LTC1448 Linear Technology, LTC1448 Datasheet - Page 7

• Manufacturer Part Number: LTC1448
• Description: Dual 12-Bit Rail-to-Rail Micropower DAC
• Manufacturer: Linear Technology

Rail-to-Rail Output Considerations
In any rail-to-rail DAC, the output swing is limited to
voltages within the supply range.
If the DAC offset is negative, the output for the lowest
codes limits at 0V as shown in Figure 1b.
Similarly, limiting can occur near full scale when the REF
pin is tied to V
APPLICATIONS
NEGATIVE
OFFSET
VOLTAGE
OUTPUT
Figure 1. Effects of Rail-to-Rail Operation on a DAC Transfer Curve: (a) Overall Transfer Function, (b) Effect of Negative
Offset for Codes Near Zero Scale, (c) Effect of Positive Full-Scale Error for Input Codes Near Full Scale When V
0V
CC
. If V
U
REF
= V
INFORMATION
INPUT CODE
U
CC
(b)
and the DAC full-scale error
W
VOLTAGE
OUTPUT
0
U
INPUT CODE
V
REF
2048
(a)
= V
(FSE) is positive, the output for the highest codes limits at
V
if V
Offset and linearity are defined and tested over the region
of the DAC transfer function where no output limiting can
occur.
CC
CC
REF
as shown in Figure 1c. No full-scale limiting can occur
is less than V
4095
CC
– FSE.
V
REF
INPUT CODE
= V
(c)
CC
LTC1448
REF
= V
CC
OUTPUT
VOLTAGE
POSITIVE
FSE
1448 F01
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