®

18

DAC7631

Figure 16 shows a DAC7631 in a 4mA to 20mA current

output configuration. The output current can be determined

by Equation 3:

I

VV

N

V

OUT =

























+ 





25

05

125

65 536

05

125

.– .

•

,

.

ΩΩ

(3)

At full-scale, the output current is 16mA, plus the 4mA, for

the zero current. At zero scale the output current is the offset

current of 4mA (0.5V/125

Ω).

FIGURE 16. 4-to-20mA Digitally Controlled Current Source (1/2 DAC7631).

Reset DAC Registers

Chip Select

Load

DGND

V

DD

SDI

CLK

CS

V

CC

I

OUT

125

Ω

V

PROGRAMMED

AGND

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

DAC7631

OPA2350

+V

+V

+2.5V

V

REFH Sense

V

REFH

V

REFL Sense

V

REFL

SDO

V

SS

V

OUT Sense

V

OUT

NC

RSTSEL

RST

LOAD

Serial Data In

Clock

Load DAC Registers

LDAC

Serial Data Out

+

0.1

µF1µF

+5V

20k

Ω

80k

Ω

100

Ω

2200pF

2200pF

1000pF

1000pF

100

Ω