Industrial V/I Converter and Protector IC

AM462

Analog Microelectronics GmbH

An der Fahrt 13, D – 55124 Mainz

Oktober 2007 – Rev.2.5 -Page 9/20

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

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

Internet:

http://www.analogmicro.de

Email: info@analogmicro.de

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4

3

4

0

2

0

R

R

R

R

V

I

V

I

REF

SET

INDAI

OUT

+

⋅

=

=

=

(4)

and thus for the ratio of the resistors R3/R4:

1

2

0

4

3

−

=

SET

REF

I

R

V

R

R

(5)

The output current range is set in conjunction with the selected external resistors R1 and R2 (or fine

adjustment with R0 ). Using Equations 1 and 2 the following is calculated for output current IOUT :

SET

GAIN

INP

OUT

I

R

G

V

I

+

=

0

8

with

2

1

1

R

R

G

GAIN

+

=

(6)

Selecting the supply voltage

System supply voltage VS needed to operate AM462 is dependent on the selected mode of

operation.

When using current output pin IOUT (in conjunction with the external transistor) the value of VS is

dependent on that of the relevant load resistor RL (max. 600Ω) used by the application. The

minimum system supply voltage VS is then:

min

max

CC

L

OUT

S

V

R

I

V

+

≥

(7)

Here, IOUTmax stands for the maximum output current and VCCmin for the minimum IC supply voltage

which is dependent on the selected reference voltage:

V

1

min

+

≥

REF

CC

V

V

(8)

VS [V]

RL [Ω]

6

35

VCCmin = 6V

RLmax = 600Ω

IOUTmax = 20mA

18

24

12

600

Working range

0

300

0

R

VV

I

L

SCCmin

OUTmax

−

Figure 4: Working range in conjunction with the load resistor