DAC0830LCM National Semiconductor, DAC0830LCM Datasheet - Page 13

• Manufacturer Part Number: DAC0830LCM
• Description: 8-Bit P Compatible/ Double-Buffered D to A Converters
• Manufacturer: National Semiconductor

DAC0830 Series Application Hints
2.6 Full-Scale Adjustment
In the case where the matching of R
R-2R ladder (typically
curacy in a particular application, the V
adjusted or an external resistor and potentiometer can be
added as shown in Figure 10 to provide a full-scale adjust-
ment.
The temperature coefficients of the resistors used for this ad-
justment are of an important concern. To prevent degrada-
tion of the gain error temperature coefficient by the external
±
0.2%) is insufficient for full-scale ac-
*THESE RESISTORS ARE AVAILABLE FROM BECKMAN INSTRUMENTS, INC. AS THEIR PART NO. 694-3-R10K-D
MSB
1
1
1
0
0
0
1
1
0
1
0
0
Input Code
1
0
0
1
1
0
fb
to the R value of the
1
0
0
1
1
0
*2.4 k
INSURE STABILITY
REF
LF356
LF351
LF357
OP Amp
1
0
0
1
1
0
voltage can be
RESISTOR ADDED FROM−INPUT TO GROUND TO
1
0
0
1
1
0
*
1
0
0
1
1
0
LSB
1
0
0
1
1
0
22 pF
22 pF
10 pF
FIGURE 8.
FIGURE 9.
C
(Continued)
C
13
+V
resistors, their temperature coefficients ideally would have to
match that of the internal DAC resistors, which is a highly im-
practical constraint. For the values shown in Figure 10 , if the
resistor and the potentiometer each had a temperature coef-
ficient of
perature coefficent would be degraded a maximum of
0.0025%/˚C for an adjustment pot setting of less than 3% of
R
(O to Full Scale)
REF
fb
.
IDEAL V
4 µs
5 µs
2 µs
t
s
±
100 ppm/˚C maximum, the overall gain error tem-
OUT
−V
REF
DS005608-39
DS005608-40
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