Datasheet

DAC7678
www.ti.com SBAS493B –FEBRUARY 2010–REVISED JULY 2012
Flexible Mode (see Table 3, Table 4, Table 5 and
internal reference operating mode. When performing
Table 6)
a power cycle to reset the device, the internal
reference is switched off (default mode). In the
Enabling Internal Reference:
default mode, the internal reference remains powered
Method 1) To enable the internal reference, write the
down until a valid write sequence is applied to power
24-bit serial command shown in Table 3 after
up the internal reference. When the internal reference
properly addressing the device. When performing a
is powered up in flexible mode, it remains powered
power cycle to reset the device, the internal reference
up, regardless of the state of the DACs.
is switched off (default mode). In the default mode,
Disabling Internal Reference:
the internal reference is powered down until a valid
write sequence is applied to power up the internal
To disable the internal reference, write the 24-bit
reference. If the internal reference is powered up, it
serial command shown in Table 5 after properly
automatically powers down when all DACs power
addressing the device. When performing a power
down in any of the power-down modes (see the
cycle to reset the device, the internal reference is
Power Down Modes section). The internal reference
switched off (default mode). When the internal
powers up automatically when any DAC is powered
reference is operated in Flexible mode, Static mode
up.
is disabled and does not work. To switch from
Flexible mode to Static mode, use the command
Method 2) To always enable the internal reference,
shown in Table 6.
write the 24-bit serial command shown in Table 4
after properly addressing the device. When the
internal reference is always enabled, any power-down
command to the DAC channels does not change the
Table 3. Write Sequence for Enabling Internal Reference (Flexible Mode)
(Internal Reference Powered On)
COMMAND AND ACCESS BYTE MOST SIGNIFICANT DATA BYTE LEAST SIGNIFICANT BYTE
C3 C2 C1 C0 A3 A2 A1 A0 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
1 0 0 1 X X X X X 1 0 0 X X X X X X X X X X X X
Table 4. Write Sequence for Enabling Internal Reference (Flexible Mode)
(Internal Reference Always Powered On)
COMMAND AND ACCESS BYTE MOST SIGNIFICANT DATA BYTE LEAST SIGNIFICANT BYTE
C3 C2 C1 C0 A3 A2 A1 A0 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
1 0 0 1 X X X X X 1 0 1 X X X X X X X X X X X X
Table 5. Write Sequence for Disabling Internal Reference (Flexible Mode)
(Internal Reference Always Powered Down)
COMMAND AND ACCESS BYTE MOST SIGNIFICANT DATA BYTE LEAST SIGNIFICANT BYTE
C3 C2 C1 C0 A3 A2 A1 A0 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
1 0 0 1 X X X X X 1 1 0 X X X X X X X 0 X X X X
Table 6. Write Sequence for Switching from Flexible Mode to Static Mode for Internal Reference
COMMAND AND ACCESS BYTE MOST SIGNIFICANT DATA BYTE LEAST SIGNIFICANT BYTE
C3 C2 C1 C0 A3 A2 A1 A0 DB15 DB14 DB13 DB12 DB11 DB10 DB9 DB8 DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
1 0 0 1 X X X X X 0 X X X X X X X X X X X X X X
Copyright © 2010–2012, Texas Instruments Incorporated Submit Documentation Feedback 25
Product Folder Link(s): DAC7678