am452 AME, Inc., am452 Datasheet - Page 11

• Manufacturer Part Number: am452
• Description: Voltage-to-current Transducer Ic With A Differential Input - Analog Microelectronics
• Manufacturer: AME, Inc.

Differences in the AM452 circuitry with 2- and 3-wire applications
Figure 4: Differences in 2-and 3-wire circuitry in conjunction with AM452
AM452 is constructed in such a way that by changing the external circuitry it is suitable for
both 2-wire and 3-wire operation.
In 3-wire operation (see Figure 4, right) the IC's connection to ground (pin 14 or GND) is
connected to the system ground (Ground) which is applied externally. System supply voltage
V
directly into AM452 (power consumption).
In 2-wire operation (see Figure 4, left) system supply voltage V
and pin 10 (VCC) to pin 9 (RS-). The overall current including the supply current then flows
via R
The IC's connection to ground pin 14 (GND) is contacted to the node between resistor R
load resistor R
the system (Ground). The output signal is tapped via load resistor R
output I
S
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
is connected to pin 10 (VCC) and pin VCC to pin 11 (RS+). Supply current I
AM452 – Voltage-to-current transducer IC
0
V/I Converter
, enabling the relevant voltage drop to be used to regulate transistor T1.
SET Stage
OUT
to the ground of the system.
L
14
(current output I
GND
11
10
9
8
R
5
with a differential input
T
R
D
1
connection
Ground
1
0
2-wire
C
I
R
OUT
L
2
V
S
OUT
). IC ground GND is thus not the same as the ground of
V/I Converter
SET Stage
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February 2008 - Rev 1.2 - Page 11/21
S
is connected to pin 11 (RS+)
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14
http://www.analogmicro.de
3-wire connection
GND
L
11
10
9
8
which links system
R
5
T
1
D
R
Ground
CC
1
0
I
R
V
OUT
then flows
L
S
5
and