MAX509 Maxim, MAX509 Datasheet - Page 15

• Manufacturer Part Number: MAX509
• Description: Quad / Serial 8-Bit DACs with Rail-to-Rail Outputs
• Manufacturer: Maxim

In unipolar operation, the output voltages and the refer-
ence input(s) are the same polarity. Figures 11 and 12
show the MAX509/MAX510 unipolar configurations.
Both devices can be operated from a single supply if
the reference inputs are positive. If dual supplies are
used, the reference input can vary from V
Table 2 shows the unipolar code.
Figure 9. Suggested MAX509 PC Board Layout for Minimizing
Crosstalk (Bottom View)
Table 2. Unipolar Code Table
Note: 1LSB = (V
Unipolar-Output, 2-Quadrant Multiplication
1 1 1 1
1 0 0 0
1 0 0 0
0 1 1 1
0 0 0 0
0 0 0 0
MSB
DAC CONTENTS
OUTC
OUTD
REFC
REFD
V
DD
REF
______________________________________________________________________________________
1 1 1 1
0 0 0 1
0 0 0 0
1 1 1 1
0 0 0 1
0 0 0 0
) (2 -8 ) = +V
LSB
SYSTEM GND
REF
+V
REF
(
+V
+V
+V
+V
––––
256
ANALOG
1
OUTPUT
(
REF
REF
REF
REF
––––
128
256
0V
)
(
(
(
(
––––
––––
––––
––––
OUTB
OUTA
V
REFB
REFA
AGND
)
255
256
129
256
256
256
SS
127
SS
1
= + –
)
)
)
)
to V
V
REF
2
–––
DD
.
with Rail-to-Rail Outputs
Quad, Serial 8-Bit DACs
Bipolar-output, 2-quadrant multiplication is achieved by
offsetting AGND positively or negatively. Table 3 shows
the bipolar code.
AGND can be biased above DGND to provide an arbi-
trary nonzero output voltage for a 0 input code, as
shown in Figure 13. The output voltage at OUTA is:
Figure 10. Suggested MAX510 PC Board Layout for Minimizing
Crosstalk (Bottom View)
Table 3. Bipolar Code Table
Bipolar-Output, 2-Quadrant Multiplication
1 1 1 1
1 0 0 0
1 0 0 0
0 1 1 1
0 0 0 0
0 0 0 0
MSB
DAC CONTENTS
REFCD
OUTC
OUTD
V
V
DD
OUTA
= V
1 1 1 1
0 0 0 1
0 0 0 0
1 1 1 1
0 0 0 1
0 0 0 0
LSB
BIAS
SYSTEM GND
+ (NB/256)(V
-V
REF
+V
+V
-V
-V
ANALOG
IN
OUTPUT
REF
REF
REF
REF
(
),
––––
128
128
0V
(
(
(
(
––––
––––
127
––––
128
––––
128
127
128
128
OUTB
OUTA
V
AGND
REFAB
1
)
SS
1
= -V
)
)
)
)
REF
15