OP490

Rev. E | Page 11 of 16

MICROPOWER SINGLE-SUPPLY QUAD VOLTAGE-

OUTPUT 8-BIT DAC

The circuit shown in Figure 23 uses the DAC8408 CMOS quad

8-bit DAC, and the OP490 to form a single-supply quad voltage

output DAC with a supply drain of only 140 μA. The DAC8408

is used in voltage switching mode and each DAC has an output

resistance (≈10 kΩ) independent of the digital input code. The

output amplifiers act as buffers to avoid loading the DACs. The

100 kΩ resistors ensure that the OP490 outputs swing below 0.8 V

when required.

DGND

A/B

28

REFERENCE

VOLTAGE

1.5V

DAC DATA BUS

PIN 9 (LSB) TO PIN 16 (MSB)

DAC A

1/4

DAC8408

OP490

DAC8408

DAC B

1/4

DAC8408

DAC C

1/4

DAC8408

DAC D

1/4

DAC8408

R4

100k

Ω

R3

100k

Ω

R2

100k

Ω

R1

100k

Ω

1

4

11

7

14

8

+5V

2

3

6

5

13

12

9

10

21

23

24

25

6

5

4

27

8

2

19

18

DIGITAL

CONTROL

SIGNALS

20

17

DS2

DS1

R/W

1/4

OP490

A

1/4

OP490

B

1/4

OP490

C

1/4

OP490

D

Figure 23. Micropower Single-Supply Quad Voltage Output 8-Bit DAC