AM411

Low-Cost Voltage Transmitter IC

March 2015 - Rev. 4.0

Page 9/10

www.analogmicro.de

With IREF = 0.2 mA and the boundary conditions for R1 and R2 given in Table 2 the following dimensioning of

the external components can be obtained:

R1 = 100 kΩ

R2 = 25 kΩ

R3 = 24 kΩ

R4 = 1 kΩ

C1 = 2.2 µF

Example 3: Desired output voltage range 0 .. 10 V, input voltage range -100 .. 100 mV

In this example a differential input voltage range of VIN = -100 mV .. 100 mV will be amplified and offset ad-

justed to an output voltage range of VOUT = 0 .. 10 V using the circuit shown in Figure 3.

With VIN,min = -100 mV, VIN,max = 100 mV, VOUT,min = 0 V and VOUT,max = 10 V and equation (3) the following

relation can be obtained for R1 and R2:

2

1

9 R

R

⋅

=

and with equation (4) the voltage at pin ZA can be calculated to VZA = 500 mV. Using equation (5) this leads

to:

4

3

9 R

R

⋅

=

With IREF = 0.16 mA (< 10 mA) and the boundary conditions for R1 and R2 given in Table 2 the following di-

mensioning of the external components can be obtained:

R1 = 27 kΩ

R2 = 3 kΩ

R3 = 27 kΩ

R4 = 3 kΩ

C1 = 2.2 µF

5. Operation Instructions

The following points have to be considered while working with AM411:

1.

A high quality ceramic capacitor has to be connected at pin VREF, even if the reference voltage source

is not used. If AM411 is exposed to large temperature changes, special care must be taken that this ca-

pacitor’s value stays inside the specified range (see Table 2).

2.

The external resistors R1 and R2, which are used for gain adjustment, have to fullfill the boundary condi-

tion R1 + R2 = 20 .. 200 kΩ.

3.

Under normal operating conditions components powered using the voltage reference (pin VREF) may

not drain more than 10 mA.

4.

Generally only positive voltage offsets can be generated if a voltage is applied at pin ZA. If Pin ZA is not

used it has to be connected to GND.

5.

In general for positive differential input voltage signals, VIN ≥ 0, a mimum output voltage VOUT,min = 0 V

can only be achieved if the minimum input voltage VIN,min = 0 V and VZA = 0 V.

6.

For negative differential or bidirectional diffferential input voltage signals with VIN,min < 0, a voltage

VZA ≥ 5 · VIN,min is necessary for operation of AM411.

7.

AM411’s output short circuit protection is realized by a continous current limitation of the output. The

minimal threshold for the current limitation is 5 mA, leading to a thermal power deposition of 180 mW (at

VCC = 36 V), when no further components are powered by the IC.

8.

AM411 is protected against reverse polarity and permutation of VOUT, VCC and GND. Please take care

that components powered by VREF have to be protected seperately in case of reverse polarity or permu-

tation of VCC versus GND.

In general ESD precautions are necessary during assembly and handling of the device. It is essential to

ground machines and personnel properly.