AM462 Datasheet, PDF (16/20 Pages) Analog Microelectronics – Industrial V/I Converter and Protector IC

Industrial V/I Converter and Protector IC
AM462
AM462
2
V_BG
OP2
3
C₁
R₃
R₄
1 13
15
16
Voltage reference
V
OP1
4
Single-ended
input voltage
5
6
R₈
V_IN
R₉
Connections setting unused function blocks in a defined operating point
Figure 9: Converting an input signal with an
3-wire connection
V_S
I ¹¹
R₀
10
9
8
T₁
D₁
14
R_{5 IOUT}
R_L
Ground
According to Equation 13 the minimum output current generated by the input offset is calculated
as:
I _{OUT min}
=
V_IN
min
⋅
R₉
R₈ + R₉
⋅¹
8R₀
= 0.5V ⋅ ^6,37 ⋅ ¹
6.37 +1 8⋅ 27Ω
≈ 2mA
To obtain an output current of I_OUT = 4...20mA, according to the above a current of I_SET = 2mA must
then be added. With reference to Equation 4 the ratio of R₃ to R₄ is calculated thus:
I _SET
!
=
2mA
=
V_REF
2R₀
⋅
R₄
R₃ + R₄
⇒ ^R3 = ^VREF −1 =
5V
−1 ≈ 45.3
R₄ 2R₀ I _SET
2 ⋅ 27Ω ⋅ 2mA
Observing the given boundary conditions, the following values are obtained for the external
components:
R₀ ≈= 27Ω
R₅ = 39Ω
R₈ ≈ 10kΩ
R_L = 0...600Ω
R₉ = 63.7kΩ
C₁ = 2.2µF
R₃ = 90.6kΩ
R₄ = 2kΩ
analog microelectronics
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December2006
16/20
Rev. 2.4