Datasheet

VOLTAGE/CURRENT CONVERTER AM422
analog microelectronics
April 99
6/10
the input voltage V
IN
has to change to
∆∆VV
R
RR
PIN IN4
2
12
=
+





 (8)
With the value of the relationship of the resistors R
1
and R
2
R
R
VV
V
IN PIN
PIN
1
2
4
4
=
−∆∆
∆
(9)
the additional offset current can be calculated as
II I I
V
R
R
RR
SET OUTmin INmin OUTmin
INmin
=−=−
+






2
0
2
12
(10)
The value of the set resistor can then be found using equation 4
In respect to the load resistor R
L
, the value of the supply voltage V
S
has to be considered with care.
The following relation is generally valid (see equation 1):
VI RV
S OUTmax L CCmin
≥+. (11)
The resulting operating range is indicated in Figure 4. Sample calculations and typical values for the
external components are listed in the Application Notes (beginning page 8).
V
S
[V]
R
L
[
Ω
]
6
35
V
CCmin
=
6V
R
Lmax
= 500
Ω
I
OUTmax
= 20mA
16
R
VV
I
L
SCCmin
OUTmax
≤
−
2412
500
Operating Area
0
300
0
Figure 4