UNIVERSAL AMPLIFIER IC

AM400

analog microelectronics

October 2005

Analog Microelectronics GmbH

Phone:

+49 (0)6131/91 073 – 0

15/21

An der Fahrt 13, D – 55124 Mainz

Fax:

+49 (0)6131/91 073 – 30

Rev.: 4.2

Internet: http://www.analogmicro.de

Email:

info@analogmicro.de

Figure 6 shows a 3-wire application in which AM400 amplifies and converts a voltage signal

referenced to ground. The blocks unused by the application (IA and OP3) are set to a defined

operating point. Alternatively, these function blocks can also be used for the supply of external

components, for example.

IN

V

OUT

V

G

V

=

with

2

.

2

1

2











+

=

=

R

R

G

G

G

OP

GAIN

V

SET

I

IN

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

+

⋅

=

a way that the output current has a range of 4...20mA and the output voltage one of 0...10V.

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

3) Typical 2-wire application with a differential input signal

ground.

Figure 7 shows a typical 2-wire application in which the differential output signal of a current-

powered measuring bridge is amplified by the IA and OP1 and converted by the V/I converter.

According to Equation 4 the following applies to the output current of the 2-wire application:

SET

I

IN

OUT

I

R

G

V

I

+

=

0

8

with

)

to

connected

(

0

GND

ZA

V