Datasheet

Industrial V/I Converter and Protector IC
AM462
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 12/20
Phone: [phone]
Fax: [phone]
Internet:
http://www.analogmicro.de
Email: info@analogmicro
.de
POINTS TO NOTE: INITIAL OPERATION OF AM462
1. When operating AM462 it is imperative that external capacitor C
1
is always connected (cf.
Figure 2). Care must be taken that the value of the capacitance does not lie beyond its given
range, even across the range of temperature (see Boundary Conditions on page 7). In 2-wire
operation ceramic capacitor C
2
must also be used (cf. Figure 8).
2. In a 2-wire setup the power consumption of the overall system (AM462 plus all external
components, including the configuration resistors) must not exceed the sum of I
OUTmin
(usually
4mA).
3. All AM462 function blocks not required by the application must be connected to a defined (and
allowed) potential.
4. A load resistance of 600Ω maximum is permitted for the current output.
5. The values of external resistors R
0
, R
1
, R
2
, R
3
, R
4
and R
5
must be selected within the permissible
range given in the boundary conditions on page 7.
APPLICATIONS
Typical 3-wire application with an input signal referenced to ground
Figure 7 shows a 3-wire application in which AM462 amplifies and converts a positive voltage
signal referenced to ground. The unused blocks (e.g. OP2) have been set to defined operating points
in the application. Alternatively, these function groups can also be used here (e.g. to supply external
components).
For output current I
OUT
the following applies according to Equations (1) and (2):
SET
GAIN
INPOUT
I
R
G
VI +⋅=
0
8
with
2
1
1
R
R
G
GAIN
+=
Example: 0…20mA Voltage-To-Current Converter
To convert a signal of V
INP
= 0...1V at the OP1 input the external components are to be dimensioned
in such a way that the output current has a range of 0...20mA (i.e. I
SET
= 0 ⇒ SET = GND). With
R
0
= 27Ω:
00
88 R
G
VI
R
G
VI
GAIN
INPSET
GAIN
INPOUT
⋅=+⋅=
The following then applies to the gain: