AM411

Low-Cost Voltage Transmitter IC

March 2015 - Rev. 4.0

Page 6/10

www.analogmicro.de

APPLICATION INFORMATION

1. Functional Principle

AM411 is an integrated voltage amplifier / transmitter, which can be used for the signal-conditioning of differ-

ential voltage input signals. As shown in Figure 2 AM411 basically consists of three functional blocks:

1.

An instrumentation amplifier with an internal gain of GIA = 5 as input stage for a differential voltage

input signal. Using pin ZA the instrumentation amplifier’s offset voltage can be adjusted / increased

to accept negative differential voltage input signals.

1

2.

An operational amplifier as output stage, whose gain can be adjusted using two external resistors R1

and R2.

3.

A voltage reference generating a stable 5 V output, which is able to source up to 10 mA and can be

used to power external devices like microprocessors or sensors. It is essential to stabilize the refer-

ence voltage with an external ceramic capacitor C1. This capacitor has to be connected even if the

voltage reference is not used.

Furthermore AM411 has a multitude of integrated protection functions, which satisfy industrial needs:

•

AM411 is protected against reverse polarity (pin VCC at GND and pin GND at VCC)

•

AM411’s output is protected against short circuit (pin VOUT at GND or pin VOUT at VCC) by an inte-

grated current limitation.

•

The pins VOUT, VCC and GND are protected against permutation across the entire supply voltage

range without the need for any additional external components.

•

Except for the pins VOUT, VCC and GND all pins are protected by internal ESD diodes.

1 The pin ZA has to be connected to GND or to a voltage within V

ZA’s input range at all times.