UNIVERSAL AMPLIFIER IC

AM400

analog microelectronics

October 2005

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.: 4.2

Internet: http://www.analogmicro.de

Email:

info@analogmicro.de

Output voltage VOUTAD at pin OUTAD is calculated as:

GAIN

INOP

OUTAD

G

V

V

⋅

=

with













+

=

1

2

1

R

R

G

GAIN

(2)

where VINOP is the voltage at the OP1 input pin INOP. Alternatively, the OP1 input pin INOP can

also be used as an input for signals referenced to ground (see Application 2, Figure 6).

3. The IC’s voltage output VOUT is realized via the current-limited operational amplifier stage

(OP2) which has integrated protection against reverse polarity. The internal gain of OP2 is set to

a fixed value of GOP = 2.2. The output is engineered as a driver stage. The following applies to

OP2’s output voltage VOUT at the IC pin VOUT:

INDAV

OP

OUT

V

G

V

⋅

=

(3)

where VINDAV is the voltage at pin INDAV (OP2 input).

V

BG

17

5

IA

7

6

10

18

15

14

13

12

11

20

V

I

16

19

Voltage reference

1

9

OP1

8

Ground

V

S

I

OUT

R

1

R

2

C

1

R

0

T

1

D

1

R

5

3

4

2

AM400-0

V

REF

OP2

OP3

V

OUT

V

ZA

V

INOP

V

SET

V

OUTAD

V

IN+

V

IN-

V

CVREF

V

CVSET

V

OUTIA

R

3

R

4

V

INDAI VINDAV

Figure 2: Block diagram of AM400 showing external components (3-wire circuit

with a current output)