AD5253 datasheet(16/32 Pages) AD

16 / 32 page

AD5253/AD5254

Data Sheet

Rev. C | Page 16 of 32

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 0, the first data byte goes to RDAC0, the second

data byte goes to RDAC1, the third data byte goes to RDAC2,

and the fourth data byte goes to RDAC3. This operation can be

continued for up to eight addresses with four unused addresses;

it then loops back to RDAC0. If the address starts at any of the

eight valid addresses, N, the data first goes to RDAC_N,

RDAC_N + 1, and so on; it loops back to RDAC0 after the

eighth address. 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 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 I2C 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 AD5253/AD5254 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)

Data Byte Description

Store RDAC0 setting to EEMEM01

Store RDAC1 setting to EEMEM11

Store RDAC2 setting to EEMEM21

Store RDAC3 setting to EEMEM31

Store user data to EEMEM4

Store user data to EEMEM5

Store user data to EEMEM6

Store user data to EEMEM7

Store user data to EEMEM8

Store user data to EEMEM9

Store user data to EEMEM10

Store user data to EEMEM11

Store user data to EEMEM12

Store user data to EEMEM13

Store user data to EEMEM14

Store user data to EEMEM15

Table 8. Addresses for Reading (Restoring) RDAC Settings

and User Data from EEMEM

(R/W = 1, CMD/REG = 0, EE/RDAC = 1)

Data Byte Description

Read RDAC0 setting from EEMEM0

Read RDAC1 setting from EEMEM1

Read RDAC2 setting from EEMEM2

Read RDAC3 setting from EEMEM3

Read User data from EEMEM4

Read user data from EEMEM5

Read user data from EEMEM6

Read user data from EEMEM7

Read user data from EEMEM8

Read user data from EEMEM9

Read user data from EEMEM10

Read user data from EEMEM11

Read user data from EEMEM12

Read user data from EEMEM13

Read user data from EEMEM14

Read user data from EEMEM15

1 Users can store any of the 64 RDAC settings for AD5253 or any of the 256

RDAC settings for the AD5254 directly to the EEMEM. This is not limited to

current RDAC wiper setting.

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