LTC1663

10

1663fd

APPLICATIONS INFORMATION

Offset and linearity are defined 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.

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

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

Figure 2. LT1460 As Power Supply for the LTC1663

1663 F01

INPUT CODE

(b)

OUTPUT

VOLTAGE

NEGATIVE

OFFSET

0V

512

0

1023

INPUT CODE

OUTPUT

VOLTAGE

(a)

(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

GND

SDA

OUT

LTC1663

GND

LT1460S3-3

0.01μF

+