XTR103 Burr-Brown Corporation, XTR103 Datasheet - Page 9

• Manufacturer Part Number: XTR103
• Description: 4-20mA Current Transmitter with RTD EXCITATION AND LINEARIZATION
• Manufacturer: Burr-Brown Corporation

There are special zener diode types specifically designed to
provide a very low impedance clamp and withstand large
energy surges. These devices normally have a diode charac-
teristic in the forward direction which also protects against
reversed loop connections. As noted earlier, reversed loop
connections would produce a large loop current, possibly
damaging R
RADIO FREQUENCY INTERFERENCE
The long wire lengths of current loops invite radio frequency
interference. RF can be rectified by the sensitive input
circuitry of the XTR103 causing errors. This generally
appears as an unstable output current that varies with the
position of loop supply or input wiring.
FIGURE 5. Reverse Voltage Protection.
FIGURE 6. Over-Voltage Surge Protection.
L
.
XTR103
XTR103
V+
I
O
10
V+
B
E
7
I
O
10
B
E
15
11
7
15
11
(1)
0.01µF
1N4001
9
NOTE: (1) Zener diode 36V: 1N4753A
General Semiconductor Transorb
Use lower voltage zener diodes with loop
power supply voltages less than 30V for
increased protection.
1N4148
D
2
D
If the RTD sensor is remotely located, the interference may
enter at the input terminals. For integrated transmitter as-
semblies with short connection to the sensor, the interfer-
ence more likely comes from the current loop connections.
Bypass capacitors on the input often reduce or eliminate this
interference. Connect these bypass capacitors to the I
terminal as shown in Figure 7. Although the DC voltage at
the I
this circuit point can be considered the transmitter’s “ground.”
1
R
L
O
terminal is not equal to 0V (at the loop supply, V
or
V
Use either D
See “Reverse Voltage Protection.”
PS
R
Maximum V
than minimum voltage rating
of zener diode.
L
™
1N6286A
1
or D
PS
2
.
must be less
V
XTR103
PS
PS
O
)
®