10
4–20mA
+In
C
T
–In
3
2
1
R
S
R
S
RCV420
(1)
13
5
11
12
15
14
V
O
(0–5V)
3
15
2
1
5
4–20mA
12
13
12kΩ
+6.25V
+6.25V
OPA237
20kΩ
C
T
RCV420
10
+10V
14
11
V
O
(5–0V)
10
+In
C
T
–In
R
CM(1)
3
2
1
R
S
R
S
RCV420
(N)
13
5
I
L
NOTE: (1) R
CM
and R
G
are used to provide a first order correction of CMR
and Gain Error, respectively. Table 1 gives typical resistor values for R
CM
and R
G
when as many as three RCV420s are stacked. Table II gives
typical CMR and Gain Error with no correction. Further improvement in
CMR and Gain Error can be achieved using a 500kΩ potentiometer for
R
CM
and a 100Ω potentiometer for R
G
.
Load
+In
R
X(1)
3
R
S
2
R
X(1)
1
R
S
12
5
11
12
15
14
V
O
(0–5V)
V
O
= 6.25V – (0.3125) (I
IN
)
R
G(1)
FIGURE 12. 4-20mA to 5-0V Conversion.
15
RCV420
13
14
V
O
(0-5V)
C
T
RCV420
1
2
3
R
CM
(kΩ)
R
G
(Ω)
0
7
23
Power
Supply
+In
∞
200
67
–40V (max)
TABLE 1. Typical Values for R
CM
and R
G
.
RCV420
1
2
3
CMR (dB)
94
68
62
GAIN ERROR %
0.025
0.075
0.200
+40V (max)
Power
Supply
+In
R
X(1)
R
S
RCV420
R
S
12
Load
I
L
NOTE: (1) R
X
= R
S
/
5
13
15
14
V
O
(0-5V)
C
T
R
X(1)
TABLE II. Typical CMR and Gain Error
Without Correction.
FIGURE 10. Series 4-20mA Receivers.
–In
I
1
(
16mA –1
)
I
L MAX
+In
C
T
3
2
1
R
S
RCV420
R
S
12
5
13
15
14
V
O
FIGURE 13. Power Supply Current Monitor Circuit.
I
2
–In
V
O
= 0.3125 (I
1
– I
2
)
Max Gain Error = 0.1% (RCV420BG)
FIGURE 11. Differential Current-to-Voltage Converter.
®
9
RCV420
BURR-BROWN [ BURR-BROWN CORPORATION ]
