0
0