CURRENT CONVERTER IC

AM402

analog microelectronics

April 99

7/8

TYPICAL THREE–WIRE APPLICATION (0/4–20mA)

Used in a three–wire circuit, pin 2 (VCC) is connected to pin 1 (RS+) and ground pin 14 (GND) is

calculated by

1

1

2

1

2

1

−

=

⇒

+

=

IA

IA

G

R

R

R

R

G

SET

IA

IN

OUT

I

R

G

V

I

+

=

0

I

V

R

R

RR

R

R

V

RI

SET

REF

REF

SET

=⋅

+

⇒=

−

22

1

0

4

34

3

40

equation

VI

R

SOUTmax

L

≥+6V

Example 1: Output current range 4...20mA

The values of the external devices ( V

8

=

IA

G

) are as follows

Ω

Ω

Ω

Ω

Ω

Ω

Ω

µF

Example 2: Output current range 0...20mA

The values of the external devices ( V

250

K

mV , V

2

=

IA

G

) are as follows

Ω

Ω

Ω

Ω

Ω

µF

8

9

10

11

12

13

16

1

2

3

5

7

14

C

1

R

2

R

1

V

REF

R

0

V

S

V

IN

R

5

I

OUT

D

1

T

1

R

L

R

3

R

4

AM 402

5/10 V reference

IA

V

I

Ground

Figure 7