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

Phone: +49 (0)6131/91 073-0

Fax: +49 (0)6131/91 073-30

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

1

V

27

.

1

1

R

R

R

R

V

V

BG

CVREF

(10)

Example : OP2 as voltage reference

A voltage of VCVREF = 3.3V is to be set. Using Equation (10) the following ratio is calculated for

external resistors R6 and R7:

6

,

1

1

6

,

2

1

7

6

=

−

≈

−

=

BG

CVREF

V

V

R

R

The following example values are produced for the resistors:

R7 = 10kΩ

R6 = 16kΩ

V

BG

AM462

OP2

1

OP2 connected as

voltage reference

2

V

CVREF

R

6

R

7

µP

Figure 6:

Using OP2 as a voltage reference