dac8408ft Analog Devices, Inc., dac8408ft Datasheet - Page 11

• Manufacturer Part Number: dac8408ft
• Description: Quad 8-bit Multiplying Cmos D/a Converter With Memory
• Manufacturer: Analog Devices, Inc.

REV. A
DAC Data Input
MSB
1 1 1 1 1 1 1 1
1 0 0 0 0 0 0 1
1 0 0 0 0 0 0 0
0 1 1 1 1 1 1 1
0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0
NOTE
1 LSB = (2
Table II. Bipolar (Offset Binary) Code Table
(Refer to Figure 7)
–7
) (V
REF
LSB
) =
128
1
(V
REF
)
Figure 7. Quad DAC Bipolar Operation (4-Quadrant Multiplication)
Analog Output
(DAC A OR DAC B)
+V
+V
0
–V
–V
–V
REF
REF
REF
REF
REF
128
127
128
128
128
127
128
128
1
1
–11–
APPLICATION HINTS
General Ground Management: AC or transient voltages be-
tween AGND and DGND can appear as noise at the DAC8408’s
analog output. Note that in Figures 5 and 6, I
I
ommended that AGND and DGND be tied together at the
DAC8408 socket. In systems where AGND and DGND are tied
together on the backplane, two diodes (1N914 or equivalent)
should be connected in inverse parallel between AGND and
DGND.
Write Enable Timing: During the period when both DS and
R/W are held low, the DAC latches are transparent and the ana-
log output responds directly to the digital data input. To pre-
vent unwanted variations of the analog output, the R/W should
not go low until the data bus is fully settled (DATA VALID).
OUT 2C
/I
OUT 2D
are connected to AGND. Therefore, it is rec-
DAC8408
OUT2A
/I
OUT2B
and