Datasheet

DAC7678
SBAS493B –FEBRUARY 2010–REVISED JULY 2012 www.ti.com
Table 13. MSDB
MSB LSB
DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8
Most Significant Data Byte (MSDB)
2. Then send a command byte for the register to be
Broadcast Address Byte
read. The device will acknowledge this event
again.
Broadcast addressing, see Table 15, is also
supported by DAC7678. Broadcast addressing can 3. Then send a repeated start with the slave
be used for synchronously updating or powering address and the R/W bit set to '1' for reading.
down multiple DAC7678 devices. DAC7678 is The device will also acknowledge this event.
designed to work with other members of the
4. Then the device writes the MSDB byte of the
DACx578 family to support multichannel synchronous
addressed register. The master should
update. Using the broadcast address, DAC7678
acknowledge this byte. Finally, the device writes
responds regardless of the states of the address pins.
out the LSDB of the register as shown in
Broadcast is supported only in write mode (Master
Table 16.
writes to DAC7678).
An alternative reading method allows for reading back
the value of the last register written. The sequence is
DAC7678 I
2
C READ SEQUENCE
a start/repeated start with slave address and the R/W
To read any register other than the power-down
bit set to '1', and the two bytes of the last register are
register the following command sequence should be
read out.
used:
Note that it is not possible to use the broadcast
1. Send a start or repeated start command with a
address for reading.
slave address and the R/W bit set to '0' for
writing. The device will acknowledge this event.
Table 14. LSDB
MSB LSB
DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
Least Significant Data Byte (LSDB)
Table 15. Broadcast Address Byte
MSB LSB
1 0 0 0 1 1 1 0
Table 16. Read Sequence
S MSB … R/W(0) ACK MSB … LSB ACK Sr MSB … R/W(1) ACK MSB … LSB ACK MSB … LSB ACK
Address Byte Command/Access Byte Sr Address Byte MSDB LSDB
From master Slave From master Slave From master slave From Slave Master From Slave Master
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