AD5142ABCPZ100-RL7 datasheet(21/29 Pages) AD

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Data Sheet

AD5122A/AD5142A

THEORY OF OPERATION

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Rev. D | 21 of 29

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 AD5122A/AD5142A allow readback of the contents of the

RDAC register and EEPROM memory through the I2C interface by

using Command 3 (see Table 13).

When reading data back from the AD5122A/AD5142A, the user

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

command 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 AD5122A/AD5142A, the

most significant byte followed by the least significant byte. Both

of these data bytes are acknowledged by the AD5122A/AD5142A.

A stop condition follows. These bytes contain the read instruction,

which enables readback of the RDAC register and EEPROM mem-

ory. 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 40. A stop condition follows. If the controller does not

acknowledge the first byte, the second byte is not transmitted by

the AD5122A/AD5142A.

The AD5122A/AD5142A do not support repeat readback.

Figure 40. AD5122A/AD5142A Interface Read Command

AD5142ABCPZ100-RL7 Datasheet(PDF) 21 Page - Analog Devices