Industrial V/I Converter and Protector IC

AM462

Analog Microelectronics GmbH

An der Fahrt 13, D – 55124 Mainz

Oktober 2007 – Rev.2.5 -Page 13/20

Phone: +49 (0)6131/91 073-0

Fax: +49 (0)6131/91 073-30

Internet:

http://www.analogmicro.de

Email: info@analogmicro.de

32

.

4

V

1

mA

20

27

8

8

0

≈

⋅

Ω

⋅

=

=

INP

OUT

GAIN

V

I

R

G

⇒

32

.

3

1

32

.

4

2

1

=

−

=

R

R

Observing the boundary conditions the following values are obtained for the external components:

R1 ≈ 33.2kΩ R2 = 10kΩ

R0 = 27Ω

R5 = 39Ω

RL = 0...600Ω

C1 = 2.2µF

Typical 2-wire application with an input signal referenced to ground

In a 2-wire version (cf. Figure 8) system supply voltage VS is connected up to pin 11 (RS+) and pin

10 (VCC) to pin9 (RS-). The ground of the IC at pin14 (GND) is connected to the node between

resistor R5 and load resistor RL. IC ground (GND) is not the same as system ground (Ground). The

output signal is picked up via load resistor RL which connects current output IOUT to the system

ground.

It must be ensured that in 2-wire operation an additional current load (use of current/voltage source)

is limited to 4mA due to the domestic current supply and limitation.

For output current IOUT the following applies according to Equations (1) (2) and (4):

SET

Gain

INP

OUT

I

R

G

V

I

+

⋅

=

0

8

with

2

1

1

R

R

G

G

GAIN

I

+

=

=

and

4

3

4

0

2

R

R

R

R

V

I

REF

SET

+

⋅

=

Ground

R

5

R

L

1

Single-ended

input voltage

Connections setting unused function blocks to a defined operating point

3-wire connection

1

2

AM462

OP2

R

1

R

2

4

OP1

5

3

Voltage Reference

R

0

14

6

13

11

8

9

10

V

I

T

1

D

1

C

1

15

16

I

SET = 0

V

INP

V

S

I

OUT

V

BG

Figure 7:

Typical application for input signals referenced to ground