AM411 datasheet(4/6 Pages) MINI

4 / 6 page

VOLTAGE TRANSMITTER IC

AM411

analog microelectronics

April 99

4/6

FUNCTIONAL DESCRIPTION

The IC AM411 is an integrated voltage transmitter for bridge input signals. With variations of a few

external components the output voltage can be adjusted over a wide range. In addition to the resis-

tors R1 and R2 the circuitry needs only one external capacitor C1 for a basic application. Using the

input of the voltage output stage the AM411 can be used for single ended input signals as well.

Typical values for the external components are listed in the Application Notes.

Basically the AM411 consists of 3 functional blocks as they are shown in Figure 1:

1. A high accuracy instrumentation amplifier with an internal gain GIA and the possibility to adjust

the bias voltage (pin ZA) for differential input signals.

2. An operational amplifier output stage used for voltage transmission and as the voltage output.

The output stage has an output current limitation protecting the IC.

3. A voltage reference can be used as an excitation for constant voltage sensors or as supply for

other external devices.

The transfer function for the output voltage of the instrumentation amplifier is:

OUTIA

with the offset voltage VZA which can be adjusted on pin ZA. For die entire output voltage VOUT of

the IC is valid

INOP

OUT

⋅

with the adjustable gain GOP

The minimum supply voltage, which has to be adjusted, can be calculated over

≥ VOUTmax + 5V

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