Datasheet

AD5251/AD5252 Data Sheet
Rev. D | Page 16 of 28
RDAC/EEMEM Write
Setting the wiper position requires an RDAC write operation.
The single write operation is shown in Figure 27, and the
consecutive write operation is shown in Figure 28. In the
consecutive write operation, if the
RDAC
is selected and the
address starts at 00001, the first data byte goes to RDAC1 and
the second data byte goes to RDAC3. The RDAC address is
shown in Table 6.
While the RDAC wiper setting is controlled by a specific RDAC
register, each RDAC register corresponds to a specific EEMEM
location, which provides nonvolatile wiper storage functionality.
The addresses are shown in Table 7. The single and consecutive
write operations also apply to EEMEM write operations.
There are 12 nonvolatile memory locations: EEMEM4 to
EEMEM15. Users can store a total of 12 bytes of information,
such as memory data for other components, look-up tables, or
system identification information.
In a write operation to the EEMEM registers, the device disables
the I
2
C interface during the internal write cycle. Acknowledge
polling is required to determine the completion of the write
cycle. See the EEMEM Write-Acknowledge Polling section.
RDAC/EEMEM Read
The AD5251/AD5252 provide two different RDAC or EEMEM
read operations. For example, Figure 29 shows the method of
reading the RDAC0 to RDAC3 contents without specifying the
address, assuming Address RDAC0 was already selected in the
previous operation. If an RDAC_N address other than RDAC0
was previously selected, readback starts with Address N, followed
by N + 1, and so on.
Figure 30 illustrates a random RDAC or EEMEM read
operation. This operation allows users to specify which RDAC
or EEMEM register is read by issuing a dummy write command
to change the RDAC address pointer and then proceeding with
the RDAC read operation at the new address location.
Table 7. Addresses for Writing (Storing) RDAC Settings
and User-Defined Data to EEMEM Registers
(R/
W
= 0, CMD/
REG
= 0, EE/
RDAC
= 1)
A4 A3 A2 A1 A0
Data Byte Description
0 0 0 0 0 Reserved
0 0 0 0 1 Store RDAC1 setting to EEMEM1
1
0 0 0 1 0 Reserved
0 0 0 1 1 Store RDAC3 setting to EEMEM3
1
0
0
1
0
0
Store user data to EEMEM4
0
0
1
0
1
Store user data to EEMEM5
0 0 1 1 0 Store user data to EEMEM6
0 0 1 1 1 Store user data to EEMEM7
0 1 0 0 0 Store user data to EEMEM8
0 1 0 0 1 Store user data to EEMEM9
0 1 0 1 0 Store user data to EEMEM10
0 1 0 1 1 Store user data to EEMEM11
0 1 1 0 0 Store user data to EEMEM12
0 1 1 0 1 Store user data to EEMEM13
0 1 1 1 0 Store user data to EEMEM14
0 1 1 1 1 Store user data to EEMEM15
1
Users can store any of the 64 RDAC settings directly to the EEMEM for
AD5251, or any of the 256 RDAC settings directly to the EEMEM for the
AD5252. This is not limited to current RDAC wiper setting.
Table 8. Addresses for Reading (Restoring) RDAC Settings
and User Data from EEMEM
(R/
W
= 1, CMD/
REG
= 0, EE/
RDAC
= 1)
A4 A3 A2 A1 A0 Data Byte Description
0 0 0 0 0 Reserved
0 0 0 0 1 Read RDAC1 setting from EEMEM1
0 0 0 1 0 Reserved
0 0 0 1 1 Read RDAC3 setting from EEMEM3
0 0 1 0 0 Read user data from EEMEM4
0 0 1 0 1 Read user data from EEMEM5
0 0 1 1 0 Read user data from EEMEM6
0 0 1 1 1 Read user data from EEMEM7
0 1 0 0 0 Read user data from EEMEM8
0 1 0 0 1 Read user data from EEMEM9
0 1 0 1 0 Read user data from EEMEM10
0 1 0 1 1 Read user data from EEMEM11
0
1
1
0
0
Read user data from EEMEM12
0
1
1
0
1
Read user data from EEMEM13
0 1 1 1 0 Read user data from EEMEM14
0 1 1 1 1 Read user data from EEMEM15