AD5121 datasheet(29/37 Pages) AD

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Data Sheet

AD5124/AD5144/AD5144A

THEORY OF OPERATION

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Rev. E | 29 of 37

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 AD5124/AD5144/AD5144A allow readback of the contents of

the RDAC register and EEPROM memory through the I2C interface

by using Command 3 (see Table 17).

When reading data back from the AD5124/AD5144/AD5144A, the

user must first issue a readback command to the device. The

readback 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 AD5124/AD5144/

AD5144A, the most significant byte followed by the least significant

byte. Both of these data bytes are acknowledged by the AD5124/

AD5144/AD5144A. 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.

The readback 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 48. A stop condition follows. If the

controller does not acknowledge the first byte, the second byte is

not transmitted by the AD5124/AD5144/AD5144A.

The AD5124/AD5144/AD5144A do not support repeat readback.

Figure 48. AD5124/AD5144/AD5144A Interface Read Command

AD5121 Datasheet(PDF) 29 Page - Analog Devices