AD5121 datasheet(23/30 Pages) AD

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Data Sheet

AD5121/AD5141

THEORY OF OPERATION

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Rev. E | 23 of 30

EEPROM Write Acknowledge Polling

After each write operation to the EEPROM, an internal write cycle

begins. The I2C interface of the device is disabled. To determine

if the internal write cycle is complete and the I2C interface is

enabled, interface polling can be executed. I2C interface polling can

be conducted by sending a start condition, followed by the target

address and the write bit. If the I2C interface responds with an

acknowledge, the write cycle is complete, and the interface is ready

to proceed with further operations. Otherwise, I2C interface polling

can be repeated until it succeeds.

Read Operation

The AD5121/AD5141 allow readback of the contents of the RDAC

Command 3 (see Table 13).

When reading data back from the AD5121/AD5141, the user must

first issue a readback command to the device. The readback com-

mand begins with a start command, followed by an address byte

(R/W = 0), after which the device acknowledges that it is prepared

to receive data by pulling SDA low.

Two bytes of data are then written to the AD5121/AD5141, the

most significant byte followed by the least significant byte. Both of

these data bytes are acknowledged by the AD5121/AD5141. A stop

condition follows. These bytes contain the read instruction, which

enables readback of the RDAC register and EEPROM memory.

The user can then read back the data. This begins with a start

command followed by an address byte (R/W = 1), after which the

device acknowledges that it is prepared to transmit data by pulling

SDA low. Two bytes of data are then read from the device, which

are both acknowledged by the controller, as shown in Figure 44.

A stop condition follows. If the controller does not acknowledge

the first byte, the second byte is not transmitted by the AD5121/

AD5141.

The AD5121/AD5141 do not support repeat readback.

Figure 44. AD5121/AD5141 Interface Read Command

AD5121 Datasheet(PDF) 23 Page - Analog Devices