AD5175

Rev. 0 | Page 15 of 20

READ OPERATION

When reading data back from the AD5175, the user must first

issue a readback command to the device, this begins with a start

command followed by an address byte (R/W = 0), after which

the AD5175 acknowledges that it is prepared to receive data by

pulling SDA low.

Two bytes of data are then written to the AD5175, the most

significant byte followed by the least significant byte; both

of these data bytes are acknowledged by the AD5175. A stop

condition follows. These bytes contain the read instruction,

which enables readback of the RDAC register, 50-TP memory,

or the control register. The user can then read back the data

beginning 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, as shown in

. A

stop condition follows. If the master does not acknowledge the

first byte, the second byte is not transmitted by the AD5175.

Figure 27

0

19

1

99

9

1

1

0

1

1

A1

A0

R/W

0

0

C3

C2

C1

C0

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

0

19

1

99

9

1

1

0

1

1

A1

A0

R/W

0

0

X

X

X

X

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

ACK. BY

AD5175

ACK. BY

AD5175

ACK. BY

AD5175

ACK. BY

AD5175

ACK. BY

MASTER

NO ACK. BY

MASTER

SCL

SDA

SCL (CONTINUED)

SDA (CONTINUED)

SCL (CONTINUED)

SDA (CONTINUED)

START BY

MASTER

SCL

SDA

START BY

MASTER

STOP BY

MASTER

STOP BY

MASTER

FRAME 1

SERIAL BUS ADDRESS BYTE

FRAME 1

SERIAL BUS ADDRESS BYTE

FRAME 2

MOST SIGNIFICANT DATA BYTE

FRAME 2

MOST SIGNIFICANT DATA BYTE

FRAME 3

LEAST SIGNIFICANT DATA BYTE

FRAME 3

LEAST SIGNIFICANT DATA BYTE

Figure 27. Read Command