am452 AME, Inc., am452 Datasheet - Page 19

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

Using OP2 as a current source
The additional operational amplifier OP2 can easily be configured as a constant current
source. Using the circuitry shown in Figure 8 the following equation is generated:
The bridge symbol is supposed to represent the component to be supplied with current (such
as a piezoresistive sensing element or a temperature sensor, for example).
Example : A supply current of I
accrued for external resistor R
Using OP2 as a voltage source
In addition to the integrated voltage reference OP2 can also be used to supply voltage to
external components such as A/D converters or microprocessors, for example. This permits
lower supply voltages of 3.3V, for example, to be generated. The following is derived from
the circuitry in Figure 9:
Example
provided for external resistors R
Example values of R
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
AM452 – Voltage-to-current transducer IC
: A voltage of V
7
= 10k and R
V
with a differential input
I
R
R
R
S
CVREF
CVREF
S
6
7
V
V
R
V
S
I
BG
BG
V
, which determines the quantity of current:
= 3.3V is to be set. Using Equation (15) the following ratio is
CVREF
S
S
6
BG
S
V
and R
= 1mA is to be set. Using Equation (14) the below value is
BG
. 1
. 1
6
1
27
R
1
27
mA
= 16k are accrued for the resistors.
1
S
7
V
V
:
R
R
2
6
7
6 .
. 1
27
1
. 1
k
27
1
V
6 .
1
R
R
6
7
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February 2008 - Rev 1.2 - Page 19/21
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(14)
(15)