am452 AME, Inc., am452 Datasheet - Page 9

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

The individual modules are described separately in the specifications. The reference voltage
source and the operational amplifier OP2 can be operated as independent circuit elements or
modules. Instrumentation amplifier IA, operational amplifier OP1 and the V/I converter form
a unit within the circuit and have the task of converting the voltage input signal into the
required output current.
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
SET stage
The SET stage permits the adjustment of the offset output current I
with the V/I converter it effects the output current I
I
external voltage divider as shown in Figure 2, for example.
Voltage-to-current converter (V/I converter)
The voltage-to-current converter (V/I converter) compares the voltage drop across the
external sensing resistor R
regulate transistor T
activates external transistor T
the power dissipation of the output stage.
External resistor R
I
where V
Reference voltage source
The reference voltage source (bandgap voltage source) enables voltage to be supplied to
external components (such as sensors, microprocessors, etc.). The reference voltage value
V
switched to ground, V
are used (inserted between pin 15 (VREF) and pin 12 (VSET) and between pin 12 (VSET)
and GND).
External capacitor C
reference is not in use. It may not undershoot the given minimum value.
Additional operational amplifier OP2
The additional operational amplifier OP2 can be used as a current or voltage source to
supply external components. OP2's positive input must be connected internally to bandgap
voltage V
range using external resistors.
SET
OUT
REF
AM452 – Voltage-to-current transducer IC
can be set at pin 8 (IOUT) e.g. with the help of the internal voltage reference and an
amplified by T
can be set using pin 12 (VSET). If pin 12 is not connected, V
OP
I
BG
OUT
is the input voltage of the V/I converter and V
so that the OP2 output voltage at pin 1 or CVREF can be set across a wide
V
OP
0
1
1
R
1
permits the output current to be finely adjusted. For the output current
with a differential input
. It generates a suitable signal at the IC output pin 8 (IOUT) which
the following ratio applies:
stabilizes the reference voltage. It must be connected even if the voltage
0
G
REF
VI
= 10V. Values between these can be set if two external resistors
0
with a value of V
I
SET
1
. This in turn supplies an output current of I
=
V
8
R
OP
0
I
SET
SET
with
G
SET
I
OUT
SET
+ V
. Via pin 16 (SET) an offset current
SET
OP
V
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February 2008 - Rev 1.2 - Page 9/21
SET
G
the voltage at pin 16 (SET).
VI
R
G
and uses the result to
0
SET
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OUTmin
REF
=
V
2R
SET
= 5V; if pin 12 is
OUT
> 0mA. Together
0
and accepts
(3)/(4)