INDUSTRIAL VOLTAGE AMPLIFIER IC

AM401

analog microelectronics

Mars 2006

Analog Microelectronics GmbH

Phone:

+49 (0)6131/91 073 – 0

16/21

An der Fahrt 13, D – 55124 Mainz

Fax:

+49 (0)6131/91 073 – 30

Rev. 2.3

Internet: http://www.analogmicro.de

Email:

info@analogmicro.de

V

BG

AM401

1

V

IN

OP2 connected as

voltage reference

V

CVREF

R

4

R

3

OP2

+

_

1

2

3

Figure 7:

AM401’s OP2 as a voltage reference

Application 5 – Connecting up OP2 as a voltage reference

In addition to the integrated voltage

reference of the AM401, the OP2 can also

be used as a voltage supply for external

components, such as A/D converters or

microprocessors, for example. Lower

voltages can be generated (e.g. 3.3V)

which with the increasing miniaturisation

of devices and need for ever lower levels

of power dissipation in digital components

is today of growing importance.

If in addition to the 5/10V reference a

further voltage source is required to power

external

components

the

second

operational amplifier OP2 can be used to

this end.

This operational amplifier can be easily configured as a voltage reference. Using the circuit in

Figure 7 the following equation is given:













+

=













+

=

3

4

3

4

1

V

27

.

1

1

R

R

R

R

V

V

BG

CVREF

(9)

A voltage of VCVREF = 3.3V is to be set. With reference to Equation 9 the following ratio is obtained

for the external resistors R3 and R4:

6

.

1

1

6

.

2

1

3

4

=

−

≈

−

=

BG

CVREF

V

V

R

R

With reference to the boundary conditions for external components given on page 6 the following

values are obtained for the resistors:

R3 = 10kΩ

R4 = 16kΩ