10

LTC1662

Figure 2. Effects of Rail-to-Rail Operation On a DAC Transfer Curve. (a) Overall Transfer Function (b) Effect of Negative

OPERATIO

TYPICAL APPLICATIO S

1662 F02

INPUT CODE

OUTPUT

VOLTAGE

NEGATIVE

OFFSET

0V

512

0

1023

INPUT CODE

OUTPUT

VOLTAGE

INPUT CODE

OUTPUT

VOLTAGE

POSITIVE

FSE

(2c)

(2a)

(2b)

+

–

LT1495

4

3.3V

3.3V

8

2

1

CS/LD

SDI

SCK

46

REF

3

2

1

8

5

GND

7

3

0.1

µF

R2

FINE

1.1M

LTC1662

U1

DAC A

DAC B

R1

COARSE

11k

3.3V

0.1

µF

0.1

µF

2

0.1

µF

LTC1258-2.5

1

2.5V

4

R2

1.1M

R1

11k

1662 F04

+

•

CODE A

1024

CODE B

1024

R1

R2

()

2.5V

+

•

=

CODE A

1024

CODE B

1024

1

100

()

Micropower Trim Circuit with Coarse/Fine Adjustment. Total Supply Current Is 9.5

µA