INDUSTRIAL VOLTAGE AMPLIFIER IC

AM401

analog microelectronics

Mars 2006

Analog Microelectronics GmbH

Phone:

+49 (0)6131/91 073 – 0

8/21

An der Fahrt 13, D – 55124 Mainz

Fax:

+49 (0)6131/91 073 – 30

Rev. 2.3

Internet: http://www.analogmicro.de

Email:

info@analogmicro.de

AM401’s transfer function

In compliance with Figure 2 the transfer function for AM401 when used as an amplifier for

differential signals with a voltage output is:

()

ZA

IN

IA

OP

OUT

V

V

G

G

V

+

=

(1)

where:

()

2

1

1

R

R

G

G

G

G

IA

OP

IA

+

=

=

(2)

Setting the instrumentation amplifier

The transfer function of the instrumentation amplifier is determined by:

ZA

IN

IA

OUTIA

V

V

G

V

+

=

with an offset voltage of VZA which can be set at pin ZA. With the circuitry shown in Figure 2 and

using the additional operational amplifier the offset voltage is determined thus:

1

2

3

4

14

13

5

6

11

15

12

V

BG

C

1

C

2

R

2

R

3

R

A

R

IN

R

B

R

4

V

OFFSET

R

1

CVREF

CVSET

IN+

IN_

GND

ZA

OUTIA

INOP

7

8

GAIN

VOUT

VCC

VREF

VSET

Ground

V

OUT

Voltage Reference

V

CC

V

IN

AM401

_

+

OP2

+

_

IA

+

_OP1

Figure 2:

The general functions of AM401