am422 AME, Inc., am422 Datasheet - Page 4

• Manufacturer Part Number: am422
• Description: Voltage/current Converter - Analog Microelectronics
• Manufacturer: AME, Inc.

VOLTAGE/CURRENT CONVERTER
FUNCTIONAL DIAGRAMS
FUNCTIONAL DESCRIPTION
The IC AM422 is an integrated voltage–to–current converter for a broad spectrum of possible single
ended input signals. With variations of a few external components the output current can be ad-
justed over a wide range. In addition to the resistors R
needs only an output transistor T
pation of the IC and the diode is protecting the transistor against reverse polarity. Typical values for
the external components are listed in the Application Notes.
In principle the AM422 can be used as a two–wire or as a three–wire voltage–to–current interface.
The schematic of the entire system for the three–wire output is demonstrated on Figure 2. The ex-
ternal reference point Ground has to be identical to the ground pin 7 (GND) and the IC supply volt-
age becomes V
analog microelectronics
V
Figure 2
V
Figure 3
IN
IN
R
R
R
R
A
A
IN
IN
CC
= V
S
. Opposed to this, the ground pin 7 in the two–wire mode (Figure 3) (GND)
Input
Amplifier
Input
Amplifier
1
and a diode D
Voltage Reference
Voltage Reference
1
. The external transistor decreases the power dissi-
0
V
V
– R
5
and the capacitor C
3Wire System
2Wire System
I
I
1
(C
2
AM422
), the circuitry
I
I
V
V
OUT
OUT
S
S
Ground
Ground
April 99
R
R
4/10
L
L