LTC1663
10
1663fd
APPLICATIONS INFORMATION
Offset and linearity are defi ned and tested over the region
of the DAC transfer function where no output limiting can
occur.
Internal Reference
In applications where a predictable output is required
that is independent of supply voltage, the LTC1663 has a
user-selectable internal reference. Selecting the internal
reference will set the full-scale output voltage to 2.5V. This
can be useful in applications where the supply voltage is
poorly regulated.
Using the LT
®
1460 Micropower Series Reference as a
Power Supply for the LTC1663
In applications where the advantages of using the internal
reference are required but the full-scale range needs to
be greater than 2.5V, an external series reference can be
used. The LT1460 is ideal for use as a power supply for
the LTC1663 and can provide 3V, 3.3V and 5V full-scale
output voltage ranges. The LT1460 provides accuracy, noise
immunity and extended supply range to the LTC1663 when
the LTC1663 is operated ratiometric to V
CC
. Since both
parts are available in SOT-23 packages, the PC board space
for this application is extremely small. See Figure 2.
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
REF
= V
CC
Figure 2. LT1460 As Power Supply for the LTC1663
1663 F01
INPUT CODE
(b)
OUTPUT
VOLTAGE
NEGATIVE
OFFSET
0V
5120 1023
INPUT CODE
OUTPUT
VOLTAGE
(a)
V
REF
= V
CC
V
REF
= V
CC
(c)
INPUT CODE
OUTPUT
VOLTAGE
POSITIVE
FSE
IN
0.1μF
1
5 (4)
1 (1)
2
4 (5)
2 (7)LTC1663 PIN NUMBERS IN PARENTHESES
REFER TO MSOP PACKAGE
3 (8)
3
3.9V TO 20V
3V
OUT
TO
μP
SCL
1663 F02
V
CC
GND
SDA
OUTLTC1663
0V ≤ V
OUT
≤ 3V
GND
LT1460S3-3
0.01μF
+
