DAC8512

–12–

REV. A

9

18

1

2

17

R1

100k

7

6

R2

5k

Ω

P1

100k

Ω

5

4

11

0.1

µF

–15V

AMP05

10

R

CS

100

Ω

0mA

2.4

µA/ BIT

12

0.1

µF

+15V

+15V

0.1

µF

4

REF02

6

2

0.1

µF

R3

3k

R4

1k

8

6

2

8

DAC8512FZ

1

CS

CLR

5

3

4

LD

SCLK

SDI

7

Figure 31. A High-Compliance, Digitally Controlled

Precision Current Source

A Single-Supply, Programmable Current Source

The circuit in Figure 32 shows how the DAC8512 can be used

with an OP295 single-supply, rail-to-rail output op amp to pro-

consumes less than 3.8 mA, maximum. The DAC’s output volt-

age is applied across R1 by placing the 2N2222 transistor in the

OP295’s feedback loop. For the circuit values shown, the full-

scale output current is 1 mA which is given by the following

equation:

DW

× 4.095V

R1

where DW = DAC8512’s binary digital input code.

FULL-SCALE

ADJUST

A1 = 1/2 OP295

+5V

6

2

8

DAC8512FP

1

CS

CLR

5

3

4

LD

SCLK

SDI

7

3

2

A1

1

+5V

0.1

µF

V

S

LOAD

2N2222

R1

4.02k

Ω

P1

200

Ω

Figure 32. A Single-Supply, Programmable Current

Source

The usable output voltage range of the current sink is +5 V to

+60 V. The low limit of the range is controlled by transistor

saturation, and the high limit is controlled by the collector-base

breakdown voltage of the 2N2222.

A Digitally Programmable Window Detector

A digitally programmable, upper/lower limit detector using two

DAC8512s is shown in Figure 33. The required upper and

lower limits for the test are loaded into each DAC individually

by controlling HDAC/LDAC. If a signal at the test input is not

within the programmed limits, the output will indicate a logic

zero which will turn the red LED on.

2

1

1/6

74HC05

HDAC/LDAC

CLR

+5V

1k

Ω

C1

C2

+5V

12

3

2

1

4

6

7

5

+5V

R1

604

Ω

RED LED

T1

34

+5V

R2

604

Ω

GREEN LED

T1

PASS/FAIL

C1, C2 = 1/4 CMP-404

1/6

74HC05

LD

SCLK

SDI

0.1

µF

+5V

2

6

8

DAC8512

1

5

3

4

7

0.1

µF

+5V

2

6

8

DAC8512

1

5

3

4

7

0.1

µF

Figure 33. A Digitally Programmable Window Detector