Datasheet

AD5175
Rev. A | 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
91
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
91
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
SD
A
SCL (CONTINUED)
SDA (CONTINUED)
SCL (CONTINUED)
SDA (CONTINUED)
START BY
MASTER
SCL
SD
A
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
08719-007
Figure 27. Read Command