Datasheet

Industrial V/I Converter and Protector IC
AM462
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 11/20
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Fax: [phone]
Internet:
http://www.analogmicro.de
Email: info@analogmicro
.de
Using OP2 as a voltage reference
In addition to the integrated voltage reference OP2 can also be used to supply voltage to external
components, such as A/D converters and microprocessors, for example. Lower voltages can be
generated (e.g. 3.3V) which with the increasing miniaturization of devices and need for ever lower
levels of power dissipation in digital components is today of growing importance.
The additional operational amplifier OP2 can easily be connected up as a voltage reference. Using
the circuit in Figure 6 the following applies:








+=








+=
7
6
7
6
1V27.11
R
R
R
R
VV
BGCVREF
(10)
Example : OP2 as voltage reference
A voltage of V
CVREF
= 3.3V is to be set. Using Equation (10) the following ratio is calculated for
external resistors R
6
and R
7
:
6,116,21
7
6
=−≈−=
BG
CVREF
V
V
R
R
The following example values are produced for the resistors:
R
7
= 10kΩ R
6
= 16kΩ
V
BG
AM462
OP2
1
OP2 connected as
voltage reference
2
V
CVR EF
R
6
R
7
µP
Figure 6: Using OP2 as a voltage reference