INDUSTRIAL VOLTAGE AMPLIFIER IC

AM401

analog microelectronics

Mars 2006

Analog Microelectronics GmbH

Phone:

+49 (0)6131/91 073 – 0

13/21

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

Example 3:

Input voltage (differential) of 0...100mV and output voltage range of 0...5V

If VIN = 0...100mV, R1/R2 = 9, IS = 1.5mA VBG = 1.27V and IREF = 1mA the values of the external

components are as follows:

R1 ≈ 90kΩ

R2 ≈ 10kΩ

GIA = 5

C1 = 2.2µF

C2 = 10nF

RSET ≈ 846.7Ω

RREF ≈ 5kΩ

Application 3 – Differential input signal, voltage output signal of 0.5...4.5V

With applications which require an output voltage of 0.5...4.5V the pin used to configure the

instrumentation amplifier offset (ZA) is connected to voltage VOFFSET (Figure 5). Gain G is set using

the two external resistors R1 and R2:

()

2

1

1

R

R

G

G

G

G

IA

OP

IA

+

=

=

(2)

The transfer function of output voltage VOUT is:

VOUT = G VIN + VOFFSET

(1)

The offset voltage (Equation 3) is calculated as:

()

VV

R

R

VV

R

R

VV

VV

OFFSET

BG

REF

BG

REF

BG

BG

OFFSET

=−

−

⇒

=

−

−

4

3

3

4

Using these equations the values of resistors

R1 and R2 can be set as follows:

R

R

VV

GV

OUT

OFFSET

IA

IN

1

2

1

=

−

−